| Abstract
| - All current routes for the synthesis of hydroquinone utilize benzene as the starting material. Analternate route to hydroquinone has now been elaborated from glucose. While benzene is a volatile carcinogenderived from nonrenewable fossil fuel feedstocks, glucose is nonvolatile, nontoxic, and derived from renewableplant polysacharrides. Glucose is first converted into quinic acid using microbial catalysis. Quinic acid is thenchemically converted into hydroquinone. Under fermentor-controlled conditions, Escherichia coli QP1.1/pKD12.138 synthesizes 49 g/L of quinic acid from glucose in 20% (mol/mol) yield. Oxidative decarboxylationof quinic acid in clarified, decolorized, ammonium ion-free fermentation broth with NaOCl and subsequentdehydration of the intermediate 3(R),5(R)-trihydroxycyclohexanone afforded purified hydroquinone in 87%yield. Halide-free, oxidative decarboxylation of quinic acid in fermentation broth with stoichiometric quantitiesof (NH4)2Ce(SO4)3 and V2O5 afforded hydroquinone in 91% and 85% yield, respectively. Conditions suitablefor oxidative decarboxylation of quinic acid with catalytic amounts of metal oxidant were also identified.Ag3PO4 at 2 mol % relative to quinic acid in fermentation broth catalyzed the formation of hydroquinone in74% yield with K2S2O8 serving as the cooxidant. Beyond establishing a fundamentally new route to an importantchemical building block, oxidation of microbe-synthesized quinic acid provides an example of how the toxicityof aromatics toward microbes can be circumvented by interfacing chemical catalysis with biocatalysis.
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