Research Of The Catalytic Synthesis Of Nitrile Compounds And Its α-alkylation On Heterogenous Catalysts

Nitrile compounds are mainly used as the raw materials or intermediates in organic synthesis,which have wide applications in agricultural chemicals,dyes and medicines.There are several traditional methods to synthesize nitrile compounds:（1）By ammoxidation of alcohols or aldehydes;（2）By dehydroamination of alcohols;（3）By the oxidation of primary amines;（4）By dehydration of amides.As far,these methods are widely studied,but there are few studies on the preparation of nitriles from aromatic ketones.In this paper,a metal free catalytic system was prepared by simple pyrolysis of biomass resource.It had high activity in catalytic oxidative cracking of C（O）-C bond in the ketones and ammoxidation of aromatic ketones.Nitriles were prepared by ammoxidation of aromatic ketones at 160°C and 10 bar O₂ with NH₃ as ammonia source.The yield was 72～97%.In addition,this catalytic system also had catalytic activity for aromatic cyclic ketones.In the presence of NH₃ or primary amines,the catalytic oxidative coupling of a variety of aromatic cyclic ketones with NH₃ or primary amines to aromatic cyclic imide reaction was achieved,and the yield was 80～99%.Through the radical quenching experiments and control experiments,the active oxygen species was determined to be·O₂^-,and reasonable reaction mechanisms for the oxidation of aromatic ketones to imides and nitriles were proposed.The experimental data and DFT calculations showed that the defective carbon and oxygen-containing functional groups,especially carboxyl groups,were important in this transformation.The defective carbons act as the sites for the activation of molecular oxygen,and the oxygen-containing functional groups promote the adsorption of carbonyl groups on the catalyst surface and improve the catalytic efficiency.Selectiveα-alkylation of nitriles is an essential conversion in organic synthesis.Traditionally,the reaction was mostly achieved through the dehalogenation reaction between haloalkanes and nitriles under the present of strong alkali.This method uses toxic halides as raw materials,which does not meet the requirements of green chemistry.Alcohols can be obtained by biomass fermentation,pyrolysis,etc.They are a kind of cheap and clean raw materials.It is a major challenge in organic conversion that how to realize selectiveα-alkylation of nitriles by the use of biomass derived alcohols,especially inert aliphatic alcohols（such as methanol and ethanol）as carbon and hydrogen source.In this paper,a kind of nitrogen-doped carbon supported cobalt nanoparticles catalyst was prepared through a simple pyrolysis process,and it was found to be active for selectiveα-alkylation of nitrile compounds with alcohols.Under the optimum condition,a variety ofα-alkylated nitriles were obtained with the yield of37～99%from different nitriles and alcohols.The control experiments showed that nitrogen doping in the support plays an important role in improving the catalytic activity of cobalt nanoparticles,mainly including stabilizing the cobalt nanoparticles to avoid their aggregation and promoting alcohol dehydrogenation as the basic site.The mechanism study shows that the reduction of C=C bond in olefin intermediates is carried out through the hydrogen-transfer pathway,and olefin intermediates,as hydrogen receptors,accelerate the dehydrogenation step of alcohol.