DE1493509A1 - Process for the preparation of aryl esters of carbocyclic, aromatic carboxylic acids - Google Patents

Description

Process for the preparation of aryl esters carbocyclic ^ aromatic carboxylic acids.

Addition to the patent (patent application C 27 396! Tb / 12 q)

laugh patent ·. (Patent application C 27 396 IYb / i2 q

be obtained Phenyleeter carbocyclic ^ aromatic mono- and polycarboxylic acids characterized in that Methylester of these acids in the presence of known transesterification catalysts, with at least equivalent amounts of phenol to temperatures above 160 ⁰ C _t, where appropriate, heated under pressure and the methyl alcohol formed continuously removed from the reaction mixture.

They transesterification is preferably carried out at a reaction temperature of 180 to 25O ⁰ C, and can be used as transesterification catalysts in particular, the fatty acid salts of the metals of the second group of periodisohen system, in particular Caloiumetearat or Zinksala the first runnings coconut fatty acid and to obtain a mögllohst quantitative transesterification 2 to 6 moles of phenol are used for each methyl ester group.

Another embodiment is used to obtain mixed methyl phenyl esters from si- or polycarboxylic acid methyl esters for each methyl ester group to be exchanged only 1 to 2 moles of phenol are used and, after splitting off the calculated amount of methanol from the reaction mixture, the mixed methyl phenyl ester is isolated by distillation.

It has now been found that when using the patent

(Patent application C 27 396 IYb / 12 q) described mode of operation also other aryl esters of carbocyolosoher ^ aromatic mono «and Polycarboxylic acids can be obtained if the phenol is wholly or partly against duroh one or more during the transesterification Alkyl and / or aralkyl groups substituted phenols and / or naphthols exchanged.

The isomeric cresols or xylenols, butylphenols, ootylphenols, benzylphenols, i-iaphthol, etc., may be mentioned as phenol-like components in the context of the invention. When using phenol gels, mixed aryl esters are obtained which are of interest for some uses because of their lower melting point. ΒΟΒΒΟώ / M ^ . ₂ -

All raw materials are used for the process according to the invention the methyl esters of the carbocyclic, aromatic monolines Polycarboxylic acids and their core substitution products »for example methyl benzoate, the methyl esters of the isomeric toluic acids, the aromatic bi- and polycarboxylic acids completely or partially esterified with methanol, such as terephthalic acid, isophthalic acid, diphenyldioarboxylic acids, Diphenylmethanedicarboxylic acids, benzophenonedicarboxylic acids, trimellitic acid, pyromellitic acid, kaphthalenedicarboxylic acids and dergleioheh.

The reaction is preferably carried out at 1Θ0 to 25O ⁰ C. The reaction temperature can, however, also be higher if the thermal stability of the reaction participants allows this. Below I6O C, the conversion is immeasurably slow. The reaction is generally carried out at atmospheric pressure. If low-boiling carboxylic acid esters are used as Auegangematerial, it may be necessary to work under excess pressure in order to achieve a reaction temperature in the specified range. On the other hand, when using very high-boiling reaction components, it can be advantageous to facilitate the removal of the split off methanol by applying a vacuum.

Transesterification catalysts known per se can be used acidic or alkaline substances are used, for example polyphosphoric acids, acidic alkali metal phosphates, alkali metal or Alkaline earth hydroxides, tertiary amines, etc. Butyl titanate and the fatty acid salts are particularly advantageous Metals of the second group of the periodic table, for example calcium stearate or the zinc salt of coconut fatty acids. Also tin compounds are very effective, especially fatty salts, for example tin nearate.

The phenolic component is used in at least an equivalent amount, based on each methyl ester group to be reacted of the carboxylic acids to be used according to the invention. It is often advantageous to add up to 6 moles of the phenol per equivalent of methyl ether use to speed up the reaction. The upper foot can after completion of the reaction duroh distillation, if necessary

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^{= 3} "H93509

in a vacuum corpse eiitfevj ..

When using d (* x * methyl esters of aromatic di- and polycarboxylic acids the reaction can also be conducted in such a way that mixed methyl aryl esters are obtained as the main products by distillation or crystallization of the diaryl esters formed and any unreacted starting material can be separated without difficulty, since the boiling points and solubility properties usually differ considerably.

Used for the production of the mixed methyl aryl esters either only as many equivalents of the phenolic component are used as methyl ester groups of the polycarboxylic acid methyl ester are to be implemented or, if an excess of the phenolic component is used, is the reaction is terminated prematurely after the amount of methanol calculated for the formation of the mixed ester has been split off.

The aryl carboxylates are of industrial importance as plasticizers and as intermediates for organic syntheses. In particular, the Dicarbonsäurediarylester valuable _f intermediates for polycondensation products. The mixed esters are particularly valuable for the production of ester amides because of the differentiated reactivity of the methyl and aryl ester groups towards amines.

example 1

256 parts by weight of dimethyl terephthalate (1.33 mol) are mixed with 358 parts by weight (3 »3 mol) of freshly distilled p-cresol Addition of 1.28 parts by weight of zinc stearate (0.5 # »based on Dimethyl terephthalate) heated with stirring in a flask equipped with a fractionating column so that the top of the Column only distilled off methanol. During the transesterification, a slow stream of nitrogen was passed through the apparatus. the The piston temperature rises from the beginning about 200 C up to about

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235 ° C on the Schlui. c he Umest-. ■ at. After 20 hours, 80.5 parts by weight of methanol (95% of the theoretical amount) have been distilled off. When the reaction mixture is worked up by distillation, 72 parts by weight of p-cresol are initially obtained. Then at 20 Torr to distill from 120 to 160 ⁰ C 3 parts by weight of unconverted dimethyl terephthalate and then at 245-285 C 45 * 5 parts by weight of methyl-p-kresylterephthalat * Subsequently, the di-p-kresylterephthalat at 1 torr at 25O ⁰ C distilled over. 357 »5 parts by weight corresponding to 76 #, based on the dimethyl terephthalate used, are obtained. After recrystallization from xylene, the melting point is 199 to 200 ° C., saponification number 328, acid number 1.5.

Example 2

300 parts by weight (2 mol) of methyl p-toluate and 452 parts by weight (4 mol) of m-cresol are added with 1.5 parts by weight of tin stearate (0.5 & based on p-toluic acid ester) as in Example 1 overturned. The temperature in the reaction flask rises τοη initially 200 ⁰ C gradually to about 230 ⁰ C. After 25 hours iet the elimination of methanol terminated and in the presentation of the calculated amount of methanol are $ 0 $ condensed. After the Abdeetillieren the excess cresols and a small amount of unreacted p-Toluylsäureesters which can be recycled into a new approach .erhält to 385 parts by weight of pure p-toluic acid-m-cresyl tob boiling point of 196-198 ⁰ C at 18 Torr . This corresponds to 85 % based on the p-toluic acid ester used, or 97% based on the ester reacted. The cresyl ester melts at 65 to 66 ⁰ Cf saponification number 248.5 (calc. 249).

Example 3

300 parts by weight of p-toluic acid ethyl ether (2 mol) and 375 parts by weight of 4-tert.-butylpb.6nol (2.5 mol) are added 3 parts by weight of tin stearate (1 ^, based on ester) as described in Example 1, reefed. The boiling temperature ± m reaction flask increases τοη begin about 230 ⁰ C to 270 ⁰ C after 20 hours. After this time, about 90 ^ of the calculated amount of methanol has condensed in the receiver. After distilling off the excess butylphenol

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and one kYes .. · '. mgü unreacted methyl p-toluylaate distill H ₄ ;:. . .Io bio 219 C at 15 torr 476 parts by weight of p-toluylic acid-4-t * «r'Ce outylphenylester, corresponding to a yield of 89% based on the toluylic acid methyl ester used or 98 $ based on the converted ester. The toluic acid butylphenyl ester melts at 75 to 76 ⁰ Cj saponification number 210 (calc. 210).

Example 4

63.3 parts by weight of ethyl dibromobenzoate (0.215 mol) and 35 parts by weight of o-Kreeol (0.325 mol) are transesterified at 200 ° C. with the addition of 70.0 0.3 parts by weight of tin stearate. After 12 hours, are in the original 6 parts by weight of methanol, corresponding to 87 i "of the calculated amount is condensed. After the excess cresol and a small amount of unreacted methyl dibromobenzoate have been distilled off, most of the o-cresyl dibromobenzoate is distilled from 180 to 190 ° C. at 0.6 Torr. 65 parts by weight, corresponding to $ 82 of theory, are obtained. The saponification number is 150 (calc. 152).

Example 5

194 parts by weight of dimethyl terephthalate (1 mol) and 515 parts by weight of technical grade ootylphenol (2.5 lol) are transesterified as described above with the addition of 0.48 parts by weight of tin stearate (0.25% based on DMT) . The reaction temperature is maintained at 280 to 29Ο ⁰ C. After 16 hours, 57 parts by weight of methanol, corresponding to 89 fi of the calculated amount, have condensed in the receiver. When the excess ootylphenol is distilled off, 116 parts by weight are recovered. Accordingly, 399 parts by weight, that is to say 97 $ of the theoretical amount, have been consumed for the transesterification. This leaves 526 parts by weight of crude di-ootylphenyl terephthalate, corresponding to 97 > \ saponification number 210 (calc. 208). After recrystallization from xylene, the product sohmilzt at 180-183 ⁰ C.

ORIGINAL BATHROOM -

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291 parts by weight of dimethyl terephthalate (1.5 mol) are mixed with 456 parts by weight of a technical 2,4 / 2,5-bimethylphenol fraction (5.75 mol) with the addition of 1.45 parts by weight of tin stearate ($ 0.5, based on DMT) interesterified as described above for 25 hours. Eb 86.5 parts by weight, corresponding to 90 ° of the calculated i Methan.0lm0n.ge condensed. 95 parts by weight of xylenol are recovered by distilling off in vacuo. Accordingly, 361 parts by weight are that are 99 ° to the calculated i Xylenolmenge, consumed for the transesterification. This leaves 555 parts by weight of crude dimethylphenyl ester of terephthalic acid with a saponification number of 3Ο5 (above 501),> the crude ester therefore still contains a small amount of methyl xylenyl ester. The Rohester shows as an isomer mixture, a melting point ranging from about 100 to I50 ⁰ C. Recrystallization from xylene as schwerstlöslicher share 282 parts by weight of a uniformly obtained at I60 to 162 C melting portion; Saponification number 300.5 (calc. 301). "

Example 7

267 parts by weight of dimethyl terephthalate (1.38 mol) and 495 parts by weight of β-naphthol (3 * 45 mol) are transesterified at 280 to 300 ° C. with the addition of 2.6 parts by weight of tin stearate. The reaction has ended after 14 hours. After distilling II 4 wt. Parts by excess beta-naphthol remain 56Ο parts by weight of crude di-ßnaphthylterephthalat, corresponding to 97 * $> theory. After recrystallization from xylene, the ester melts at 230 to 232 ° C | Saponification number 27Ο (calc. 268.5).

Example 8

194 parts by weight of dimethyl terephthalate (1 mol) UTTD 46Ο parts by wt. P-benzylphenol (2.5 mol) are transesterified with the addition of 0.95 wt. Parts by tin stearate at 25Ο to 280 ⁰ C, until after 25 hours

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about 95 i to the calculated amount of Me than oil are condensed in the template ° "After the excess Abdesiiliieren Benzylphenols in vacuo and TJmkristallisation of the residue from xylene gives 46o g of di-benzylphenylterephthalat, corresponding to 92 ia of theory; Melting point I65bis 167 ⁰ C, saponification value 224 (calc. 225).

Example 9

388 parts by weight of dimethyl terephthalate (2 mol) and 300 parts by weight 4-tert-butylphenol (2 mol) with the addition of 1.94

Parts by weight of tin stearate interesterified. The temperature in the reaction e

vessel rises from initially 240 to 29O ⁰ O after a reaction time of 8 hours. 57 parts by weight of methanol are then condensed in the receiver; that is 89 $ of the amount calculated for the transesterification of a methyl group in dimethyl terephthalate. In the distillation, 111.5 parts by weight of dimethyl terephthalate and 24.5 parts by weight of unreacted butylphenol are initially recovered. Then distill at 220 to 225 ° C at 0.8 Torr 320 parts by weight of methyl 4-tert-butylphenyl terephthalate, which melt after recrystallization from gasoline at 88 to 89 C and show the saponification number 359 (calc. 361) * the crystalline distillation residue consists of I50 parts by weight of di-4-Butylphenylterephthalat which melts after recrystallization from xylene at 224-225 ⁰ C; Saponification number 261.5 (calcd. 262). %

Example 10

512 parts by weight of methyl terephthalic acid dimethyleeter (1.5 mol) and 405 parts by weight of o-cresol (3 * 75 mol) are transesterified for 29 hours with the addition of 1.56 parts by weight of tin stearate. The reaction temperature rises from I98 to about 23O C. After distilling off the überschussigen-cresols, and a small amount of unreacted MethylterephthaJ-säuredimethylesters distill at 230 ⁰ C for I5 Torr IO9 parts by weight Methylterephthalsäuremethyl-phenyleeter with der.Verseifungszahl 393 (calc . 396). Then distill from 232 to

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236 ⁰ O at 0.4 Torr 364 parts by weight of methylterephthalic acid diphenyl ester, which melts ^{at 80 to 82 0 C after recrystallization from a little xylene;} Saponification number 312.2 (calc. 312).

Example 11

369 (each ».- parts of 3-chloro-4-methyl-benzoic acid methyl ester (2 Hol) and 552 parts by weight of p-benzylphenol (3 mol) with the addition of 1.85 parts by weight of tin stearate at 260 to 300 ⁰ C transesterified 18 hours. After the excess Abd'estillieren Benzylphenols and 50 parts by weight unumgeesterten Methylesters 569 parts by weight of distilled at 235-239 ° C at 0.4 torr 3- hlor ^{c-4-methyl-benzoic} acid p -benzylphenyl ester as a viscous oil | saponification number 169 (calc. 167.5). This corresponds to a yield of $ 85, based on the methyl ester used, or 98 #, based on the methyl ester converted.

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Claims (1)

-9- Η935Ό9- Claims ι 1 · Process for the preparation of esters of aromatic liono- and polycarboxylic acids by heating methyl esters of these acids in the presence of known transesterification catalysts with at least equivalent amounts of phenol to temperatures above 160 -C _t, optionally under pressure, and continuous removal of the methyl alcohol formed from the Reaction mixture according to patent .......... (patent application C 27 396 IVb / 12 q), characterized in that during the reaction the phenol is wholly or partially counteracted one or more alkyl and / or aralkyl groups φ substituted phenols and / or ITaphthols exchanged will. 2 » Process according to claim 1, characterized in that the reaction is carried out at 180 to 250 ⁰ O. 3. The method according to claims 1 to 2, characterized in that that to achieve a quantitative transesterification 2 to 6 Hol were substituted by alkyl and / or aralkyl groups Phenols and / or naphthols, optionally mixed with phenol, are used on each methyl ester group. 4. Method according to claims "Ibis 2, characterized in that that aan for the production of mixed methyl phenyl esters from Di- or polyoebonic acid methyl star for each to be exchanged Methyl ester group 1 to 2 mol through alkyl = · and / or aralkyl groups substituted phenols and / or naphthols, optionally mixed with phenol, and after cleavage the calculated amount of methanol from the reaction mixture, the mixed methyl phenyl ester. by distillation isolated. November 29, 1962. PaV, -Abt. / · 909804/1354