Method for producing sulfonimide or its salt

Details Method for producing sulfonimide or its salt Method for producing sulfonimide or its salt

2000-02-15

2001-06-26

O'Sullivan, Peter (Department: 1621)

Organic compounds -- part of the class 532-570 series

Organic compounds

Amino nitrogen containing

C564S096000

Reexamination Certificate

active

06252111

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a sulfonimide or its salt. Sulfonimide compounds are useful as Lewis acid catalysts and ion transport agents, in the fields of organic compound syntheses, electrolytes and the like.
U.S. Pat. No. 5,723,664, corresponding to Japanese Patent Publication JP-A-8-81436, discloses a method for producing a sulfonimide or its salt. The product obtained by this method, however, may contain an impurity such as (1) a sulfonamide represented by the general formula RfSO
2
NH
2
or (2) a sulfonic acid represented by the general formula RfSO
3
H. The removal of this impurity may prevent a problem of the decrease of potential of an aluminum collector and other problems, when the product (i.e., lithium salt of sulfonimide) is used for electrolyte of a lithium cell.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a method for producing a sulfonimnide or its salt with high purity, which method is economical in an industrial scale production.
According to the present invention, there is provided a method for producing a sulfonimide represented by the general formula (1), an alkali metal salt thereof represented by the general formula (2), or another salt thereof represented by the general formula (3).
H[Rf
1
SO
2
—N—SO
2
Rf
2
]  (1)
where Rf
1
and Rf
2
represent the same or different groups each of which has a carbon atom number from 1 to 12 and is straight-chain or branched-chain and one selected from the group consisting of perfluoroalkyl groups, fluoroalkyl groups, fluoroalkenyl groups and fluoroallyl groups,
 A[Rf
1
SO
2
—N—SO
2
Rf
2
]  (2)
where A is an alkali metal selected from the group consisting of K, Na and Li, and Rf
1
and Rf
2
are defined as above,
M
1
[Rf
1
SO
2
—N—SO
2
Rf
2
]
n1
  (3)
where M
1
represents a positive ion having a first valence, Rf
1
and Rf
2
are defined as above, and n1 represents an integer that is the same as said first valence. This method comprises (a) reacting a precursory salt of said sulfonimnide with a base contained in a basic aqueous solution, said base being selected from the group consisting of potassium hydroxide, sodium hydroxide and lithium hydroxide, said precursory salt being represented by the general formula (4) and formed when said sulfonimide is reacted with a tertiary amine or a heterocyclic amine, said tertiary amine being represented by the general formula (5), thereby producing a first aqueous solution comprising said alkali metal salt and an amine; (b) removing said amine from said first aqueous solution to obtain a second aqueous solution comprising said alkali metal salt; and (c) crystallizing said alkali metal salt in said second aqueous solution,
M
2
[Rf
1
SO
2
—N—SO
2
Rf
2
]
n2
  (4)
where M
2
represents a positive ion having a second valence, Rf
1
and Rf
2
are defined as above, and n2 represents an integer that is the same as said second valence,
(R
1
)
3
N  (5)
where R
1
represents the same ox different alkyl groups each having a carbon atom number of from 1 to 5.
According to the invention, it becomes possible to obtain the alkali metal salt with high purity by crystallizing the alkali metal salt in the second aqueous solution.
In the invention, the method further optionally comprises reacting said alkali metal salt, which has been obtained by the crystallizing, with a strong acid, thereby producing the sulfonimide. The method still further optionally comprises reacting the sulfonimide with a compound selected from the group consisting of metal hydroxides, metal oxides, metal carbonates, metal acetates, ammonia and substituted ammonias, thereby producing said another salt of said sulfonimide with high purity.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
It is possible to conduct the crystallization of the alkali metal salt in the second aqueous solution by adjusting the concentration of a base (e.g., potassium hydroxide), which is the same as that used in the reaction with the precursory salt of the sulfonimide, in the second aqueous solution. This adjustment can be conducted by adding the base to the second aqueous solution to increase the concentration.
Prior to the reaction of the precursory salt of the sulfonimnide with the base, it is optional to conduct the following exemplary reactions, as follows. At first, one or two sulfonyl fluorides or chlorides, which are represented by the formulas Rf
1
SO
2
NH
2
and Rf
2
SO
2
X, are reacted with a tertiary amine, which is represented by the formula (R
1
)
3
N, as expressed by the following reaction formula.
Rf
1
SO
2
NH
2
+Rf
2
SO
2
X+2(R
1
)
3
N→(R
1
)
3
NH
+
(Rf
1
SO
2
NSO
2
Rf
2
)
−
+(R
1
)
3
NH
+
X
−
where Rf
1
, Rf
2
and R
1
are defined as above, and X is fluorine or chlorine. This reaction is disclosed in U.S. Pat. No. 5,723,664, of which disclosure is incorporated herein by reference. Then, the obtained precursory salt of the sulfonimide, which is represented by the formula (R
1
)
3
NH
+(Rf
1
SO
2
—N—SO
2
Rf
2
)—, is reacted with the base, which is represented by AOH, by adding the base to the reaction product, as expressed by the following reaction formula.
(R
1
)
3
NH
+(Rf
1
SO
2
NSO
2
Rf
2
)
−
+(R
1
)
3
NH
+
X
−
+2AOH→A
+
(Rf
1
SO
2
NSO
2
Rf
2
)
−
+2(R
1
)
3
N+A
+
X
31
+2H
2
O
where A is defined as above. Then, a by-product, which is represented by the formula AX and insoluble, is removed from the reaction product (first aqueous solution) by filtration. After that, another by-product, that is, tertiary amine represented by the formula (R
1
)
3
N, is distilled away, thereby obtaining the second aqueous solution. Then, the base, which is the same as that used in the reaction with the precursory salt, is added to the second aqueous solution such that the alkali metal salt, which is represented by the formula A[Rf
1
SO
2
—N—SO
2
Rf
2
], is crystallized in the remaining aqueous solution. With this crystallization, the alkali metal salt is separated from an impurity dissolved in the remaining aqueous solution. Therefore, it becomes possible to obtain the alkali metal salt with high purity by filtration. This impurity may contain (1) a sulfonamide salt represented by the general formula RfSO
2
NHA and/or (2) a sulfonate represented by the general formula RfSO
3
A where Rf is identical with the abovedefined Rf
1
or Rf
2
and A is defined as above. The thus obtained alkali metal salt may be reacted with a strong acid (e.g., concentrated sulfric acid), followed by distillation, thereby obtaining the sulfonimide represented by the formula H[Rf
1
SO
2
—N—SO
2
Rf
2
]. Furthermore, this sulfonimide may be reacted with a compound selected from the group consisting of metal hydroxides, metal oxides, metal carbonates, metal acetates, ammonia and substituted ammonias, thereby producing the another salt of the sulfonimide with high purity, represented by the formula M
1
[Rf
1
SO
2
—N—SO
2
Rf
2
]
n1
.
In case that the base is potassium hydroxide, the reaction of the precursor salt with the base can be conducted at a temperature of 80-90° C. Within this range, it becomes possible to distill the tertiary amine (R
1
)
3
N away. If the reaction temperature is out of this range, the amine may be dissolved into the potassium hydroxide aqueous solution. With this, the degree of the crystallization of the alkali metal salt from the aqueous solution may become insufficient. The concentration of the potassium hydroxide in the potassium hydroxide aqueous solution is adjusted to preferably at least 1.5 moles, more preferably falling within a range of 1.5-3.6 moles, per liter of the potassium hydroxide aqueous solution. If it is less than 1.5 moles per liter, the degree of crystallization of the alkali metal salt (potassium sulfonimide) may become insufficient. If it is greater than 3.6 moles per liter, the above-mentioned impurities, that

Affiliated with

Also associated with

Rating

Method for producing sulfonimide or its salt does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Method for producing sulfonimide or its salt, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for producing sulfonimide or its salt will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2463847