Obtaining phenolic compounds by alkaline depolymerization of technical hydrolysis lignin

Alkaline destruction of technical hydrolysis lignin (THL) has been performed under different conditions (treatment duration - 2, 4 and 6 hours, NaOH concentration - 3, 5 and 7%, lignin:NaOH solution ratio (hydromodule - h.m.) - 1:6; 1:8; 1:10), and was followed by the extraction and the identification of obtained compounds. Process temperature - 180C. The optimal conditions for obtaining low molecular mass phenolic compounds (LMPC) have been established as follows: lignin: NaOH ratio - 1:10, process duration - 6 hours. The LMPC yield was of 1.33%mass from the initial lignin. The effects of some parameters (e.g. pH of the water phase, ratio between the organic and water phases, number of extractions) on the degree of LMPC extraction have been studied. The obtained LMPC have been extracted with toluene - triple extraction at toluene -, under the established optimal conditions: a constant water phase ratio of 1:5 and pH=2. By gas-chromatographic/mass- spectrometric analysis, the following compounds have been identified: 2-methoxyphenol, 2.6-dimethoxyphenol, 3-hydroxy-4-methoxybenzaldehyde (vanillin) etc.