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Chen K.,Zhejiang GongShang University | Chen K.,Zhejiang University | Xie H.,Zhejiang NHU Company Ltd | Jiang K.,Hangzhou Normal University | Mao J.,Zhejiang NHU Company Ltd
Chemical Physics Letters | Year: 2016

The structure-reactivity relationship of new hydroxyimide organocatalysts based on the heterocyclic replacements of the phenyl ring of N-hydroxyphthalimide (NHPI) has been theoretically investigated to gain a mature understanding of this particular catalysis for aerobic oxidation. We find that the reactivity of catalysts with the common five-member aromatic rings is lower than that of NHPI. The catalyst with the recyclable structure of imidazolium ionic liquid may serve as a novel model catalyst for further improvements due to its reactivity comparable to that of NHPI. The catalytic reactivity of multi-nitroxyl catalysts is theoretically more fascinating than that of the highly efficient N,N-dihydroxypyromellitimide. Source

ZHEJIANG NHU Co., Zhejiang University and Shandong Nhu Amino Acids Co. | Date: 2013-01-06

The present invention discloses a clean method for preparing a D,L-methionine comprising the steps of: preparing a potassium cyanide solution using a crystallized mother solution containing potassium carbonate as an absorbing liquid to absorb hydrocyanic acid, then reacting the potassium cyanide solution with 3-methylthio propionaldehyde and an ammonium bicarbonate solution at 50-150 C. for 3-15 minutes so as to obtain a 5-(-methylthioethyl)glycolyurea solution, then bring the 5-(-methylthioethyl)glycolyurea solution to a temperature of 140-220 C. and subjecting to a saponification reaction for 2-5 minutes, after the completion of the saponification, reducing the temperature to 0-40 C., extracting with an organic solvent, neutralising the water phase with CO

Zhejiang University and Zhejiang Nhu Company Ltd | Date: 2010-03-18

A method of preparing nano-dispersed high-all-trans-carotenoid microcapsules is provided, comprising: preparing 10-20% carotenoid suspension by milling the high-all trans-carotenoid crystals with dichloromethane until the particle size thereof is in the range of 2-5 m, then supplying the suspension together with preheated dichloromethane of another pass into a dissolving tank to obtain a solution of 0.5-2%; delivering the solution together with ethanol or isopropanol into a crystallization device having high gravity rotating packed bed simultaneously and continuously, and then into a wiped-film evaporator for desolvation until the solid content is 10-20%, then a transparent alcohol dispersion of carotenoid is obtained; mashing the alcohol dispersion together with an aqueous solution containing an antioxidant and protective colloid and spray drying to obtain nano-dispersed high-all-trans-carotenoid microcapsules. As the crystals are nano-dispersed and the content of trans-isomer is more than 90%, the carotenoid microcapsules of present inventions exhibit high bioavailability.

Ma Q.,Zhejiang University | Liang C.,Zhejiang University | Chen K.,Zhejiang GongShang University | Liu K.,Zhejiang University | And 3 more authors.
Journal of Molecular Catalysis A: Chemical | Year: 2016

The investigation of alkali acting as the key component during the liquid-phase catalytic oxidation of p-cresols to p-hydroxyl aromatic aldehydes is far from satisfied, thus a detailed exploration is presented. It was observed that the p-cresols were activated by alkali to form phenolate salt to ensure mild reaction conditions demonstrated by comparing the oxidation of p-cresol and its phenolate sodium. It was also found that excess alkali improved the selectivity of aldehyde by inhibiting the formation of dimeric side products in view of an analysis of the side products distribution. The alkaline alcoholic anion facilitates the 1,6-addition reaction between p-benzoquinone methide and solvent. Thus, more alkali was needed in solvents with high pKa values and high water content. The detection of trace acid during the oxidation of p-cresols suggested the phenoxy radical mechanism rather than the classic benzyl radical mechanism proposed for interpreting the oxidation of non-hydroxyl aromatic hydrocarbons. These conclusions contribute significantly to both the understanding of role of alkali during the reaction process and the mechanism study for the catalytic oxidation of cresols and non-hydroxyl aromatic hydrocarbons. © 2016 Elsevier B.V. All rights reserved. Source

Lu W.,Zhejiang University | Ye L.,Zhejiang University | Lv X.,Zhejiang University | Xie W.,Zhejiang University | And 5 more authors.
Metabolic Engineering | Year: 2015

In this report, UbiE and UbiH in the quinone modification pathway (QMP) were identified in addition to UbiG as bottleneck enzymes in the CoQ10 biosynthesis by Rhodobacter sphaeroides. The CoQ10 content was enhanced after co-overexpression of UbiE and UbiG, however, accompanied by the accumulation of the intermediate 10P-MMBQ. UbiH was then co-overexpressed to pull the metabolic flux towards downstream, resulting in an elevated CoQ10 productivity and decreased biomass. On the other hand, the expression levels of UbiE and UbiG were tuned to eliminate the intermediate accumulation, however at the sacrifice of productivity. To alleviate the detrimental effect on either productivity or cell growth, we tried to fuse UbiG with UbiE and localize them onto the membrane to elevate intermediate conversion. By fusing UbiE and UbiG to pufX, CoQ10 was accumulated to 108.51±2.76mg/L with a biomass of 12.2±0.9g/L. At last, we combined the optimized QMP and the previously engineered 2-methyl-d-erythritol-4-phosphate pathway (MEP) to further boost CoQ10 biosynthesis, resulting in a strain with 138±2.64mg/L CoQ10 production. © 2015 International Metabolic Engineering Society. Source

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