Improved catalytic process for the manufacture of copper phthalocyanine

Abstract: Improved catalytic process for the manufacture of copper phthalocyanine by allowing phthalic anyhydride to react with urea and a copper compound, in the presence of a hydrophobic liquid (dispersing agent), characterised by the presence, along with the catalyst and the dispersing agent, of a promoter selected from particular classes of amides, imides, ureas, thioureas, guanidines, amines or sulphoxides.

Description: The invention relates to an improved catalytic process for the manufacture of copper phthalocyanine in the beta crystalline form, by allowing phthalic anhydride to react with urea and a copper compound; this phthalocyanine is a well known dyestuff used, for example, in the field of photography, inks and pigmentation of plastic materials. The catalyst, as known, is generally selected from compounds of molybdenum or vanadium and (optionally) phosphorus, for instance MoO₃, (NH₄) ₂Mo0₄ ammonium phosphomolybdate etc. The process can be a dry process, namely in the absence of liquids, as described in U.S. Patent 4 118 391, or in the presence of a hydrophobic organic compound (see UK Patent 1 533 354 and Japanese Patent Publication 81-43 357), which disperses and/ or partially dissolves the reaction mixture. The above mentioned techniques enable high yields to be obtained having a high degree of purity and good pigmentation characteristics, but show some not neglectable drawbacks; in fact, they request high reaction temperatures and long contact times. These drawbacks are very deleterious not only as to the high energy cost, but also as to the negative impact of the high temperature on organic products; in fact, these last degrade although in a low percentage, at temperatures higher than 200°C, giving rise, in some cases, to by-products which change the chromatic tone of the phthalo-cyanine. Furthermore, the "dry" method requires particularly delicate and sophisticated apparatus, especially when a continuous production (requiring a strict control of temperatures and times) is performed. Processes performed at temperatures higher than 180°C are particularly harmful when the dispersing agent is tri-chlorobenzene, as it usually happens on a large scale; in fact, it is known that at high temperatures the reaction mixture (urea + phthalic anhydride + copper or copper compound) causes a degradation of trichlorobenzene, thus forming polychlorodiphenyls, very toxic and difficult to remove from the finished product. The Applicants have now found that a particular class of promoters diminish remarkably (and without any drawback) these temperatures and at the same time increase the reaction rate. In particular the Applicants noted that the reduction of times and temperatures for the reaction drastically reduces the formation of the degradation products. This is particularly important if the dispersing medium is trichlorobenzene or dichlorobenzene; in fact, in this case, a lowering of the reaction temperatures involves a drastic reduction of polychlorodiphenyls, which originate from the above mentioned solvents. Also Japanese Patent Publication 77- 052 927 teaches to reduce the temperature thus saving energy and reducing polychlorobenzenes) by adding, besides the catalyst, suitable amounts of caustic soda; however, this method is unsatisfactory because of the high ecologic risk connected with the heating of trichlorobenzenes in the presence of caustic soda, which may trigger a strong reaction and consequent uncontrollable production of dioxinic pollution. In its broadest aspect the invention relates to an improved catalytic process for the production of copper phthalocyanine in the beta crystalline form, by allowing phthalic anhydride to react with urea and copper or a copper compound, in the presence of a hydrophobic liquid dispersing agent and a catalyst, characterised by the presence, of a promoter selected from: A) Amides, imides, ureas, thioureas and guanidines of general formula (I), (II) or (III) wherein Y is S, NH or O and R, R', R'' and R''' the same or different, are H or alkyl, alkenyl (in particular alkylvinyl), aryl, cycloaliphatic or heterocyclic (the hetero atom being N or O) groups, containing from 1 to 15 C atoms, the groups of couples (R+R') and (R+R''), respectively, being optionally bound among each other, as to give a carbocyclic or heterocyclic ring (the hereto atom being N,) at least one of the groups R,R', R'' and R''' being different from H; B) Amines of general formula (IV): wherein R and R' have the above mentioned meaning; C) Sulfoxides of general formula (V) wherein R and R' have the above mentioned meaning; the amount of promoters being in the range of from 5 to 100 mols per 100 mols of copper or copper compound. The amounts of phthalic anhydride, urea, copper, dispersing agent and catalyst are reported in details in UK Pat. 1533 354 as well as in Japanese Patent Publications 81-43 357 and 77-052927, that is as integrating part of the present description. Generally, the following values can be used: copper or copper compound: between 10 and 30% by mols on the phthalic anhydride; urea: between 200 and 600% by mols on the phthalic anhydride; catalyst: between 100 and 5000 ppm, on the phthalic anhydride: dispersing agent: between 150 and 1000% by weight, on the phthalic anhydride. We mention briefly some advantages which arise from the present invention: selected promoters allow performance of the synthesis at lower temperatures and/or within reduced times, thus improving the colour tone of the phthalocyanine and reducing the formation of undesired by-products; the synthesis can be performed in the presence of low-boiling dispersing agents such as chlorobenzene, trichlorobenzenes (for example mesitylene); tert.butyl benzene; tert.butyl toluene; 2-chloro-paraxylene and other dispersing agents which, because of their low boiling point, cannot be used in the usual high temperature processes (or require an expensive apparatus which can withstand pressure). The copper compound, which has to react with phthalic anhydride and urea, is generally selected from Cu₂0, CuO, copper phosphate, CuX or CuX₂ wherein X is selected from Cl, Br, I, OH, HS0₄, S0₄, NO₃, CH₃COO etc., according to the copper valence; obviously, copper acetate can be replaced by other copper carboxylates, such as copper benzoate, naphthenate, 2-ethylhexanoate, n-octanoate, sebacate, phthalate etc. The synthesis temperature, owing to the action of promoters, can be very low (110°c) indeed; generally temperatures between 110 and 170°C, preferably between 130 and 170°C and most preferably between 145 and 170°C can be used, the reaction time generally being approximately two hours or more. The heating is generally performed under agitation and the promoter can be added either at the start of the synthesis reaction or during the reaction, that is while heating the reaction mixture. The chromatographic analysis proved that the promoters according to the invention remain substantially unchanged until the reaction is completed; therefore, they can be recovered and recycled without prejudice of their effectiveness, through filtration, distillation (or extraction) operations, according to usual procedures, well known to anyone skilled in the art. If the promoter is an amine, the product to be recycled is a derivative of the amine, generally a phthalimide. Particularly advantageous promoters have been proved to be N,N,N',N'-tetramethylurea and/ or thiourea; N-methyl-2-pyrrolidone; 1,3-dimethyl-2-imidazolidone; N,N-dimethyl-acetamide; di-sec.butylamine; 1,1,3,3-tetramethyl-guanidine; isobutylamine; dimethylsulfoxide; diethylsulfoxide. Abbrevations of promoters, reported in the examples, have the following meanings: TMU = N,N,N'N'-tetramethylurea; DSBA = di-sec.butylamine NMP = N-methyl-2-pyrrolidone; TMTU = N,N,N',N'-tetramethylthiourea DMI = 1,3-dimethyl-2-imidazolidone; TMG = 1,1,3,3,-tetramethyl- guanidine DMA = N,N-dimethylacetamide; IBA = isobutylamine With the purpose of evidence, we report formulae of some promoters: -N-methyl-2-pyrrolidone (NMP): -1,3-dimethyl-2-imidazolidone (DMl): The hydrophobic dispersing agent can be selected from trichlorobenzene; dichlorobenzene; dichlorotoluenes; 2-chloroparaxylene; nitrobenzene; alkyl-benzenes (for instance mesitylene, 4-tert.butil-toluene; 1,3-diisopropylbenzene): diphenyl; diphenylether; polychloroalkanes, polychloroalkenes (for instance hexachlorobutadiene): alpha and/or beta methylnaphthalene; tetrahydronaphthalene; decahydronaphthalene; quinoline and mixtures thereof. The catalyst may be selected from a lot of compounds; in particular we mention: Mo0₃; (NH₄) ₂Mo0₄; ammonium phosphomolybdate, W0₃ ammonium tungstate, ammonium phosphotungstate, ammonium isopolytungstate and ammonium hetero-polytungstate. Furthermore, it is possible to use, along with catalyst and promoter, a modifier, for instance tetrahydrophthalic anhydride (or derivatives thereof), a tetrahydrophthalimide (or derivatives thereof), a sulfonic derivative of phthalic anhydride (or of phthalimide or of copper phthalocyanine itself), or one of other agents described in European Patent 266 219. As known, a modififer of this type involves a better of phthalocyanine crystals to be ground, a better chromatic tone and a better moldability. The following examples have a merely illustrative purpose. EXAMPLE 1 Into a 250 cm³ flask, provided with blade agitator, thermometer, cooler and external heating bath, there were introduced in the order: 40.5 g urea 29.92 g phthalic anhydride 1.2 g N,N,N',N'-tetramethylurea 0.155 g molybdic anhydride 4.72 g CuCl (technical grade) 108 g technical grade trichlorobenzene The mass was brought up to 170°C in 90 minutes while stirring and was then kept at 170°C for 5 h. Thereafter, the volatile portion was distilled off (at 6.67 kPa (50 mmHg)), while keeping the temperature of the external bath at 150°C. The residue was digested (at 90°C for 2 h, under stirring with 560 g of an aqueous solution of H₂S0₄ (10% b.w.). The filtrate, dried in an oven at 100°C for 24 h, was consisting of 26.4 g of phthalocyanine in the beta crystalline form. Yield on CuCl = 96.1% EXAMPLE 2 (COMPARISON EXAMPLE) Into the same apparatus used in example 1 a test was carried out according the same modalities, using the same amounts of reactants, excepting N,N,N',N'-tetramethylurea, which was omitted. From the ran reaction product, treated as in example 1, only 2 g of copper phthalocyanine were obtained. Yield on CuCl = 8.0% EXAMPLE 3 (TEST WITH N-METHYL-2-PYRROLIDONE) Into the apparatus of example 1 were introduced: 40.5 g urea 29.92 g phthalic anhydride 2 g N-methyl-2-pyrrolidone 0.155 g molybdic anhydride 4.72 g CuCl (technical grade) 108 g trichlorobenzene (technical grade) By working as in example 1, 26.4 g of copper phthalocyanine in crystalline form (beta) were obtained; yield on the used CuCl = 96.1%. EXAMPLE 4 Example 1 was repeated, by omitting the addition of fresh N,N,N',N'-tetramethylurea and using the mixture of volatile products obtained from the distillation of example 1 (containing TMU) instead of technical trichlorobenzene. By working always as in example 1, 26.4 g of copper phthalocyanine were obtained. This test proves that tetramethylurea can be used again in subsequent tests, in that it remains practically unchanged during the test and for the most part it is distilled off along with the dispersing agent in the final post-treatment. Data and results are reported in Table I. EXAMPLE 5 were introduced in the above order into the reactor of example 1; the reaction mixture was heated from 20 to 170°C in 90 minutes while stirring and was then kept at 170°C for 5 h. The volatile portion was distilled off under vacuum (6.67 kPa ((50 mmHg)) by keeping the temperature of the bath at about 150°C. The residue was digested as in example 1. The filtrate, dried in an oven at 100°C for 24 h, was consisting of 17.3 g of copper phthalocyanine in the beta crystalline form. The yield on copper was 89.6%. Examples 6-13 Example 5 was repeated by changing the copper source, the promoter, temperatures and times, as indicated in Table II, which reports also the obtained results. EXAMPLE 14 were introduced in this order into the reactor of example 1. The reaction mixture was heated from 20 to 155°C in 3 h, while stirring and was then kept at 155°C for 8 hour. The volatile portion was distilled off under vacuum (6.67 kPa ((50 mHg)) while keeping the temperature of the bath at about 150°C. The residue was digested as in example 1. The filtrate, dried in an oven at 100°C for 24 h, consisted of 16.2 g of copper phthalocyanine in the beta crystalline form. The yield on the copper was 88.5% EXAMPLES 15-20 Example 14 was repeated changing dispersing agent, promoter, temperatures and times as indicated in Table III, which reports also the obtained results. EXAMPLE 21 75 cm³ of a mixture (50/50) of alpha- and beta-methylnaphthalene were introduced, in the above order, into the reactor of example 1. The reaction mixture was heated from 25 to 170°C in 2 h, under stirring, and was kept at 170°C for 4 h. The volatile portion was distilled off under vacuum (6.67 kPa (50 mmHg)) while keeping the temperature of the bath at about 150°C. The residue was digested as in example 1. The filtrate, dried in an oven at 100°C for 24 h, consisted of 26.2 g of copper phthalocyanine in the crystalline beta form. The yield on copper was 95.4%. EXAMPLES 22 AND 23 Example 21 was repeated by changing dispersing agent, promoter, temperatures and times, as indicated in table IV, which reports also the obtained results.

Claims: A process for the manufacture of copper phthalocyanine, in the beta crystalline form, by reaction of phthalic anhydride with urea and copper or copper compound, in the presence of a hydrophobic liquid dispersing agent and a catalyst characterised by the presence, of a promoter selected from: A) Amides, imides, ureas, thioureas and guanidines, of general formula: wherein Y is S, NH or O and R,R',R'' ad R''', the same or different, are H or alkyl or alkenyl gropus (in particular alkylvinyl groups), aryl, cycloaliphatic or heterocyclic groups (wherein the hetero atom is N or O), containing from 1 to 15 C atoms, the groups of couples (R+R') and (R+R''), respectively, being optionally bound between each other to form a carbocyclic or heterocyclic ring (wherein the hetero atom is N), at least one of the groups R,R', R'' and R''' being different from H; B) Amines of general formula (IV) wherein R and R' have the above specified meaning; C) Sulfoxides of general formula (V): wherein R and R' have the above specified meaning; the amount of promoter being between 5 and 100 mols per 100 mols of copper or copper compound. A process according to claim 1, wherein the copper compound is selected from Cu₂O, CuO, copper phosphate, CuX or CuX₂, X being selected from C1 Br, I, OH, HSO₄ SO₄, NO₃ and carboxylic anions (such as CH₃COO), according to the copper valence. A process according to any preceding claim, wherein the reaction temperature is between 110 and 170°C, preferably between 130 and 170°C, most preferably between 145 and 170°C. A process according to any preceding claim comprising a first stage in which the reaction mixture is heated to a temperature of from 110 to 170°C and a second stage in which that tempeature is maintained for at least two hours. A process according to any preceding claim, wherein the reaction mixture is heated, heating is performed under stirring, the promoter being added either at the start of the reaction or during heating. A process according to any preceding claim wherein the promoters are recovered and recycled by filtration, distillation or extraction. A process according to any preceding claim wherein the promoter is selected from N,N,N′,N′'-tetramethyl-urea and/or thiourea; N-methyl-2-pyrrolidone; 1,3 dimethyl-2-imidazolidone; N,N-dimethyl-acetamide; di-sec.butylamine; 1,1,3,3-tetramethyl-guanidine; isobutyl-amine; dimethyl-sulfoxide, diethyl-sulfoxide and mixtures thereof. A process according to any preceding claim whrein the hydrophobic dispersing agent is selected from alkyl-benzenes,, preferably toluene tert.butyl-benzene or tert.hexyl-benzene; polyalkylbenzenes preferably mesitylene, 4-tert.-butyl-toluene or 1,3-diisopropyl-benzene; diphenyl; diphenylether; alpha and/or beta-methyl-naphthalene; tetrahydronaphthalene, decahydronaphthalene, quinoline and mixtures thereof. A process according to any of claims 1 to 7, wherein the hydrophobic dispersing agent is selected from trichlorobenzene; dichlorobenzene; dichlorotoluenes; 2-chloro-para-xylene; nitrobenzene; polychloroalkanes and polychloroalkenes and mixtures thereof. A process according to any preceding claim, wherein the catalyst is selected from the compounds of molybdenum and/or tungsten and optionally also phosphorus. A process according to any preceding claim characterised by the use of the following amounts of reactants and catalyst: copper or copper compound: between 10 and 30% by mols on the phthalic anhydride; urea: between 200 and 600% by mols, on the phthalic anhydride; catalyst: between 100 and 5000 ppm, on the phthalic anhydride; dispersing agent: between 150 and 1000% by weight, on the phthalic anhydride. A process according to claim 1 for the manufacture of copper phthalocyanine, in which the copper compound is cuprous chloride (CuCl), and the reaction takes place at a temperature of from 145 - 170°C, in the presence of a molybdenum and/or tungsten compound, as the catalyst, and in the presence of a promoter selected from N-methyl-2-pyrrolidone and tetramethylurea. A process according to any preceding claim, wherein the catalyst is selected from MoO₃, ammonium molybdate, ammonium phosphomolybdate, ammonium isopolymolybdate, ammonium heteropolymolybdate, WO₃, ammonium tungstate, ammonium phosphotungstate, ammonium isopolytungstate and ammonium heteropolytungstate. A process according to any preceding claim, characterised by the presence of a modifier. A process according to claim 14 in which the modifier is tetrahydrophthalic anhydride (or derivatives thereof), a tetrahydrophthalimide (or derivatives thereof), a sulfonic derivative of phthalic anhydride or of phthalimide or of copper phthaocyanine itself.

Inventors: AGNES GIOVANNI, BORNENGO GIORGIO, BOTTACCIO GIORGIO, BOZZOLASCO ZEFFERINO, DOMENIS DANILO, MENCONI AUGUSTO, AGNES, GIOVANNI, BORNENGO, GIORGIO, BOTTACCIO, GIORGIO, BOZZOLASCO, ZEFFERINO, DOMENIS, DANILO, MENCONI, AUGUSTO
Applicants: ACNA CHIMICA ORGANICA, ACNA CHIMICA ORGANICA S.P.A.
Application year: 1990
Main classification: C09B47
IPC codes: C09B62, C09B47