| abstract |
Prodn. of low-molecular-wt. cpds. (I) from S-free lignin comprises dissolving the lignin in an organic solvent, oxygenating the soln. (sic;) and irradiating the soln. with UV light with a wavelength of at least 140 nm for at leat 20 min at 20-90 deg C in the presence of an immobilised catalyst. The oxygen is esp. supplied by an oxidising agent such as Na persulphate. The Na persulphate concn. is 0.05-0.2 M. The catalyst is TiO2 or WO3, e.g. deposited on a tubular filter in a photoreactor. The solvent is phenol, dioxan, MeOH or EtOH. The lignin concn. is 70-100% (esp. 92%) of satn.. USE - (I) are stated to include cpds. useful for the synthesis of pharmaceuticals, e.g. guaiacol, catechuic acid, isohemipinic acid, 4-n-propylguaiacol, vanillol and eugenol. (I) may be reduced to the corresp. cyclohexadiene derivs., which may be oxidised to dicarboxylic acids. |