Hydrocarbon Synthesis via Photoenzymatic Decarboxylation of Carboxylic Acids.

Wuyuan Zhang,Wilson A Smith,Frank Hollmann,Evgeny A Pidko,Sabrina De Boer,Georgy A Filonenko,Willem J H Van Berkel,Jonathan Z Bloh,Mieke M E Huijbers,Ming Ma,Bastien O Burek,Morten Van Schie

doi:10.1021/jacs.8b12282

Abstract

A recently discovered photodecarboxylase from Chlorella variabilis NC64A (CvFAP) bears the promise for the efficient and selective synthesis of hydrocarbons from carboxylic acids. CvFAP, however, exhibits a clear preference for long-chain fatty acids thereby limiting its broad applicability. In this contribution, we demonstrate that the decoy molecule approach enables conversion of a broad range of carboxylic acids by filling up the vacant substrate access channel of the photodecarboxylase. These results not only demonstrate a practical application of a unique, photoactivated enzyme but also pave the way to selective production of short-chain alkanes from waste carboxylic acids under mild reaction conditions.

Highlights

Valorization of biobased feedstock into chemicals[1−4] and fuels[5−7] represents one of the pillars of a more sustainable society
The highest acceleration of methane production was achieved in the presence of tetradecane (Figure 2b). Both in the absence and presence of a decoy molecule, the enzyme reaction rate depended on the concentration of acetic acid (Figure 2c). In both cases half-maximal rates were obtained at comparable acetic acid concentrations, suggesting that the decoy molecule did not facilitate the binding of the carboxylic acid but rather increased the enzyme reaction rate
In the present study we have demonstrated the resulting in the relaxation of the excited state to the original S0 and the formation of a covalent dearomatized methylquinone flavin adduct

Summary

■ INTRODUCTION

Valorization of biobased feedstock into chemicals[1−4] and fuels[5−7] represents one of the pillars of a more sustainable society. Catalytic methodologies for the conversion of biobased carboxylic acids, are largely limited to esterification or amidation reactions.[8] More recently, chemical[9−12] and biocatalytic[13−17] reduction reactions of carboxylic acids have been developed as well as some approaches for the oxidative decarboxylation into terminal alkenes.[18−21]. Redox-neutral decarboxylation of carboxylic acids into the corresponding alkanes represents an attractive method for the synthesis of alkanes for fuel and synthetic applications. Conventional methods, require harsh reaction conditions and high loadings of precious metal catalysts This implies a significant environmental impact of these reactions and questions their economic feasibility. CvFAP, shows a marked preference for long-chain fatty acids (C16−C17) with its catalytic activity dropping dramatically with shorter chain carboxylic acids. We propose using simple alkanes as decoy molecules, as cocatalysts, to accelerate the CvFAP-catalyzed decarboxylation of short-chain carboxylic acids

■ RESULTS AND DISCUSSION

■ CONCLUSION

■ REFERENCES