Title
Products of nitrobenzene oxidation from non-wood lignin isolated by sulphuric acid
Authors
M. JABLONSKY A. HAZ A. SKULCOVA L. DUBINYOVA I. SURINA F. KACIK and D. KACIKOVA

Received February 27, 2015
Published Volume 50 Issue 7-8 July-August
Keywords precipitated lignin,sulphuric acid, nitrobenzene oxidation, vanillin

Abstract
Lignin is a very attractive and promising raw material to produce vanillin. Lignin was isolated from black liquor by adding sulphuric acid at four levels of concentration (5, 25, 50 and 72 wt%) and subsequently adjusting the pH to 5.The alkaline nitrobenzene procedure for determining lignin structural units has been applied to non-wood lignin and qualitative and quantitative analyses of oxidative-cleavage reaction were evaluated. The total yield of the oxidation products ranged from 34.1 to 36.3 µmolesg-1 pure lignin. The dominant phenolic compound was vanillin followed by syringaldehyde. For precipitated lignin samples, the G:S:H ratio varies between 9:3:1 and7:3:1. It was confirmed that the yield of nitrobenzene oxidation and the contentof phenolic products depends on the isolation procedure.