PROCESS FOR THE PREPARATION OF DIBENZENESULFONIMIDE
FIELD OF THE INVENTION
The present invention provides a process for the preparation of
5 dibenzenesulfonimide of Formula I.
BACKGROUND OF THE INVENTION
The dibenzenesulfonimide of Formula I is a useful intermediate for the preparation
10 of corresponding N-fluorosulfonimide of Formula II. The use of Nfluorosulfonimide
for fluorination of nucleophilic organic compounds is well
known. Further, these fluorine substituents play an important role in preparation of
pharmaceutical and agrochemical agents.
S
N
S
O
O
O
O
R H 1 R2
15 Formula I
S
N
S
O
O
O
O
R F 1 R2
Formula II
where R1 and R2 are independently selected from group consisting of
20 fluorine, chlorine, bromine, iodine, C1-6 alkyl, C1-6alkoxy, C1-6alkylsulfonyl, C1-
6perfluoroalkylsulfonyland cyano.
2
The process for the preparation of substituted and un-substituted
benzenesulfonimides has been studied widely, for example, US Patent Nos.
2,891,979 and 5,254,732. Most recently the CN patent application 101671285
provides a process for preparation of dibenzenesulfonimide by reacting
5 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
10 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.
15
OBJECT OF THE INVENTION
It is an object of the present invention to provide a process for the preparation of
dibenzenesulfonimide of Formula I:
S
N
S
O
O
O
O
R H 1 R2 20
Formula I
25
3
SUMMARY OF THE INVENTION
The present invention provides a process for the preparation of
dibenzenesulfonimide of Formula I,
S
N
S
O
O
O
O
R H 1 R2
5 Formula I
the process comprising;
a) treating compound of Formula III with compound of Formula IV in the
presence of compound of Formula V,
S
NH2
O
O
R1
10 Formula III
S
Cl
O
O
R2
Formula IV
N
R5
R4
R3
15
Formula V
4
where R1 and R2 are independently selected from group consisting of
fluorine, chlorine, bromine, iodine, C1-6 alkyl, C1-6alkoxy, C1-6alkylsulfonyl, C1-
6perfluoroalkylsulfonyl and cyano,
the R3, R4 and R5 are independently selected from optionally substituted C1-6
5 alkyl and optionally substituted C1-6 aryl, and
b) isolating the compound of Formula I from the reaction mixture.
DETAILED DESCRIPTION OF THE INVENTION
10 In an aspect, the present invention provides a process for the preparation of
dibenzenesulfonimide of Formula I,
S
N
S
O
O
O
O
R H 1 R2
Formula I
the process comprising;
15 a) treating compound of Formula III with compound of Formula IV in the
presence of compound of Formula V,
S
NH2
O
O
R1
Formula III
5
S
Cl
O
O
R2
Formula IV
N
R5
R4
R3
5 Formula V
where R1 and R2 are independently selected from group consisting of
fluorine, chlorine, bromine, iodine, C1-6 alkyl, C1-6 alkoxy, C1-6alkylsulfonyl,
C1-6perfluoroalkylsulfonyl and cyano,
10 the R3, R4 and R5are independently selected from optionally substituted C1-6
alkyl and optionally substituted C1-6 aryl, and
b) isolating the compound of Formula I from the reaction mixture.
The compounds of Formula III and Formula IV are obtainable by known processes
15 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 0oC to about 100oC, for example, about 10oC to
about 40oC for about 10 minutes to about 10 hours, for example, for about 2 hours to
20 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.
6
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. 5
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.
10
EXAMPLE
Example 1
Preparation of Dibenzenesulfonimide
Benzenesulfonamide (50 g), acetonitrile (150 g) and triethylamine (97 g) were taken 15 in a reaction vessel and stirred for 45 minutes. The benzene sulfonyl chloride (69 g) was added drop-wise to the reaction mixture at 20oC. The reaction mixture was additionally stirred at 25oC 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 20 hydrochloric acid (35%) to obtain the title product.
Yield (g): 90
Purity (% by HPLC): 99.2

We claim:
1. A process for the preparation of dibenzenesulfonimide of Formula I,
S
N
S
O
O
O
O
R H 1 R2 5
Formula I
the process comprising;
a) treating compound of Formula III with compound of Formula IV in the
presence of compound of Formula V,
S
NH2
O
O
10 R1
Formula III
S
Cl
O
O
R2
Formula IV
15
N
R5
R4
R3
Formula V
8
where R1 and R2 are independently selected from group consisting of fluorine, chlorine, bromine, iodine, C1-6 alkyl, C1-6alkoxy, C1-6alkylsulfonyl, C1-6perfluoroalkylsulfonyl and cyano,
the R3, R4 and R5 are independently selected from optionally substituted C1-6 alkyl and optionally substituted C1-6 aryl, and 5
b) isolating the compound of Formula I from the reaction mixture.
2. The process of claim 1, wherein step a) take place at a temperature in the range of 10oC to 40oC.
3. The process of claim 1, wherein step a) takes place in the presence of 10 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 15 purity greater than 98%.