~™ llll III II II III II III I II II III (19) J European Patent Office Office europeen des brevets (1 1 ) EP0 751 131 A1 (12) EUROPEAN PATENT APPLICATION (43) Date of publication: (51) Int. CI.6: C07D 233/18, C07C 51/60, 02.01.1997 Bulletin 1997/01 C07C 303/02, C07B 41/1 0 (21) Application number: 96108936.4 (22) Date of filing: 04.06.1996 (84) Designated Contracting States: • Hayashi, Hidetoshi DE FR IT NL Ohmuta-shi, Fukuoka-ken, 836 (JP) • Mizuta, Hideki (30) Priority: 20.06.1995 JP 152826/95 Ohmuta-shi, Fukuoka-ken, 837 (JP) (71) Applicant: MITSUI TOATSU CHEMICALS, Inc. (74) Representative: Strehl Schubel-Hopf Groening & Chiyoda-Ku Tokyo 1 00 (JP) Partner Maximilianstrasse 54 (72) Inventors: 80538 Munchen (DE) • Nagata, Teruyuki Ohmuta-shi, Fukuoka-ken, 836 (JP) (54) A process for preparing an acyl halide or sulfonyl halide (57) A preparation process of acyl halide or sulfonyl halide which comprises reacting corresponding carboxylic acid or sulfonic acid with a haloiminium salt represented by the general formula (1): R'-N -R2 X ( 1 ) XCrU/n wherein R1 and R2 are same or different lower alkyl groups, X is a halogen atom, and n is an integer of 2 or 3. CO LO o Q_ LU Printed by Rank Xerox (UK) Business Services 2.13.10/3.4 EP0 751 131 A1 Description 1 . Field of the Invention 5 The present invention relates to a preparation process of acyl halide or sulfonyl halide. 2. Description of the Related Art In recent years, acyl halide has become important in industry as an intermediate for preparing heat resistant resin, 10 medicines and agricultural chemicals. For example, lauroyl chloride is used in industry as an intermediate in the prep- aration of peroxides and surface active agents. Further, terephthaloyl chloride is used for preparing polyesters in indus- try. 5-Amino-2,4,6-triiodoisophthaloyl dihalide which is obtained by halogenating the acid portion of 5-amino-2,4,6-trii- odoisophthalic acid (hereinafter referred to simply as TIPA) is an important compound as a raw material of X-ray con- 15 trast medium. Sulfonyl halide has also become important in industry as an intermediate for preparing medicines and agricultural chemicals. Acyl halide is generally prepared by chlorinating carboxylic acid with a chlorinating agent such as thionyl chloride, phosphorus pentachloride, phosphorus trichloride, phosphoryl chloride and phosgene. However, thionyl chloride, phos- 20 phorus pentachloride, phosphorus trichloride and phosphoryl chloride are expensive, and have problems on the treat- ment of sulfur oxides, phosphate compounds and other byproducts which are formed by the reaction. Thus, production in an industrial scale accompanies various disadvantages and difficulties in view of economy and environmental pro- tection. Further, phosgene has lower reactivity than the above chlorinating agents and requires use of a catalyst. Exem- plary catalysts which can be used include dimethylformamide, quaternary ammonium salt and sulfonium salt. 25 Dimethylformamide and other lower aliphatic amides are generally used as inexpensive catalysts having high activity. However, even though these catalysts are used, an active species which is formed from phosgene and dimethylfor- mamide and the other lower aliphatic amides is labile at high temperatures and leads to a problem of drastically increas- ing the formation velocity of tarry materials at temperatures higher than 100 °C. Further, sulfonyl halide is generally prepared, for example, by chlorinating sulfonic acid with a chlorinating agent 30 such as thionyl chloride and phosphorus pentachloride. For example, methanesulfonyl chloride is prepared from meth- anesulfonic acid and thionyl chloride. However, thionyl chloride, phosphorus pentachloride and other chlorinating agents are expensive, and have problems on the treatment of sulfur oxides, phosphate compounds and other byprod- ucts which are formed by the reaction. Thus, production in an industrial scale accompanies various disadvantages and difficulties in view of economy and environmental protection. Chlorosulfonic acid is frequently used for preparing sulfo- 35 nyl chloride in industry. For example, p-toluenesulfonyl chloride is prepared in industry from toluene and chlorosulfonic acid and benzenesulfonyl chloride is prepared in industry from benzene and chlorosulfonic acid. However, chlorosul- fonic acid causes a violent decomposition reaction with water and forms hydrochloric acid and sulfuric acid. Conse- quently, handling of chlorosulfonic acid accompanies considerable disadvantages and difficulties as a result of severe corrosivity and strong toxicity. 40 2-Chloro-1 ,3-dimethylimidazolinium chloride has been known as a halogenating agent of a primary hydroxyl group in Japanese Laid Open Patent Hei 4-308538. However, the example of utilizing the compounds for preparation of acyl halide or sulfonyl halide has not yet been known. SUMMARY OF THE INVENTION 45 The present invention has been carried out in order to overcome the problems on the conventional preparation process of acyl halide or sulfonyl halide. The first object of the invention is to provide an excellent preparation process in economy. The second object of the invention is to provide an excellent process in view of environmental protection. As a result of an intensive investigation in order to achieve these objects, the present inventors have completed the so invention having the following constitution. That is, the aspect of the invention is, 1) a preparation process of corresponding acyl halide or sulfonyl halide comprising reacting carboxylic acid or sul- fonic acid with a haloiminium salt represented by the general formula (1): 55 2 EP0 751 131 A1 wherein R1 and R2 are same or different lower alkyl groups, X is a halogen atom, and n is an integer of 2 or 3, and 2) a preparation process of corresponding acyl halide or sulfonyl halide comprising blowing phosgene into carbox- ylic acid or sulfonic acid in the presence of a cyclic urea compound represented by the general formula (2): wherein R1 and R2 are same or different lower alkyl groups, and n is an integer of 2 or 3, forming a haloiminium salt represented by the general formula (1): wherein R1 and R2 and n are the same as above, and X is a halogen atom, and reacting said carboxylic acid or said sulfonic acid with the haloiminium salt. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS The haloiminium salt which can be used in the invention is represented by the general formula (1). Exemplary lower alkyl groups represented by R1 and R2 in the general formula (1) include lower alkyl groups having 1 - 4 carbon atoms such as a methyl, ethyl, n-propyl, isopropyl, n-butyl and isobutyl group. Exemplary halogen atoms represented by X include a fluorine, chlorine, bromine and iodine atom. The chlorine atom is preferred in particular. Preferred examples of the haloiminium salt represented by the gen- eral formula (1) include 2-chloro-1,3-dimethylimidazolinium chloride (hereinafter referred to simply as DMC), 2-chloro- 1 ,3-diisopropylimidazolinium chloride, and 2-chloro-1,3-dimethyl-3,4,5,6-tetrahydropyrimidinium chloride. The haloiminium salt can be obtained with ease by reacting a cyclic urea compound which is known as a readily available solvent and is represented by the formula (2): wherein R1 and R2 and n are the same as above, with a known halogenating agent such as oxalyl halide, phosphorus trihalide. phosphorus pentahalide, phosphorus oxyhalide, phosgene and trichloromethyl chloroformate. Phosgene is now in mass production in a polyurethane industry, inexpensive, and free from generation of industrial wastes such as EP0 751 131 A1 phosphorus compounds, and thus is most preferred. The reaction is carried out by dissolving either the compound of the general formula (2) or the halogenating agent in a suitable solvent such as carbon tetrachloride, adding the other reagent by portions to the solution obtained, and reacting for several to dozens of hours at room temperature to 70°C. The haloiminium salt of the general formula (1) 5 thus obtained can be used after isolation. However, the reaction mixture can also be used as intact for the reaction of the invention without isolating the haloiminium salt. In the first place, the method for reacting the haloiminium salt with carboxylic acids will be illustrated. The amount of the haloiminium salt is stoichiometric or more, preferably 1 .0 - 2.0 times by equivalent, more prefer- ably 1.1 - 1 .3 times by equivalent for the carboxylic acid. 10 After finishing the reaction, the haloiminium salt returns to the compound represented by the formula (2), and the compound can be converted again into the haloiminium salt by reacting with the halogenating agent. The invention includes embodiments for reacting formed iminium chloride with carboxylic acid while preparing imi- nium chloride wherein X is chlorine atom in the general formula (1). That is, the desired acid chloride can be obtained by charging phosgene into a solution containing the carboxylic acid raw material and the cyclic urea compound of the 15 general formula (2). In the reaction, the cyclic urea of the general formula (2) reacts at first with phosgene to form imi- nium chloride wherein X is chlorine atom in the general formula (1), and successively carboxylic acid is halogenated by iminium chloride to form the desired carbonyl chloride. In this step, iminium chloride wherein X is chlorine atom in the general formula (1) returns to original cyclic urea of the general formula (2). Consequently, the amount of cyclic urea of the general formula (2) for use in the reaction is preferably 0.01 equiv- 20 alent or more, more preferably 0.05 - 0.1 equivalent for an equivalent of carboxylic acid. Use of cyclic urea in still more amount does not increase reaction velocity. The amount of phosgene used in the reaction is 1 .0 - 2.0 equivalents, preferably 1.1 - 1 .3 equivalents for an equiv- alent of carboxylic acid.