Organic compounds -- part of the class 532-570 series – Organic compounds – Sulfonic acids or salts thereof
Reexamination Certificate
2002-03-20
2002-11-12
McKane, Joseph K. (Department: 1626)
Organic compounds -- part of the class 532-570 series
Organic compounds
Sulfonic acids or salts thereof
C562S119000
Reexamination Certificate
active
06479698
ABSTRACT:
The present invention relates to a process for preparing sulfonate salts via alkaline hydrolysis of the corresponding sulfonyl chlorides.
The conventional method for obtaining a sulfonate salt from a sulfonyl chloride consists in carrying out the hydrolysis of the sulfonyl chloride using inexpensive bases, such as alkali metal or alkaline earth metal carbonates or hydroxides, e.g. sodium hydroxide. However, the literature includes only a few cases of alkaline hydrolysis of sulfonyl chloride by this kind type of bases: mention may be made, among these rare examples, of R. N. Haszeldine (J. Chem. Soc., 2901 (1955)), who describes a quantitative alkaline hydrolysis of trifluoromethanesulfonyl chloride by 15% sodium hydroxide, i.e. by a sodium hydroxide solution with a relatively low concentration.
It should be noted that the hydrolysis of a sulfonyl chloride, and in particular of a (per)fluorinated sulfonyl chloride, is generally difficult to carry out, especially because of the covalent nature of the SO
2
—Cl bond, and in view of the fact that these substrates are generally better oxidizing agents than electrophiles. In this respect, it should actually be emphasized that similar compounds, such as sulfuryl chloride SO
2
Cl
2
, are commonly used as chlorinating agents. Generally, sulfonyl chlorides are therefore often not very reactive with respect to the hydrolysis reaction.
Consequently, the problem encountered during the alkaline hydrolysis of a sulfonyl chloride is as follows: the hydrolysis reaction of the sulfonyl chloride is a reaction which, on the one hand, intrinsically has a significant exothermic nature and which, on the other hand, is characterized by significant inertia, due to the fact that the reactants are present in two, separate phases, which accentuates the exothermicity of the reaction. This inertia does not give rise to any complication during the hydrolysis of small amounts and/or with dilute alkaline solutions, such as those described in the literature; however, it raises real safety problems as soon as attempts are made to carry out the reaction with higher concentrations of base and/or on industrial amounts: this is because the inertia of the reaction then leads to a buildup of sulfonyl chloride during the reaction which can represent up to 20% of the amount of sulfonyl chloride introduced and which, in conjunction with the high intrinsic exothermicity of the hydrolysis reaction, can lead to runaway of the reaction.
To avoid such problems, the only currently existing solution consists in carrying out the alkaline hydrolysis by means of a dilute hydroxide solution, which involves removing the water by additional distillation stages, harmful in terms of industrial productivity.
The aim of the present invention is specifically to provide a method for the preparation of sulfonate salts which are simultaneously inexpensive, fast and reliable, by carrying out the alkaline hydrolysis of a sulfonyl chloride with a concentrated basic solution, but while avoiding the problem of buildup of the sulfonyl chloride due to the inertia of the reaction.
More specifically, the resent invention relates to a process for preparing an alkali metal or alkaline earth metal sulfonate salt corresponding to the anion of general formula (I):
R—CF
2
—SO
3
31
(I),
wherein R is:
(a) a hydrogen atom;
(b) a halogen, preferably a light halogen (that is to say, with an atomic number at most equal to that of chlorine), and more preferably fluorine;
(c) an alkyl chain optionally substituted by one or more halogen atom(s);
(d) an alkenyl chain optionally substituted by one or more halogen atom(s);
(e) an aryl group which is optionally substituted by one or more halogen atom(s) and which can comprise one or more heteroatoms;
(f) an arylalkyl group optionally substituted by one or more halogen atom(s), it being possible for the aryl group to comprise one or more heteroatoms; or
(g) a sulfonyl heavy halide group,
with it being possible for R, when it is a group as defined in (c), (d), (e) and (f), to be substituted by a sulfonyl heavy halide group,
said sulfonate salt being obtained from a sulfonyl chloride of general formula (II)
R—CF
2
—SO
2
Cl
wherein R is as defined above,
said process comprising at least one stage of alkaline hydrolysis of the sulfonyl chloride (II) in the presence of at least one compound acting as a phase transfer agent.
The R group present in the sulfonyl chlorides employed in the process of the invention is preferably an electron-withdrawing group, that is to say a radical with a &sgr;p value generally greater than 0, preferably greater than 0.1 and advantageously at least equal to 0.5.
R is advantageously a fluorine atom or a perfluoroalkyl radical R
f
optionally substituted by a sulfonyl heavy halide group.
Within the meaning of the invention, a sulfonyl heavy halide group refers to a group carrying a sulfonyl halide functional group or a halogen and chlorine or bromine and preferably chlorine and for which the carbon atom adjoining the sulfur atom is perhalogenated by halogens with an atomic number at most equal to that of chlorine and is preferably perfluorinated. This group can have from 1 to 10 carbon atoms.
Thus, the claimed process s especially suitable for preparing alkali metal or alkaline earth metal sulfonate salts which exhibit at least one, indeed even two, sulfonyl group(s), the carbon atom(s) adjoining the sulfur atom(s) being perfluorinated.
These bisulfonate compounds can be useful in particular for preparing polymeric compounds or alternatively cyclic compounds, when the number of linking units separating the two sulfonate functional groups is 2, 3 or 4. The linking units which separate the two sulfonate functional groups are advantageously CF
2
linking units.
Furthermore, it should be pointed out that the, carbonaceous chains present in the sulfonyl chlorides employed in the process of the invention are preferably saturated chains, so as in particular to avoid phenomena of untimely polymerization. Furthermore, the sulfonyl chlorides employed in the process of the invention generally comprise a total carbon atom number advantageously of less than 30.
Within the meaning of the present invention, the term “phase transfer agent” denotes a compound capable of compensating for the inertia of the hydrolysis reaction and of preventing the problem of the buildup of the sulfonyl chloride due to the fact that the reactants are found in two separate phases.
This phase transfer agent may be either of cryptant type, such as crown ethers, or of onium type, or an alcohol.
Thus, according to a first aspect of the invention, the role of phase transfer agent is played by a phase transfer agent of onium cation type.
Oniums are compounds with names, in the nomenclature, comprising the sequence of letters “onium” as affix, generally as suffix. They are semimetallic compounds, in particular from the nitrogen column and from the sulfur column, which are sufficiently substituted to carry a positive charge. Thus, the atoms from the nitrogen column, when they are substituted four times by a hydrocarbonaceous radical, constitute oniums.
Thus, quaternary ammoniums or quaternary phosphoniums can be used as phase transfer agent.
Sulfoniums (tertiary in their case) themselves also constitute phase transfer agents, but they are less advantageous, since they are relatively more unstable than the others.
The oniums used as phase transfer agent are known to a person skilled in the art.
The most commonly used are tetraalkylammoniums and tetraalkyl- or tetraphenylphosphoniums. The latter exhibit, however, the disadvantage of being relatively expensive.
The preferred phase transfer agents among said, onium cations are tetraalkylammonium comprising saturated, unsaturated or aromatic hydrocarbonaceous chains comprising a total of 4 to 28 carbon atoms, preferably of 4 to 16 carbon atoms.
To avoid &bgr;-elimination reactions, the most widely used onium is tetramethylammonium, although it is relatively unstable from approximately 150° C.; mention may also be made of benzyltrimet
Danerol Pierre
Pevere Virginie
Burns Doane Swecker & Mathis L.L.P.
McKane Joseph K.
Murray Joseph
Rhodia Chimie
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