简介：ThereactionofsingletoxygenwithethylenehasbeenstudiedattheabinitiolevelwithbothHF/3-21GandHF/6-31Gbasissets,fullyoptimizingthegeometriesofthecriticalpoints.Thetransitionstateleadingtotheintermediateperoxiranefromtheinitialreactantsisfound,Iocatedat81.71kJ/molabovethedissociationlimit.Thevibrationalanalysisisdonewithtwobasissets.Fromtheresultsitcanbeseenthatthefrequencieshavenotbeenmadeanimprovementobviouslywithaugmented6-31Gcomparedto3-21Gbasis;itfollowsthatmainreasonfortoohighHF/3-21Gfrequencycouldmainlybethevibrationalanharmonicity.TheeigenvectorcorrespondingtothesingleimaginaryvibrationalfrequencyisdominatedbythelargerO-Odistance.Thefindingofthetransitionstateconfirmsthattheperoxiraneminimumcanbereachablepassingthroughaperoxirane-likesaddlepoint.Inaddition,themechanismsofthereactionformingoxiranearediscussedaswell.

简介：Sphere-likecompoundC8H17Si(OPhC12H25)3N(1)formsmesophases.Inordertoinvestigatetherelationshipbetweenmolecularstructureandliquidcrystalproperties,structuralstudiesarecarriedoutonthemodelmoleculesofcompound1anditssubstitutedderivativesusingahinitiocalculations.TheresultsshowthatthecyanoorchlorosubstitutedtribenzosilatranecompoundsR1Si(OPhR2)3N(R1R2=CNorCl)havemuchbiggerdipolemomentsoranisotropyofpolarizabilityandmorelikespherethanthecorrespondingalkylsubstitutedcompounds.Cyanoorchlorosubstitutedtribenzosilatraneswouldbebettercandidatesforsphere-likemeso-gens.

简介：Theabinitiomolecularorbitalmethodisemployedtostudytheenantioselectivereductionofacetophenonewithboranecatalyzedbythiszolidino[3,4-c]oxazaborolidine.Computationresultshowsthatthecontrollingstepforthereductionisthedecompositionofthecatalyst-alkoxyboraneadductandthereductionleadstoS-alcohols.ThetransitionatateofthehydridetransferfromtheboranemoietytothecarbonylcarbonofacetophenoneisatwistedchairstructurewithaB(2)-N(3)-BBH3-HBH3-CCo-OCO6-memberedring.

简介：AbinitiomolecularorbitalcalculationsofdoublynegativechargedB16H162-(D2)andneutralB16H16(Td)havebeendoneattheHF/6-31Glevel.TheyarepredictedtobechemicallyandkineticallystablebyvibrationalanalysesontheirrespectiveenergyhypersurfaceoftheHF/6-31Glevel.ThegeometricalstructureofthespeciesB16H1622-(D2)wasdiscussed.

简介：辽宁省营口市风光化工有限公司依靠科技创新不断壮大，2007年抗氧剂产品销量达到5800吨，销售收入1．1266亿元，利润达到601万元。其产品市场占有率居国内第一，还出口到美国、欧洲、中东和东南亚等国家和地区，一跃成为国内抗氧剂行业的龙头企业。

简介：据报道，科聚亚（Chemtura）公司表示，对全球抗氧化剂供应链进行重组，以提高其在世界塑料市场的竞争力，以便更好地为全球客户提供优质服务。它将关闭意大利的两套抗氧化剂生产设备，及在法国装置上停止生产两种中间体化工产品。科聚亚说，关闭装置可使科聚亚有1500—2000万美元的税前收入。