238 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS •'"o o / cL Na 0 3 • o /• J '•-. C L CL S02 I CooH Examples have also been described in the patent literature (47) which contain as many as four sulphonic acid groups, for instance This is obtained by direct reaction of the dye intermediate with cobalt

CHEMISTRY OF SYNTHETIC DYES USED IN COSMETICS 239 sulphate in dilute aqueous alkaline solution and is a yellowish orange dye of good general fastness on wool. The foregoing examples are only a few dyes selected more to show the extensive variations in structure which are now possible with metal complex dyes rather than to survey the field comprehensively. Other commercial ranges of premetallized dyes than those mentioned previously include: These are 1:2 metal complex dyes for wool and silk with a water solubility of the order of 5-10%. They are usually applied to wool under slightly acid conditions in the presence of ammonium sulphate or ammonium acetate. A vilon fast dyes These are 1:2 metal complex dyes for heavy shades on polyamide fibres. (Received: 7st February 7966) REFERENCES (1) Heald, R. C. Am. Perruiner Cosmetics 78 (April 1963). (2) Brit. Pat. 878,098. (3) Brit. Pat. 993,923. (4) Brit. Pat. 995,948. (5) Brit. Pat. 979,266. (6) Brit. Pat. 896,197. (7) Brit. Pat. 983,207. (8) Brit. Pat. 973,599. (9) Brit. Pat. 995,870. (10) Brit. Pat. 987,342. (11) Brit. Pat. 951,509. (12) Brit. Pat. 899,051. (13) Brit. Pat. 992,150. (14) Brit. Pat. 889,812. (15) Brit. Pat. 887,579. {16) U.S. Pat. 3,041,244. (17) U.S. Pat. 3,168,442. (18) Brit. Pat. 707,618. (19) U.S. Pat. 3,088,877. (20) U.S. Pat. 3,088,878. (21) Brit. Pat. 954,253. (22) Brit. Pat. 990,334. (23) Brit. Pat. 938,045. (24) Brit. Pat. 957,119. (25) U.S. Pat. 3,168,441. (26) Brit. Pat. 919,824. (27) Brit. Pat. 979,292. (28) Brit. Pat. 918,597.