Synthesis of Diphenyl Ether-4, 4′-diacetic Acid

Application of formaline and HCl-gas in glacial AcOH solution of diphenyl ether under the presence of ZnCl2 gives 4, 4′-dichloromethyl-diphenyl ether, m.p. 64°, white, scaly crystals with the formula of C14H12OCl2. This gives a methyl ester of m.p. 154° by methylation of the acid obtained by oxidation with KMnO4. This compound was determined by the mixed fusion with dimethyl diphenyl ether-4, 4′-dicarboxylate. This proves the fact that the chloro-methylation occurs in the 4, 4′-position of diphenyl ether nucleus. This dichloromethyl derivative can be led to dicyanomethyl derivative and then decomposed by 50% H2SO4 to 4, 4′-diphenyl ether-4, 4′-diacetic acid, m.p. 207-208°, which gives a formula of C16H14O5 by analysis and corresponds to the objective substance.