MXPA99000196A - Continuous procedure for the preparation of pivaloyl chloride and chloride chloride - Google Patents

Abstract

The invention relates to: A continuous process for preparing pivaloyl chloride and aroyl chloride, mainly benzoyl chloride, which consists in reacting the pivalic acid with a compound aromatic trichloromethyl, in the presence of a catalyst and at a temperature comprised between 60 and 180 OC, under reduced pressure. The products formed are continuously removed from the reaction zone, the hydrogen chloride formed is treated in a washing zone in which a trichloromethyl compound flows countercurrently.

Description

CONTINUOUS PROCEDURE FOR THE PREPARATION OF PIVALOYL CHLORIDE AND AROYL CHLORIDE FIELD OF THE INVENTION The present invention relates to a continuous process for the preparation of pivaloyl chloride and aroyl chloride, namely, benzoyl chloride.

BACKGROUND OF THE INVENTION Pivaloyl chloride constitutes a very important synthesis intermediate for the chemical industry. It is widely used for the synthesis of various pharmaceutical products (antiviral, anti-inflammatory agents) or phytosanitary (herbicides, insecticides). It is also used for the synthesis of peresters, such as tertiobutyl perpivalate and tertioamyl perpivalate, which are mainly used as initiators for polymerization radicals. Aroyl chlorides are also important synthesis intermediates and are used mainly for the manufacture of peroxides and peresters and in the synthesis of various dyes, insecticides, rubber additives. The main access routes to chloride P1012 / 99MX pivaloyl comprise processes which react classical reagents, such as phosgene, sulfonyl chloride, tri- or pentachloride phosphorus, thionyl chloride, oxalyl chloride, with the pivalic acid or else with carbon oxide, in the presence of catalyst, on tert-butyl chloride. However, all these procedures represent complex technologies taking into account the reagents that are used and the need to carry out costly treatments on the products obtained and on the effluents required for an industrial production. Also, for example, in the process described by Butlero (Justus Liebigs Ann. Chem., P.373, 1874), which consists in reacting the pivalic acid on phosphorus pentachloride, according to the following reaction: (CH3) 3CCOOH + PC15? (CH3) 3CC0C1 + P0C13 + HCl P0C13 and pivaloyl chloride obtained have very close boiling temperatures (104-106 ° C) which makes it almost impossible to separate them. Also, the author of this method adds to the obtained reaction medium, potassium pivalate in order to transform P0C13 into P20s, according to the following reaction: 3 (CH3) 3 C C02K + 2P0C13? 3 (CH3) 3 CCOC1 + P205 + 3KC1 Other authors (Bull. Soc. Chim. Fr., pp. 350-351, P1012 / 99MX 1939) in light of this procedure, have proposed to directly prepare the pivaloyl chloride in a single step by reaction of sodium pivalate with P0C13 according to the reaction: 3 (CH3) 3CC02 Na + 2P0C13? 3 (CH3) 3 CC0C1 + P20s + 3NaCl With a molar excess of 25% sodium pivalate, the molar yield of pivaloyl chloride is only 81% in relation to the P0C13 used, which is well above required by an industrial process, while the price of sodium pivalate is much higher than the price of the desired pivaloyl chloride. In place of PC15, it is proposed to use phosphorus trichloride (J. Am. Chem. Soc., 54, pp. 3438-41, 1932). According to the reaction: PC13 + (CH3) 3 C COOH - (CH3) 3 CC0C1 + H3P03 + HCl The hydrochloric acid formed is continuously removed and the pivaloyl chloride is purified by distillation after decanting the phosphorous acid, what can be valued However, the molar yield of pivaloyl chloride is less than 90% in relation to the pivalic acid used and it is very difficult to remove the last traces of phosphorous acid (reducing product), which are detrimental to the use of pivaloyl chloride in some syntheses. One of the methods of synthesis of chloride P1012 / 99MX of pivaloyl, which is the most mentioned in the literature, is to react thionyl chloride according to the reaction: (CH3) 3 C COOH + S0C12? (CH3) 3 C COCÍ + S02 + HCl In general, the reaction is carried out in the presence of a molar excess of 20% to 50% of S0C12. According to these conditions, molar distilled pivaloyl chloride yields approaching 90% are obtained. The addition of catalyst as DMF, pyridine or N-methylacide, allow to increase the kinetics of the reaction and decrease the selectivity (decreasing the percentage of secondary products, such as anhydride). However, this process has the drawback of producing a pivaloyl chloride capable of containing sulfur. In addition, if a catalyst is used, recycling is difficult. Pivaloyl chloride can also be obtained from phosgene according to the following reaction: (CH3) 3CC02H + C0C12? (CH3) 3CC0C1 + HCl + C02 or else by carbonylation of tert-butyl chloride in the presence of catalysts such as A1C13, FeCl3 according to the reaction: (CH3) 3CC1 + CO? (CH3) 3CC0C1 However, these procedures have the drawback of using very toxic, difficult reagents P1012 / 99MX to manipulate and that need to use catalysts to obtain good selectivity and yields greater than 90%. It should be noted that in the case of carbonylation of tert-butyl chloride, the use of catalysts is liable to cause the formation of impurities or to cause retrogradation of the formed product. The access routes to the aroyl chlorides, namely a benzoyl chloride also comprising processes that react the classical reagents such as PC15 / C0C12, S0C12, on the aromatic acids. More precisely, benzoyl chloride is obtained industrially by partial hydrolysis of phenylchloroform according to the reaction: C6H5CC13 + H20? CSHSC0C1 + 2HC1 or by reaction of benzoic acid on the phenylchloroform according to the reaction: CSH5CC13 + CeH5C02H? 2CSH5C0C1 + HCl Simultaneous production of pivaloyl chloride and aroyl chloride, more precisely benzoyl chloride, can be described in the literature. This simultaneous production of acid chlorides is based on the reaction: RCOOH + C6H5CC13? RCOC1 + C6H5C0C1 + HCl P1012 / 99MX which is a chlorodehydroxylation reaction of RCOOH by C6HSCC13. Thus, in JP 86-021 617 B, a method of batch preparation of pivaloyl chloride and benzoyl chloride is described. This process consists in reacting in a first stage the pivalic acid and the phenylchloroform, in stoichiometric quantities, at atmospheric pressure, in the presence of FeCl 3, at a temperature between 40 ° C and 150 ° C and then eliminating the HCl formed, by distillation under reduced pressure of pivaloyl chloride. Subsequently, in a se < After the introduction of a new catalyst charge, the reaction medium is heated to a temperature between 40 ° and 160 ° C and then the formed benzoyl chloride is distilled under reduced pressure. Even though this method makes it possible to obtain acceptable yields comprised between 90 and 95% of pivaloyl chloride and benzoyl chloride, this method of operation has several disadvantages. Therefore, it is necessary to eliminate all of the pivaloyl chloride before carrying out the second stage, at the risk of carrying out the decarbonylation of the pivaloyl chloride according to the following reaction:? P1012 / 99MX (CH3) 3 C COCÍ - > (CH3) 3 C Cl + CO FeCl, In order to avoid this, the authors of the aforementioned patent have perfected the distillation by extracting the residual pivaloyl chloride by a partial distillation of the formed benzoyl chloride, under reduced pressure. Under these conditions, the distillation fraction consists essentially of benzoyl chloride, a certain percentage of pivaloyl chloride and other unidentified compounds. This way of operating has an important drawback when it is known that several by-products can be formed as an effect of secondary reactions, of which the most important are the following: a transhalogenation equilibrium reaction between benzoyl chloride and pivalic acid: (CH3) 3 C COOH + C6H5COC1 ^ (CH3) 3CC0C1 + CsH5C02H 2 - the reaction of the benzoic acid formed with the benzoyl chloride to produce the benzoic anhydride: CeH5C02H + CSHSC0C1 > (CsHsC0) 2 O + HCl These byproducts formed during the first stage are difficult to avoid. Also, the authors of the aforementioned patent add, during the second stage, a significant amount of FeCl 3 in order to transform the secondary products and, namely, the benzoic anhydride, in the presence P1012 / 99MX of CSHSCC13 not transformed according to the equation: (CsH5CO) 2 O (_g.p.5C_L »3 -> 3CSH5C0C1 Finally, this batch procedure has long, successive, transient and unproductive operations. the procedure is quite silent with respect to any evaluation of the hydrochloric acid formed.

SUMMARY OF THE INVENTION The applicant has currently found a continuous process for the preparation of pivaloyl chloride and aroyl chloride (2) by reacting the pivalic acid on an aromatic trichloromethyl compound (1) according to the reaction: < R) m- | - O - < CC! 3) n + p (CH3) 3 CC02H? < 1 > n (CH3) 3CCOC! + (R) m (COQ) n + nHCI (I) (2.}. wherein R represents a halogen atom such as F, Cl, Br, an alkenyl radical, linear or branched, having a carbon number of 1 to 4, a perfluoroalkyl radical, P1012 / 99MX linear or branched, having a carbon number of 1 to 4, a radical -COCÍ, m = 0, 1 or 2; n = 1, 2 or 3, wherein the -CC13 groups are located on the non-adjacent carbon atoms when n > l; in the presence of at least one Friedel-Crafts type catalyst, this process is characterized in that it consists in: introducing simultaneously, in a continuous form, to a reaction zone, the pivalic acid, at least one trichloromethyl compound (1) and at least one Friedel-Crafts-type catalyst, and reacting them with stirring and under reduced pressure at a temperature comprised between 60 ° C and 180 ° C and, preferably, between 120 ° C and 150 ° C, separating in a manner the unreacted reactants of the formed products continue, from the gaseous flow leaving the head of the reaction zone, to partially condense said formed products into a liquid mixture comprising pivaloyl chloride and aroyl chloride (2), - to treat, in a wash zone in which an aromatic trichloromethyl compound (1) circulates countercurrently, the remaining non-condensed gas mixture comprising hydrogen chloride, and extract in a manner that continued at the bottom of the reaction zone, a liquid mixture comprising P1012 / 99MX mainly aroyl chloride (2) formed and the catalyst used in the reaction zone, the mixture is treated in a so-called "reactive" distillation zone from which the aroyl chloride (2) is extracted as head. Unreacted reagents advantageously return to the reaction zone. According to the present invention, the aromatic trichloromethyl compound (1) used in the washing zone can be introduced partially or totally into the reaction zone, after having been used in the washing zone. Preferably, it is introduced completely into the reaction zone in order to advantageously recycle pivaloyl chloride absorbed by the aromatic trichloromethyl compound (I) in the washing zone. According to the present invention, the mixture is extracted from the bottom of the reaction zone and comprises mainly aroyl chloride and also aromatic trichloromethyl unreacted compound (1), catalyst, aroyl anhydride and, optionally, small amounts of byproducts, and it is treated in a distillation zone called "reactive" under reduced pressure and at a temperature at least equal to 120 ° C. An additional amount of Friedel-Crafts type catalyst, identical or different to that used in the reaction zone, can also be used. The part recovers in the head P1012 / 99MX complementary to the aroyl chloride formed in the process. In the background, the heavy fractions that are destroyed are recovered, namely by incineration. Reaction (I) is carried out with a molar ratio of: aromatic trichloromethyl compound (1) pivalic acid from 0.90 n to 1.10 n and, preferably, between ln and 1.03n. According to the present invention, the reaction zone is operated under a reduced pressure of at least 500 mbar and, preferably, between 100 mbar and 400 mbar. As a Friedel-Crafts-type catalyst, a Lewis acid or a Bronsted acid is currently designated. As an example, the Lewis acid "used in the present invention falls within the following: FeCl3, ZnCl2, SnCl4, A1C13, SbCl5, CoCl2, BF3 ... Preferably FeCl3 is used. As an example of Brónsted acid usable according to the invention, sulfuric acid, phosphoric acid, polyphosphoric acids, pyrosulfuric acid, fluorosulfonic acid, chlorosulfonic acid are mentioned. Sulfuric acid is preferably used.

P1012 / 99MX These Friedel-Crafts type catalysts can be introduced into the reaction zone as they are or in the form of aqueous solutions or in solutions with one of the reactants or in solution with the pivaloyl chloride and the aroyl chloride. According to the present invention, a molar amount of Lewis acid comprised between 0.01% and 1% and, preferably, between 0.05% and 0.2% relative to the amount of pivalic acid which is used is used. According to the present invention, a molar amount of pure Brónsted acid comprised between 0.1% and 5% and, preferably, between 0.5% and 2% is used, relative to the amount of pivalic acid that is used. A scope of the invention is not deviated if the aromatic trichloromethyl compound circulating countercurrent in the wash zone is different from that introduced in the reaction zone. The pure hydrogen chloride leaving the head of the washing zone is subsequently advantageously absorbed in the water to bring it to the commercial aqueous solutions of HCl. The liquid mixture extracted at the top of the reaction zone constituted by a mixture of pivaloyl chloride and aroyl chloride is advantageously subjected to P1012 / 99MX a distillation under reduced pressure, which allows the separation of different chlorides formed. As an illustration of the aromatic trichloromethyl compounds (1) usable according to the present invention, there will be mentioned: trichloromethylbenzene or phenylchloroform, 2-chloro, 3-chloro and 4-chloro-l-trichloromethylbenzenes, 1,3- and 1, 4- bis (trichloromethyl) benzenes, 4-fluoro-1-trichloromethylbenzene, 3,4-dichloro-1-trichloromethylbenzene, 4-trifluoromethyl-1-trichloromethylbenzene. The process of the invention applies very particularly to the preparation of pivaloyl chloride and benzoyl chloride from pivalic acid and phenylchloroform. The process has the advantage of producing chlorides of acids of high purity and of a constant quality, with high yields, greater than 96%, a total conversion of reactants and a high productivity. In addition, the hydrogen chloride formed is directly evaluated. This process also has the advantage of generating few by-products and, above all, does not produce gaseous effluents.

P1012 / 99MX The following example illustrates the invention. It is introduced continuously, with agitation and under pressure of 133 mbars, 130 kg / h of pivalic acid with 0.5 kg / h of an aqueous solution at 40% by weight of FeCl3 and 285.5 kg / h of a flow of phenylchloroform containing 35.5 kg / hr of pivaloyl chloride, in a vitrified reactor of 2.5 m3, stored at 135 ° C, in a stabilized regime, containing a mixture comprising benzoyl chloride, phenyl chloroform and benzoic anhydride. Under these conditions, the pivaloyl chloride is formed immediately and evaporated as well as a part of the benzoyl chloride. The gaseous products of the reaction are continuously removed from the head of the reactor and are drawn into a small separation column equipped with a filling structure of 6 theoretical plates, where the non-transformed reactants are separated. Unreacted reagents return to the reactor. After the condensation of the gaseous product mixture, the following is continuously extracted: on the one hand a liquid mixture consisting of 147. 7 kg / h of pivaloyl chloride, 82.8 kg / h of benzoyl chloride and 0.9 kg / h of tert-butyl chloride, the mixture is sent to a storage bench for later to undergo a distillation that allows P1012 / 99MX recover pivaloyl chloride with a purity higher than 99.5%, on the other hand, a gaseous flow constituted of 47.8 kg / h of hydrogen chloride (HCl gas), 35.6 kg / h of pivaloyl chloride and 2.7 kg / h of tertiobutyl chloride, which is sucked up by a liquid ejector and sent to a washing column provided with 9 theoretical plates, wherein the hydrogen chloride is washed countercurrently by 200 kg / h of phenylchloroform at 10 ° C. At the head of this washing column 47.5 kg / h of gaseous HCl are recovered, which are sent to an isothermal descending film absorber or where they are absorbed by 95.5 kg / h of water to form 144.9 kg / h of an aqueous solution 33% by weight of HCl. At the bottom of the wash zone, the phenyl chloroform that has been absorbed to the organic compounds contained in the gas flow is introduced into the said washing column and is sent to the reactor, this forms a part of the 285.6 kg / h of phenylchloroform used. At the bottom of the reactor, a liquid mixture containing 55.6 kg of benzoyl chloride, 16.9 kg of phenylchloroform, 21.3 kg of benzoic anhydride, P1012 / 99MX 2.8 kg of pivaloyl chloride, 1.4.3 kg / h is continuously extracted from the reactor. kg of benzoic acid, catalyst and heavy residues bound to phenylchloroform impurities that are used. This liquid mixture is subjected to vacuum in a storage bench and then subjected to reactive distillation in a column of 20 theoretical plates, under reduced pressure, at a temperature comprised between 120 ° C and 150 ° C and in the presence of 0.1% in FeCl3 weight in relation to the weight of the mixture. Exit through the head of the column, the residual pivaloyl chloride and then the benzoyl chloride with a purity greater than 99.9%. Heavy products are eliminated by incineration. After the distillations, the yields of pivaloyl chloride and benzoyl chloride are respectively greater than 96.8% and 97%. The hydrochloric acid obtained in this process is a commercially available 33% aqueous solution of HCl.

P1012 / 99MX

Claims (14)

1. NOVELTY OF THE INVENTION Having described the present invention, it is considered as a novelty and, therefore, the content of the following CLAIMS is claimed as property: 1. A continuous process of preparation of pivaloyl chloride and aroyl chloride by reaction of the Pivalic acid on an aromatic trichloromethyl compound according to reaction (1): (R) m- - O 4- < CCI3) p + n (CH3) 3 CC02H < D n (CH3) 3CCOC! + (R) m - | - O (COCI) n + nHCI (I) (2) where R represents a halogen atom such as F, Cl, Br, an alkyl radical, linear or branched, having a number of carbon atoms between 1 to 4, a linear or branched perfluoroalkyl radical, having a number of carbon atoms, carbon between 1 to 4, a radical -COCÍ, m = 0, 1 or 2, n = 1, 2 or 3 and where the -CC13 groups are located on the non-adjacent carbon atoms when n > l; in the presence of at least one Friedel-type catalyst P1012 / 99MX Crafts, characterized in that it consists of: introducing simultaneously, continuously, into the reaction zone, pivalic acid, at least one aromatic trichloromethyl compound and at least one Friedel-Crafts type catalyst, and reacting them with stirring and under reduced pressure, at a temperature between 60 ° C and 180 ° C, separate, continuously, from the gaseous flow leaving the head of the reaction zone, the unreacted reagents of the formed products, partially condense the formed products in a liquid mixture comprising pivaloyl chloride and benzoyl chloride, - bringing to a washing zone in which a countercurrent aromatic trichloromethyl compound circulates, the remaining non-condensed gas mixture comprising hydrogen chloride, and extract, continuously, at the bottom of the reaction zone, a liquid mixture comprising mainly aroyl chloride formed and the catalyst used in the area The mixture is treated in a distillation zone called "reactive", from which head the aroyl chloride is extracted. P1012 / 99MX 2. The process according to claim 1, characterized in that the reactive distillation is carried out in the presence of an additional quantity of Friedel-Crafts type catalyst. 3. The process according to claim 1, characterized in that the temperature in the reaction zone is comprised between 120 ° C and 150 ° C. 4. The process according to any of claims 1 to 3, characterized in that the reaction zone is operated under reduced pressure, much like 500 bars. The process according to claim 4, characterized in that the process operates in the reaction zone under a reduced pressure comprised between 100 mbars and 400 mbars. The process according to any of claims 1 and 3 to 5, characterized in that the reaction is carried out with the following molar ratio: aromatic trichloromethyl pivalic acid compound which is 0.90 n to 1.10 n and preferably comprises between ln and 1.03n. The process according to any of claims 1 to 6, characterized in that the Friedel-Crafts type catalyst is a Lewis acid. P1012 / 99MX 8. The process according to claim 7, characterized in that the Lewis acid is FeCl 3. The method according to any of claims 7 or 8, characterized in that a molar amount of Lewis acid is used, comprised between 0.01% and 1% and, preferably, comprised between 0.05% and 0.2% in relation to the amount of Pivalic acid that is used. The process according to any of claims 1 to 6, characterized in that the Friedel-Crafts type catalyst is a Brónsted acid. The process according to claim 10, characterized in that the Brónsted acid is sulfuric acid. The process according to any of claims 10 or 11, characterized in that a molar amount of Brónsted acid comprising between 0.1% and 5% is used in relation to the amount of the pivalic acid used. The process according to any of claims 1 to 12, characterized in that the trichloromethyl compound used in the washing zone is introduced completely into the reaction zone. 14. The method according to any of claims 1 to 13, characterized in that the P1012 / 99MX aromatic trichloromethyl compound is trichloromethylbenzene (or phenylchloroform). P1012 / 99MX