Study On Synthesis Of Biomass Platform Derivatives Methyllevulinate And Dimethyl Succinate

At present,the energy and chemicals consumed in the world mainly come from fossil resources,but due to the non-renewable characteristics of fossil resources,various renewable resources have been tried to replace fossil resources.Biomass refers to various organisms formed through photosynthesis.It has the characteristics of reproducibility,low pollution,wide distribution,abundant resources and carbon neutrality.It is considered to be the most potential substitute for fossil resources.With the increasing demand for chemicals in social development,it is of great significance to convert renewable biomass into high value-added chemicals.Methyl levulinate and dimethyl succinate are biomass chemistry platform molecules that are widely used in fuel additives,pharmaceuticals,solvents,organic chemistry,fragrances,coatings,adhesives,and plasticizers.This thesis mainly explores the one-pot conversion of 5-hydroxymethylfurfural（HMF）to methyl levulinate and D-fructose to dimethyl succinate.Methyl levulinate（ML）is a biobased platform molecule,which has versatile applications in fine chemical synthesis and food additives.However,during the ML production,one of the main barriers is that humins are usually cogenerated,which leads to poor reaction efficiency and catalyst deactivation.In this paper:in a catalytic system with H-beta 25,molecular oxygen could act as both a humins cleaner and a reaction accelerator for the synthesis of value-added ML from 5-hydroxymethylfurfural（HMF）or furfuryl alcohol（FA）.The reaction efficiency and the catalyst reusability were significantly improved in the presence of oxygen.Besides,the effects of different reaction parameters as well as catalysts have been investigated.The intermediate capture experiments showed that the formation of ML from HMF in the presence of oxygen was carried out by decarbonylation,and the role of O₂ in the removal of humic substances was discussed.Dimethyl succinate（DMS）,an important building block of bio-based platform chemicals,was produced from D-fructose under one-pot and metal-free conditions for the first time.In the presence of 1.5 mmol D-fructose,75 mg Amberlyst-70 and 10 bar O₂,31%of DMS along with 23%of methyl levulinate（ML）was yielded at 130℃ for4 h.The effects of different reaction parameters as well as side products from the solvent on the reaction efficiency were systematically investigated.In order to portray the scope of the process,various biomass derivatives,such as 5-hydroxymethylfurfural,furfural,furfuryl alcohol,etc.,were used as promising starting materials for the onepot synthesis of DMS using the same catalytic system.Besides,the stability of the catalyst was assessed,and the reaction pathway was also proposed based on the experimental results and observations.