WO2009034169A1 - Processes for the preparation of the alpha crystal polymorph of metal phthalocyanines - Google Patents

Abstract

Methods for producing a stabilised alpha copper phthalocyanine are described. More specifically such methods comprise forming a mixture of (a) a compound of the general formula (II), in which, R1 and R2 are independently -CN or -C(O)OH, or R1 and R2 together are -C(O)OC(O)-, -C(O)NHC(O)- or -C(NH)NH(NH)C-, and form a fused five-membered ring structure and R3, R4, R5 or R6 which may be the same or different are -H, a halide, an C1- C5 alkyl, or a substituent group containing a heteroatom; and (b) a tethered compound of the general formula (III), wherein, any adjacent two of R7, R8 and R9 and any adjacent two of R12, R13 and R14 are independently -CN or -C(O)OH, and any of R7, R8, R9, R12, R13 and R14 which are not -CN or - C(O)OH, are -H, a halide, a C1 - C5 alkyl or a substituent group containing a heteroatom, or any adjacent two of R7, R8 and R9 and any adjacent two of R12, R13 and R14 are either -C(O)OC(O)-, -C(O)NHC(O)- or -C(NH)NH(NH)C-, and form a fused five-membered ring structure, the ring structures being the same or different and any R substituents that are not part of the ring structure are -H, a halide, a C1 - C5 alkyl or a substituent group containing a heteroatom; and X is a chain having a backbone of up to two substituted or unsubstituted atoms and the chain comprises an alkane, an alkene or an alkenyl group or a group containing at least one heteroatom; and reacting the mixture with a source of copper in the +I or +II oxidation state to form copper phthalocyanine in predominantly the alpha crystalline form.

Description

Title: Processes for the preparation of the alpha crystal polymorph of metal phthalocyanines Field of the Invention

The invention relates to novel metal phthalocyanines. In particular, the invention relates phthalocyanine complexes, their crystalline polymorphs and to their uses as colourants/pigments. For example, the compounds may be used as a colourant, as a pigment in the inks, paint and plastics industries. Phthalocyanine complexes find use as pigments in specialist applications such as paints, ink jet applications, electrophotography, colour photocopying, laser printing, colour filters for liquid crystal displays. Zinc phthalocyanines are used as photobleaches. In particular, the invention relates to a new method of preparation of copper phthalocyanine compounds in the alpha crystalline form.

Background to the Invention

Phthalocyanines are macrocyclic compounds, which coordinate hydrogen or metal cations by way of four central isoindole nitrogen atoms of the macrocyclic ligand. Metal phthalocyanines and in particular copper phthalocyanines are used commercially as pigments, and produce a range of colours of which copper phthalocyanines employed for their blue colours are frequently utilised. The colour of the complex depends on ligand substituents, functional groups and crystalline modifications. A range of different crystalline forms of metal phthalocyanines and in particular copper phthalocyanine can be obtained. These include alpha, beta and epsilon crystalline forms. The various forms have varying usefulness as pigments, the alpha and beta forms being the most commonly used. The different crystalline forms have different properties that make particular crystalline forms more suitable for particular pigment formulation applications. Such properties include varying degrees of stability, particle size and colour properties such as tint and solubility. The epsilon form is the least stable of the polymorphs.

In industry, beta crystalline polymorphs of copper phthalocyanines are prepared by reaction of starting materials such as phthalic anhydride¹, phthalonitrile², phthalimide⁹ or 2-cyanobenzoic acid with copper salts. The preparation of many metal phthalocyanines generally involves similar preparations using the appropriate metal salt of interest.

The reaction profiles using phthalic anhydride, phthalonitrile and phthalimide are shown in Figure 1. Both methods require a copper source, such as a Cu salt, e.g., copper (II) acetate, copper (II) chloride, copper (II) trifluroracetate, copper (II) bromide, copper (II) nitrate, copper (I) chloride, copper (I) bromide or copper (II) sulfate pentahydrate.

The phthalic anhydride process requires nitrogen sources such as urea or ammonium chloride. Catalysts/promoters such as ammonium molybdate are also necessary.

The known processes using phthalonitrile, phthalimide and 2-cyanobenzoic acid are generallycarried out in high boiling inert solvents, in particular methanol, ethanol, isopropanol, butanol, pentanol, octanol and N,N-dimethylaminoethanol can be used, in conjunction with a base. Dimethylformamide is more preferably used, since when employed in conjunction with hexamethyldisilazane (HMDS), the reaction conditions are milder and a high yield of copper phthalocyanine is achieved. The phthalonitrile process is easier to control and is chemically superior, but is more expensive. In principle, the phthalonitrile process requires only copper salts and a base. Alcohol solvents such as methanol, ethanol, isopropanol, butanol, pentanol, octanol and N, N- dimethylaminoethanol have been used in combination with bases such as ammonia, sodium alkoxides, lithium alkoxides or strong organic bases such as diazabicycloundecene (DBU) and l,5-diazabicyclo[4.3.0]non-5-ene (DBN). The hexaalkyldisilazanes e.g., hexamethyldisilazane [HMDS] were found to simultaneously act as bases and nitrogen sources in the phthalonitrile process, when used with DMF as solvent to give phthalocyanines in good yield.

The crystal form of copper phthalocyanine obtained from any of these processes is the beta crystal polymorph. This crystal form, often named Pigment Blue 15:3, provides crystals which are relatively coarse and are suitable for high-volume lower-value applications such as blue and green pigments for cars and blue and/or cyan dyes for textiles and paper.

The beta form is the most stable crystal form and readily resists recrystallization to other forms. However, when effected, recrystallization of the beta crystal polymorph of copper phthalocyanine from concentrated sulphuric acid gives the more useful and thus valuable alpha crystal polymorph of copper phthalocyanine. The alpha crystal form of copper phthalocyanine is also known as Pigment Blue 15:0. Crystals of the alpha crystal polymorph are relatively fine crystals (that is compared to the beta crystal form) which are suitable for use in higher-value applications such as specialist paints, printing applications such as ink jet applications and laser printing, electrophotography, colour photocopying and as colour filters for example for liquid crystal displays. The alpha crystal form is also preferred for paint manufacture due to its superior colour properties. The alpha crystalline form exists as finer particles than those of the beta form and so are more suitable for use as a pigment.

Concentrated sulphuric acid is the only known solvent suitable for recrystallising copper phthalocyanine. This property makes the compounds useful in pigment applications, since very low solubility is a necessary requirement for pigment compounds.

A process difficulty arises in producing the alpha form. The alpha form is less stable than the beta form and will gradually convert to the more stable, green shade, beta crystal if processing conditions are not carefully controlled. When suspensions of commercially available alpha copper phthalocyanine in xylene are heated to 60⁰C or greater, transformation to the beta crystal form occurs within one hour³. In paint formulations, the alpha form can gradually revert to the coarse beta form, resulting in colour change and loss of colour strength over time. The chemical difference between the alpha and the beta crystal forms lies in the packing of the copper phthalocyanine molecules in the three dimensional crystals. The crystal structure of the beta form is well established⁴. It consists of copper phthalocyanine molecules stacked in a 'herringbone¹ pattern. The crystal structure of the alpha form is well less established. Recent information⁵ suggests that in the alpha form, the copper phthalocyanine molecules are stacked in a parallel rather than in a herringbone pattern (see the comparative packing arrangements illustrated schematically in Figure 2). Other crystal forms of copper phthalocyanine are also known, but these are not commercially significant.

Thus it is desirable to provide an alternative process for producing metal phthalocyanine in predominantly the alpha crystal polymorph which is simple, effective and relatively inexpensive. Such a process would advantageously provide for production of copper phthalocyanine in predominantly the alpha crystal polymorph.

It is also desirable to provide a stabilised form of the alpha polymorph, which does not as readily revert to the beta form postproduction and so provides a longer lasting crystalline form that can then be employed as a pigment that is more durable.

Furthermore, the provision of a method of producing alpha copper phthalocyanine without the need for concentrated sulfuric acid recrystallisation steps, which will allow for cleaner more economical industrial processes would be welcomed.

Provision of a series of metal phthalocyanine starting materials, which can be used to encourage and maintain alpha crystal polymorph production in metal phthalocyanine production processes would be advantageous to industry. Such starting materials can be used as an additive material to be introduced into the typical metal phthalocyanine production processes to produce the metal phthalocyanine in predominantly the alpha crystalline form. Such additive starting material compounds perform particularly well in the production of alpha copper phthalocyanine in classic copper phthalocyanine production reactions.

Finally, it is desirable to to provide compound which is particularly effective at promoting alpha polymorph production when used as an additive in the copper phthalocyanine production process using phthalonitriles as starting material.

Summary of the Invention Copper Phthalocyanine Alpha Crystalline Polymorphs

According to the present invention there is provided a method of producing alpha copper phthalocyanine comprising forming a mixture of

(a) a compound of the general formula II,

in which,

R¹ and R² are independently -CN or -C(O)OH, or R¹ and R² together are -C(O)OC(O)-, -C(O)NHC(O)- or -C(NH)NH(NH)C-, and form a fused five-membered ring structure and

R³, R⁴, R⁵ or R⁶ which may be the same or different are -H, a halide, an Ci - C₅ alkyl, or a substituent group containing a heteroatom; and

(b) a tethered compound of the general formula III,

wherein, any adjacent two of R⁷, R⁸ and R⁹ and any adjacent two of R¹², R¹³ and R¹⁴ are independently -CN or -C(O)OH, and any of R⁷, R⁸, R⁹, R¹², R¹³ and R¹⁴ which are not

-CN or -C(O)OH, are -H, a halide, a Ci - C₅ alkyl or a substituent group containing a heteroatom, or any adjacent two of R⁷, R⁸ and R⁹ and any adjacent two of R¹², R¹³ and R¹⁴ are either -C(O)OC(O)-, -C(O)NHC(O)- or -C(NH)NH(NH)C-, and form a fused five-membered ring structure, the ring structures being the same or different and any R substituents that are not part of ring structure are -H, a halide, a Ci - C₅ alkyl or a substituent group containing a heteroatom; and X is a chain having a backbone of up to two substituted or unsubstituted atoms and the chain comprises an alkane, an alkene, an alkenyl group or a group containing at least one heteroatom; and reacting the mixture with a source of copper in the +1 or +11 oxidation state to form copper phthalocyanine in predominantly the alpha crystalline form.

Thus, in a preferred embodiment, in compound of the general formula II,

R¹ and R² are both -CN or both -C(O)OH, and wherein in a tethered compound of the general formula III,

any adjacent two of R⁷, R⁸ and R⁹ and any adjacent two of R¹², R¹³ and R¹⁴ are both -CN or both -C(O)OH. Thus the invention provides a new method for producing copper phthalocyanine in the alpha form by introducing a small amount of a tethered compound (of formula (III)) into the starting material mixture for the copper phthalocyanine production, before carrying out the synthetic reaction. Preferably, the tethered compounds may be based on the typical starting materials used in the synthesis. In other words, the general structure of the tethered compounds used may be complimentary to the structure of the starting material used, since the tethered compounds become incorporated in the phthalocyanine skeleton during the reaction process and therefore ideally are of suitable structure to do so.

The method for producing copper phthalocyanines predominantly in the alpha form involves reacting the compound having general formula II and the tethered compound having general formula III in the presence of an additive system to form copper phthalocyanine in predominantly the alpha crystalline form.

The method works excellently for classic copper phthalocyanine production processes e.g. those employing unsubstituted phthalic anhydride, phthalonitrile or phthalimide starting materials. However, the method of the present invention will also work for more unusual phthalocyanine starting materials such as 2-cyanobenzoic acid and derivates of same. However, the preferred starting materials include phthalic anhydride, phthalonitrile or phthalimide, however the person skilled in the art will appreciate that the scope of the invention will not be restricted to methods of copper phthalocyanine production commencing with these particular starting materials. Other similar starting materials will also function effectively, and choice of starting material will depend on the desired functional groups or substituents required to form the phthalocyanine ligand. For example, in a particular embodiment, the invention provides for the use of compounds according to general formula II in the phthalocyanine production process, which can be selected from the group consisting of phthalic anhydrides, phthalonitriles, phthalimides, 1,3-diiminoisoindolines, 2-cyanobenzoic acids and phthalic acids, all of which may be substituted or unsubstituted, as required.

2-cyanobenzoic acid

In particular, it is preferred that substituted phthalocyanines, substituted phthalic anhydrides and substituted phthalimides are used in the methods of this invention.

The linker or chain "X" may contain a heteroatom selected from the group consisting of O, N, S, P. More particularly, such heteroatom containing linkers or chains may include but are not limited to, for example, -NH-, -NH-NH-, -NH-O-, -N=N-, -S-S-, -S-, -0-, -Se-, -CH=N-, -NHC(O)- , -NHCH₂-, -C(O)CH₂-, -C(O)C(O)-, -CO₂ ^", -HCN-, -CNH-,-CH₂CH(OH)-, -CH₂(O)-, -S(O)-, -CC-, - CS-, -PO₂ -, -SO₂-, -Se- or -SO₂NH-. Suitably, the linker may be O-, -S- or -C(O)-. The skilled person will appreciate that other chemical groups and groups containing heteroatoms may suitably be employed as linker or chain X, in the tethered compounds of the invention. In another aspect non-heteroatom containing linkers comprising -CH=CH-, -CC- and -CH₂-CH₂-, may be used. Heteroatom containing substituents on the aromatic ring(s) of compound of general formula II or III contain heteroatoms which may be selected from the group consisting of O, N, S and P. More particularly, heteroatom containing groups comprising -SO₃H, -C(O)OH, -OH, -NH₂, - N(CHs)₂, -CN, -NO₂, -SO₂CI, -CHO, -OCH₃, -OCH₂CH₃ or -PO(OH)₂ are the preferred heteroatom containing substituents. The skilled person will appreciate that other heteroatom containing groups may suitably be used. In a preferred embodiment, the heteroatom containing group may comprise -CN, -NO₂, -SO₂, -COOH or -CHO. Used herein, an alkyl group is understood to mean any of a series of univalent groups of the general formula C_nH_2n+I derived from aliphatic hydrocarbons, wherein n = 1 to 5. The methyl group (-CH₃) represents a Ci alkyl group, ethyl (- C₂H₅) represents a C₂ alkyl group, propyl (-C₃H₇) represents a C₃ alkyl group, butyl (-C₄H₉) represents a C₄ alkyl group and pentyl (-C₅H₇) represents a C₅ alkyl group. Alkyl chains or groups can be straight or branched.

Suitable halide substituents on the aromatic ring(s) of compound of general formula II or III include, but are not limited to -Cl, -Br, -F, -I. In particularly, -Cl substituents are the preferred halide substituent. In one aspect, the compound of general formula II and the tethered compound of general formula III are reacted in the presence of an additive system for catalysing or promoting the reaction of compound of general formula II and the tethered compound of general formula III to form copper phthalocyanine, in predominantly the alpha crystalline form. An additive system is intended to mean a compound or series of compounds which are added to the reactants to facilitate production of the copper phthalocyanine, e.g, bases, sources of nitrogen, solvents, catalysts, promoters etc. The skilled person will appreciate the additives required depending on the starting materials used.

Suitably, the tethered compound having general formula III may be structurally symmetrical or unsymmetrical. However, symmetrical tethered compounds are preferred, since they are more easily prepared and are cheaper than the unsymmetrical versions.

In one embodiment R³, R⁴, R⁵ and R⁶ of the general formula II are -H, according to the structure IV:

In a different embodiment, the invention provides a method wherein R³, R⁴, R⁵ and R⁶ of the compound having general formula II, are -H according to the structure V:

In another embodiment, for the compound having general formula II, R¹ and R² together may be -C(O)OC(O)-, -C(O)NHC(O)- or -C(NH)NH(NH)C-, and form a fused five-membered ring structure according to the structures VI, VII and VIII:

In another embodiment, the compound having general formula III, any adjacent two of R⁷, R⁸, R⁹ and R⁸, R¹², R¹³ and R¹⁴ may be -CN, according to the structures IX and X:

Other compounds with may be suitable used are those exemplified by general formula III, wherein R⁷ and R¹² are independently -H or -C(O)OH, R⁸ and R¹³ are independently -C(O)OH, R⁹ and R¹⁴ are both -H or both -C(O)OH, and those wherein R⁷ and R¹² are both -H or both - C(O)OH, R⁸ and R¹³ are both -C(O)OH, R⁹ and R¹⁴ are both -H or both -C(O)OH.

Further suitable compounds arise wherein in general formula III, any adjacent two of R⁷, R⁸ and R⁹ and any adjacent two of R¹², R¹³ and R¹⁴ are either -C(O)OC(O)-, -C(O)NHC(O)- or - C(NH)NH(NH)C- and form a fused five-membered ring structure, the ring structures being the same, and R¹⁰, R¹¹, R¹⁵ and R¹⁶ are -H, according to the following structures:

(XVIII)

In one aspect, the invention provides a method wherein the compound having general formula III, is selected from the group consisting of compounds according to structures XIX, XX, and XXIV, the structures of which are shown below:

(XIX) (XX)

In the processes of the invention, the copper source may be selected from any group of compounds that can provide a source of copper cations, such compounds being preferably a copper salt, having copper in the +11 or +1 oxidation state. Salts such as copper (II) acetate, copper (II) chloride, copper (I) chloride, copper (II) trifluroroacetate, copper (I) chloride, copper (II) nitrate, copper iodide, copper fluoride, copper (II) sulfate pentahydrate, copper (II) bromide and copper (I) bromide may be suitably be used. It is preferable to use copper halides such as copper bromide, for example. Hydrated copper salts may also be suitably be used. It is particularly preferred to use hydrated copper salts as the copper source. For example, copper sulfate pentahydrate (CuSO₄.5H₂O) may be suitably used as a preferred source of copper in the processes of the invention.

As discussed above, the copper phthalocyanine reaction generally requires a suitable additive promotion system, to drive the reaction and lead to efficient product production. An additive promotion system (additive system) is understood to mean at least one chemical that may be added to the reactants at the start of the phthalocyanine synthetic process and which promotes the formation of the phthalocyanine product. Such an additive system may be catalytic or otherwise. Chemicals that may be added include bases, solvents, nitrogen sources, catalysts, promoters, stabilisers etc. In a particular embodiment, wherein the compound as defined in general formula II is a phthalic anhydride or a phthalic anhydride derivate, the reaction may be carried out in the presence of an additive system which is typically catalytic and results from the combination of: a nitrogen source, a molybdate catalyst and an ammonium halide. It will be appreciated that the exact nature of the additive system will depend on which starting material and process is employed e.g., the process starting with phthalic anhydride requires use of an additive promotion system having a nitrogen source comprised of urea. Addition of ammonium molybdate or ammonium chloride (in catalytic quantities) effect the reaction. In a particular embodiment, the nitrogen source may be urea, the molybdate catalyst may be ammonium molybdate and the ammonium halide may be ammonium chloride or ammonium bromide or the like. However, it is particularly preferably, that ammonium chloride be used.

The process involving phthalonitriles, phthalimides, 2-cyanobenzoic acids requires use of an additive promotion system comprising a solvent, a nitrogen source and a base. The nitrogen source and base may be the same or may be different. For example hexamethyldisilazide can be used, in which case it functions simultaneously as a base and a nitrogen source. Preferably, the reaction is carried out in a high boiling inert solvent such as dimethylformamide. Hexaalkyldisilazides such as l,l,3,3,-tetramethyl-l,3-diphenyldisilazane, 1,3-dimethyl-l, 1,3,3- tetraphenyldisilazane may be used. It is preferable to use hexamethyldisilane. However, if a hexamethyldisilazide is used, alcoholic solvents cannot be employed, since they lead to the break down of the hexamethyldisilazide. Thus in processes where hexamethyldisilazide is used, it is preferred to use dimethylformamide as a solvent. In some embodiments, the additive system comprises the combination of an alcoholic solvent and a base selected from the group consisting of ammonia, an alkali alkoxide and an organic base. Alcoholic solvents may selected from methanol, ethanol, isopropanol, butanol, pentanol, octanol or N,N-dimethylaminoethanol. N,N-dimethylaminoethanol may be preferably used in combination a base selected from the group including, but not limited to, ammonia, alkali alkoxides and strong organic bases. Suitable alkali alkoxides include for example, sodium alkoxide and lithium alkoxide. Strong organic bases such as diazabicycloundecene (DBU) or l,5-diazabicyclo[4.3.0]non-5-ene (DBN) may be suitably used. As used herein, a strong organic base is one with a pKa for the conjugate acid in water of greater than 8.0. The pKa for the conjugate acid in water is 12.0 and 13.5 for DBU and DBN respectively. The skilled person will appreciate that other bases will function equally well depending on the requirements.

The reaction conditions are also dependent on the starting copper phthalocyanine process selected. In the case of the phthalonitrile-based process and the phthalimide-based process, it is desirable that the reaction is carried out in a polar solvent, preferably a high boiling solvent such as dimethylformamide, ethanol, propanol, isopropanol, butanol, pentanol, octanol or N,N- dimethylaminoethanol. It is particularly preferred that dimethylformamide is used as the solvent. In the case of the phthalic anhydride process, solvent is not required and the reaction may be carried out neat, in the liquid phase of the reactants.

A reaction time of at least one hour is desirable, but preferably the reaction time is at least 4 hours. Suitably, the reaction time is at least 10 hours or longer. The reaction may continue for up to and including about 80 hours. A reaction temperature of at least 50 °C is desirable. It is preferred that a temperature of at least 100 °C is used. The most preferred temperature to useis about at least 200 °C, depending on the copper phthalocyanine process used. It will be appreciated that the optimum temperature will depend on the process in question.

The quantity of tethered compound added to the copper phthalocyanine starting materials at the start of the copper phthalocyanine process has a significant influence on the success of the method. The quantity required depends on which phthalocyanine process is selected and the chemical nature of the tethered compound introduced into the reaction. It is preferable that the tethered compound having general formula III is present in an amount that is at least up to

10% w/w, but more preferably in an amount of between about 2% of the amount of the compound of general formula III. In fact, it is preferred that from 1 to 5% w/w of the amount of the compound of general formula III to startign material is used. The method requires the addition of at least 1% w/w of tethered compound in order for the alpha polymorph to be formed. However, it is preferable to add at least 2% w/w of tethered compound to the starting material. It is particularly preferred to use at least 5% w/w of the tethered compound relative to the amount of phthalic anhydride, phthalonitrile or phthalimide starting material used in the reaction. The method of the present invention offer advantages over the prior art method of copper phthalocyanine production in so far as the product of the modified method described herein is a composition comprising a stabilised alpha polymorph of copper phthalocyanine. Stabilised alpha copper phthalocyanine does not revert to the beta form as easily as traditional copper phthalocyanine. The stabilised form is conveniently produced by the reaction of copper phthalocyanine starting materials and tethered copper phthalocyanine starting materials, whereby one of the tethered compounds is added to copper phthalocyanine starting material at the start of copper phthalocyanine production process, and the reaction of the tethered compound and the traditional starting materials results in the production of stabilised alpha polymorph. The alpha polymorph composition is characterised by the powder X-ray diffraction pattern of Figure 7 and the infra-red spectrum shown in Figure 8(b).

The PXRD patterns and infra-red spectra of the alpha copper phthalocyanine composition obtained by the methods of the invention are identical with the reported literature patterns and spectra, and also with patterns and spectra recorded by the inventors of (i) samples of alpha copper phthalocyanine prepared by recrystallisation from H₂SO₄ according to literature procedures and (ii) commercial samples of Pigment Blue 15:0. The PXRD and IR data does not show the presence of any detectible impurity to the limit of detection of the techniques.

Advantageously, the methods of the invention promote the crystallization of alpha copper phthalocyanine polymorph by reaction of a mixture of copper phthalocyanine and tethered copper phthalocyanine, whereby the tethered compounds of the invention are added to copper phthalocyanine starting material at the start of copper phthalocyanine production process to result in the formation of a composition containing predominantly the stabilised alpha form.

A further advantage of the modification of existing copper phthalocyanine production processes as described herein is the promotion of crystallization of the alpha polymorph of copper phthalocyanine, whereas the beta polymorph is traditionally the predominant product of the reactions. Furthermore, desirably, the modified production process of the present invention results in the inhibition of crystallization of the beta form of copper phthalocyanine and the postproduction inhibition of the gradual reverse transformation of the alpha polymorph of copper phthalocyanine to the more stable beta polymorph.

The method provides crystals of the alpha polymorph of copper phthalocyanine with greatly improved stability with respect to hindered transformation to the beta form. Alpha crystal polymorphs provided by these methods have greater stability than previously known alpha copper phthalocyanine crystalline polymorphs. Solid-to-solid transformation of the alpha form to the beta form requires the copper phthalocyanine molecules to re-orientate with respect to each other throughout the crystal. This requires a certain input of energy. The presence of the tethered molecules dispersed throughout the crystals increases the overall rigidity of the structure and raises the energy barrier to transformation.

The method and tethered compounds have a considerable number of advantageous uses.

Existing processes for the production of the alpha form of copper phthalocyanine require preparation of the beta form from phthalic anhydride/phthalonitrile/phthalimide starting materials, followed by recrystallization from concentrated sulphuric acid to give the alpha form. The present invention is advantageous in so far as no recrystallization steps are required to produce the alpha form. The processes do not require the use of concentrated sulphuric acid and so are less costly and have less dangers associated with acid handling.

In another aspect, the invention relates to a mixture comprising an alpha-crystalline composition of coordination complex as described above, wherein the alpha-crystalline polymorph is present in the composition in an amount greater than 95%, more preferably in an amount greater than 98%, more preferably still in an amount greater than 99%. The metal phthalocyanine crystalline compositions of the present invention exists predominately in the alpha polymorph form. The predominantly alpha crystalline metal phthalocyanine composition comprises the mononuclear metal phthalocyanine coordination complex and the tethered coordination complex arranged together in the crystal lattice in such an arrangement that the alpha form is kinetically stabilized.

Linked Structures (Tethered Compounds)

The following tethered compounds are based on the typical starting materials used in the phthalocyanine production process, and are particularly directed for use in the copper phthalocyanine production processes described by the present invention. Examples include, but are not limited to compounds such as those represented by structures XIX, XX and XXI and bis(phthalimide) compound represented by structure (XXIV) below:

(XXIV) The skilled person will appreciate that a variety of tethered compounds can be chosen and the tethered compounds need not be limited to the examples provided herein. It will be understood that such tethered compounds can be selected or synthesised to correspond with any particular starting materials required to provide the desired phthalocyanine ligand functional groups or substituents. Examples of such possibilities have been described earlier in the text and include tethered 2-cyanobenzoic acid derivates and non-symmetrical versions of the tethered compounds including non-symmetrical tethered 2-cyanobenzoic acid and derivates thereof.

In another aspect, the invention provides an example of a particularly efficient tethered compound for use as a particularly efficient promoter in the modified copper phthalonitrile production process of the present invention. Structure XIX, represents a novel chemical entity, and when used as a starting material additive the process of the present invention provides a means for very efficient production of the alpha polymorph directly from copper phthalocyanine starting materials, starting with phthalonitrile. Addition of up to 3% w/w of compound having structure XIX to 30 g of phthalonitrile starting material will afford the alpha polymorph. However it is also preferable to add up to 10% w/w of compound XIX (bis(l,2- dicyanophenyl)sulfide) to 30 g of phthalonitrile starting material to afford the alpha polymorph. It is particularly preferred to add between 3 and 10% w/w of compound XIX (bis(l,2- dicyanophenyl)sulfide) to 30 g of phthalonitrile starting material to produce the alpha polymorph. It has been found that a minimum of 2% w/w compound XIX (bis(l,2- dicyanophenyl)sulfide) to 30 g of phthalonitrile starting materials required to produce the alpha polymorph.

This tethered compound is particularly useful for inducing crystallisation of the alpha polymorph. In fact, addition of up to 3 % w/w of compound XIX (bis(l,2-dicyanophenyl)sulfide) to 500 g of phthalonitrile starting material will still afford the alpha polymorph. However, addition of between 3 and 10% w/w of compound XIX may be added to 50Og of phthalonitrile starting material will produce the alpha polymorph. It is particularly preferred to add between 2% w/w and 15% w/w compound XIX to 50Og of starting material to provide the alpha polymorph.

Addition of up to 2% w/w of compound having structure XXIV of 30 g of phthalimide starting material will afford the alpha polymorph. However it is also preferable to add up to 10% w/w of compound XIX (bis(l,2-dicyanophenyl)sulfide) to 30 g of phthalonitrile starting material affords the alpha polymorph. It has been found to be particularly preferred to add between 2 and 10% w/w of compound XXIV (bis(l,2-dicyanophenyl)sulfide) to 30 g of phthalimide starting material to produce the alpha polymorph. At least 1 % w/w of compound XXIV is required to be added to 30 g of phthalimide starting material to afford the alpha polymorph. Addition of up to 10% w/w of compound having structure XXIV of 500 g of phthalonitrile starting material will afford the alpha polymorph. However it is also preferable to add between 2 - 10% w/w of compound XIX (bis(l,2-dicyanophenyl)sulfide) to 500 g of phthalonitrile starting material affords the alpha polymorph. It has been found to be particularly preferred to add between 1% and 15% w/w of compound XXIV (bis(l,2-dicyanophenyl)sulfide) to 500 g of phthalimide starting material to produce the alpha polymorph. It is particularly preferred to add between 1% w/w and 15% w/w compound XIX to 50Og of starting material to provide the alpha polymorph.

Addition of up to 10% w/w of compound having structure XXIV to 500 g of phthalimide starting material affords the alpha polymorph. Use of at least 2 % w/w of compound having structure XXIV is preferred. However it is particularly preferred to use at least 1 % w/w of compound having structure XXIV to 500 g of phthalimide starting material to afford the alpha polymorph.

Use of the polymorph compositions

In another embodiment, the metal and copper phthalocyanines complexes and compositions can be use as a colorant or in the manufacture of a colorant. Colorants include pigments, inks, dyes and paints. Such colorants can be used alone as a pigment or can be added to a suitable carrier vehicle in the manufacture of a dye. The colorant may be made by adding the phthalocyanine coordination complex or the crystalline compositions to a suitable carrier vehicle. Suitable carrier vehicles include water, alcohols, water-miscible solvents and emulsions with water.

The invention provides for production of a stabilised alpha copper phthalocyanine colorant composition comprising the colorant in a suitable carrier vehicle, wherein the colorant can be pigment or dye based.

Novel Ligand Structures (Tethered Compounds) In yet another embodiment, the invention provides a previously unknown chemical entity which functions particularly well as one of the tethered compounds in the method of the invention described herein. The compound is of the general formula III in which, R⁷ and R⁸ are -CN; R¹² and R¹³ are -CN; R⁹, R¹⁰, R¹¹, R¹⁴, R¹⁵ and R¹⁶ are -H; and X is S; according to the structure XIX below.

This compound can be produced by the reaction of 3-iodophthalonitrile with a suitable coupling agent, in the presence of a suitable source of nucleophilic sulfur and a copper catalyst. The reaction is preferably carried out in a basic solvent system since this leads to improved yields of the compound represented by structure XIX (bis(l,2-dicyanophenyl)sulfide). The coupling agent and sulfur source can be the same or different and are preferably both sodium sulfide. The catalyst is required to drive the reduction reaction and is preferably a copper catalyst such as Cu (copper bronze), copper iodide, Cu₂O, Cu₂S or CuS, preferably copper iodide is used. The basic solvent system can be any inert solvent system such as acetonitrile, dimethylformamide, ethylene glycol, N-methylpyrrolidone, but most preferably acetonitrile is used. The person skilled in the art will appreciate that many coupling agents, sulfur sources, bases and solvents will function equally well in the method of synthesis of this compound. The reaction conditions require heating the mixture to at least a temperature of about 50 degrees centigrade and more preferably temperatures of about 81 degrees centigrade are used. A reaction time of at least about 48 hours is required, more preferably about 78 hours. By about, it is meant that the temperature can vary in the range of ± 10 degrees centigrade and the reaction time can vary in the range of ± 12 hours, and still produce product.

Molecular Structures for Forming Ligand Structures According to the present invention, there is provided a molecular structure for forming a ligand structure, said ligand structure comprising a first unit which can coordinate a first atom and a second unit which can coordinate a second atom, wherein the first and second units are joined by a linker unit, where in said ligand structure:

(i) the first unit is selected from at least one of the group consisting of phthalic anhydrides, phthalonitriles, phthalimides, 2-cyanobenzoic acids and combinations thereof, arranged in the ligand structure for coordinating a first metal atom; and

(ii) the second unit is selected from at least one of the group consisting of phthalic anhydrides, phthalonitriles, phthalimides, 2-cyanobenzoic acids and combinations thereof, arranged in the ligand structure for coordinating a second metal atom; and (iii) the linker unit is arranged between the first and second units and has a covalent bond to each unit and is selected from at least one of the group consisting of linking heteroatoms, linking groups and combinations thereof.

These types of ligand structures are called "tethered" or "linked" compounds since the two units are linked or tied together by way of a linking group. Ligand Structures

According to the present invention, these molecular structures or "tethered" compounds can then be used as starter materials for ligand structures such as phthalocyanine ligands, wherein the molecular structures become incorporated into the phthalocyanine ligand skeleton to form linked or "tethered" phthalocyanine compounds, which contains two connected phthalocyanine units. In this role, these tethered compounds may behave as crystal polymorph promoters that encourage growth of one crystalline polymorph over another.

The present invention provides examples of ligand structures wherein the phthalic anhydrides are substituted with at least one group selected from the group consisting of -CH₃, -C₂H₅, - C(CHs)₃, -OCH₃, -OC₂H₅, -OC₃H₇, -OC₆H₅ or -OCH₂C(CH₃),.

Most preferably, the invention provides a ligand structure wherein the phthalic anhydride is unsubstituted phthalic anhydride.

In another embodiment, the present invention provides a ligand structure wherein the phthalonitriles are selected from the group consisting of selected from the group consisting of - CH₃, -C₂H₅, -C(CH₃)₃, -OCH₃, -OC₂H₅, -OC₃H₇, -OC₆H₅ or -OCH₂C(CH₃)₃.

In another embodiment, the present invention provides a ligand structure wherein the phthalimides are selected from the group consisting of selected from the group consisting of - CH₃, -C₂H₅, -C(CH₃)₃, -OCH₃, -OC₂H₅, -OC₃H₇, -OC₆H₅ or -OCH₂C(CH₃)₃.

The phthalic anhydrides, phthalonitriles, phthalimides and 2-cyanobenzoic acids may be unsubstituted or substituted. Suitable halide substituents, include but are not limited to, -Cl, -

Br, -F or -I. In particular, -Cl substituents are preferred. Suitable heteroatom containing substituents can be selected from groups comprising the heteroatoms O, N, S or P. Particularly preferred heteroatom containing groups are -SO₃H, -C(O)OH, -OH, -NH₂, -N(CH₃)₂, -CN, -NO₂, -

SO₂CI, -CHO, -OCH₃, -OCH₂CH₃ or -PO(OH)₂. The skilled person will appreciate that other heteroatom groups may be equally well used.

In another aspect the invention provides a ligand structure wherein the phthalonitrile is unsubstituted phthalonitrile (2-cyanobenzonitrile, alternatively o-dicyanobenzene).

In a different embodiment the invention provides a ligand structure wherein the phthalic anhydride is unsubstituted phthalic anhydride. In yet another embodiment, the invention provides a ligand structure wherein the phthalimide is an unsubstituted phthalimide. In another aspect the invention provides a ligand structure wherein the 2-cyanobenzoic acid is unsubstituted 2-cyanobenzoic acid.

In one embodiment of the invention, the ligand structure contains a first unit and a second unit that are the same. The linking groups corresponding to X may contain a heteroatom selected from the group O, N, S or P. Particularly preferred heteroatom containing groups include, but are not limited to, -NH- , -NH-NH-, -NH-O-, -N=N-, -S-S-, -S-, -0-, -Se-, -CH=N-, -NHC(O)-, -NHCH₂-, -C(O)CH₂-, - C(O)C(O)-, -CO₂-, -CNH-, -CH₂CH(OH)-, -CH₂(O)-, -S(O)-, -CC-, -CS-, -PO₂ -, -SO₂-, -Se- or - SO₂NH-. More particularly preferred is a linker selected from the group consisting of -0-, -S- and -C(O)-. The skilled person will appreciate that other chemical groups and groups containing heteroatoms can be employed as a linking group. Suitably linking groups also comprise non-heteroatom containing groups, for example as -CH=CH- or -CH₂-CH₂-.

Most preferably, the linker group is selected from the group consisting of -CO, -S, and -O. Ligand Structure Coordination Complexes In a further aspect, the invention relates to a co-ordination complex comprising a ligand structure which contains at least one coordination nucleus, which is capable of coordinating an ion, and in particular a metal cation. More preferably, the coordination complex contain metal cation coordinated in the nucleus and selected from the group consisting of cations of the following metals Cu, Zn, Ni, Co, In, Al, Mg and Fe. The person skilled in the art will appreciate the metal cation is not limited to cations of the metals listed, it is possible to incorporate many other metals into the phthalocyanine ligand structure. It may be possible to coordinate alkali and alkali earth metals. The predominate limitation is the size of the ion which can be coordinated in the ligand coordination centre, which in turn will be determined by the atomic number of the atom and oxidation state of said metal. The present invention is typically concerned with first row transitional metals and their cations.

According to the present invention, if metal cations are co-ordinated by the tethered ligand, then a co-ordination complex comprising a tethered metal-ligand structure is formed. Such metal-ligand structures may be formed by reacting the ligand complex directly with metal salts, particularly salts in which the metal in the +1 or +11 oxidation state. Suitable metal salts include but are not limited to metal halides, metal acetates and metal sulfate salts. Typically, metals selected from the group consisting of copper, zinc, nickel, cobalt, indium, aluminium, magnesium and iron. The person skilled in the art will appreciate that many metal salts can function equally well. Most preferably, the metal atom is copper, particularly copper in the +1 or +11 oxidation state, more particularly still copper in the +11 oxidation state. In one particular embodiment, the invention provides a method for producing metal phthalocyanines comprising forming a metal phthalocyanine having two metal atoms, coordinated as cations, a first metal cation being at least partially coordinated by the first unit and the second metal cation being at least partially coordinated by the second unit, the coordinated metal cations being linked together through their coordination groups by the linker. The co-ordination complexes may be produced by using the tethered compounds of the present invention as starting materials in the metal phthalocyanine production process.

The invention also provides that such tethered metal phthalocyanine compounds can be produced in situ during the course of the metal phthalocyanine production process. Thus, one embodiment of the invention provides a method for the production of compounds of the general formula I and Ib.

in which, Z and Y, are copper and X may be selected from the group consisting of O, S and carbonyl (CO). The skilled person will appreciate that many other types of metal and linker group X, can be equally well employed. Examples of such linking groups have been described earlier.

Such tethered metal ligand complexes are formed in a one step synthesis where the tethered compounds of the present invention as added to the metal phthalocyanine ligand starting materials and are reacted together to form metal salts to directly form the coordination complex. The skilled person will appreciate there are several methods that can be employed to make such complexes with different degrees of success. Functional methods are not limited to those described in the invention. The skilled person will appreciate that the tethered coordination compounds will be dispersed throughout the metal phthalocyanine product in concentrations that will depend on the ratio of tethered compound and regular phthalocyanine starting material used in the production process. Metal Phthalocyanine Compositions

The invention provides methods for producing metal phthalocyanine compositions in the alpha crystalline form, wherein the composition contains predominantly unimolecular untethered metal phthalocyanine units dispersed with varying levels of the tethered metal phthalocyanine. The level of tethered metal phthalocyanine present depends on the %w/w of tethered starting material (formula III) introduced at the start of the process, up to 10%w/w can be used, it is preferable that about 2 - 5% w/w of the amount of the compound of general formula III is used. The method requires the addition of at least 1% w/w, but more preferably, 2% w/w and more preferably yet 5% w/w of the tethered compound relative to the amount of phthalic anhydride, phthalonitrile or phthalimide starting material used in the reaction.

Such a method involves reacting the tethered starting materials of the invention with untethered phthalocyanine or untethered phthalonitrile, phthalimide, phthalic anhydride or 2- cyanobenzoic acid phthalocyanine starting materials and a source of metal in the +1 or +11 oxidation state, to form a metal phthalocyanine. Suitable additives systems can be used to ensure a better reaction, shorter reaction time and better yield.

In one embodiment, the invention provides a method for producing metal phthalocyanine compositions as described above, wherein one of the tethered compounds as described above is reacted with a compound as defined in the general formula II,

in which,

R¹ and R² independently are -CN or -C(O)OH, or

R¹ and R² together are -C(O)OC(O)-, -C(O)NHC(O)- or -C(NH)NH(NH)C-, and form a fused five-membered ring structure and

R³, R⁴, R⁵ or R⁶ which may be the same or different are -H, a halide, an Ci - C₅ alkyl, or a substituent group containing a heteroatom; are reacted with a source of copper in the +11 oxidation state in the presence of an additive system to form copper phthalocyanine in predominantly the alpha crystalline form. In a preferred embodiment, the method comprises use of compound as defined in the general formula II, in which, R¹ and R² are both -CN or both -C(O)OH.

Brief Description of the Drawings

Figure 1 shows classic reaction schemes for the production of copper phthalocyanine using phthalic anhydride or phthalonitrile as starting materials.

Figure IB shows the phthalimide and 1,3 diminoisoindoline starting materials.

Figure 2 shows the polymorph crystal packing patterns alpha and beta schematically, a 'side on' view of the molecules is shown.

Figure 3 shows the reaction scheme for the production of copper phthalocyanine and tethered copper phthalocyanine, starting with phthalic anyhydride and tethered compound IX.

Figure 4 shows the reaction scheme for the production of copper phthalocyanine and tethered copper phthalocyanine, starting with phthalonitrile and tethered compound IX.

Figure 5 shows the polymorph crystal packing patterns alpha and hindered beta packing schematically, a 'side on' view of the molecules is shown. Figure 6 shows the powder X-ray diffraction pattern of beta copper phthalocyanine. Figure 7 shows the powder X-ray diffraction pattern of alpha copper phthalocyanine.

Figure 8(a) shows the infra-red spectrum of the beta-crystal polymorph of Copper Phthalocyanine.

Figure 8(b) shows the infra-red spectrum of the alpha-crystal polymorph of Copper Phthalocyanine.

Figure 9 shows an example of chlorinated copper phthalocyanine and sulfonated copper phthalocyanines in which R¹, R², R³, R⁴ can be from 1 up to 4 sulfonic acid (SO₃H) groups located on each benzene, the remainders being hydrogens.

Detailed Description of the Invention The invention is based on the effect that the addition of small levels of compounds with two phthalic anhydride, phthalonitrile or phthalimide groups tethered together by some group 'X', (e.g. such as an oxygen, sulfur atom or a group such as carbonyl) to copper phthalocyanine starting materials (up to 10% w/w tethered compound/total starting material weight, but up to 5% w/w is more preferably used), has on the production of crystalline structure of copper phthalocyanine. The addition of these so called "tethered compounds" has the effect that the alpha crystalline polymorph is produced in contrast to the usual beta crystalline product of these reactions. The tethered compounds can be mixed in small proportion (up to 10 %w/w, more preferably up to 5% w/w, most preferably still up to 3.5 % w/w) with phthalic anhydride or phthalonitrile starting materials in known copper phthalocyanine preparations. The molecular products of these processes are a mixed composition of copper phthalocyanine molecules, in predominantly the alpha crystalline form, wherein tethered molecules comprised of two copper phthalocyanine units tethered together (Figure 3 and 4) are dispersed through out the composition.

The relative proportions of untethered copper phthalocyanine and tethered copper phthalocyanine molecules produced and found in the crystalline lattice would depend on the relative proportions of phthalic anhydride, phthalonitrile, phthalimide or 2-cyanobenzoic acid and tethered phthalic anhydrides, phthalonitriles, phthalimides or 2-cyanobenzoic acid used as the starting materials.

It is the presence of these tethered compounds that lead to the production of the alpha copper phthalocyanine. The tethered molecules add to crystal nuclei of the beta form and impede the addition of further molecules to the correct growth sites for the beta structure, thus inhibiting growth of the nuclei into mature crystals. It is also possible that, as the tethered molecules are high molecular weight, they precipitate early and act as nucleation sites for alpha crystals.

It would be possible to accommodate the tethered copper phthalocyanine molecules in the crystal structure of the alpha form copper phthalocyanine but it would not be possible to accommodate them in the crystal structure of the beta form, as due to their structural nature, they cannot fold into the herringbone pattern that characterises the beta polymorph (Figure 5). When the tethered compound is present in the correct proportion relative to the copper phthalocyanine starting material, sufficient tethered copper phthalocyanine will be formed and will be present in the lattice on crystallization, to force crystal growth in predominately the alpha form.

Depending on the amount of "doped " tethered copper phthalocyanine present, the alpha crystal polymorph will have the ability to resist transformation to the generally more stable beta form.

Experimental Methods

Copper Phthalocyanine Production Process

Phthalic anhydride Method a) Copper sulphate pentahydrate (1.31 g, 5.25 mmoles), phthalic anhydride (2.96 g, 20 mmoles) and excess of urea with a catalytic amount of ammonium chloride and ammonium molybdate were finely ground and the mixture was heated at 180°C for 4 hours. The crude product, a solid cake, was ground and washed with methanol, hydrochloric acid and methanol. (Blue solid, 65 %). Phthalonitrile Method b) A mixture of phthalonitrile (2.56 g, 20 mmoles), copper (II) bromide (1.12 g, 5 mmoles) and hexamethyldisilazane (2.08 mL, 10 mmoles) in 10 mL of DMF was heated at 100°C for 10 hours. The precipitate was filtered and washed with acetone. (Blue solid, 63 %) Addition of tethered compounds

% w/w tethered compounds are calculated as % total weight of phthalic anhydrides/ phthalonitriles or phthalimides or phthalic acid added. For example, if the above phthalonitrile method is carried out with 3% w/w of

the following method is used:

^■ A mixture of phthalonitrile (12.8 g, 0.1 moles), bis(l,2-dicyanophenyl)sulfide (structure XIX) (0.36 g, 1.25 mmol), copper (II) bromide (5.60 g, 25 mmoles) and hexamethyldisilazane (8.0 g) in 50 mL of DMF was heated at 100°C for 10 hours. The precipitate was filtered and washed with acetone. (Blue solid, 63 %) or alternatively:

^■ A suspension of 214.6 g (0.96 mol) of CuBr₂ in 783.5 g of DMF was prepared by carefully pouring the salt portion wise with efficient stirring (exothermic step and CuBr₂ tends to coagulate at the bottom of the flask). 492.1 g (3.84 mol) of phthalonitrile and 13.78 g (48.3 mmol; 2.8% w/w) of bis(l,2-dicyanophenyl)sulfide (structure XIX) were intimately mixed till homogenous and charged in the round-bottomed flask containing the copper salt in DMF. Finally 619.8 g (15.36 mol) of HMDS was poured and the mixture was maintained at 100°C for 10 hours. The product was then allowed to cool and filtered. The blue cake was washed with 921 parts of methanol and 915 parts of acetone to give 415 g (75%) of alpha copper phthalocyanine. Phthalimide process

■ A suspension of CuBr₂ in DMF was made by pouring 186.2 g (0.83 mol) of the copper salt portion wise in a round-bottomed flask containing 233.6 g of DMF. 471.0 g (3.20 mol) of phthalimide, 9.42 g (29.4 mmol; 2.0 w/w) of the additive (3,3',4,4'- benzophenonetetracarboxylic diimide) and 60.87 g (0.32 mol) of p-TsOH.H₂O were intimately mixed till homogenous and charged into the flask. Finally 2.069 Kg (12.8 mol) of HMDS were added and the mixture maintained at 100⁰C for 10 hours. The blue pigment was then filtered off and washed with 1165 parts of water, 921 parts of methanol and then 915 parts of acetone to give 297 g (65%) of alpha copper phthalocyanine.

Results

Compound represent by Structure XIX Addition of > 3% w/w of compound represented by structure XIX to preparations of copper phthalocyanine by the phthalonitrile process using 3.0 g of phthalonitrile as starting material gave copper phthalocyanine as the alpha crystal polymorph.

The alpha copper phthalocyanine crystals obtained did not transform to the beta form when suspended in boiling xylene for two hours. Addition of > 3% w/w of compound XIX to preparations of copper phthalocyanine by the phthalonitrile process using 30 g of phthalonitrile gave copper phthalocyanine as the alpha crystal polymorph.

Addition of > 3% w/w of compound XIX to preparations of copper phthalocyanine by the phthalonitrile process using 492.1 g of phthalonitrile gave copper phthalocyanine as the alpha crystal polymorph.

Experiments with 2% gave the beta form only. Compound represent by Structure XX

Addition of > 2% w/w of compound represent by structure XX to preparations of copper phthalocyanine by the phthalic anhydride process using 3.0 g of phthalic anhydride gave copper phthalocyanine as the alpha crystal polymorph.

The alpha copper phthalocyanine crystals obtained transform to the beta form when suspended in boiling xylene for two hours.

Addition of > 2% w/w of compound XX to preparations of copper phthalocyanine by the phthalic anhydride or phthalimide process using 30.0 g of phthalic anhydride gave copper phthalocyanine as the beta crystal polymorph.

Experiments with 1% gave the beta form only. Compound XXI

Addition of > 1.1% w/w of compound represented by structure XXI to preparations of copper phthalocyanine by the phthalic anhydride process using 3.0 g of phthalic anhydride gave copper phthalocyanine as the alpha crystal polymorph. It has been found that at least 0.5% w/w of compound represented by structure XXI is required to provide the alpha polymorph.

The alpha copper phthalocyanine crystals obtained did not transform to the beta form when suspended in boiling xylene for two hours. Addition of > 2% w/w of compound XXI to preparations of copper phthalocyanine by the phthalic anhydride process using 30.0 g of phthalic anhydride gave copper phthalocyanine as the alpha crystal polymorph.

Experiments with 1% gave the beta form only. Compound XXIV

Addition of > 2% w/w of compound having structure XXIV to preparations of copper phthalocyanine by the phthalimide process using 29.4 g of phthalimide as starting material gave copper phthalocyanine as the alpha crystal polymorph.

The alpha copper phthalocyanine crystals obtained did not transform to the beta form when suspended in boiling xylene for two hours.

Addition of > 2% w/w of compound having structure XXIV to preparations of copper phthalocyanine by the phthalimide process using 471.0 g of phthalimide gave copper phthalocyanine as the alpha crystal polymorph.

Experiments with 1% gave the beta form only. Characterisation of the crystalline polymorphs

The polymorphic form of the copper phthalocyanine crystals was determined by powder X-ray diffraction (PXRD). Typically, PXRD patterns for both forms are shown in Figures 6 and 7.

Other tethered phthalic anhydrides and phthalonitriles were also investigated but were not found to result in formation of the alpha crystal polymorph. It is likely that this is because these tethered compounds were not good spatial mimics of adjacent phthaolocyanines in the alpha form. Such compounds that did not work are provided below:

attempted with 5% and 25% w/w attempted with 2% w/w only (XXII) (XXIII)

attempted with 3% w/w only (χχ\Λ Characterisation of Compound XIX

The following data was recorded as proof of structure of novel compound represented by structure XIX:

¹H NMR (CDCI₃): 7.73-7.87 (m, 6H, H arom), ¹H NMR (CD₃CN) 7.62-7.72 (m, 4H, ArH), 7.85 (dd, 2H, ⁴J = 1.5 Hz, ³J = 7.5 Hz) : ¹³C NMR (DMSOd⁶) : 114.5, 115.9 (4 CN), 117.3, 117.8 (4 C-CN), 134.2, 135.2, 137.6 (6 CH), 138.7 (2 C-S). m.p. 225-227°C. Ci₆H₆N₄S calc. : C 67.12, H 2.11, N 19.57, S 11.20. found : C 67.07, H 2.22, N 19.22, S 11.36.

It is thought that compound represented by structure XIX gives the 'best fit' within the crystal structure of the alpha form. The tethered phthalocyanines derived from the two tethered phthalic anhydrides do not match the position of adjacent phthalcyanines in the alpha form as well. The tethering group is not attached to the benzene ring at the optimal point of attachment to give a good match (based on comparison of the molecular structures of the compounds with recent data on the crystal structure of the alpha form [Reference 4b]). Crystals of the alpha form containing tethered phthalocyanines derived from these may have some imperfections in the crystal packing in the regions of the tethered phthalocyanines.

Production of Stabilised Pigments and Dyes

Chlorinated copper phthalocyanine and sulfonated copper phthalocyanines in which R¹, R², R³, R⁴ of the structure shown in Figure 9 can be from O up to 4 sulfonic acid (SO₃H) groups on each benzene, the remainders being hydrogens. These derivatives are manufactured directly from copper phthalocyanine.

Sulfonation Procedure

The stabilised alpha crystals obtained by the process of the invention were sulfonated in oleum 30 % at 100°C for 1 hour (US patent 6,793,727). The reaction led to a turquoise dye (sulfonic acid, highly hydroscopic) which was transformed into the corresponding sulfochloride in order to get elemental analyses and thus to determine the degree of sulfonation of CuPc obtained. A turquoise dye comprising of sulfochlorinated copper phthalocyanine having an average composition of CuPc(SO₂CI)₀.₅₃ are obtained, which is in accordance with the literature.

Chlorination Procedure

Samples of the stabilised alpha crystals obtained by the process of the present invention were chlorinated by chlorine gas in an eutectic melt (US patent 2,247,752 ; Example 7). The alpha form obtained by the process of the invention led to a green pigment of formula CuPcCI₇₁₅.

The words "comprises/comprising" and the words "having/including" when used herein with reference to the present invention are used to specify the presence of stated features, integers, steps or components but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

It is appreciated that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention, which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub-combination.

References

1. B.N. Achar, K.S. Lokesh, J. Solid State, 2004, 177, 1987; J.H. Weber, D.H. Busch, Inorg. Chem., 1965, 4, 470. 2. H. Uchida, H. Tanaka, H. Yoshiyama, P.Y. Reddy, S. Nakamura, T. Toru, Synlett, 2002, 1649.

3. F. H. Moser, A. L. Thomas, 'Phthalocyanine¹, Reinhold, New York, 1963.

4. C. J. Brown, J. Chem. Soc. (A) 1968, 2488-2493. Hoshino, Y. Takenaka, H. Miyaji, Acta Cryst., 2003, B59, 393-403. 5. H. Uchida, M. Mitsui, P. YeIIa Reddy, S. Nakamura, T. Toru, ARKIVOC, 2005, 17-23.

6. H. Uchidsa, P. YeIIa Reddy, S. Nakamura, T. Toru, J. Org. Chem., 2003, 68, 8736-8738.

7. C. C. Leznoff, P. I. Svirskaya, B. Khouw, R. L. Cerny, P. Seymour, A. B. P. Lever, J. Org. Chem., 1991, 56, 82-90.

8. C. C. Leznoff, H. Lam, S. M. Marcuccio, W. A. Nevin, P. Janda, N. Kobayashi, A. B. P. Lever, JCS Chem. Commun., 1987, 699-701.

9. H. Uchida, H. Tanaka, H. Yoshiyama, P. Y. Reddy, S. Nakamura, T. Toru, Synlett, 2002, 1649.

Claims

Claims

1. A method for producing alpha copper phthalocyanine comprising forming a mixture of (a) a compound of the general formula II,

in which,

R¹ and R² are independently -CN or -C(O)OH, or

R¹ and R² together are -C(O)OC(O)-, -C(O)NHC(O)- or -C(NH)NH(NH)C-, and form a fused five-membered ring structure and

R³, R⁴, R⁵ or R⁶ which may be the same or different are -H, a halide, an Ci - C₅ alkyl, or a substituent group containing a heteroatom; and (b) a tethered compound of the general formula III,

wherein, any adjacent two of R⁷, R⁸ and R⁹ and any adjacent two of R¹², R¹³ and R¹⁴ are independently -CN or -C(O)OH, and any of R⁷, R⁸, R⁹, R¹², R¹³ and R¹⁴ which are not -CN or -C(O)OH, are -H, a halide, a Ci - C₅ alkyl or a substituent group containing a heteroatom, or any adjacent two of R⁷, R⁸ and R⁹ and any adjacent two of R¹², R¹³ and R¹⁴ are either -C(O)OC(O)-, -C(O)NHC(O)- or -C(NH)NH(NH)C-, and form a fused five- membered ring structure, the ring structures being the same or different and any R substituents that are not part of the ring structure are -H, a halide, a Ci - C₅ alkyl or a substituent group containing a heteroatom; and X is a chain having a backbone of up to two substituted or unsubstituted atoms and the chain comprises an alkane, an alkene or an alkenyl group or a group containing at least one heteroatom; and reacting the mixture with a source of copper in the +1 or +11 oxidation state to form copper phthalocyanine in predominantly the alpha crystalline form.

2. A method according to claim 1 wherein in compound of the general formula II,

R¹ and R² are both -CN or both -C(O)OH, and wherein in a tethered compound of the general formula III,

any adjacent two of R⁷, R⁸ and R⁹ and any adjacent two of R¹², R¹³ and R¹⁴ are both -CN or both -C(O)OH.

3. A method as claimed in claim 1 or 2, wherein the tethered compound of formula III is unsym metrical.

4. A method as claimed in any preceeding claim wherein R³, R⁴, R⁵ and R⁶ are -H.

5 A method as claimed in any preceeding claim wherein any adjacent two of R⁷, R⁸, R¹² and R¹³ or any adjacent two of R⁸, R⁹, R¹³ and R¹⁴ are -CN and R¹⁰, R¹¹, R¹⁵ and R¹⁶ are -H.

6. A method as claimed in any preceeding claim wherein R⁷ and R¹² are both -H or both - C(O)OH, R⁸ and R¹³ are both -C(O)OH, R⁹ and R¹⁴ are both -H or both -C(O)OH.

7. A method as claimed Claims 1 to 5 wherein any adjacent two of R⁷, R⁸ and R⁹ and any adjacent two of R¹², R¹³ and R¹⁴ are either -C(O)OC(O)-, -C(O)NHC(O)- or -C(NH)NH(NH)C- and form a fused five-membered ring structure, the ring structures being the same, and R¹⁰, R¹¹, R¹⁵ and R¹⁶ are -H.

8. A method as claimed in any preceeding claim, wherein the compound of general formula II, is selected from the group comprising phthalic anhydrides, phthalonitriles, phthalimides, 1,3-diiminoisoindolines, phthalic acids and 2-cyanobenzoic acids, which may be substituted or unsubstituted.

9. A method as claimed in any preceeding claim, wherein X is -NH-, -NH-NH-, -NH-O-, - N=N-, -S-S-, -S-, -O-, -Se-, -CH=N-, -NHC(O)-, -NHCH₂-, -C(O)CH₂-, -C(O)C(O)-, -CO₂ ^", -HCN-,- CNH- -CH₂CH(OH)-, -CH₂(O)-, -S(O)-, -CC-, -CS-, -PO₂ -, -SO₂-, -Se-, -SO₂NH-, -CH=CH- or - CH₂-CH₂-.

10. A method as claimed in claim 9, wherein X is O-, -S- or -C(O)-.

11. A method as claimed in any preceeding claim wherein the compound of general formula III, is selected from the group comprising compounds according to formulae XIX, XX, XXI and XXIV:

12. A method as claimed in any preceeding claim, wherein the compound of general formula II and the tethered compound of general formula III are reacted in the presence of an additive system for catalysing the reaction of compound of general formula II and the tethered compound of general formula III to form copper phthalocyanine in predominantly the alpha crystalline form.

13. A method as claimed in any preceding claim wherein the copper source is selected from the group comprising copper (II) acetate, copper (II) chloride, copper (I) chloride, copper (II) bromide, copper (I) bromide, copper iodide, copper fluoride, copper (II) trifluroroacetate, cupric sulfate and hydrated copper salts, such as copper sulfate pentahydrate.

14. A method as claimed in any preceding claim wherein the compound of general formula II is a phthalic anhydride or phthalic anhydride derivate, the reaction is carried out in the presence of an additive system which is the combination of a nitrogen source, a molybdate catalyst and an ammonium halide.

15. The method as claimed in claim 14 wherein the nitrogen source is urea.

16. The method as claimed in claim 14 or 15, wherein the molybdate catalyst is ammonium molybdate.

17. The method as claimed in claim 14 to 16, wherein the ammonium halide is ammonium chloride.

18. The method as claimed in any one of claims 1 to 13, wherein the compound as defined in general formula II is a phthalonitrile, 2-cyanobenzoic acid or a phthalimide or their derivates, the additive system comprises a base.

19. The method as claimed in claim 18 wherein the additive system further comprises a solvent, and a nitrogen source, wherein the nitrogen source and base can be the same or different.

20. The method as claimed in claims 18 or 19, wherein the base is ammonia, a sodium alkoxide, a lithium alkoxide, a hexaalkyldisilazane or a strong organic base.

21. The method as claimed in claim 20, wherein the strong organic base is diazabicycloundecene (DBU) or l,5-diazabicyclo[4.3.0]non-5-ene (DBN).

22. The method as claimed in claims 19 to 21 wherein, the solvent is dimethylformamide.

23. The method as claimed in claims 19 or 20 wherein the nitrogen source and the base is a hexamethyldisilazide, such as hexamethyldisilane, l,l,3,3,-tetramethyl-l,3-diphenyldisilazane or l,3-dimethyl-l,l,3,3-tetraphenyldisilazane.

24. The method as claimed in claims 19 to 21 wherein the solvent is an alcohol and the base is selected from the group comprising ammonia, an alkali alkoxide, or a strong organic bases such as diazabicycloundecene (DBU) or l,5-diazabicyclo[4.3.0]non-5-ene (DBN).

25. The method as claimed in claim 21 wherein the additive system comprises the combination of an alcohol solvent, and a base selected from the group comprising ammonia, an alkali alkoxide and an organic base.

26. The method as claimed in any preceeding claim wherein, the tethered compound of general formula III, is present in an amount that is up to 10% w/w of the amount of the compound of general formula II.

27. A method as claimed in any preceeding claim wherein the compound of general formula II or III has at least one halide substituent which is F, Br, Cl or I.

28. A method as claimed in any preceeding claim wherein the compound of general formula II or III has at least one substituent group containing a heteroatom which is S, N, O or P.

29. A method as claimed in claim 28, wherein the substituent group containing a heteroatom is -SO₃H, -C(O)OH, -OH, -NH₂, -N(CH₃J₂, -CN, -NO₂, -SO₂CI, -CHO, -OCH₃, -COOH, - OCH₂CH₃ or -PO(OH)₂.

30. A composition comprising alpha copper phthalocyanine produced by the method as claimed in any preceeding claim.

31. A copper phthalocyanine composition characterised by the powder X-ray diffraction pattern of Figure 7.

32. The tethered compound of general formula XIX,

33. The method of production of the compound

comprising heating: (i) 3-iodopthalonitrile

(ii) a coupling agent (iii) a source of sulfur (iv) a catalyst together to form the compound of formula XIX.

34. The method as claimed in claim 33 wherein the coupling agent and the sulfur source are the same.

35. The method as claimed in any one of claims 33 and 34 wherein the coupling agent and sulfur source are both sodium sulfide.

36. The method as claimed in any one of claim 33 to 35 wherein the catalyst is cuprous iodide.

37. The method as claimed in any one of claim 33 to 36 wherein the mixture is reacted in acetonitrile.

38. The method as claimed in any one of claims 33 to 37 wherein the mixture is heated to at least 50 °C.

39. The method as claimed any one of claims 33 to 37 wherein, the mixture is heated for at least a period of 48 hours.

40. A colorant comprising the composition as claimed in claims 30 or 31.

41. A colorant as claimed in claim 40, wherein the colorant is selected from the group comprising pigment, ink, dye and paint.

42. A colorant as claimed in any one of claims 40 or 41, wherein the colorant further comprises a suitable carrier vehicle.

43. In a method of preparing a colorant, the step of adding a composition of Claims 30 or 31 to a suitable carrier vehicle.

44. Use of a composition according to claims 30 or 31 in the manufacture of a colorant.

45. Compounds of the general formula (I) and (Ib)

in which,

Z and Y, are a metal, preferably copper,

X is selected from the group comprising O, S, carbonyl.

46. A stabilised alpha sulfonated copper phthalocyanine composition having an average composition of CuPc(SO₂CI)_{0 53} characterised in that the composition comprises tethered copper phthalocyanine.

47. A stabilised alpha chlorinated copper phthalocyanine composition having an average composition of CuPcCI_{7 5} characterised in that the composition comprises tethered copper phthalocyanine.

48. A process as described herein with reference to the examples and the accompanying drawings.

49. A copper phthalocyanine composition as described herein with reference to the examples and the accompanying drawings.