Cross-Coupling Reaction Of Lignin Model Compounds With Amines

It is rich in the presence of lignin in nature,in terms of total volume,the number of lignin is second only to cellulose,accounts for ca.30%of the organic carbon on earth.So far,lignin has been mainly used as waste in the pulp and paper industry,there are also some have been burned to recover its heat.And lignin may be one of the sources of a few renewable aromatic chemicals in the future.Therefore,the degradation and reuse of lignin and polyphenylene ether has been widely concerned by scientists.On the structure,lignin is a complex polyphenols containing a large number of phenolic C-O bonds and ether C-O bonds（includingα-O-4,β-O-4 and 4-O-5 bonds）.Therefore,the cleavage of C-O ether linkages in lignin is a critical step in obtaining biofuels and commercial chemicals.However,due to the difference in strength and stability of these ether C-O bonds,2-phenethylphenyl ether,benzyl phenyl ether and diphenyl ether are usually selected as the model compound for cutting-offβ-O-4,α-O-4,and 4-O-5 type ether C-O bonds,respectively.Among the three C-O ether bonds,the bond dissociation energy of the 4-O-5 type ether bond(BDE=314 kJ·mol^-1)is much stronger than theα-O-4 type ether bond(BDE=218 kJ·mol^-1)andβ-O-4 type ether bond(BDE=289 kJ·mol^-1).Therefore,the cutting of the 4-O-5 type ether C-O bond still has great challenges.Amine compounds are an important component of various organic molecules and optoelectronic materials,and are one of the most common structural motifs in drugs.And ammonia is a very cheap and abundant industrial inorganic chemical.If lignin is converted to high value-added nitrogen-containing organic chemicals by reaction with organic amines and inorganic ammonia,it will provide a huge economic advantage for lignin utilization。In order to solve the above problems,we have carried out the following work around the conversion of lignin model compound C-O bond cleavage with organic amines or inorganic ammonia compounds to aniline derivatives,and strive to achieve the goal of recycling waste.1.We carried out the cross-coupling reaction of diaryl ether model of lignin 4-O-5 with organic amine by palladium-catalyzed C-O bond cleavage to obtain a series of nitrogen-containing organic compounds.2.Different arylamine derivatives were obtained by cross-coupling reaction of palladium-catalyzed lignin 4-O-5 model compound C-O bond cleavage with inorganic ammonia.3.We also obtained different carbazole derivatives for the cross-coupling reaction of palladium-catalyzed lignin phenolic model substrates C-O bond cleavage with inorganic ammonia.