Process for the preparation of diphenic acid

摘要

A process for the preparation of diphenic acid from phenanthrene which comprises (i) heating phenanthrene and glacial acetic acid, at a temperature in a range of 75 Deg C to 85 Deg C, (ii) adding drop-wise a pre-determined amount of 30% hydrogen peroxide, over a period of from 30 to 60 minutes to form a resulting mixture, (iii) heating the resulting mixture for 3 to 7 hours after completion of drop-wise addition of hydrogen peroxide, (iv) distilling the resulting mixture under reduced pressure to make the volume half, (v) cooling the mixture until diphenic acid crystallizes out, (vi) filtering the cooled mixture to form a residue and a filtrate, and boiling the residue after adding 10% solution of sodium carbonate and activated charcoal, (vii) filtering and discarding the residue; (viii) acidifying the filtrate with hydrogen chloride to form a resultant mixture; (ix) cooling the resultant mixture until more diphenic acid crystallizes out; and (x) repeating filtration until pure diphenic acid is obtained.