GB595211A - Manufacture of condensation products having a tanning action from dihydroxy-diphenyl and dihydroxy-ditolyl sulphones - Google Patents

Abstract

Products having tanning properties in acid medium are made by condensing a mixture of 1 mol. of a dihydroxy-diphenyl- or dihydroxy-ditolyl-sulphone and 1-5 mols. of a dihydroxy-diphenyl or dihydroxy-di-tolyl sulphone sulphonic acid in an acid medium with urea and formaldehyde or with an intermediate condensation product of urea and formaldehyde, for example, a condensation product, for instance, dimethylol urea, obtainable by heating a mixture of 1 mol. of urea to 2 mols. of formaldehyde in a neutral or weakly alkaline medium. Preferably, 1/2 -1 molecular proportion of urea, or of the intermediate condensation product of urea and formaldehyde is used for each molecular proportion of the sulphone mixture, such proportions yielding a product soluble in acid medium. The mixture of sulphone and sulphonic acid may be made by partially sulphonating the sulphone or mixture of sulphones. In examples: (1) 4 : 41-dihydroxy-diphenyl sulphone is sulphonated to the extent of 60 per cent with sulphuric acid, the melt then diluted and urea dissolved in it, and formaldehyde added at 45-50 DEG C. and the mixture stirred for 20 hours, the product being then neutralized and made weakly acid with formic acid. A similar product results by partially neutralizing the sulphonation mixture with ammonia and then condensing at 55-60 DEG C. for 20 hours; (2) a sulphonation mixture prepared as in (1) after cooling and dilution is mixed with a condensation product obtained by boiling urea and formaldehyde in weakly alkaline medium for half an hour, and the mixture is then kept at 45-50 DEG C. for 17 hours and neutralized and acidified with an organic acid; (3) a sulphonation mixture prepared as in example (1) is mixed with dimethyl-dihydroxy-diphenyl sulphone (prepared from crude cresol) and urea is added followed by formaldehyde. The mixture is heated at 45-50 DEG C. for 18 hours and then rendered weakly acid with formic acid; (4) the sulphone prepared from crude cresol is partially sulphonated, and a solution of urea in formalin added in two parts, with stirring for 2 hours at 45-50 DEG C. between the two additions followed by further stirring for 18 hours at this temperature. The product is then made acid with an organic acid; (5) a sulphonation mixture prepared as in example (1) has added a mixture of urea and biuret, followed by the slow addition of formaldehyde, and the mixture is heated at 45-50 DEG C. for 18 hours and made weakly acid with formic or acetic acid. The Specification as open to inspection under Sect. 91 describes the products obtained by condensing a mixture of di-hydroxy di-aryl sulphone and di-hydroxy di-aryl sulphone sulphonic acid in an acid medium with urea and formaldehyde or with a condensation product of urea and formaldehyde. This subject-matter does not appear in the Specification as accepted.