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Title: Tandem catalysis for the production of alkyl lactates from ketohexoses at moderate temperatures

Retro-aldol reactions have been implicated as the limiting steps in catalytic routes to convert biomass-derived hexoses and pentoses into valuable C 2, C 3, and C 4 products such as glycolic acid, lactic acid, 2-hydroxy-3-butenoic acid, 2,4-dihydroxybutanoic acid, and alkyl esters thereof. Due to a lack of efficient retro-aldol catalysts, most previous investigations of catalytic pathways involving these reactions were conducted at high temperatures (≥160 °C). Here, we report moderate-temperature (around 100 °C) retro-aldol reactions of various hexoses in aqueous and alcoholic media with catalysts traditionally known for their capacity to catalyze 1,2-intramolecular carbon shift (1,2-CS) reactions of aldoses, i.e., various molybdenum oxide and molybdate species, nickel(II) diamine complexes, alkali-exchanged stannosilicate molecular sieves, and amorphous TiO 2–SiO 2 coprecipitates. Solid Lewis acid cocatalysts that are known to catalyze 1,2-intramolecular hydride shift (1,2-HS) reactions that enable the formation of α-hydroxy carboxylic acids from tetroses, trioses, and glycolaldehyde, but cannot readily catalyze retro-aldol reactions of hexoses and pentoses at these moderate temperatures, are shown to be compatible with the aforementioned retro-aldol catalysts. The combination of a distinct retro-aldol catalyst with a 1,2-HS catalyst enables lactic acid and alkyl lactate formation from ketohexoses at moderate temperatures (around 100 °C), with yields comparable tomore » best-reported chemocatalytic examples at high temperature conditions (≥160 °C). As a result, the use of moderate temperatures enables numerous desirable features such as lower pressure and significantly less catalyst deactivation.« less
 [1] ;  [1]
  1. California Inst. of Technology (CalTech), Pasadena, CA (United States)
Publication Date:
Grant/Contract Number:
Published Article
Journal Name:
Proceedings of the National Academy of Sciences of the United States of America
Additional Journal Information:
Journal Volume: 112; Journal Issue: 38; Related Information: CCEI partners with the University of Delaware (lead); Brookhaven National Laboratory; California Institute of Technology; Columbia University; University of Delaware; Lehigh University; University of Massachusetts, Amherst; Massachusetts Institute of Technology; University of Minnesota; Pacific Northwest National Laboratory; University of Pennsylvania; Princeton University; Rutgers University; Journal ID: ISSN 0027-8424
National Academy of Sciences, Washington, DC (United States)
Research Org:
Energy Frontier Research Centers (EFRC), Washington, D.C. (United States). Catalysis Center for Energy Innovation (CCEI)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; catalysis (homogeneous); catalysis (heterogeneous); biofuels (including algae and biomass); bio-inspired; hydrogen and fuel cells; materials and chemistry by design; synthesis (novel materials); synthesis (self-assembly); synthesis (scalable processing)
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1370715