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Multistep conversion of cresols by phenol hydroxylase and 2,3-dihydroxy-biphenyl 1,2-dioxygenase

Frontiers of Environmental Science & Engineering 2014年第4期8卷 539-546页

作者： Shengnan SHI Fang MA Tieheng SUN Ang LI Jiti ZHOU Yuanyuan QU State Key Laboratory of Urban Water Resource and Environment School of Municipal and Environmental Engineering Harbin Institute of Technology Harbin 150090 China Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education) School of Environmental Science and Technology Dalian University of Technology Dalian 116024 China

A mulfistep conversion system composed of phenol hydroxylase （PHrND） and 2,3-dihydroxy-biphenyl 1,2-dioxygenase （BphCLA_4） was used to synthesize methylcatechols and semialdehydes from o- and m-cresol for the first time. Docking studies displayed by PyMOL predicted that cresols and methylcatechols could be theoretically transformed by this multistep conversion system~ High performance liquid chromatography mass spectrometry （HPLC-MS） analysis also indicated that the products formed from multistep conversion were the corresponding 3-methylcatechol, 4-methylcatechol, 2- hydroxy-3-methyl-6-oxohexa-2,4-dienoic acid （2- hydroxy-3-methyl-ODA） and 2-hydroxy-5-methyl-6-oxo- hexa-2,4-dienoic acid （2-hydroxy-5-methyl-ODA）. The optimal cell concentrations of the recombinant E. coli strain BL21 （DE3） expressing phenol hydroxylase （PHrND） and 2,3-dihydroxy-biphenyl 1,2-dioxygenase （BphCLA_4） and pH for the multistep conversion of o- and m-cresol were 4.0 （g-L-1 cell dry weight） and pH 8.0, respectively. For the first step conversion, the formation rate of 3- methylcatechol （0.29μmol·L-1·min-1·mg-1cell dry weight） from o-cresol was similarly with that ofmethylca- techols （0.28 μmol·L-1·min-1·mg-1 cell dry weight） from m-cresol by strain PHrND. For the second step conversion, strain BphCLA_4 showed higher formation rate （0.83 μmol·L-1·min-1·mg-1 cell dry weight） for 2-hydroxy-3-methyl- ODA and 2-hydroxy-5-methyl-ODA from m-cresol, which was 1.1-fold higher than that for 2-hydroxy-3-methyl- ODA （0.77 μmol·L-1·min-1·mg-1. mglcell dry weight） from ocresol. The present study suggested the potential application of the multistep conversion system for the production of chemical synthons and high-value products.

关键词： multistep conversion cresols phenol hydro-xylase 2 3-dihydroxybiphenyl 1 2-dioxygenase methyl-catechols

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Competing pathways of cresol formation in toluene photooxidation:OH-toluene adducts react with NO_(2) or with O_(2)?

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Journal of Environmental Sciences 2022年第4期34卷 211-220页

作者： Baocong Zhao Yongpeng Ji Dandan Qin Yuemeng Ji Jiangyao Chen Taicheng An Guangdong Key Laboratory of Environmental Catalysis and Health Risk Control Guangdong-Hong Kong-Macao Joint Laboratory for Contaminants Exposure and HealthInstitute of Environmental Health and Pollution controlGuangdong University of TechnologyGuangzhou 510006China Key Laboratory of City Cluster Environmental Safety and Green development Guangzhou Key Laboratory of Environmental Catalysis and Pollution ControlSchool of Environmental Science and EngineeringGuangdong University of TechnologyGuangzhou 510006China

Methyl-hydroxy-cyclohexadienyl radicals(OTAs)are the key products of the photooxidation of toluene,with implications for the fate of ***,we investigated the photooxidation mechanisms and kinetics of three main OTAs(o-OTA,m-OTA,and p-OTA)with NO_(2)using quantum chemical calculations as well as the fate of OTAs under the different concentration ratios of NO_(2)and O_(2).The mechanism results show that the pathway of Habstraction by NO_(2)to anti-HONO(anti-H-abstraction)is more favorable than the syn-Habstraction pathway,because the strong interaction between OTAs and NO_(2)is formed in the transition states of the anti-H-abstraction *** branching ratios of the antiH-abstraction pathways are more than 99%in the temperature range of 216-298 *** total rate constant of the OTA-NO_(2)reaction is 9.9×10^(-12)cm^(3)/(molecule·sec)at 298 K,which is contributed about 90%by o-OTA+NO_(2),and the main products are o-cresol and *** half-lives of the OTA-NO_(2)reaction in some polluted areas of China are 35 times longer than those of the OTA-O_(2)*** the atmosphere,the NO_(2^(-))and O_(2^(-))initiated reactions of OTAs have the same ability to form cresols as[NO_(2)]is up to 142.1 ppmV,which is impossible to *** implies that under the experimental condition,the[NO_(2)]/[O_(2)]should be controlled to be less than 7.8×10^(-5)to simulate real atmospheric oxidation of *** results reveal that for the photooxidation of toluene,the yield of cresol is not affected by the concentration of NO_(2)under the atmospheric environment.

关键词： Methyl-hydroxy-cyclohexadienyl radicals Toluene photooxidation Reaction mechanism Kinetics cresols

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Selective aerobic oxidation of p-cresol with co-catalysts between metalloporphyrins and metal salts

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Chinese Journal of Chemical Engineering 2018年第7期26卷 1493-1498页

作者： Yuanbin She Yao Fan Lei Zhang Ying Xu Min Yu Haiyan Fu State Key Laboratory Breeding Base of Green Chemistry-Synthesis Technology College of Chemical Engineering Zhejiang University of Technology The Modernization Engineering Technology Research Center of Ethnic Minority Medicine of Hubei Province School of Pharmaceutical Sciences South Central University for Nationalities

A green and efficient method for the selective aerobic oxidation of p-cresol to p-hydroxybenzaldehyde catalyzed by co-catalysts between metalloporphyrins and metal salts was investigated and developed. The relationship between the synergistic catalytic effects and the composition as well as amount of co-catalysts was investigated. Moreover, the influence of different reaction conditions was studied in details. A high p-cresol conversion （〉99%） and p-hydroxybenzaldehyde selectivity （83%） were obtained using only 1.125 × 10- 5 mol T（p-CH3O）PPFe111Cl-Co（OAc）2 used under mild, optimized reaction conditions. A possible mechanism for the reaction was also proposed. This work would be meaningful and instructive for the further researches and applications of co-catalyst system on oxidation of cresols and could give some enlightenment on the selectively catalytic oxidation of the side-chain alkyls of aromatics.

关键词： Aerobic Oxidation Selectivity Co-catalyst Metalloporphyrin cresols

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