The reaction mechanism between(Me)3CO· radical and trans-3-hexene in benzene was studied for the first time at the B3LYP/6-311++G(d,p)//B3LYP/6-31G(d)+ZPVE level.Two distinct elementary channels were identified as:(1) abstraction-addition;(2) addition-addition-elimination.Analysis of the potential energy surface demonstrates that for the title reaction,channels(1) and(2) have the major and minor contribution,respectively.Our calculated results can well explain the recently observed product distribution by Coseri et al.(J.Org.Chem.2005,70,4629).However,we found that the addition-abstraction channel proposed by Coseri et al.is kinetically infeasible.
Recent studies have shown that the inner phase of carbon nanotubes(CNTs) can not only change the properties of molecules inside the tube,but also enhance or restrain the SN2 reactions.Thus,the CNTs can be considered a form of solid solvent.In this paper,we study the [2+2] cycloaddition reaction between CH2O and PH3CH2 in the gas phase,benzene solution and inner phase of CNT using the density functional theory(DFT).The results indicate that the inner phase of CNT has little effect on the [2+2] cycloaddition reaction.This can be explained as that while taking the linear arrangement for SN2 reaction,the reactants do not possess the axial symmetry for the studied [2+2] cycloaddition reaction.Therefore,although the CNT has large axial polarizability,it can exert little influence on the [2+2] cycloaddition reaction.Our studies will be helpful for further understanding of the inner phase chemistry of CNTs.
In order to predict potential molecules with Pb≡C bonding, we investigated the potential energy sur-face of a tetra-atomic system [PbCN2] at the CCSD(T)//B3LYP level. We found that the linear isomer PbCNN possesses good thermodynamic and kinetic stability. The combined molecular orbital analysis, hydrogenation heat, bond energy and bond dissociation energy all proved that PbCNN is composed of Pb≡ C triple bonding.
