Boosting effect of ortho- propenyl substituent on the antioxidant activity of natural phenols
摘要:
Seven new antioxidants derived from natural or synthetic phenols have been designed as alternatives to BHT and BHA antioxidants. Influence of various substituents at the ortho, meta and para positions of the aromatic core of phenols on the bond dissociation enthalpy of the ArO-H bond was evaluated using a DFT method B3LYP/6-311++G(2d,2p)//B3LYP/6-311G(d,p). This prediction highlighted the ortho-propenyl group as the best substituent to decrease the bond dissociation enthalpy (BDE) value. The rate constants of hydrogen transfer from these phenols to DPPH. radical in a non-polar and non-protic solvent have been measured and were found to be in agreement with the BDE calculations. For o-propenyl derivatives from 2-tert-butyl-4-methylphenol, BHA, creosol, isoeugenol and di-o-propenyl p-cresol, fewer radicals were trapped by a single phenol molecule, i.e. a lower stoichiometric number. Reaction mechanisms involving the evolution of the primary phenoxyl radical ArO are proposed to rationalise these effects. (C) 2015 Elsevier Ltd. All rights reserved.
A concise synthesis of carpanone using solid-supported reagents and scavengers
作者:Ian R. Baxendale、Ai-Lan Lee、Steven V. Ley
DOI:10.1039/b203388g
日期:2002.8.8
Polymer-supported reagents have been applied to the synthesis of the natural product carpanone resulting in a clean and efficient synthesis without the requirement for conventional purification techniques. A new polymer-supported transition metal isomerisation catalyst is also reported.
Method of extracting qualitative and quantitative information from mixtures
申请人:Chau Foo-tim
公开号:US20080319681A1
公开(公告)日:2008-12-25
The present invention relates to methods for extracting qualitative and quantitative information from natural ingredient mixtures, utilizing two or more data sets and newly developed chemometric method known as improved alternative moving window factor analysis (IAMWFA).
[EN] IMPROVER FOR VISBREAKING AND PROCESS FOR CO-VISBREAKING TO COAL TAR OR BIO-OIL CONTAINING THE SAME AND HEAVY OIL<br/>[FR] AMÉLIORANT POUR LA RÉDUCTION DE VISCOSITÉ ET PROCÉDÉ POUR LA CO-RÉDUCTION DE VISCOSITÉ DE GOUDRON DE HOUILLE OU D'HUILES BIOLOGIQUES EN CONTENANT ET D'HUILE LOURDE
申请人:SHENHUA GROUP CORP LTD
公开号:WO2013091451A1
公开(公告)日:2013-06-27
Disclosed is an improver for vis - breaking processing containing organic oxygen functional groups, such as carbonyl group [-C(O)-]; ether group [R-O-R']; aldehyde group [-CHO]; ketone group [R-C(O)-R']; quinine group [C6H4O2]; furan group [C4H4O] and/or any substituted derivative of furan and quinine, wherein R and R' independently are alkyl radicals or other organic groups respectively, as well as a process for co-vis breaking to coal tar or bio-oil containing the above organic oxygen functional groups and heavy oil.