Phenol → Benzoic acid, 2-hydroxy-4-methoxy-, phenyl ester

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2,4-Dihydroxybenzoic acid was converted to 2-hydroxy-4-methoxybenzoic acid by treatment with dimethyl sulfate according to the procedure of M. Gomberg and L. C. Johnson (J. Amer. Chem. Soc., 1917, 39, 1687). Treatment of 2-hydroxy-4-methoxybenzoic acid with phenol and phosphorus oxychloride according to the general method of N. G. Gaylord and P. M. Kamath (Organic Syntheses, Coll. Vol. IV, p. 178, 1963) gave phenyl 2-hydroxy-4-methoxybenzoate in 66% yield. Reaction of this phenyl ester with two molar equivalents of benzamidine in boiling ethanol for 20 hours gave a precipitate of 2,4-diphenyl-6-(2'-hydroxy-4'-methoxyphenyl)-s-triazine, which recrystallised from formdimethylamide as pale yellow needles, m.p. 211°-212° C., in 44% yield. Elemental analysis: C, 74.0%; H, 4.4%; N, 11.6%. C22H17N3O2 requires C, 74.4%; H, 4.8%; N, 11.8%. This compound was then sulfonated by treatment with 1.1 molar equivalents of chlorosulfonic acid in boiling chlorobenzene for one hour. The resultant precipitate was collected, rinsed with light petroleum, and treated with sodium hydroxide solution to give the sodium salt of 2,4-diphenyl-6-(2'-hydroxy-4'-methoxy-5'-sulfophenyl)-s-triazine. It was obtained in 87% yield after recrystallisation from 30% aqueous ethanol. Elemental analysis: C, 55.6%; H, 3.6%; N, 9.0%; S, 6.4%. C22H16N3O5SNa.1H2O requires C, 55.6%; H, 3.6%; N, 8.8%; S, 6.7%.

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