Selective C—O bond cleavage of oxidized lignin and lignin-type materials into simple aromatic compounds

摘要

A method to cleave C—C and C—O bonds in β-O-4 linkages in lignin or lignin sub-units is described. The method includes oxidizing at least a portion of secondary benzylic alcohol groups in β-O-4 linkages in the lignin or lignin sub-unit to corresponding ketones and then leaving C—O or C—C bonds in the oxidized lignin or lignin sub-unit by reacting it with an organic carboxylic acid, a salt of an organic carboxylic acids, and/or an ester of an organic carboxylic acids. The method may utilize a metal or metal-containing reagent or proceed without the metal or metal-containing reagent.

主权项

1. A method to cleave C—C and C—O bonds in β-O-4 linkages in lignin or lignin sub-units, the method comprising:
(a) oxidizing at least a portion of secondary benzylic alcohol groups in (β-O-4 linkages in the lignin or lignin sub-unit to corresponding ketones, resulting in an oxidized lignin or lignin sub-unit, wherein step (a) comprises contacting the lignin or lignin sub-unit with a catalyst comprising nitric acid (HNO3) in combination with another Brønsted acid, in the absence of a metal-containing catalyst, thereby yielding the oxidized lignin or lignin sub-unit; and then (b) cleaving C—O or C—C bonds in the oxidized lignin or lignin sub-unit by reacting it with reagent selected from the group consisting of organic carboxylic acids, salts of organic carboxylic acids, and esters of organic carboxylic acids, for a time and a temperature at which at least a portion of β-O-4 linkages in the oxidized lignin or lignin sub-unit are cleaved.