Patent GB-815215-A (GB)
Title: Production of nuclear sulphonated vinyl aromatic compounds
Inventor: MOCK RICHARD ARMITAGE
IPC: C07C309/28
Filed: 1957-10-17
Abstract: The invention comprises beta haloethyl aromatic sulphonic acids and a method for making salts of vinyl aromatic sulphonic acids of general formula H2C=CH-Ar-SO3H, where Ar is an aromatic radical.  The salts of vinyl aromatic sulphonic acids are prepared by reacting together approximately equimolecular amounts of sulphur trioxide and a beta bromo or chloroethyl aromatic compound, treating the resulting beta haloethyl aromatic sulphonic acid with a theoretical amount of an aqueous alkali at least as great as that required to neutralize the same and the hydrogen halide which results from dehydro halogenation of the beta haloethyl aromatic sulphonic acid, and then reacting the alkali with the beta haloethyl sulphonic acid between room temperature and 100 DEG  C.  Suitable starting materials are those of general formula Ar-CH2-CH2-X, where X is chlorine or bromine, e.g. beta-chloroethyl benzene, betabromoethylbenzene, the corresponding toluenes xylenes, mesitylenes, naphthalenes, chlorobenzenes and bromobenzenes.  The beta haloethyl aromatic compound is sulphonated by treatment with up to 1.2 times its molecular equivalent of sulphur trioxide.  The reactants may be admixed in any order, the sulphur dioxide being preferably fed into a liquid body comprising the beta haloethyl aromatic reactant, and the reaction mixture is preferably well stirred. The sulphur trioxide may be diluted preferably with one-third or more of its volume of a diluent, or undiluted and may be in liquid or vaporized form.  Examples of suitable diluents are nitrogen, liquid or gaseous sulphur dioxide, carbon tetrachloride, tetrachloroethylene, ethylene chloride, chloroform and methylene chloride.  The beta haloethyl aromatic compound should be in liquid form or in solution when sulphonated, preferably in the presence of one or more of the above-mentioned diluents.  The solution should preferably contain not more than 70 per cent by weight of the compound.  The sulphonation may be carried out at - 20-80 DEG  C. at atmospheric or superatmospheric pressure.  Any precipitate which forms may be filtered off.  The beta haloethyl aromatic sulphonic acids may be separated from byproducts such as organic sulphones by washing with water, and separating the aqueous extract containing the acids.  The aqueous extract is then preferably washed with one of the abovementioned solvents.  The aqueous extract is then preferably treated with a sufficient amount of an alkali, preferably a basic alkali metal or alkaline earth metal compound to form a salt of the beta haloalkyl aromatic sulphonic acid and to neutralize the acid formed by complete dehydrohalogenation of the same, preferably in 10-40 per cent excess over the stoichiometric proportion mentioned. Basic compounds specified are sodium, potassium, calcium and barium hydroxide, and sodium and potassium carbonate.  The reaction between the alkali and beta haloethyl aromatic sulphonic acid takes place at room temperature or lower, but the aqueous extract is preferably heated to 50-100 DEG  C. prior to, during or after the addition of the alkali.  The reaction is preferably continued until at least 75 per cent of the stoichiometric amount of alkali has been consumed. Any excess alkali may be neutralized with, e.g. hydrochloric, hydrobromic, sulphuric or acetic acid.  The amount of water employed in the above extraction is preferably such that the reaction mixture contains 20 per cent by weight or more of the vinyl aromatic sulphonate product.  Examples are given of the preparation of (1) beta bromoethylbenzene sulphonic acid and sodium para styrene sulphonate; (2) 1-(beta bromoethyl) 2 - chlorobenzene sulphonic acid and potassium ar-chlorostyrene sulphonate; (3) beta bromo ethyltoluene sulphonic acid and ar-methylstyrene sulphonate; 4,41-bis-(betabromoethyl) diphenylsulphone is mentioned as a by-product.