WO1984001947A1

WO1984001947A1 - New chelate forming quinoline compounds and processes for recovering metals

Info

Publication number: WO1984001947A1
Application number: PCT/SE1983/000387
Authority: WO
Inventors: Sverker Hoegberg; Bjoern Elman; Hay Liem; Khorshed Madan; Christina Moberg; Mamoun Muhammed; Birger Sjoeberg; Michael Weber
Original assignee: Individual
Current assignee: Individual
Priority date: 1982-11-10
Filing date: 1983-11-08
Publication date: 1984-05-24
Anticipated expiration: 1986-05-08
Also published as: SE8206378D0; SE8206378L; EP0124577A1

Abstract

Novel quinoline compounds having the general formula (I), wherein R4 is selected from the group consisting of hydrogen, hydroxy, alkyl and alkenyl, R3, R5 and R6, which may differ or be identical, are selected from the group consisting of hydrogen and a lipophilizing group and R8 is selected from the group consisting of alkoxy and alkenoxy, with the proviso that at least one of the substituents R3, R4, R5, R6 and R8 is a lipophilizing group. R3, R5 and R6 may be aliphatic or aromatic, straight or branched, saturated or unsaturated, and optionally connected to the quinoline nucleus through an ether linkage. The compounds of the formula (I) may be used as chelate forming agents.

Description

NEWCHELATEFORMINGQUINOLINECOMPOUNDSANDPROCESSES FORRECOVERINGMETALS

The present invention relates to new organic quinoline compounds with chelate forming abilities. The new co - pounds are intended for use as key chemicals, e.g. rea¬ gents or specialty chemicals, in different technical processes.

An important feature of the new compounds is that they exhibit improved selectivity effects when binding to metal ions or ionic compounds such as solid or dissol¬ ved metal salts, minerals, and metal surfaces, when compared with previously known compounds. The improved selectivity applies especially to ions and ionic com- pounds of certain heavy metals, such as copper and zinc, over ions and ionic compounds of other metals and non- metals, such as ferrous and ferric ions. The compounds described in the present invention also exhibit selec¬ tivity for copper and zinc over cadmium, nickel, cobalt, chromium, manganese, alkali and alkaline earth metals.

In view of the technical and economical importance of heavy metals and their impact on the environment, selec¬ tive processes for their recovery from low grade and/ or complex deposits are of utmost importance.

Thus, one object of the present invention is to provide new chelate forming agents for selectively separating heavy metal ions or ionic compounds from a mixture of metal ions or ionic compounds.

Another feature is to provide a process for selectively separating heavy metal ions and ionic compounds from a mixture of metal ions and ionic compounds.

OMPl _ Since the new compounds are also excellent extraction agents, further objects of the invention are to provide new extracting agents and new extracting processes based on the use of the new quinoline compounds of the present invention.

In particular this invention relates to processes for extracting metal ions from aqueous solutions, e.g. from aqueous solutions obtained on recovering metals from ores and from natural, industrial or urban effluents. The processes involve treatment of the aqueous solu¬ tion with a water-immiscible organic solution of the extracting agent or reagent of the invention and sub¬ sequent separation of the aqueous phase from the orga- nic phase containing the complexed metal ions.

According to the invention new selective chelatecom¬ pounds are provided which give improved results in com¬ parison with previously known compounds of this type, e.g. the compounds disclosed in the U.S. patents 3 697 400, 3 637 476, 3 787 418 and 3 941 793.

The new chelate forming agents are quinaldic acids which may be represented by the general formula I:

^R8

wherein R^ is selected, from the group consisting of hydrogen, hydroxy, alkyl and alkenyl, R,, R_ς and R_fi, which may differ or be identical, are selected from the group consisting of hydrogen and a lipophi. izinσ group and R_g is selected from the group consisting of alkoxy and alkenoxy, with the proviso that at least one of the substituents R,, R. , R,- , R, and R„ is a lipophilizing group. R,, R_g and R_fi may be aliphatic or aromatic, straight or branched, saturated or unsatura¬ ted, and optionally connected to the quinoline nucleus through an ether linkage.

Specifically preferred are those compounds wherein R., is hydrogen, alkyl or alkenyl, R. is hydrogen and R- and R,, which may differ or be identical, are hydrogen, alkyl and/or alkenyl. Furthermore it is preferred that the groups in the.3-, 4-, 5-, 6- and 8-positions of the quinoline nucleus have a combined total of no more that 35 carbon atoms, and in these positions it is suitable that the carbon chains have 3-18 carbon atoms, optimally 3-12. The groups in the 8-position should contain 1-18 carbon atoms, optimally 6-12. Suitable substituents are n-hexyl, n-dodecyl, n-tetradecyl and 1- (5,5,7,7-tetrameth l-2-octenyl) groups.

The following list discloses some of the compounds according to the invention which have particularly interesting properties: 8- (1-hexyloxy)-quinoline-2- carboxylic acid, 8- (1-dodecyloxy)quinoline-2-carboxylic acid, 8-[l-(2-ethylhexyloxy)] quinoline-2-carboxylic acid, 8-[l- (3,7-dimethyloctyloxy)] quinoline-2-carboxy- lic acid, 8-[1- (5,5,7,7-tetramethyl-2-octenyloxy) ]qui- noline-2-carboxylic acid, 3-[1- (2-propenyl) ]-4-hydroxy- 8-(1-hexyloxy)quinoline-2-carboxylic acid, 3-[3- (5,5,7,7-tetramethyl-l-octenyl) ]-4-hydroxy-8- (1-hexyl¬ oxy) quinoline-2-carboxylic acid, 3-[1- (2-propenyl)] - 4-hydroxy-8-. (1-dodecyloxy)quinoline-2-carboxylic acid, 4-(3-heptyl)-8-[l-(5,5,7,7-tetramethyl-2-octenyl)] qui- noline-2-carboxylic acid, 5- (1-hexyloxy) -8-(1-hexyloxy)- quinoline-2-carboxylic acid, 5-dodecyloxv-8- .i-hexy-- * loxy) quinoline-2-carbox lie acid, 5- [1- (3, 7-dimethyl- octyloxy)] -8- (1-hexyloxy)quinoline-2-carboxylic acid, 5-[1- (5,5,7,7-tetramethyl-2-octenyloxy)]-8- (1-hexylox )- quinoline-2-carboxylic acid, 5- (1-hexyloxy)-6-[ 3-

5,5,7,7-tetramethyl-l-octenyl)] -8- (1-hexyloxy) quino- line-2-carboxylic acid.

The advantages attained with the compounds according to the present invention in comparison with those disclo¬ sed in the U.S. patents mentioned above relate to the^' high selectivity for ions and ionic compounds of cer¬ tain heavy metals especially copper and zinc over ions and ionic compounds of other nonmetals and metals such as iron. The chelate forming agents according to the present invention also exhibit selectivity for copper and zinc over cadmium, nickel, cobalt, chromium, manga¬ nese, alkali and alkaline earth metals.

In brief, the improved selectivity of the new compounds according to the present invention can be ascribed to

a) the metal bonding groups in the reagent, that is the quinoline nitrogen and the carbox lic oxygen, and

b) special, so called primary, structure elements, the function of which is to direct and limit the coordina¬ tion geometry of the metal complex by sterical influence.

In addition to the primary structure elements, the function of which is common for all compounds according to the present invention, there are secondary structure elements which are decided by and adapted for the tech¬ nical processes for which the compounds are intended. The secondary structure elements modify the physical properties of the compounds such as solubility, hydro- phobicity etc., properties determining the distribu¬ tion of the compounds between different phases in mul¬ tiple phase systems such as oil/water, solid phase/ liquid phase. The secondary elements are designed and positioned so that they do not interfere with the func¬ tion of the primary structure elements and with the bon¬ ding ability of the compounds.

An essential feature of the structure of the compounds of the invention is the primary structure element, the substituent in the 8-position of the quinoline nucleus. As defined above this substituent should be an alkoxy or an alkenoxy group. According to the present invention it has been found that compounds without substituent ■ in the 8-position demonstrate little or no selectivity for copper or zinc ions over ferric and ferrous ions. Furthermore it has been found that quinoline compounds with groups such as methyl and chlorine in the 8-posi- tion are not suitable, because these groups strongly suppress the extracting power of the compounds for all metal ions.

Another essential feature of the present compounds is the lack of substituent in the 7-position. It has been found that a substituent in this position dramatically decreasesthe extracting power. A possible theoretical explanation to this effect is that the substituent in the 7-position prevents comple a ion by sterical hind- ranee in the sensitive complex-binding area. The 7-posi¬ tion must therefore be avoided when the secondary lipo¬ philizing elements are introduced into the parent mole¬ cule.

The substituents in the 3-, 4-, 5- and 6-positions of the quinoline nucleus are not critical as long as they are lipophilizing. However, the total number of carbon atoms in the positions 3, 4, 5 and 6 should, together with the number of carbon atoms in the position 8 pre- ferably not exceed 35.

The high selectivity of the new bidentate quinaldic acids seems to depend on a substituent of suitable ste- ric size and geometry, preferably an alkoxy group, in the 8-position. It is believed that this substituent generates large non-bonded repulsive steric inter¬ actions within a hypothetical, completely lipophilized, three-to-one complex, which are sufficient to disfavour formation of the complex. Thus the extraction of cer- tain hexacoordinating metal ions such as Fe 3+ and Fe2+ ions is diminished. On the other hand the formation of a two-to-one complex is favoured, that is the extrac¬ tion of certain metal ions which may have tetrahedral coordination, as copper and zinc. The pivotal parameter for extraction is the extent to which the chelate forming compounds can replace the hydrophilic inorganic ligands coordinated to the metal ion in the original aquo-complex.

The new quinaldic acid derivatives of the present inven¬ tion can be obtained by conventional means startingfroi. 8-hydroxyquinolines which can be synthezised by litera¬ ture methods or are commercially available. The 8-hyd¬ roxyquinolines are oxidized to the N-oxides, which are transformed into 8-hydroxy-l-methoxy-quinolinium ethyl sulfates using dimethyl.sulfate. Reaction with sodium cyanide gives 8-hydroxy-2-cyanoquinolines, which are O-alkylated using an appropriate alkylating agent, for instance alkyl or alkenyl halides, alkyl or alkenyl tosylates. Hydrolysis of the nitrile function gives the 8-alkoxy ox 8-alkenoxy quinaldi.'^* acids.

The new quinaldic acids are excellent reaqents for the solvent extraction of metal ions that can form a complex compound soluble in an organic solvent, in particular copper (II) and zinc (II) .

Any organic solvent or mixture of solvents may be used which is immiscible with water and chemically stable. Non-flammability and low toxicity are desirable pro¬ perties. Modifiers such as long chain aliphatic alco¬ hols, which improve solubility, phase separation and general extraction performance may be added, suitably in amounts from 0.4 to 20% by weight of the organic solvent. Emulsification may be reduced by the addition of surface active agents such as ethylene oxide/alkyl phenyl condensates. Solubility and extraction perfor¬ mance may be further enhanced by using mixtures of quinaldic acids with different lipophilizing substi- tuents R-.-Rg, Rg.

Since acid is liberated during the extraction process, it may be necessary to add alkali to .maintain the pH of the aqueous phase at the proper level.

Generally solutions containing from 5 to 50% by weight of the quinaldic acids are most effective. The extrac¬ tion is conveniently carried out at ambient or near ambient temperatures but elevated temperatures may sometimes be required to improve the solubility of the extracted complexes.

The process of the invention may be applied to aqueous leach solutions of minerals, scrap metal or other metal- containingby-products or residues obtained by treatment

OMPI thereof with acids such as sulphuric, sulphurous, hydrochloric or nitric acids. The extraction may be performed in any pH range in which the metal hydro¬ xides are not precipitated. The pH may be chosen in such a way that only the desired metal ion is extrac¬ tedj a convenient pH range is 1 to 5.

The process is in general particularly suitable for the recovery of metals from solutions containing at least 5 g per litre.

The liquid-liquid contacting mixture should be mixed intimately in order to obtain maximum mass transfer. It should also be given a sufficiently long setting or quiescent period to allow the phases to separate.

These conditions may be fulfilled by using mixer-sett¬ lers, differential contactors or centrifugal separa¬ tors.

To recover the extracted metal from the chelate, the organic phase is stripped with a strong aqueous acid. The organic phase may then be conditioned in a wash step to remove complexed acid prior to the next load¬ ing step.

Due to the dependance on a constant distribution coef¬ ficient and on proper timing for phase separation, the extraction process is essentially a steady-state pro¬ cess and should be run as a continous, rather than batch, operation. If a series of mixer-settlers are used they should always be run with countercurrent flows for maximum efficiency.

The metal ion selectivities expressed by the present class of chelating compounds can be advantagously used in other separation processes such as liquid or solid supported membrane technique and flotation. The speci¬ fic compounds used in these other separation methods are derived from parent structures possessing the same primary structural elements as described above, but with different secondary elements specifically adopted for the actual process.

The invention is illustrated but not limited by the following examples.

Example 1

8-Hydroxyquinoline (87 g, 0.6 mol) in acetic acid (180 ml) was heated to 65-70°C. 35% H₂0₂ (46 ml) was added and a further two portions of 35% H„0₂ (2 x 36 ml) were added after 1 h 20 min and 2 h 40 min respective¬ ly. The reaction mixture was kept at 65-70 C for 5 h and then left at room temperatureovernight. Evaporation of the solvent gave 117 g of an oil which was partly dissolved in CH-Cl,, (0.6 1). This solution was washed with 10% Na-CO-_j (100 + 50 ml) and dried. The solvent was evaporated and the residue extracted with boiling water (0.7 + 0.3 1). The product precipitated as yellow crystals (24 g, 28%) , m.p. 130-7°C (A.N.Bhat and B.D. Jain, J. Scient. Ind. Res. 19B (1960) 16 and K. Ramaiah and V.R. Srinivasan, Proc. Indian Acad. Sci. A55 (1962) 360) .

Dimethyl sulfate (4-5% excess) was added to 8-hydroxy- quinoline-1-oxide, (55 g, 0.34 mol) and the mixture was heated to 75 C for 3-5 h. When the mixture was allowed to reach room temperature 8-hydroxy-l-methoxy- quinolinium methyl sulfate slowly crystallized. The product was washed with ether and dissolved in water

t ty-. WIPO _ (200 ml) . This solution was added to sodium cyanide (50 g, 1 mol) in water (200 ml) at -5 C during 45 min. After stirring at 0 C for a further 2 h, a 1:1 mixture of acetic acid and water (100 ml) was added. The pre- cipitate formed was filtered off, washed with water and dried. Recrystallization of the crude product (54 g) from petroleum ether (100-125°C) (1.6 1) with decolorizing carbon gave 8-hydroxyquinoline-2-carbo- nitrile (47 g, 0.27 mol, 80%) , m.p. 134-5°C (V.M. Dziαm- ko, I.A. Krasavin and Yu. Radin, Chem. Abstr. 65 (1966) 5437, 7139).

8-Hydroxyquinoline-2-carbonitrile (3.40 g, 20 m ol) and potassium carbonate (2.76 g, 20 mmol) were stirred at 50 C in dimethyl formamide (DMF) (35 ml) for 15 min and 3,6-dioxa-l-σctyl-g-toluene sulfonate (5.76 g, 20 mmol) in DMF (20 ml) was added. After 3,5 h at 50°C more tos la e (1 g) in DMF (5 ml) was added. After an¬ other 1 h 50 min stirring the reaction mixture was pou- red into water (300 ml) and extracted with ether (2 x

200 ml) . The combined extracts were washed with 2 M NaOH, water and brine. The solvent was evaporated and the residue chromatographed on silica gel with chloroform: ethanol 100:1 as the mobile phase. Recrystallization from ether - petroleum ether gave 8-[1-(3,6-dioxaoctyl- oxy) ] quinoline-2-carbonitrile (37%) , m.p. 54-55°C. Anal Calc. for ^ci6^H 8^N2°3^{: C:67}-¹²- H:6.34, N:9.78. Found: C:67.22, H:6.32, N:9.72.

The nitrile (2.12 g, 7.4 mmol) was hydrolyzed with KOH (4.14 g, 74 mmol) in glycol (12 ml) at 115°C for two days. The mixture was poured into 1 M H_SO. (75 ml) . The precipitate formed was filtered off, washed with a small amount of water and recrystallized from methanol: water 1:1 to give 1.94 g (82%) of 8-[l-(3,6-dioxaoctyl- oxy) ] quinoline-2-carboxylic acid (R 305) m.p. 78-81°C. Anal. Calc. for C1,6-H1.9_ftNO5_: C:62.92, H.6.27, N 4.59.

Found: C:62.92, H.-6.28, N 4,51.

Example 2

A mixture of 8-hydroxyquinoline-2-carbonitrile (17.0g , 0.10 mol), potassium carbonate (13.8 g, 0.10 mol) and DMF (75 ml) was stirred at 60°C for 20 min, then 1- chloro-5,5,7,7-tetramethyl-2-octene was added. After 15 h at 60 C the mixture was poured into water (700ml) and extracted with ether (500 ml) . The organic phase was washed with potassium hydroxide (3 x 300 ml 2% g. ) , water and brine. The solvent was evaporated to yield 29.5 g crude product. Recrystallization from pet- roleu ether yielded 8- [1- (5,5,7,7-tetramethyl-2- octenyloxy)] quinoline-2-carbonitrile as white crystals m.p. 63-6°C. Anal. Calc. for ^C ₂₂ ^H28^N2^{0: C:78}**⁵³' H:8.39, N:8.33. Found: C:78.53, H:8.37, N:8.33.

The crude nitrile (82.4 g, 0.245 mol) was hydrolyzed in a solution of potassium hydroxide (156 g) , ethanol (1105 ml) and water (195 ml) at reflux for 12.5 h. About half of the solvent was evaporated. Cone. HCl (200 ml) was added with cooling and then water (700 ml), ether (700 ml) and 2 M HCl (100 ml) . The aqueous phase was extracted with ether (300 ml) . The ether solution was washed with water and brine. Evaporation of the solvent gave 81 g product. Addition of cyclohexane yielded 36.9 g of 8-[ 1- (5,5,7,7-tetramethyl-2-octeny- loxy) ]quinoline-2-carboxylic acid (R 355-0) as a crys¬ talline product, m.p. 76-78 C. Further recrystalliza¬ tion from ether-petroleum ether raised the m.p. to 78-82°C. Anal. Calc. for C₂,H₂9^N03^{: C:74}-³³' H.8.22. N:3.94. Found: C:73.96, H:8.18, N:3.88.

OMPI Example 3

8- (1-Hexyloxy) quinoline-2-carboxylic acid (R 273) was prepared by reaction of a 8-hydroxyquinoline-2-carbo- nitrile (3.44 g, 20 mmol) with hexyl bromide (20 mmol) and sodium carbonate (20 mmol) in DMF (100 ml) at 80°C followed by hydrolysis of the nitrile group. Yield 72%, m.p. 73-76°C. Anal. Calc. for C 1,6-H1. _n9NO_.: C: 70.31,

H:7.01, N:5.13. Found: C:69.77, H:7.01, N:5.03.

Example 4

8- (1-Dodecyloxy)quinoline-2-carboxylic acid (R 357) was prepared from potassium carbonate, 1-bromododecane and 8-hydroxyquinoline-2-carbonitrile in DMF, followed by hydrolysis of the nitrile group. M.p. 95-9β°C. Anal. Calc. for ^c ₂2^H3l^N03^{: C:73}-⁹**-. H.-8.74, N-.3.92. Found: C:74.0, H:8.7, N:3.6.

Example 5

8-(1-Tetradecyloxy)quinoline-2-carboxylic acid (R 385) was prepared by the method described in example 4 using 1-bromotetradecane in place of 1-bromododecane. Yield 68%, m.p. 98-100°C. Anal. Calc. for C₂₄H₃₅N0₃: C:74.8, H:9.15, N:3.63. Found: C:74.7, H:9.1, N:3.4.

Example 6

8- (1-Octadecyloxy) quinoline-2-carboxylic acid (R 441) was prepared by the method described in example 3 using

1-bromooctadecane in place of 1-bromohexane. ield 61%, m.p ^c. 72-72.5°C. Anal. Calc. for C.2_o8H4,3_N03,: C:76.15,

H.9.81, N:3.17. Found: C:75.6, H.9.81, N:3.06.

Example 7

8-Hydroxyquinoline-2-carbonitrile (1.70 g , 10 mmol was treated with one equivalent of 3,7-dimethyloctyl- tos late and K₂C0₃ in DMF (11 ml) overnight at 70°C. The resulting product was purified by column chroma- tography on silica gel (CH₂C1₂) . Yield 89%. The nit¬ rile was hydrolyzed in KOH, EtOH, H₂0 to give 8-[l- (3,7-dimethyloctyloxy)] quinoline-2-carboxylic adid (R 329) .

Example 8

8-[1- (2-Ethyl)hexyloxy]quinoline-2-carboxylic acid (R 301-8) was prepared by the method described in example 6 using 2-ethylhexyltosylate in place of 3,7-dimethyloctyltos late. Yield: 71%, yellow oil that slowly crystallized.

Example 9

Crude 8- (1-dodecenyloxy)quinoline-2-carbonitrile (29.5 g) in decalin (290 ml) was refluxed for 5.5 h. Most of the decalin was distilled off under reduced pressure. The product was filtered, washed and re- crystallized from petroleum ether (40-60 C) yielding 19.2 g (57% yield based on 8-hydroxyquinoline-2-carbo- nitrile) . M.p. 96-98 C. Additional recrystallization gave 7- [3- (5,5,7,7-tetramethyl-l-octenyl)] -8-hydroxy- quinoline-2-carbonitrile, m.p. 98-99°C. Anal. Calc. for C₂₂H_2gN₂0: C-.78.53, H:8.39, N:8.33. Found: C:78.56, H:8.31, N:8.30.

Alkylation of 7-[ 3- (5,5,7,7-tetramethyl-l-octenyl)] -8- hydroxyquinoline-2-carbonitrile with 1-bromooctane.

OMPI subsequent hydrolysis of the nitrile group gave

7- 3- (5 , 5 , 7 , 7-tetramethyl-l-octenyl)] -8-octyloxy- quinoline-2-carboxylic acid (R 467) . Anal. Calc. for

C3-.0-.H4.5-NO3,: C-77.05, H:9.70, N-.2.99. Found: C:77.5, H.-9.7, N:2.9.

Example 10

7-C3-(5,5,7,7-Tetramethyl-l-octenyl)] -8-hydroxyquino- line-2-carbonitrile (1.34 g, 4.0 mmol) was reacted with K₂C0₃ (1.42 g, 4.4 mmol) in DMF (6 ml) at 60°C. Bromoa^'cetic acid methyl ester (0.67 g, 4.4 mmol) was added. The reaction was completed in 10 min. The mix¬ ture was worked up by ether extraction and column chromatography on silica gel eluting with CH₂Cl₂-petro-* leum ether 3:1. [2-Carboxy-7-[3-(5,5,7,7-tetramethyl- l-octenyl) ]~8-quinolinylox]acetic acid (R 413) was ob¬ tained by hydrolysis with KOH-EtOH-H-O at reflux.

M.p. 168-170 C, yield 53%,

Example 11

7-[3- (5,5,7,7-Tetramethyl-l-octenyl)] -8-hydroxyquino- line-2-carbonitrile (2.0 g, 6.0 mmol), was hydrolyzed in 10% potassium hydroxide in ethanol at reflux during two days. 7-[3-(5,5,7,7-Tetramethyl-l-octenyl) ]-8- hydroxy-quinoline-2-carboxylic acid (R 355-C) (2.1 g) separated after addition of water and 2 M HCl. Anal. Calc. for C ₂H NO..: C:74.33, H:8.22, N:3.94. Found: C:73.35, H.8.17. N.3.81.

Example 12

7-Hydroxyquinoline (2.25 g, 15.5 mmol) (A. Campbell and J. Kenyon, J. Chem. Soc. (1947) 437) was stirred with 3-chloroperbenzoic acid (3.40 g) in chloroform (100 ml) for 3 h. The solvent was evaporated and etha¬ nol (10 ml) was added. The N-oxide was filtered and washed with ethanol. 7-Hydroxyquinoline-l-oxide (.1.73 g, 10.7 mmol) was reacted with dimethyl sulfate (1.43 g, 6% excess) at 75-80 C for 4 h. The resulting product was dissolved in water (7 ml) and added dropwise to a solution of sodium cyanide (1.47 g, 7 ml) under ice cooling. After 3 h under ice cooling acetic acid (1ml) was added. The precipitated product, 7-hydroxy-quinoline- 2-carbonitrile, was filtered and washed with water. Yield: 1.42 g (based on N-oxide), m.p. 248-250°C. Anal.

Calc. for Ci__ΛϋH,6,N___0: C:70.58, H.3.55, N.16.46. Found:

C:70.26, H:3.67, N.16.22.

7-Hydroxyquinoline-2-carbonitrile was reacted with l-chloro-5,5,7,7-tetramethyl-2-octene by the procedure described for the 8-hydroxy compound in example 2 to give 7-[1- (5,5,7,7-tetramethyl-2-octenyloxy) ]quinoline- 2-carbonitrile, m.p. 109-111°C. Anal. Calc. for

C₂₂ ^H28^N2°^{: C:78}-⁵³' H:8.39, N:8.33. Found: C:78.56, H:8.37, N:8.27.

7-[1- (5,5,7,7-Tetramethyl-2-octenyloxy)] quinoline-2- carboxylic acid (R-7-355-0) was obtained in 79% yield by hydrolysis of the nitrile as described for the 8- substituted compound. M.p. 96-98.5 C (petroleum ether 100-125°C) . Anal. Calc. for ,₂H NO : C:74.33, H:8.22,

N:3.94. Found: C:74.03, H.8.19, N:3.89,

Example 13

6-Hydroxyquinoline-2-carbonitrile was prepared by trea¬ ting 6-hydroxyquinoline (2.64 g, 18 mmol) with 3- chloroperbenzoic acid (4.0 g) in chloroform (200 ml) during 2 h at room temperature. The solvent was evapo¬ rated and 3-chlorobenzoic acid was removed by sublima¬ tion at 80 C in a vacuum. The residue (mostly N-oxide) was heated to 70°C with dimethyl sulfate (2.30 g, 18 mmol) and a few ml of acentonitrile, during about 4 h. Evaporation of solvent in a vacuim gave 5.25 g of methylated N-oxide. This product was dissolved in water (13 ml) and the solution was added to an ice-cooled solution of sodium cyanide (2.6 g) in water (13 ml) under nitrogen atmosphere during 45 min. Acetic acid: water 1:1 (6 ml) was added after an additional 4 h time in the cold. The product was filtered off and washed with water to give 1.70 g (56% yield), m.p. 217-219°C (toluene) , (218-219°C. C. Kaneko, H. Hasegawa, S*.. Tanaka, K. Sunayashiki and S_ Yamada, Chem. Lett (1947) 123) .

6-Hydroxyquinoline-2-carbonitrile (1.67 g, 9.8 mmol) in DMF (11 ml) was reacted with K CO. (1.43 g) at 70°C, then 1-bromodcdecane (2.74 g, 11 mmol) was added and the reaction was continued overnight. The reaction mix¬ ture was poured into water (100 ml), the precipipated product, 6-(1-dodecyl-oxy)-quinoline-2-carbonitrile, was filtered and dried. An analytical sample had m.p. 86-87.5°C (MeOH) . Anal. Calc. for C-₂H- N 0: C:78.06, H:8.93, N:8.28. Found: C:77.90, H:8.94, N:8.23. The above nitrile was hydrolyzed with KOH in aq. 80% EtOH. The resulting carboxylic acid, 6-(1-dodecyloxy)quino- line-2-carboxylic acid (R 6-357-0), had m.p. 148-_50°C (toluene) , yield 79% (based on 6-hydroxyquinoline-2- carbonitrile) . Anal. Calc. for C₂₂H₃_ O_.: C:73.92, H-.8.74, N:3.92. Found: C.- l_ . ll , H:8.71, N:3.89.

Example 14

8-Methylquinoline (1.43 g, 10 mmol) and 90% 3-chloro- perbenzoic acid (2.28 g, 20% excess) were stirred in

OMPI CHC1-. (5 ml) overnight. The solution was filtered, washed with 10% NaHCO, and the solvent was evaporated. Chromatography of the combined residues from three such reactions on silica gel (160 g) with 5% EtOH in CHC1₃ as the mobile phase gave 1.90 g of 8-methylqui- noline-1-oxide as a red-brown oil (40%) (P. Hamm and W.vphilipsborn, Helv. Chim. Acta _54 (1971) 2363). The product could be purified by adding a small amount of methanol followed by extraction with n-hexane (4 x 70 ml) (1.44 g, 23%) .

8-Methylquinoline-l-oxide (1.78 g 11 mmol) was allowed to react with dimethyl sulfate (1.41 g, 11 mmol) for 3 h at 75 C. The product was dissolved in water (7 ml) , the solution filtered and dropped into sodium cyanide (1.65 g , 34 mmol) in water (7 ml) at 0°C. After 1 h 50 min stirring at 0°C, the product was filtered orf and recrystallized from cyclohexane to give 0.90 g 8-methylquinaldonitrile (48%) , m.p. 125-127°C. In an- other run 47% of a product with m.p. 126-126.5 C was obtained. Anal. Calc. for C 1.1.Ho₀N„ _: C:78.55, H:4.79, N:16:66. Found: C:78.59, H:4.75, N:16.67.

8-Methylquinoline-2-carbonitrile (0.84 g, 5 mmol), 2-ethylhexanoic acid (3.60 g, 25 mmol, 1M H₂SO (5 ml), CH₃CN (5 ml) and Ag N0₃ (0.17 g, 0.1 mmol) were heated to 70°C (F.Minisci, R. Bernardi, F. Bertini, R. Galli and M. Perchinummo, Tetrahedron 21_ (1971) 3575) . To this solution was added (NH -,t) —_S_,._0o_Q (3.42 g, 15 mmol) in water (8 ml) during 0.5 h with stirring. Stirring was continued for 40 min, the mixture was poured into ice-water and ammonia and extracted with ether. The organic phase was washed with 2M NaOH and water. Chro- matography on silica gel (60 g) with ethyl acetate: petroleum ether 1:10 as the mobile phase gave 4-(3-heptyl)-8-methylquinoline-2-carbonitrile (0.59 g, 44%) together with unreacted starting material (0.11 g) . The product was distilled at--' 175 C/0.17 mm Hg (2.3 kPa) . Anal. Calc. for C₁₈ ^H ₂2^N2^: C:81.16, H.-8.32, N.10.52. Found: C:81.18, H:8.34, N.10.39.

The nitrile was hydrolyzed with KOH in ethanol-glycol to give 4-(3-heptyl)-8-methylquinoline-2-carboxylic acid (R 285) (82%) as a yellow oil. Anal. Calc. for

CJ-.Lo₀H_3.NO.: C:75.76, H:8.12, N:4.91. Found: C:75.65,

H:-8.13, N:4.74.

Example 15

4-(3-Heptyl)quinoline-2-carboxylic acid (R 271) was obtained from quinoline-2-carbonitrile and 2-ethyl- hexanoic acid by the method described in example 14 Yield 57%, m.p. 102-3°C. Anal. Calc. for C₁₇H₂- 0₂: C:75.24, H:7.80, N:5.16. Found: C:75.04, H:7.77, N:5.13.

Example 16

An aqueous solution of a mixture of equal parts of me-

"_ -4- _J-J- _?-J>_ _)^■ _J— ^*?-A- tal sulfates (Cu , Zn , Fe , Ni and Co ) was prepared by dissolving the metal salts in dilute sul- furic acid. The metal concentrations were kept around 2 mM and the pH of the solution was adjusted to aboul 2 . A 10 mM chloroform solution of the reagent was prepa¬ red, and equal volumes of the two phases were thorou¬ ghly agitated until equilibrium was reached. The two phases were then separated by centrifugation and the distribution of each metal between the two phases was determined. The percentage of metal ions extracted is given below.

Reagent pH Cu²⁺ Zn²⁺ Fe²⁺ Ni²⁺ C -o2+

Kel -ex * 1.8 97 5 12 5 8

R 305 2.0 29 8 2 1 1

R 355-0 1.8 98 13 0 0 2

R 273 1.9 97 7 0 0 0

** R 630 1.9 97 10 2 0 0

R 301-8 1.9 83 0 0 0 0

R 329 1.9 94 5 0 0 0

R 467 2.0 6 1 1 1 2

R 413 1.9 92 0 9 3 0

R 355-C 1.9 30 6 18 3 2

R 271 1.8 99 3 22 4 2

R 285 2.0 2 4 9 3 0

* Kelex is a registered trade mark for 7-substi- tuted quinoline compounds manufactured by the Ashland Chemical Co. ** R 630 is a 1:1 mixture of R 273 and R 357

Example 17

An aqueous sulfuric acid solution at pH 2 containing equal concentrations of metal sulfates (Cu 2+, Zn2+, Fe 3+, Cd2+ and K+) was contacted with an equal volume of a chloroform solution of the appropriate ligand until equilibrium was reached. The two phases were separated and the distribution of each metal between the two phases was determined. The results (percentage of metal ions extracted) are given below. Reagent pH Cu²⁺ Z_■n2+ Fπ.e³⁺ cd²⁺ κ²

Kelex® 1.8 97 5 26 2 0

R 305 1.9 23 4 4 0 0

R 355-0 1.8 98 13 1 0 0

R 273 1.8 96 0 4 0 0

R 630 1.9 97 8 4 0 0

R 301-8 1.9 80 0 2 - 0

R 329 1.9 91 5 3 - 0

R 467 2.0 9 1 1 1 0

R 413 1.8 91 0 58 - 0

R 355-C 1.9 30 6 82 0 0

R 271 1.8 99 7 71 3 0

R 285 2.0 2 4 3 2 0

Example 18

Equal amounts of sulfate salts of metals (Cu 2+, Zn2+, Ni 2+, Co2+ and Cd2+) were dissolved in dilute sulfuric acid at pH4. This solution was equilibrated at 25 C with a chloroform solution of the ligand concerned. The two phases were separated and the distribution of each metal between the two phases was determined. The results

(percentage of metal ions extracted from the water phase) are given below.

Reagent pH rCu ²⁺ Zn²⁺ Ni²⁺ Cθ²⁺ Cd²⁺

Kelex ®^ 2.4 98 9 7 66 6

R 305 2.5 71 10 2 2 0

R 355-0 2.3 100 52 3 4 0

R 273 2.5 100 29 0 0 0

R 357 2.5 100 40 0 0 0

R 301-8 2.6 97 9 0 0 -

R 329 2.5 98 23 0 0 -

R 467 2.9 33 2 4 0 8

R 413 2.3 100 16 4 2 -

R 355-C 2.5 83 6 4 13 0

R 271 2.4 100 7 12 2 6

R 285 3.2 15 4 5 2 5

R 630 2.5 98 33 0 0 0

Example 19

A series of sulfuric acid solutions of single metal sul- fates at pH 2 were shaken with equal volumes of a chloro¬ form solution of the R 7-355-0, R 357 and R 385 extrac- tants. The percentage of metal removed from each solution is given below.

Reagent pH Cu²⁺ pH τ F.e²+ pH Zn²⁺ pH Fe

R 7-355-0^a 1.7 85 2.0 5 2.0 3 1.7 36

R 357^b 2.1 99 2.1 0 2.1 15 2.1 0

R 385^b 1.9 98 2.1 1 2.1 17 2.1 6

Extractant cone. 20 mM, metal sulfate cone. 10 M

Extractant cone. 20 mM, metal sulfate cone. 2 mM Example 20 An aqueous zinc sulfate solution at pH 4 was shaken with an equal volume of a chloroform solution of R 355-0, R 7-355-0, R 357 and R 385, 20 mM of each. The percen¬ tage of zinc extracted is given below.

Reagent pH % Zn 2+

R 355-0^a 2.3 33

R-355-0 2.6 23

R 357^b 2.7 73

R 385^b 2.6 71

Metal sulfate cone. 10 mM Metal sulfate cone. 2 mM

Example 21

The aqueous solution described in example 16 was equi¬ librated with the appropriate ligand in eyclohexane, toluene or Shellsol^*—^*"A (Shellsol A is a registered trade mark for an organical solvent manufactured by Shell Int. Petroleum Co. Ltd) . The percentage of metals removed from the aqueous phase is given below.

2+

Reagent Ph Cu 2+ Zn Fe 2+ Ni 2+ Co2+ Solvent

Kelex® 1.8 98 4 21 9 10 Cyclohexane

R 271 1.8 100 2 11 4 1 Toluene

R 271. 1.9 100 4 2 0 1 Cyclohexane R 357 2.0 31 4 5 0 0 Shellsol®A

R 355-0 1.9 93 3 2 0 0 Toluene

R 355-0 1.8 98 73 5 5 5 Cyclohexane

Example 22

The aqueous solution described in example 17 was equili¬ brated with the appropriate ligande in cyclohexane, tolu¬ ene or Shellsol® A. The results are shown below.

O P Reagent pH Cu²⁺ Zn²⁺ Fe³⁺ Cd²⁺ κ⁺ Solvent

Kelex® 1.9 95 5 45 3 0 Cyclohexane

R 271 1.8 100 2 28 3 0 Toluene R 271 1.8 100 4 19 0 0 Cyelohexane

R 357 2.0 28 0 7 0 0 Shellsol® A

R 355-0 1.9 93 3 2 0 0 Toluene

R 355-0 1.8 98 73 4 -0 0 Cyclohexane

Example 23

The aqueous solution described in example 18 was equili¬ brated with the appropriate ligand in cyclohexane, tolu¬ ene or Shellsol® A. The percentage of metal ions extrac¬ ted is shown below.

2+

Reagent pH Cu 2+ Zn 2+ Ni Co 2+ Cd 2+

Solvent

Kelex® 1.9 95 5 98 97 1 Cyclohexane

R 271 2.4 100 3 10 3 3 Toluene

R 271 2.5 100 20 35 10 10 Cyclohexane R 357 2.7 85 0 0 0 0 Shellsol^'^^' A

R 355-0 2.3 99 28 0 3 0 Toluene

R 355-0 2.2 99 96 0 3 0 Cyclohexane

-

Example 24

A series of single metal sulfate solutions were prepared and contacted with a 20 mM chloroform solution of R 355-0. The equilibrium pH value of the aqueous phase was adjusted to a given value. The amount of metal extracted at a given equilibrium pH value was determined. The pH,-₀ values (the pH value at which 50% of the metal is extracted) for each metal were calculated and are given below.

OMPI ^"WIPO Metal pH_5Q

Cu 2+ 0.7 Zn 2+ 2.1

Example 25

An emulsion consisting of water in oil was prepared as follows: an

A solution of R 355-0 (4 parts per 100 parts) was vigorously mixed with an aqueous solution containing 0.33 M H«SO. for 3 minutes. The emulsion was stabilized by the addition of Span®80

(registered trade mark for sorbitane monooleate emulsifier manufactured by ICI Americas Inc.) in a concentration of 2-5 volume per cent. The emulsion was contacted and gent¬ ly stirred with a solution of copper sulfate in dilute sulfuric acid at initial H 2.7. The amount of copper re¬ moved from the aqueous solution is given below.

1 10

4 23

12 34

20 39

30 44

45 46

Example 26

A plastic film containing the reagent R 355-0 dissolved in Shellsol^ A was placed in such an arrangement that

OMPI it separated two solutions, one containing zinc sulfate (feed solution) at acidic pH = 2.0, and the other con¬ taining H₂SO. at 0.5 M. The zinc was transfered from its feed solution to the other side of the membrane as given in the following table.

time/min %Zn transfered

3 3

9 8

12 10

24 15

30 19

60 35

OMPI

Claims

1. New quinoline compounds characterized by the formula

wherein R. is selected from the group consisting of H, OH, alkyl and alkenyl, R₃, R_? and R_fi, which may differ or be identical, are selected from the group consisting of hyd¬ rogen and a lipophilizing group and R„ is selected from the group consisting of alkoxy and alkenoxy, with the pro¬ viso that at least one of the substituents R₃, R., Re. R_fi and R_R is a lipophilizing group.

2. Compounds according to claim 1, characterized in that the lipophilizing groups R_, R_ and R_fi are aliphatic or aromatic, optionally connected to the quinoline nucleus through an ether linkage.

3. Compounds according to claim 2, characterized in that the aliphatic group is straight or branched, saturated or unsaturated.

4. Compounds according to any of the claims 1-3, charac¬ terized in that the total number of carbon atoms in the 3-, 4-, 5-, 6- and 8-positions of the quinoline ring does not exceed 35.

5. Compounds according to any of the preceding claims characterized in that the lipophilizing group(s) in the 3-, 4-, 5- and/or 6-position of the quinoline ring is (are) alkyl or alkenyl or, where appropriate, alkoxy or alkenoxy having 3-18, preferable 3-12, carbon atoms.

6. Compounds according to any of the preceding claims characterized in that R„ comprises 1-18, preferably 6-12, carbon atoms.

7. A mixture of quinoline compounds as claimed in the preceding claims.

8. A process for optionally selectively recovering metal values, from a mixture of metal ions or ionic com¬ pounds, characterized in that a quinoline compound or a mixture thereof as claimed in any of the preceding clamis is used as a chelate forming agent.

9. A process for selectively separating copper and/or zinc metal values from a mixture of metal ions or ionic compounds, characterized in that a quinoline compound or a mixture thereof as claimed in claims 1-7 is used as chelate forming agent.

10. A process for extracting metal values from an aqueous solution characterized in that the aqueous phase is trea¬ ted with a water-immiscible organic solution of a quinoline compound or a mixture thereof as claimed in claims 1-7, and that the organic phase containing the eomplexed metal ions is separated from the aqueous phase.

OMPI