PROCESS FOR THE PREPARATION OF DIBENZENESULFONIMIDE

Abstract

The present invention provides a process for the preparation of dibenzenesulfonimide.

Description

FIELD OF THE INVENTION

The present invention provides a process for the preparation of dibenzenesulfonimide of Formula I.

BACKGROUND OF THE INVENTION

The dibenzenesulfonimide of Formula I is a useful intermediate for the preparation of corresponding N-fluorosulfonimide of Formula II. The use of N-fluorosulfonimide for fluorination of nucleophilic organic compounds is well known. Further, these fluorine substituents play an important role in preparation of pharmaceutical and agrochemical agents.

where R₁ and R₂ are independently selected from group consisting of fluorine, chlorine, bromine, iodine, C_1-6 alkyl, C_1-6alkoxy, C_1-6alkylsulfonyl, C_1-6perfluoroalkylsulfonyl and cyano.

The process for the preparation of substituted and un-substituted benzenesulfonimides has been studied widely, for example, U.S. Pat. Nos. 2,891,979 and 5,254,732. Most recently the CN patent application 101671285 provides a process for preparation of dibenzenesulfonimide by reacting benzenesulfonamide with benzene sulfonyl chloride in the presence of sodium hydroxide and water.

The present inventors have observed that use of inorganic strong bases and water, such as alkali hydroxides and water, while condensation of benzenesulfonamide with benzene sulfonyl chloride results in great yield loss. This is primarily because benzene sulfonyl chloride gets hydrolysed to corresponding acid in the presence of inorganic strong bases and water, thus resulting in yield loss. Further, the inventors of the present invention found that the condensation of benzenesulfonamide with benzene sulfonyl chloride in the presence of compound of Formula V results in unexpected increase of reaction yield and simultaneously avoids any side reactions.

OBJECT OF THE INVENTION

It is an object of the present invention to provide a process for the preparation of dibenzenesulfonimide of Formula I:

SUMMARY OF THE INVENTION

The present invention provides a process for the preparation of dibenzenesulfonimide of Formula I,

the process comprising;

• • a) treating compound of Formula III with compound of Formula IV in the presence of compound of Formula V,

• • where R₁ and R₂ are independently selected from group consisting of fluorine, chlorine, bromine, iodine, C_1-6 alkyl, C_1-6alkoxy, C_1-6alkylsulfonyl, C_1-6perfluoroalkylsulfonyl and cyano,
  • the R₃, R₄ and R₅ are independently selected from optionally substituted C_1-6alkyl and optionally substituted C_1-6 aryl,
  • b) isolating the compound of Formula I from the reaction mixture.

DETAILED DESCRIPTION OF THE INVENTION

In an aspect, the present invention provides a process for the preparation of dibenzenesulfonimide of Formula I,

the process comprising;

• • a) treating compound of Formula III with compound of Formula IV in the presence of compound of Formula V,

where R₁ and R₂ are independently selected from group consisting of fluorine, chlorine, bromine, iodine, C_1-6 alkyl, C_1-6 alkoxy, C_1-6alkylsulfonyl, C_1-6perfluoroalkylsulfonyl and cyano,

• • the R₃, R₄ and R₅are independently selected from optionally substituted C_1-6 alkyl and optionally substituted C_1-6 aryl,
  • b) isolating the compound of Formula I from the reaction mixture.

The compounds of Formula III and Formula IV are obtainable by known processes or commercially available. The condensation of compound of Formula III and compound of Formula IV takes place in the presence of compound of Formula V. The condensation of compound of Formula III and compound of Formula IV may take place at a temperature of about 0° C. to about 100° C., for example, about 10° C. to about 40° C. for about 10 minutes to about 10 hours, for example, for about 2 hours to about 5 hours. The condensation of compound of Formula III and compound of Formula IV may take place in the presence of solvent, for example, acetonitrile. The condensation may be facilitated by stirring the reaction mixture. The reaction completion is monitored by High Performance Liquid Chromatography.

The compound of Formula I is isolated from the reaction mixture by layer separation, distillation, filtration, evaporation and decantation or mixture thereof. The compound of Formula I, obtained by present invention, has the purity greater than about 98%, preferably greater than 98.5%, more preferably greater than 99% by High Performance Liquid Chromatography.

While the present invention has been described in terms of its specific embodiments, certain modifications and equivalents will be apparent to those skilled in the art and are intended to be included within the scope of the present invention.

EXAMPLE

Example 1

Preparation of Dibenzenesulfonimide

Benzenesulfonamide (50 g), acetonitrile (150 g) and triethylamine (97 g) were taken in a reaction vessel and stirred for 45 minutes. The benzene sulfonyl chloride (69 g) was added drop-wise to the reaction mixture at 20° C. The reaction mixture was additionally stirred at 25° C. for 45 minutes. The acetonitrile was recovered by evaporation and solid reaction mass was dissolved in sodium hydroxide (20%, 300 g). The aqueous layer was separated, washed with chloroform and acidified with hydrochloric acid (35%) to obtain the title product.

Yield (g): 90

Purity (% by HPLC): 99.2

Claims

1. A process for the preparation of dibenzenesulfonimide of Formula I,

2. The process of claim 1, wherein step a) take place at a temperature in the range of 10° C. to 40° C.

3. The process of claim 1, wherein step a) takes place in the presence of solvent.

4. The process of claim 3, wherein the solvent is acetonitrile.

5. The process of claim 1, wherein step b) is carried out by layer separation, distillation, filtration, evaporation and decantation or mixture thereof.

6. The compound of Formula I, as obtained by the process of claim 1, has the purity greater than 98%.