Patent GB-662466-A (GB)
Title: Improvements in or relating to sulphuric acid ester salts or sulphonates and soap products derived therefrom
Filed: 1949-03-03
Abstract: Aqueous solutions containing capillary active sulphuric acid ester salts or sulphonates are concentrated by mixing with an amount of alkali hydroxide insufficient in itself to effect separation into two layers and with an organic solvent containing oxygen and/or nitrogen atoms in the molecule, allowing the mixture to settle into layers, removing the upper more concentrated layer of capillary active salts from the lower aqueous layer, and, if desired, recovering organic solvent present in the said upper layer.  By this means products are obtained which contain less free alkali than those prepared by salting out with an alkali hydroxide without a solvent and less alkali is required.  Solvents specified are mono- or dihydric alcohols with 5 to 10 C atoms, representative being pentanols, cyclohexanol, benzyl alcohol and pentane or hexane diols; ketones with preferably 5 or more C atoms including hexanones, cyclohexanone, mesityl oxide and isophorone; keto-alcohols, e.g. diacetone alcohol; higher aldehydes including pentanol and furfural; dioxane and its homologues; alkane diols; alkane diol mono- or di-ethers and dialkyl ethers; nitrogen-containing compounds such as cyclohexylamine and hexylene diamine; and amino-alcohols such as 5-aminopentanol-1 and 6-aminohexanol-1.  The use of readily hydrolysable solvents such as esters is less suitable.  The solvents may be mixed with substantially non-polar solvents such as hydrocarbons.  Usually an amount of alkali hydroxide equivalent to 30-60 per cent of that required to effect a solvent-free separation is added and is preferably such that only small quantities, e.g. 5-10 per cent of the initial solution, of solvent is required.  Sodium hydroxide is preferred.  Usually elevated temperatures, e.g. about 75-100 DEG  C., are used.  The free alkali may be neutralized with any acidic substance, many of which are specified, and if fatty acids are used a soap composition is obtained (cf. Group III).  Some solvents, e.g. alkane diols, may remain in the product after neutralization. Neutralization is preferably effected at elevated temperatures, e.g. about 100 DEG  C.  A Table is provided showing the use of the following solvents: methyl-3-butanol-1, methyl-4-pentanol-2, cyclohexanol, decanol-2, methyl - 2 - pentanediol - 2 : 4, dimethyl - 2 : 6 - heptanol-4, heptanone-2 and heptadecanol-2 in separating sodium alkyl sulphate solutions prepared from C10-C18 alkenes with the addition of caustic soda. 20 Parts by weight of alkali and 10 parts by volume per 100 parts by weight of ester salt solution are used at 90-100 DEG  C. no separation being obtained in the absence of a solvent.  Other Tables show the effect of varying the quantity of solvent, methyl-2-pentanediol-2 : 4, with a fixed ratio of caustic soda and varying the quantity of the latter with a fixed ratio of the former a similar ester solution being used.  In examples: (1) 100 parts sodium alkyl sulphate solution containing about 21 per cent of ester and about 7 per cent of sodium sulphate and derived from C10-C18 alkenes, are treated with 20 parts solid sodium hydroxide and 10 parts by volume of methyl-2-pentanediol-2 : 4 at 90-100 DEG  C., and allowed to settle into layers and in (2) 100 parts of a sulphonate solution made by sulphochlorination of a dearomatized gas oil fraction, with subsequent saponification, containing 20 per cent of sodium alkyl sulphonate and 2.3 per cent sodium chloride is treated at 95-100 DEG  C. with 20 parts by weight sodium hydroxide and 10 parts by volume of cyclohexanol and allowed to settle into layers.ALSO:Aqueous solutions containing capillary active sulphuric acid ester salts or sulphonates are concentrated by mixing with an amount of alkali hydroxide insufficient in itself to effect separation into layers and with an organic solvent containing at least four carbon atoms and one or more polar groups containing oxygen and/or nitrogen atoms in the molecule, allowing the mixture to settle into layers, removing the upper more concentrated layer of capillary active salts from the lower aqueous layer and converted into soap products by neutralising the free alkali in the salt, before or after removal of the solvent, with a fatty acid or mixture thereof with inorganic acid substances.  The concentration is described in Group IV (b). Alkane-diols containing 5 or 1/2 C atoms, e.g. methyl-2-pentanediol-2 : 4, are solvents which are particularly useful in the final product.  Fatty acids specified are of conventional type.  The products have a higher percentage of ester salt or sulphonate than do corresponding products made by relying solely on the alkali hydroxide to effect separation: thus the percentage of the ester salt or sulphonate may be greater than that of the soap.  Neutralisation is preferably effected at elevated temperatures, e.g. about 100 DEG C.  The products may contain additional washing promoters, e.g. carboxymethyl cellulose, fillers, colourants and perfumes and they may be compressed into cakes.  In Examples (1) a concentrated sodium alkyl sulphate solution containing some sodium sulphate, derived from C10-C18 alkenes, is neutralised with fatty acids from beef tallow at about 100 DEG C., cooled and compressed into cakes, and in (2) it is stated that a concentrated sulphonate solution derived from a dearomatised gas oil fraction by sulphochlorination followed by saponification may be similarly worked up with fatty acids.