PROCESS FOR THE PREPARATION OF AROMATIC OR HETEROAROMATIC SULFONYL HALIDES

Abstract: The present invention is directed to a process for preparing an aromatic or heteroaromatic sulfonyl halide represented by the formula (3), the process comprising halogenating an aromatic or heteroaromatic methyl sulfide represented by the formula (1) or an aromatic or heteroaromatic methyl sulfoxide represented by the formula (2) with a halogenating agent in the presence of water Ar(SCH 3-m X m ) n Ar(SOCH 3-m X m ) n Ar(SO 2 Y) n wherein Ar is an aromatic ring or a heteroaromatic ring which is unsubstituted or which has an optional substituent or substituents, X and Y are halogen atoms, m is an integer of 0 to 3 and n is 1 or 2. According to the present invention, aromatic or heteroaromatic sulfonyl halides can be produced industrially cheaply and easily.

Description: The present invention relates to a process for preparing aromatic or heteroaromatic sulfonyl halides. Aromatic or heteroaromatic sulfonyl halides are useful compounds which are used in various applications such as pharmaceuticals, agricultural chemicals, and functional materials. Many processes have been known for preparing aromatic sulfonyl halides. These processes are classified as follows. (A) Process involving sulfonation Halogen substitution reaction of sulfonate R. Adams, C.S. Marvel, Org. Synth., I,84 (1941) Sulfonation with chlorosulfuric acid or the like M.S. Morgan, L.H. Cretcher, J. Am. Chem. Soc., 70.375 (1948) (B) Process involving formation of diazonium salt H. Meerwein, E. Buchner, K. van Emster, J. Prakt, Chem., [2]152.251 (1939) (C) Process utilizing metallization reaction T. Hamada and O. Yonemitsu, Synthesis, 1986, 852 (D) Process involving chlorination of thiol derivative I.B. Douglass, T.B. Johnson, J. Am. Chem. Soc., 60, 1486 (1938) Y. J. Park, H. Hyun, Y.H. Kim, Chem. Lett., 1483, 1992 However, these known processes entail the following drawbacks when industrially carried out. In the process (A), it is difficult to conduct the reaction when there is an aromatic ring having a nitro group, a cyano group, a carboxyl group or the like attached, or a pyridine ring. In this process, generally at least two halogenated sulfonyl groups cannot be easily introduced into one aromatic ring. This process (B) tends to involve a lengthy procedure and poses a problem about the disposal of waste water which arises from the use of a large amount of copper salt. Thus, the process is undesirable from the viewpoints of economy and the protection of the environment. Further, a diazonium salt itself is far from being stable and is problematic as to safe operation. The process (C), if industrially practised, is not economical in many instances because of a low yield and the use of an expensive reagent. In the process (D), the aromatic substituted thiol derivative used as a raw material is often difficult to obtain at low cost on an industrial scale. In addition, EP-A-0094821 discloses the halogenation of an aryl methyl sulphide to a sulphonyl halide in the presence of water and a halogenating agent. J.C.S. Chem. Comm. 1973, No.2., p.50 teaches the chlorination of PhSCH 2 Cl in the presence of water and chlorine. As described above, conventional processes for preparing aromatic sulfonyl halides are uneconomical and are not easy to industrially carry out in most cases. Consequently there has been a demand for processes capable of industrially manufacturing various aromatic sulfonyl halide derivatives at low cost. It is an object of the present invention to provide a process for preparing an aromatic or heteroaromatic sulfonyl halide industrially at low costs and with ease. The present inventors conducted extensive research to overcome the foregoing prior art drawbacks and have found that the contemplated aromatic or heteroaromatic sulfonyl halides can be produced in high yield when using an aromatic or heteroaromatic sulfoxide as the raw material, and halogenating said compound in the presence of water. While the reaction mechanism remains to be clarified, it is presumed that a bond between the sulfur atom and the carbon atom of the methyl group in the aromatic or heteroaromatic methyl sulfoxide used as the raw material is selectively and easily split, and the oxidation or halogenation of the sulfur atom occurs substantially coincidentally. The present invention provides a process for producing a sulphonyl halide of formula (3) Ar―(SO 2 Y) n wherein Ar is an aromatic ring or a heteroaromatic ring which is unsubstituted or substituted by one or more substituents, Y is a halogen and n is 1 or 2, which process comprises halogenating a methyl sulfoxide of formula (2) Ar―(SOCH 3-m X m ) n wherein X is a halogen, m is 0 or an integer of 1 to 3 and Ar and n are as defined above, with a halogenating agent in the presence of water. According to the present invention, a halogenated sulfonyl group can be easily introduced into an aromatic ring having a cyano group or the like as a substituent, or a pyridine ring, and one or two halogenated sulfonyl groups can be easily introduced into one aromatic ring. Before now, however, such a synthesis has been difficult or a multi-step procedure has been necessitated. The sulfoxide represented by the formula (2), which is used as the raw material in the present invention includes those prepared by any methods and can be more easily prepared, e.g. by the process for preparing 2,5-dichloroalkylthiobenzene which process was elucidated by the present inventors (Japanese Unexamined Patent Publication (Kokai) No. S6760/1994). A sulfide can be easily prepared by reacting an aromatic or heteroaromatic compound having no substituent or having one or more substituents with an alkanethiol in a heterogeneous system, that is, in the presence of a base and a quaternary ammonium salt as a catalyst in water or a water/water-insoluble organic solvent mixture. The sulfoxide can be produced by the oxidation or halogenation of the obtained sulfide. The aromatic or heteroaromatic rings represented by Ar in the formulas are not specifically limited in the present invention and include a wide variety of aromatic or heteroaromatic rings which are unsubstituted or which have an optional substituent or substituents. Examples of useful aromatic or heteroaromatic rings are a benzene ring, naphthalene ring, pyridine ring, pyrazole ring, pyrazine ring, triazine ring, triazole ring, oxazole ring, isoxazole ring, thiazole ring, isothiazole ring, thiophene ring, benzothiophene ring, furan ring, benzofuran ring, pyrrole ring, indole ring, etc. Preferred examples are a benzene ring, pyridine ring, thiophene ring, thiazole ring and isothiazole ring. Examples of optional substituents are halogen, cyano group, nitro group, formyl group, alkylcarbonyl group, carboxyl ester group, carbamoyl group, alkyl group, alkoxyl group, substituted phenylthio group, etc. X in the sulfoxide of the formula (2) represents a chlorine atom or a bromine atom. From an economic viewpoint the compound wherein X is a chlorine atom is preferred. While m is an integer of 0 to 3, a compound wherein m is 0 is generally easily available. However, when the yield of the desired product is to be increased, a better result is given by a compound wherein m is 1, namely a halomethyl sulfoxide, or a compound wherein m is 2, namely a dihalomethyl sulfoxide. In the present invention, the reaction is made to proceed for converting a sulfoxide to a sulfonyl halide in a high yield by the addition of a halogenating agent in the presence of water. The amount of water to be used in the present invention is not specifically determinable since it is variable depending on sulfoxide selected as the raw material. Yet, usually the amount of water to be used is 1 to 100 moles, preferably 3 to 50 moles, per mole of sulfoxide used as the raw material. The Halogenating agent used in the reaction includes, for example, chlorine, bromine, sulfuryl chloride, sulfuryl bromide and so on among which chlorine is preferred from the economical viewpoint. The amount of the halogenating agent to be used is not specifically determinable because it is variable depending on the raw material used. Yet, usually the amount is 2 to 50 moles, preferably 3 to 20 moles, per mole of the sulfoxide used as the raw material. There is no specific limitation on the solvent insofar as it is inert to the sulfonyl halides produced. While water can be used, useful solvents are various and include hydrocarbons such as hexane, cyclohexane and heptane, halogenated hydrocarbons such as dichloroethane, dichloromethane and chloroform, and aromatic hydrocarbons such as chlorobenzene, dichlorobenzene and trichlorobenzene. When a solvent is used, the amount of the solvent is not specifically limited but is usually 0.1 to 10 times the weight of the sulfoxide. The reaction temperature is usually in the range of -10 to 100°C, preferably 0 to 50°C. If the reaction temperature is too low, the reaction rate is reduced, whereas if the reaction temperature is too high, a side reaction occurs, leading to a low yield. The reaction time is usually in the range of about 0.5 to about 10 hours. The aromatic or heteroaromatic sulfonyl halide thus obtained can be easily isolated by common distillation or crystallization. The aromatic or heteroaromatic sulfonyl halides which can be produced according to the present invention include various compounds such as 4-chlorobenzenesulfonyl chloride, 4-bromobenzenesulfonyl bromide, 2,5-dichlorobenzenesulfonyl chloride, 1,2-benzenedisulfonyl chloride, 4-nitrobenzenesulfonyl chloride, 2-nitrobenzenesulfonyl chloride, 4-cyanobenzenesulfonyl chloride, 2-cyanobenzenesulfonyl chloride, 4-methylbenzenesulfonyl chloride, (4-chlorosulfonylphenyl)ethyl ketone, 4-chlorosulfonylbenzoic acid amide, 4-chlorosulfonylbenzoic acid methyl ester, 2-cyano-3-chlorobenzenesulfonyl chloride, (4-chlorosulfonylphenyl)phenyl sulfide, 2-chlorosulfonylpyridine, 2,6-dichlorosulfonylpyridine, 2-chlorosulfonylthiophene, 2,5-dichlorosulfonylthiophene, 2-chlorosulfonylpyrazine, 4-chlorosulfonyltriazole, 2-chlorosulfonyloxazole, 4-chlorosulfonylisoxazole, 2-chlorosulfonylthiazole, 4-chlorosulfonylisothiazole and so on. Preferred are 2-cyanobenzenesulfonyl chloride, 4-cyanobenzenesulfonyl chloride, 2-nitrobenzenesulfonyl chloride and 4-nitrobenzenesulfonyl chloride. The compounds which can be produced in the present invention are not limited at all to the examples given above. The present invention provides a novel process for preparing aromatic or heteroaromatic sulfonyl halides which are used in various applications as pharmaceuticals, agricultural chemicals, functional materials and so on. According to the process of the present invention, the contemplated product can be obtained in a high yield by a simple process comprising halogenating an industrially available aromatic or heteroaromatic methyl sulfoxide in the presence of water. Thus, the process of the invention is of economically, industrially high value. The present invention is described-below in more detail with reference to the following examples. Reference Example 1 4-cyanophenyl methyl sulfide used as the raw material was prepared in accordance with the process disclosed in Japanese Unexamined Patent Publication (Kokai) No. 56760/1994. Stated more specifically, 165.1 g (1.2 moles) of 1-chloro-4-cyanobenzene and 17.8 g (0.055 mole) of tetra-n-butylammonium bromide as a phase transfer catalyst were added to a 2-liter, 4-necked flask equipped with a stirrer, thermometer and condenser. Then, 616.0 g (1.3 moles) of an aqueous solution of a sodium salt of methanethiol adjusted to a concentration of 15% by weight was added. The mixture was stirred at 80°C for 3 hours. The reaction mixture was cooled to room temperature, and the precipitated crystals were collected by filtration and recrystallized from methanol, giving 170.4 g of 4-cyanophenyl methyl sulfide. The 4-cyanophenyl methyl sulfide thus obtained (149.0 g, 1.00 mole) was charged into a 2-liter, 4-necked flask equipped with a stirrer, thermometer, condenser and gas inlet tube. To the flask was added 80 g of water and 800 g of monochlorobenzene after which 497 g (7.00 moles) of chlorine was blown into the flask at 25°C over a period of about 5 hours to complete the reaction. After completion of the reaction, the oil layer was separated, about 50 g of anhydrous sodium sulfate was added and the mixture was left to stand for about 1 hour to remove-the water. Thereafter the solvent was distilled off to give crude crystals. The crude crystals were dissolved in monochlorobenzene. A poor solvent was added for recrystallization to produce 183.5 g of 4-cyanobenzenesulfonyl chloride as white crystals in a yield of 91% as calculated based on 4-cyanophenyl methyl sulfide. Examples 1 to 3 The same procedure as described in the latter part of Reference Example 1 was conducted with the exception of altering the aromatic or heteroaromatic methyl sulfide used as the starting material to the compounds as shown below in Tables 1 and 2, giving the corresponding aromatic or heteroaromatic sulfonyl chlorides.

Claims: A process for producing a sulphonyl halide of formula (3) : Ar―(SO 2 Y) n wherein Ar is an aromatic ring or a heteroaromatic ring which is unsubstituted or substituted by one or more substituents, Y is a halogen and n is 1 or 2, which process comprises halogenating a methyl sulfoxide of formula (2) : Ar―(SOCH 3-m X m ) n wherein X is a halogen, m is 0 or an integer of 1 to 3 and Ar and n are as defined above, with a halogenating agent in the presence of water. A process according to claim 1 wherein X is a chlorine atom. A process according to claim 1 wherein m is zero. A process according to claim 1 wherein m is 1 or 2. A process according to any one of the preceding claims wherein the halogenating agent is chlorine. A process according to any one of the preceding claims wherein Ar is a benzene, pyridine, thiophene, thiazole or isothiazole ring and is unsubstituted or substituted as defined in claim 1. A process according to claim 1 wherein Ar is an aromatic or heteroaromatic ring which is substituted by one or more substituents selected from halogen, cyano, nitro, formyl, alkylcarbonyl, alkyl, alkoxyl, substituted phenylthio, a carboxyl ester group and a carbomoyl group. A process according to any one of the preceding claims wherein the compound of formula (3) is 2-cyanobenzenesulfonyl chloride, 4-cyanobenzenesulfonyl chloride, 2-nitrobenzenesulfonyl chloride or 4-nitrobenzenesulfonyl chloride.

Inventors: GODA HIROSHI, KARINO HITOSHI, NISHIGUCHI HIDEAKI, SAKAMOTO JUN-ICHI, YOSHIDA KATSUHIKO, GODA, HIROSHI, KARINO, HITOSHI, NISHIGUCHI, HIDEAKI, SAKAMOTO, JUN-ICHI, YOSHIDA, KATSUHIKO, GODA, Hiroshi, Sumitomo Seika Chemicals Co., Ltd., KARINO, Hitoshi, Sumitomo Seika Chemicals Co., Ltd, NISHIGUCHI, Hideaki, Sumitomo Seika Chem. Co., Ltd, SAKAMOTO, Jun-ichi, Sumitomo Seika Chem. Co., Ltd., YOSHIDA, Katsuhiko, Sumitomo Seika Chem. Co., Ltd.
Applicants: SUMITOMO SEIKA CHEMICALS, SUMITOMO SEIKA CHEMICALS CO., LTD.
Application year: 1995
Main classification: C07C309
IPC codes: C07D241, C07C303, C07D263, C07C319, C07D277, C07C315, C07C323, C07D251, C07C309, C07D213, C07D275, C07C317