DE2031430A1 - Substd anthraquinones prepn - using phosphorus cpd in ring closure - Google Patents

Abstract

Substd. anthraquinones, having alkyl substituents with >2C, are prepared from substd. benzoyl benzoic acids in which the ring closure is carried out in the presence of 1-25 wt. % (based on the acid) of a phosphorus cpd. obtd. by hydrolysis of phosphoric acid at temps. of >100 degrees C. The anthraquinones are used in the prepn. of H2O2 and dyes.

Description

Process for the preparation of substituted anthraquinones Present The invention relates to a method for the synthesis of substituted anthraquinones according to the phthalic anhydride method.

Substituted anthraquinones are not only used as starting materials Manufacture of dyes has gained economic importance, but become i.a. e has been increasingly used in the chemical industry for around two decades Reaction carrier in the anthraquinone process for the production of hydrogen peroxide used.

For the production of substituted anthraquinones comes in technology only the so-called phthalic anhydride method is used, which - like described below - chemically takes place in 2 stages.

Level 1: Friedel-Crafts (Benzoylbenzoic acid) Stage 2: ring closure (Anthraquinone) While mostly quite good in the first stage. Yields are obtained, the yield in the second stage is very poor when alkyl anthraquinones with a longer side chain than G2 are to be prepared.

This is how you get propyl or butyl anthraquinone in the production in the second stage only yields of around 65, in the production of iÄmylanthraquinone according to the USA patent specification 3,022,560 only about 70% and in the production of amylanthraquinone according to British patent specification 883 226 even only 50%.

Have higher alkylated anthraquinones, but have such good solubility, that they are proposed as the preferred reaction carrier for the anthraquinone process be e.g. B. Propyl anthraquinone in U.S. Patent 2,935,381, butyl anthraquinone and amylanthraquinone in German patents 892,747 and 1,085,861, as well as in German Auslegeschrift 1 106 737 and US Pat. No. 3,041,143.

Despite the economically expensive and technically complex production are then also z. B. t-butyl anthraquinone and amyl anthraquinone on a large scale Systems used for H2O2 production according to the A process, also during production Such substituted anthraquinones are used for ring closure in stage 2, concentrated Sulfuric acid or oleum at a higher temperature. This operation leads not only leads to poor yields, but is also very costly because the work-up of the resulting 2-phase system technically only in several sub-operations and poses difficult sewage problems.

It has therefore made no attempt to improve the ping closure operation absent. For example, in Japanese patent application 7.380 / 68 (priority ii. Sept. 63) suggested that the water formed during ring closure at higher temperatures towed under aceotropic conditions, the actual ring closure being catalytic is effected by p-toluene sulfonic acid. This method also fails during production substituted anthraquinones or gives yields that are even smaller than that achievable by the sulfuric acid-oleum method.

It has now been found that the ring closure of substituted eenzoylb.nzoic acids to carry out substituted anthraquinones in the presence of phosphorus compounds can and seem with catalytic amounts very high conversions and almost quantitative Obtaining yields Among phosphorus compounds are said to be the various phosphoric acids (e.g. meta-phosphoric acid, ortho-phosphoric acid, polyphosphoric acid) or such compounds which result in phosphoric acid on hydrolysis (e.g. phosphorus pentoxide, Phosphorus halides, easily saponifiable phosphoric acid esters). Of the phosphorus compounds mentioned are technically those best suited, the economically the easiest are accessible, d. H. Phosphorus pentoxide and phosphoric acid.

The ring closure operation according to the invention in the presence of said Phosphorus compounds can be solvent-free (wet route) or without solvents (dry way).

When carrying out on the wet route, you bring the reactants (Benzoylbenzoic acid derivative / phosphorus compounds) at temperatures above 1000 C in a solvent for the reaction and, if necessary, trim this in the reaction resulting water from the system by distillation. Appropriately, one chooses a solvent that has a low water solubility and a high solubility for the resulting anthraquinone derivative. In this case, after Ring closure a purification, the organic anthraquinone solution z. B. by simple Alkali / water washes made and the solvent then from the resulting Quinone can be separated by distillation.

A particularly simple embodiment of the wet path results darni, little the anthraquinone derivative as a reaction vehicle in the anthraquinone process to be used for the production of hydrogen peroxide; in this hall granulate the components of the so-called working solution (especially the quinone dissolver the working solution) itself is used as a solvent for the ring closure operation will. After the ring has closed and the organic phase has been purified, it can - without isolation of the anthraquinone derivative - directly into the cycle of the anthraquinone process be fed in.

The implementation of the dry route according to the invention is also not only technically much easier than the well-known ring closure according to the H2SO4 method, but also gives we2 t better yields. When performing the The dry route brings about an intimate mixture (e.g. melt) of the reactants by increasing the temperature to over 100 ° C to react and work the resulting Product z. B. by distillation in vacuo. Because of the short response time you can the partial steps (reaction + distillation) are combined in such a way that one one Melt the reactants directly into a vacuum distillation apparatus, preferably in a thin film evaporator. Of course, combinations also lead the described ways to the goal The temperatures at which the ring closure after the process according to the invention is carried out can vary within wide limits, z. B. from 100 - 2300 C. While temperatures are too low, long reaction times for Result, temperatures that are too high as a result of decomposition occasionally lead to reductions in yield, For this reason, temperatures in the range of 140 - 1900 C are preferred, what When working according to the dry way, this is also associated with the advantage is that in this temperature range many anthraquinone derivatives by vacuum distillation can be cleaned.

The proportions of benzoylbenzoic acid derivative: phosphorus compound in the reaction mixture depend on the type of technical implementation of the reaction. In general there are proportions of the benzoic acid derivative to the phosphorus compound from 1 ; 0.01-0.3, preferably from 1: 0.03-0.09, for use if the The proportions mentioned and the temperature conditions result in that according to the invention Procedure in some ring-closing operations using the sulfuric acid-oleum method succeed very well (e.g. 2-ethylanthraquinone), only poor yields, while it gives very good results where the known ring closure process is inadequate is working. The method according to the invention and the known method thus complement each other in that that now also previously difficult to access, but technically important anthraquinone derivatives by the process according to the invention technically simple and with good yields can be produced.

These are in particular derivatives of the general formula in which the alkyl radical R has a carbon chain of more than 2 carbon atoms.

using the example of the production of t-butyl anthraquinone the process according to the invention is explained below, without the process being restricted to the production of this typical anthraquinone derivative, which is of great economic importance.

Example 1: Production of t-butyl-benzoylbenzoic acid (BBS) at a Temperature of 50 ° C was a batch in a stirred flask with attached condenser consisting of 1,500 ml chlorobenzene 280 g t-butylbenzene (2.09 mol) 300 g phthalic anhydride (2.02 mol) at intervals of 30 minutes with five 100 g portions of AlCl3 (anhydrous) added (total amount of AlCl3 = 500 g = 3.75 mol).

The batch was then stirred for a further 10 h at 50 ° C. and after Cool down on 1 kg of ice cubes. This resulted in 2 phases, of which the aqueous Phase was drawn off in the separating funnel and discarded. The organic phase was to get rid of unreacted phthalic acid twice with 2 liters of boiling water each time moved out. 500 ml of NaOH (20%) were then added to the organic phase and the Solvent driven off with steam. After that, the approach acidified, whereby the butylbenzoylbenzoic acid was obtained as dough, which only after three times Washing with 2 liters of boiling water turned into a crumbly product, which is filtered off and dried in vacuo (100 ° C) (512 g).

A further amount of 16 g can be obtained, whereby the BBS raw amount increased to 520 g (BBS raw yield = 93.5%). The crude acid (melting point 145 ° -148 ° C.) can be used directly for the synthesis of butyl anthraquinone can be used. For the following examples an acid was used, which was purified by recrystallization from toluene (melting point 153 ° -154 ° C.).

Example 2: Ring closure according to the H2SO4 method 80 g of butylbenzoylbenzoic acid (BBS) were added to 400 ml of oleum (with an SO3 content of approx. 10%). i3ei At a temperature of 950 ° C., the mixture was stirred for 40 minutes and then cooled and decomposed on 1 kg of ice, the organic matter which separated out solidified very quickly and was filtered off while the filtrate was discarded.

The filter cake was boiled 5 times with 100 ml of ether each time. the combined ethereal extracts were successively 1 times with 100 ml of water, 2 times with 100 ml each of a 3% sodium hydroxide solution, washed once with 100 ml water, with approx. 20 g Na2SO4 dried, filtered and finally concentrated to dryness. Included incurred: 50 g of t-butylanthraquinone (TBA) as a black-green residue (corresponding to a crude yield of 67%). The residue was distilled in vacuo (10-2 torr); the product passing between 165 and 175 ° C. was light yellow and had a melting point from 100 - 102 ° C (theoretical mp 105 ° C) and away 48 g (corresponding to a pure yield of 64%).

Example 3: Ring closure with P2O5 (dry way) 25 g BBS were with 2 g P2O5 triturated, filled into a distillation flask and immersed in an oil bath (bath temperature: 180 ° C) melted. The flask was then heated to an oil bath connected in vacuo with a distillation receiver At a vacuum of 10-2 Torr 23.5 g of distillate passed over in the temperature range from 165 to 1750 C (distillation residue 2.8 gA.

The distillate contains 3.0 unreacted BBS 20.5g TBA, which corresponded to a BBS conversion of 88%. Calculated on the converted acid, it was found a TBA yield of 99%.

The BBS / TBA separation is an operation that is easy to perform.

In the laboratory the distillate was dissolved in 250 ml of ether and three times in a row extracted with 50 ml of 2% NaOH each time. After the ether had evaporated the remaining residue already had a melting point of 102-1040 C. If the residue was also distilled, then the melting point increased to 103/4 ° C. From the united The unreacted BBS was recovered from alkali extracts by acidification and one another batch was added.

Example 4: Ring closure with H3PO4 (dry way) 25 g BBS were stirred with 2 ml H3PO4 (85%) for 20 minutes at 180 ° C and then by distillation (according to Example 3) worked up. The work-up resulted in: 4. g of unreacted BBS (corresponding to a conversion of k 83.2% 18.2 g TBA corresponding to a 94% igen Yield (based on converted BBS).

Example 5: Ring closure with PC16 (dry way) 25 g BBS were with 6 g of PCl6 triturated, melted at 1800 C and then by distillation (according to Example 3) worked out.

The work-up resulted in: 1.3 g BBS (corresponds to a conversion of 95) 22.2 g of TBA corresponding to a quantitative yield of the reacted BBS is related).

Example 6. Ring closure with polyhosphoric acid (dry route) One Melt consisting of 25 g BBS and 2.5 g polyphosphoric acid was used for 30 minutes stirred at 1800 and then worked up by distillation (according to Example 3). The work-up resulted in: 1.9 g of unreacted BBS (corresponding to 92.5% Conversion 3 21.3 g of TBA corresponding to a 99% yield (based on converted BBS).

Example 7: Ring closure with P2O5 (wet way) 25 g BBS were put together with 1g P2O5 in a 1 liter flask (placed with a reflux condenser), the one with 400 ml.

t-butylbenzoi was filled; the batch was boiled for 24 hours. After cooling down, the organic phase was washed twice with 200 ml of Natrolange (4th %) and washed out twice with 100 ml of water each time, from the combined aqueous After acidification, an amount of 4.3 g BBS could be recovered from extracts (Sales 0 83%) 17.6 g of TBA were dissolved in the organic phase. On the converted acid related, this corresponds to a yield of 91%.

The organic phase was so pure that it went straight into the working solution could be added to an experimental apparatus for the anthraquinone process.

Claims (6)

P a t e n t a n s p p ü c h e 1. Process for the preparation of substituted antraquinones which d: ie as substituents in particular alkyl groups with more than 2 carbon atoms own, from substituted benzoylbenzoic acids, characterized in that the Ring closure in the presence of 1 - 25% by weight of a phosphoric acid during hydrolysis resulting phosphorus compound (based on benzoylbenzoic acid) at temperatures of over 100 ° C is performed 2 * method according to claim 1, characterized in, that phosphorus pentoxide and / or phosphoric acid is used as the phosphorus compound. 3. The method according to claims 1-2, characterized in that temperatures from 100 - 230 ° C, especially from 150 - 190 ° C, can be used, 4. Procedure according to Claims 1-3, characterized in that the ring closure quantitative ratios from 0.01-0.3, preferably 0.003-0.09, parts by weight of the phosphorus compound 1 part of the substituted benzoylbenzoic acid must be complied with. 5. Procedure according to. Claims 1 - 4, characterized in that the ring closure operation carried out in the presence of a solvent and, if necessary of the substituted anthraquinone without prior isolation in the anthraquinone process is used to make hydrogen peroxide. 6. The method according to claims 1-4, characterized in that the ring closure is carried out without solvents and the reactants in distillation apparatus, preferably in a thin film evaporator, reacted and the resulting reaction products separated from each other in a vacuum.