| abstract |
PCT No. PCT/DK85/00108 Sec. 371 Date Mar. 20, 1986 Sec. 102(e) Date Mar. 20, 1986 PCT Filed Nov. 21, 1985 PCT Pub. No. WO86/03194 PCT Pub. Date Jun. 5, 1986.p-Amino phenols of the formula <IMAGE> (I) wherein R1 nd R2 are independently hydrogen, optionally substituted alkyl, halogen, COOH, SO3H or NO2, are produced by electrolytic reduction of p-phenylazophenols of the formula <IMAGE> (II) wherein R1 and R2 are as defined above, in an aqueous basic medium at a pH value at least equal to the pKa value of the p-phenylazophenol and at a temperature of at least 50 DEG C., preferably 70 DEG to 100 DEG C. The compounds (I) can hereby be produced without problems, in particular of an environmental nature, which are associated with the chemical reducing methods. The process is particularly useful for the preparation of the compound 5-aminosalicylic acid which is a valuable active component of certain medicaments for the treatment of colitis ulcerose and Crohn's disease. |