GB157856A - Manufacture of tanning stuffs and process of tanning therewith - Google Patents

Abstract

Synthetic tanning-agents are prepared from tars or tar oils by converting the components thereof into phenols by sulphonation and alkali fusion, coupling the resulting phenols by appropriate elements or radicals, and solubilizing the products by introducing acid groups; alternatively the acid groups are introduced into the phenols and the metal salts of the products then coupled. According to examples:-a tar oil is sulphonated and converted through the calcium salt into the sodium salt which is then subjected to alkali fusion; the resulting phenol is heated with phosphorus pentoxide and sulphuric acid and the product neutralized or nearly neutralized with alkali; or the phenol is sulphonated by concentrated sulphuric acid and condensed with sulphur monochloride and the product nearly neutralized with caustic soda; or the phenol is sulphonated and condensed with formaldehyde and neutralized as described above, or alternatively the phenol is sulphonated, the product made feebly alkaline and condensed with formaldehyde, the resulting solution being made feebly acid before use. The sulphuric acid may be replaced by sodium sulphite or bisulphite &c. The products may be used in tanning, alone or mixed with other tanning-agents. Hides tanned with these materials may be dyed by treatment with diazo compounds. Specification 157,852 is referred to.ALSO:Hides tanned with certain synthetic tanning agents may be dyed by treatment with diazo-compounds. These tanning-agents are prepared from tars or tar oils by converting the components thereof into phenols by sulphonation and alkali fusion, coupling the resulting phenols by appropriate elements or radicals, and solubilizing the products by introducing acid groups; alternatively the acid groups are introduced into the phenols and the metal salts of the products then coupled. Specification 157,852 is referred to.