Patent GB-491817-A (GB)
Title: Improvements in the manufacture and production of synthetic tanning agents
IPC: C14C3/20
Filed: 1937-04-20
Abstract: Tanning-agents are obtained by subjecting (a) a water-soluble sulphonated product obtained by condensing a phenol or a naphthol or a sulphonic acid thereof with formaldehyde, and afterwards sulphonating if necessary, to an after-treatment with (b) an unsulphonated phenol or naphthol and formaldehyde, and at any stage of the process effecting a condensation with (c) sulphite cellulose lye, with or without an aldehyde, and also if desired a condensation with (d) urea and formaldehyde; reagents which yield formaldehyde may be used in place of formaldehyde.  The procedure may be, for example, (1) component (a) is treated with component (b) and then with component (c), or (2) component (a) is treated simultaneously with components (b) and (c), or (3) component (a) is treated with component (d) and the product is condensed with components (b) and (c).  When components (b) and (c) are used simultaneously, use may be made of the condensation products of sulphite cellulose lye and aromatic hydroxy compounds, obtainable as described in British Specification 189,190, [Class 2 (iii)], and German Specification 480,898; condensation products of these products with formaldehyde may also be used.  The reactions may be effected in an acid or neutral medium or also in an alkaline medium, except when phenols and sulphite cellulose lye are used simultaneously; condensation in an alkaline medium may be assisted by addition of sodium bisulphite.  In the examples, (1) a mixture of phenol, cresols and xylenols, obtained in the hydrogenation of brown coal, is sulphonated and condensed with formaldehyde, and the product is treated with the phenolic mixture mentioned above, sulphite cellulose lye, and formaldehyde; alternatively, the initial sulphonated product may be treated first with the phenolic mixture mentioned above and formaldehyde, and then with sulphite cellulose lye; (2) the initial sulphonated product of example 1 is treated with urea and formaldehyde, and the product is condensed with the phenolic mixture mentioned in example 1, sulphite cellulose lye, and formaldehyde; (3) the initial sulphonated product of example 1 is treated with urea and formaldehyde, and the product is treated with sulphite cellulose lye, 4 : 41-dioxydiphenylsulphone, and formaldehyde; (4) the initial sulphonated product of example 1 is treated with urea and formaldehyde, and the product is treated first with the phenolic mixture mentioned in example 1 and formaldehyde, and then with sulphite cellulose lye and formaldehyde in the presence of sodium bisulphite; (5) the initial sulphonated product of example 1 is treated in turn with sulphite cellulose lye, urea and formaldehyde, and the product is treated with the phenolic mixture mentioned in example 1 and formaldehyde; (6) a condensation product from sulphonated crude cresol and formaldehyde is treated with urea and formaldehyde, and the product is treated first with crude cresol and formaldehyde and then with sulphite cellulose lye and formaldehyde; (7) the initial sulphonated product of example 1 is treated with urea and formaldehyde, and the product is heated, after addition of more formaldehyde, with a product obtained by heating sulphite cellulose lye, in the presence of sulphuric acid, with the phenol mixture mentioned in example 1; (8) the initial sulphonated product of example 6 is treated with urea and formaldehyde, and the product is heated, after addition of more formaldehyde, with a product obtained by heating sulphite cellulose lye, in the presence of sulphuric acid, first with the phenolic mixture mentioned in example 1 and then with formaldehyde; most of the examples describe the treatment of the products to eliminate calcium as calcium sulphate.  British Specification 478,280 also is referred to.