DE2339463A1 - Methallyl sulphonate prepn - by direct sulphonation of isobutylene - Google Patents

Abstract

Methallyl sulphonates, useful as co-monomers with acrylonitrile in copolymer prodn., are prepd. by (a) reacting 1 mole SO3 with >0.8 moles dialkyl sulphoxide of formula R'R"S=O (where R' and R" each is 1 - 8 C alkyl, esp. Me) in an inert solvent, esp. C2H4Cl2, to form an SO3/dialkyl sulphoxide complex; (b) reacting the complex, at 10 - 80 degrees C, with isobutylene, in a 0.9 to 1.2 : 1 isobutylene : SO3 mol. ratio, and (c) neutralising the reaction prod. formed with a base, esp. NaOH.

Description

Process for the preparation of a methallyl sulfonate The invention relates to a process for the preparation of a nethallyl sulfonate, in particular a Process for the preparation of a methallyl sulphonate, in which a sulfur trioxide / dialkyl sulphoxide complex is used for the sulfonation of isobutylene.

For the production of Methallylsulfonaten, which are particularly advantageous The way to react with acrylonitrile to form corresponding copolymers are those various processes known. One of these methods is to begin with To chlorinate isobutylene and to react the methallyl chloride obtained with sodium sulfite. The disadvantage of this process, however, is that it is a relatively by-product Form large amounts of sodium chloride, causing the polymerization of the obtained Sodium methallyl sulfonate is affected.

Another method is the direct sulfonation of Isobutylene, the reaction between the isobutylene and the sulfur trioxide is carried out in liquid sulfur dioxide at a temperature of -200C (cf.

"Bull. Soc. Chim. France", p. 787, 1965). This method is but of no practical value, since this involves larger amounts of polyisobutylene as a by-product are formed.

Process for the sulfonation of isobutylene with the aid of certain sulfur trioxide complexes are for example from "J. Am.

Chem. Soc. ", Vol. 65, p. 978 (1941) and Japanese Patent Application 41527/1971 known. In the first process, a sulfur trioxide / dioxane complex, a sulfur trioxide / alkyl amide complex is used in the latter process.

The disadvantage of the former process is that it is not only the complex that is difficult is to be kept stable, but that larger amounts of the yield of the desired End product degrading by-products arise. In the latter process, leaves Although the complex remains stable and reacts with isobutylene, this is disadvantageous is, however, that the use of superfluous alkylamide for the reaction process indispensable and the methallylsulfonate formed is somewhat discolored as a result. Consequently So the latter process also leaves much to be desired.

The invention was based on the object of the sulfonation process to improve isobutylene with the help of sulfur trioxide complexes such that they in high yield with the greatest possible suppression of side reactions non-discolored methallyl sulfonates.

The invention thus provides a process for the preparation of a methallylsulfonate by direct sulfonation of isobutylene with the aid of a sulfur trioxide complex, which is characterized in that a) by reaction between sulfur trioxide and, based on 1 mol of sulfur trioxide, more than 0.8 mol of a dialkyl sulfoxide of the general formula wherein the radicals R 'and R "each represent an alkyl radical with 1 to 8 carbon atoms, forms a sulfur trioxide / dialkyl sulfoxide complex in an inert solvent; b) the resulting sulfur trioxide / dialkyl sulfoxide complex at a temperature of 100 to 80 ° C with , based on 1 mol of sulfur trioxide, 0.9 to 1.2 mol (s) of isobutylene is reacted and c) the reaction product formed is neutralized with a base.

The use of heavy el trioxide / dialkyl sulfoxide complexes as So far, sulfonating agents have only been tried with very special alcohols. In in these cases it was imperative to use an excess of dialkyl sulfoxide to work to keep the complex stable. Even with the complex on though keeps stable in this way, it is impossible to produce the sulfonate in high yield. It has now been shown that such sulfur trioxide / dialkyl sulfoxide complexes suitable for the sulfonation of isobutylene, this reaction being from a customary Sulphonation reaction in which the methallylsulphonic acid is formed via a sultone is different. When using such a sulfur trioxide / dialkyl sulfoxide complex for the sulfonation of isobutylene and subsequent neutralization can be used according to the invention Produce non-discolored methallylsulfonates in high yield.

In the formation of those used in the process according to the invention Sulfur trioxide / dialkyl sulfoxide complexes become the sulfur trioxide reactants and dialkyl sulfoxide reacted with one another in a molar ratio of at least 1: 0.80. If the amount of dialkyl sulfoxide is below 0.80 moles per 1 mole of sulfur trioxide, the ability of the sulfur trioxide to react cannot be determined in a suitable manner attenuate, which tends to discolor the reaction product. Implementation between the sulfur trioxide and the dialkyl sulfoxide to form the complex takes place in Presence of an inert solvent. Under an inert solvent here and in the following is to be understood as such that the complex formed is stable able to hold and practically does not react with the isobutylene. Suitable inert Examples of solvents are hydrocarbons, halogenated hydrocarbons, liquid sulfur dioxide, dialkyl sulfoxides and the like. The amount of each inert solvent used must be at least so large that the formed Complex does not fail. The amount of solvent required for the specific case can easily be determined by simple trial and error.

In the process according to the invention, the sulfur trioxide / dialkyl sulfoxide complex react and the isobutylene dissolved or dispersed with each other in an inert solvent in the manner described, with 0.9 to 1.2 mol (s) of isobutylene per 1 mol of sulfur trioxide is (are) added. When the amount of isobutylene is below the specified minimum value unreacted sulfur trioxide remains. In the case that the amount of isobutylene exceeds the specified maximum value, unreacted isobutylene remains. Both cases are undesirable. The sulfonation reaction is said to be part of the process run according to the invention at a temperature of 100 to 800C.

In the event that the reaction temperature is below 10 0C, the reaction rate is low and the yield of the desired end product decreases. In the event that the If the reaction temperature exceeds B0Oc, not only part of the formed decomposes Methallylsulfonic acid, but there is also severe discoloration of the end product.

For the reasons mentioned, a reaction temperature must be within of the specified range are adhered to.

The sulfonation product obtained is then treated with a base neutralized to give the desired end product Methilylsulfonat. For neutralization either organic bases or inorganic bases are suitable, with in the Usually alkali metal hydroxides or organic amines are preferred.

As already stated, can be according to the method according to the invention when using a sulfur trioxide / dialkyl sulphide complex under the specified Reaction conditions readily produce a methallyl sulfonate. According to the invention one obtains a complex ideally suited for the sulfonation of isobutylene, without that, based on the sulfur trioxide, a molar excess of dialkyl sulfoxide needed. Because the dialkyl sulfoxide compared to that used as a neutralizing agent Base is relatively stable, a non-discolored methallyl sulfonate can be obtained. In comparison, you need in the Japanese patent application 41527/1971 known method, which with a sulfur trioxide / alkylamide z. B. Dimethylformamide complex works, the use of a, based on the sulfur trioxide, molar excess on the alkyl amide.

The compared to dialkyl sulfoxide in the context of the known The instability given to the method used alkylamides is obviously the Cause of discoloration of the desired final methallyl sulfonate product. Under With this in mind, the method according to the invention is an excellent one Method for obtaining non-discolored methallyl sulfonates in high yield represent.

The following examples are intended to further illustrate the process according to the invention illustrate.

Example 1 This example illustrates the influence of the reaction temperature on the sulfonation reaction.

29 g of dimethyl sulfoxide were dissolved in 150 g of dichloroethane, whereupon the resulting solution within about 30 minutes a temperature 30 g of sulfur trioxide were added from 10 ° C. The molar ratio of dimethyl sulfoxide to sulfur trioxide was 1.00. The resulting solution was then heated to 300C heated and stirred vigorously for about 1 hour. The resulting suspension of the Sulfur trioxide / dimethyl sulfoxide complex in dichloroethane was liquefied with 22 g Isobutylene was added to a temperature of 25 ° C. The molar ratio of isobutylene to Sulfur trioxide was 1.05. The reaction mixture obtained then became 1> 5 vigorously moved for hours (to age). After removing the dichloroethane Evaporation at a temperature of 400C under reduced pressure left the evaporation residue with 43 g of a 35% strength by weight aqueous sodium hydroxide solution to a pH of 7.5 neutralized. Eventually the dimethyl sulfoxide and water were evaporated, whereupon the neutralized evaporation residue was dried. The white product was extracted with 90% ethanol, the sodium salt being used as the extract the methallylsulfonic acid was obtained in a given amount.

The following table contains information about the selected temperature for the sulfonation reaction, based on the yield of the sodium salt of methallylsulfonic acid on sulfur trioxide, and the degree of whiteness of the reaction product obtained.

The degree of whiteness was measured using the APHA method with a 10% aqueous solution.

Table 1 Experiment no. 1 2 3 4 5 Reaction temperature (oC) -10 10 50 70 90 Yield (ffi) 52 73 97 95 83 Degree of whiteness below below below 10 50 5 5 5 As As can be seen from Table 1, the yield in Experiment No. 1 is very low in Experiment No. 5 the degree of whiteness is very bad.

Example 2 This example illustrates the influence of the used Amount of dialkyl sulfoxide on the sulfonation reaction.

First, dimethyl sulfoxide was dissolved in 200 g of dichloroethane, whereupon the solution obtained within about 40 minutes at a temperature of 200C with 40 g of sulfur trioxide was added. The solution then became vigorous for about 1 hour moves, with a sulfur trioxide / dimethyl sulfoxide complex practically quantitatively moving formed. The complex obtained was now one with 29.3 g of liquefied isobutylene Temperature of 20 0C added, whereupon the reaction mixture (for aging) 1 hour was moved vigorously for a long time. The dichloroethane was then at one temperature evaporated from 400C under reduced pressure and the evaporation residue with 57> 3 g of a 35% strength by weight aqueous sodium hydroxide solution was neutralized to a pH of 7.5. The dimethyl sulfoxide and water were then evaporated and the neutralized Dry evaporation residue to give a white reaction product. If this was extracted with 90% ethanol, the sodium salt of methallylsulfonic acid could can be extracted in a given amount.

The following table 2 contains information about the amount of dimethyl sulfoxide used, the yield of sodium methallyl sulfonate based on sulfur trioxide and the whiteness degree of the reaction product obtained. The measurement of the degree of whiteness was carried out as described in Example 1.

Table 2 Experiment No. 6 7 8 9 Amount of dimethyl sulfoxide used in g 23.4 31.2 39 78 molar ratio of dimethyl sulfoxide to sulfur trioxide (0.6) (0.8) (1.0) (2.0) Yield in ß 81 94 96 96 Degree of whiteness 40 8 under 5 under 5 Example 3 This example illustrates the influence of the isobutylene to SO3 molar ratio on the sulfonation reaction.

After the formation of a sulfur trioxide / dimethyl sulfoxide complex by adding 40 g of sulfur trioxide to 150 g of dimethyl sulfoxide within 40 For 1 hour at a temperature of 40 ° C., the complex formed became vigorous emotional. The agitated, for example stirred, complex was then mixed with liquefied Isobutylene is added to a temperature of 40 ° C, whereupon the reaction mixture (for Aging) was heated to a temperature of 500C for about 1 hour.

Subsequently, by adding 57.3 g of a 35 wt .-% aqueous Sodium hydroxide solution neutralized to a pH of 7.5. When the Dimethyl sulfoxide and water and drying the neutralized evaporation residue a white product was obtained. If this was extracted with 90% ethanol, the sodium salt of methallylsulfonic acid could be extracted in a given amount.

The following table 3 contains information about the amount of used Isobutylene, the yield of sodium methallyl sulfonate based on sulfur trioxide, and the degree of whiteness of the reaction product obtained. The measurement of the degree of whiteness took place as described in Example 1.

Table 3 Experiment No. 10 11 12 13 14 Amount of isobutylene used (g) 22.4 28 30.8 33.6 39.2 Mel ratio isobutylene to SO3 (0.8) (1.0) (1.1) (1.2) (1.4) Yield in% 78 97 98 97 85 Degree of whiteness 50 below below below below 5 50 5 5 5 Example 4 After the formation of a sulfur trioxide / dimethyl sulfoxide complex by Addition of 40 g of sulfur trioxide to 150 g of dimethyl sulfoxide within 40 min At a temperature of 30 ° C., the complex obtained was vigorously agitated for 1 hour. The agitated, for example guided, complex was then liquefied with 31 g Isobutylene is added to a temperature of 25 ° C, whereupon the resulting reaction mixture (for aging) was heated to a temperature of 500C for 1 hour. After that was obtained by adding 100 g of a 40% strength by weight aqueous sodium hydroxide solution neutralized at a temperature of about 50 ° C.

The neutralized mixture obtained was then left to stand, whereby it separated into two layers. The top layer became 170 g of one Dimethyl sulfoxide and water containing liquid mixture obtained.

The lower layer was cooled to 1000, leaving 63 g of sodium methallyl sulfonate precipitated as precipitation. The filtrate filtered off from the precipitate formed still contained about 17 g of sodium methallyl sulfonate, 20 g of sodium hydroxide and 42 g Water. This filtrate was used for neutralization in one manner as described used repeated second attempt. In this second attempt, sodium methallyl sulfonate was used as a precipitate in a yield of 93% based on that used Sulfur trioxide, obtain. This precipitate was 99% pure sodium methallyl sulfonate and contained 1 ffi inorganic salt (Glauber's salt).

Example 5 By dissolving 74 g of butylpropyl sulfoxide in 150 g of dichloroethane and adding 40 g of sulfur trioxide to the resulting solution over a period of 30 minutes at a temperature of 35 ° C and then vigorously moving for about one hour, e.g.

Stir, at the indicated temperature, a sulfur trioxide / butyl propyl sulfoxide complex manufactured. The complex obtained was then liquefied with 29.5 g of isobutylene added and the reaction mixture formed for 1 hour at a temperature of Aged 500C. This was followed by the addition of 57.3 g of a 35 % strength by weight aqueous sodium hydroxide solution was neutralized to a pH of 7.5. After removing the dichloroethane, the water and the butylpropylsulfoxide the neutralized mixture was washed with ethanol to give a white reaction product was obtained. The yield of dry reaction product was 74 g, correspondingly a yield of 92%, based on the sulfur trioxide.

Comparative Example Experiment No. 12 of Example 3 was repeated, but with the exception that instead of 150 g of dimethyl sulfoxide 140 g of dimethylformamide were used. When the sulfonation was carried out, a pale yellow color finally emerged Product received. The yield of sodium methallyl sulfonate based on that used Sulfur trioxide, was 94%.

The degree of whiteness of the reaction product was, as described in Example 1, to be determined.

Became an ionomer mixture of acrylonitrile and acrylic acid methyl ester in a molar ratio of 93: 7 with 1.9% of the sodium methallylsulfonate obtained according to the comparative example was added and the whole was copolymerized in the customary known manner obtained a light yellow polymerization product. If, on the other hand, the test no. 12 sodium methallylsulfonate obtained according to Example 3 was added and the whole was copolymerized, a white polymerization product was obtained.

Claims (3)

PATENT CLAIMS Process for the preparation of an ethallylsulphonate by direct sulphonation of isobutylene with the aid of a sulfur trioxide complex, characterized in that a) by reaction between sulfur trioxide and, based on 1 mol of sulfur trioxide, more than 0.8 mol of a dialcylsulphoxide of the general formula wherein the radicals R 'and R "each represent an alkyl radical with 1 to 8 carbon atoms, in an inert solvent-forms a sulfur trioxide / dialkyl sulfoxide complex; b) the resulting sulfur trioxide / dialkyl sulfoxide complex at a temperature of 10 ° to 80 ° C with, based on 1 mole of sulfur trioxide, reacts 0.9 to 1.2 mole (s) of isobutylene and c) neutralizes the reaction product formed with a base. 2. The method according to claim 1, characterized in that as Dialkyl sulfoxide and dimethyl sulfoxide used as the inert solvent dichloroethane. 3. The method according to claim 1, characterized in that the reaction product formed neutralized with sodium hydroxide.