Microwave assisted synthesis of dehydrated sugar derivatives hydroxymethylfurfural, levulinic acid, anhydrosugar alcohols, and ethers thereof

Abstract

Methods for the production of dehydrated sugars and derivatives of dehydrated sugars using microwave (MW) irradiation and methods of purifying the same are described. The dehydrated sugars derivatives include 5-hydroxymethyl-2-furfural (HMF) and anhydrosugar alcohols such as sorbitans and isosorbide. The derivatives include HMF ethers, levulinic acid esters, and ether derivatives of the anhydrosugar alcohols. The described methods require lower reaction temperatures and shorter reaction times than similar non microwave mediated reactions known in the art. Typical reaction conditions are 120-210° C., and typical reaction times are 30 minutes or less.

What is claimed is: 
     
         1 . A method of producing a dehydrated sugar derivative comprising,
 a. forming a reaction mixture comprising a solvent and a reactant selected from the group consisting of a hexose, a sugar alcohol, and an anhydrosugar alcohol, wherein the reaction mixture does not contain a catalyst; and   b. contacting the reaction mixture with microwave radiation to achieve a temperature of between 180° C. and 210° C. for a time sufficient to convert at least 40% of the reactant into at least one desired dehydrated sugar derivative product.   
     
     
         2 . The method of  claim 1  wherein the reactant is a fructose and the desired dehydrated sugar derivative is HMF. 
     
     
         3 . The method of  claim 1  wherein the reactant is a sugar alcohol and the desired dehydrated sugar derivative is an anhydrosugar alcohol. 
     
     
         4 . The method of  claim 1  wherein the solvent of the reaction mixture is water. 
     
     
         5 . The method of  claim 1  wherein the reactant is a hexose and the desired dehydrated sugar derivative is levulinic acid. 
     
     
         6 . The method of  claim 1  wherein greater than 50% of the reactant is converted to the desired dehydrated sugar derivative. 
     
     
         7 . The method of  claim 1 , further including at least partially purifying the desired dehydrated derivative from the reaction mixture by at least:
 adding an immiscible organic solvent to the mixture, thereby partitioning the dehydrated sugar derivative into immiscible organic solvent solution;   collecting the partitioned immiscible organic solvent; and   evaporating the collected solvent to produce an extract enriched in the desired dehydrated sugar derivative.   
     
     
         8 . The method of  claim 7 , wherein the immiscible organic solvent is selected from the group consisting of ethyl acetate, methyl t-butyl ether, diethyl ether, toluene, methyl ethyl ketone, ethyl lactate, methyl isobutyl ketone, octanol, pentanol, butyl acetate, chloroform, and any combinations thereof. 
     
     
         9 . The method of  claim 1 , wherein the reactant is fructose, the dehydrated sugar derivative is HMF, and the reaction solvent is selected from a group consisting of: dimethylacetamide, dimethylformamide, N-methyl pyrrolidinone.