The thermal decomposition of ethanol and its reactions with OH and D have been studied with both shock tube experiments and ab initio transition state theory-based master equation calculations. Dissociation rate constants for ethanol have been measured at high T in reflected shock waves using OH optical absorption and high-sensitivity H-atom ARAS detection. The three dissociation processes that...

In the quest for accurate molecular energies, the vehicle most often taken for the first leg of the journey is Hartree-Fock (HF) theory.’ This method generally yields more than 99% of the true (Born-Oppenheimer) energy, but the path for recovering the remaining one percent or so, the correlation energy, is much less clear. A wide variety of techniques are available for predicting the correlatio...

This article presents a multifaceted study of the reaction H+C(2)H(6)-->H(2)+C(2)H(5) and three of its deuterium-substituted isotopologs. First we present high-level electronic structure calculations by the W1, G3SX, MCG3-MPWB, CBS-APNO, and MC-QCISD/3 methods that lead to a best estimate of the barrier height of 11.8+/-0.5 kcal/mol. Then we obtain a specific reaction parameter for the MPW dens...

The nucleophilic substitution of N2 in benzenediazonium ion 1 by one H2O molecule to form protonated phenol 2 has been studied with ab initio (RHF, MP2, QCISD(T)//MP2) and hybrid density functional (B3LYP) methods. Three mechanisms were considered: (a) the unimolecular process SN1Ar with steps 1 --> Ph+ + N2 and Ph+ + H2O --> 2, (b) the bimolecular process SN2Ar with precoordination 1 + H2O -->...

Monomers of (tetrazol-5-yl)-acetic acid (TAA) were obtained by sublimation of the crystalline compound and the resulting vapors were isolated in cryogenic nitrogen matrices at 13 K. The conformational and tautomeric composition of TAA in the matrix was characterized by infrared spectroscopy and vibrational calculations carried out at the B3LYP/6-311++G(d,p) level. TAA may adopt two tautomeric m...

Two major pathways exist in substitution reactions of nucleophiles with allylic substrates (Scheme l).IF3 Attack of the nucleophile at the carbon atom bearing the allylic leaving group leads to direct displacement in a classic sN2 mechanism. Alternatively, attack can also occur at the terminal carbon atom of the allylic double bond, displacing the leaving group in a concerted or consecutive man...

A program able to use hybrid free rotor plus harmonic oscillator basis functions for the variational study of large and small amplitude vibrations is developed. The Hamiltonian matrix elements between harmonic oscillator eigenfunctions and polynomial terms are calculated using a recursive algorithm. This technique permits use of only one basic algorithm to compute the kinetic and potential part...

A new potential energy surface for the molecular ion He±H‡2 is used to predict microwave transitions that may be observable in environments such as circumstellar envelopes and planetary nebulae. For the vibrational ground state, transitions are predicted at wavelengths of 1215, 608, 405, 304, 244, 203, 175, 154, 137 and 124 mm. Key words: molecular processes ± ISM: molecules. 1 I N T R O D U C ...

Methanol experimental data are obtained under pyrolysis, fuel lean (φ = 0.75) and stoichiometric mixtures with methane in a flow reactor. Methanol pyrolysis experiments are performed under isothermal conditions of 1073K over a pressure range from 1 to 10 atm. Oxidation environments are performed over a temperature range from 873 1073K and a pressure range from 1 5 atm. Oxidation experiments con...