Production of alpha-hydroxy carboxylic acids and esters from higher sugars using tandem catalyst systems
AssigneeCalifornia Institute of Technology
InventorsMarat Orazov, Mark E. Davis
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Abstract
The present disclosure is directed to methods and composition used in the preparation of alpha-hydroxy carboxylic acids and esters from higher sugars using a tandem catalyst system comprising retro-aldol catalysts and Lewis acid catalysts. In some embodiments, these alpha-hydroxy carboxylic acids may be prepared from pentoses and hexoses. The retro-aldol and Lewis catalysts may be characterized by their respective ability to catalyze a 1,2-carbon shift reaction and a 1,2-hydride shift reaction on an aldose or ketose substrate.
Claims15
A method comprising contacting a carbohydrate feedstock with a tandem catalyst system at a temperature in a range of from 60° C. to 200° C., the contacting resulting in the formation of an α-hydroxy carboxylic acid or α-hydroxy carboxylic acid ester, wherein the carbohydrate feedstock comprises a monosaccharide;
- and
- wherein the tandem catalyst system comprises two materially different discrete catalysts, the catalysts being:
- (a) a first retro-aldol catalyst, wherein the first retro-aldol catalyst comprises
- (i) an optionally substituted oxo(hydroxy)molybdate, an optionally substituted sulfomolybdate, an optionally substituted oxy(hydroxy)tungstate;
- (ii) a Ni(II) diamine complex;
- (iii) an alkali-exchanged hafno-, stanno-, titano-, or zirconosilicate, an optionally substituted amorphous hafnium-, tin-, titanium-, or zirconium-silicate co-precipitate;
- or
- (iv) a combination thereof;
- and
- (b) a second Lewis acid catalyst, wherein the Lewis acid catalyst comprises a crystalline microporous hafno-, stanno-, titano-, or zirconosilicate containing pores equal to or greater than 10-MR.
Dependencies are inferred from the claim text.