Studies on the Utilization of Alkali Lignin (Part 2)

Conditions necessary for oxidation of lignin by nitrobenzene and alkali have been studied. Variables considered were : time of reaction, temperature, weight of nitrobenzene, concentration of alkali, volume of H2O, KOH and NaOH as alkali. Vanillin was identified as an important product of the reaction when carried out at high temperature.Studies were made on the use of crude alkali lignin from black liquor of soda pulp waste liquor as raw material for the production of vanillin. The results indicated that crude alkali lignin was as amenable to alkaline nitrobenzene oxidation as wood flour, HCl lignin and pure alkali lignin. Optimum conditions yield of vanillin was about 6% of lignin (in vanillin 2, 4-dinitrophenylhydrazone, 11%).The oxidizing agent nitrobenzene depending upon conditions was reduced to azoxybenzene, azobenzene, aniline, and recoverd as such.