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Chemistry

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A study of the vacuum pyrolysis of para-substituted diazoacetophenones with He(I) ultraviolet photoelectron spectroscopy

Article Abstract:

An ultraviolet photoelectron (PE) spectrometer that uses a tunable 50 W CW CO(sub)2 laser for a heat source analyzes vacuum pyrolysis of diazoacetophenone and its p-methyl, p-methoxy, p-chloro, and p- nitro analogs. Using He(I) ultraviolet PE spectroscopy for analyzing the pyrolysate has shown that, with the laser at the 26 W power level, (500 +/- 50 degrees Celsius), diazoacetophenone and the p-methyl, p-chloro and p-methoxy analogs yield the corresponding phehylketenes, which are the products of the Wolff rearrangement of the incipient ketocarbenes.

Analysis, Cyclic compounds, Pyrolysis, Vacuum technology, Vacuum equipment

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A search for an inexpensive calculational method for the reliable prediction of the first adiabatic and vertical ionization potentials of carbenes; photoelectron spectra of two stable carbenes

Article Abstract:

A search has been made for an inexpensive calculational method for the reliable prediction of the first adiabatic and vertical ionization potentials of carbenes. Using semiempirical methods, among them PM3 and ab initio HF, the first adiabatic ionization potential (IP) of eight electronically different carbenes was calculated. CBS-4 and DFT calculations agree well with experimental findings. The best method for predicting the first ionization potentials of carbenes is likely Becke3LYP/6-31+G*//Becke3LYP/3-21G(*).

Methods, Electronic structure, Atomic structure

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A computational study on the sources of deuterium secondary kinetic isotope effects in carbocation-forming reactions

Article Abstract:

A study of sources of deuterium secondary kinetic isotope effects in carbocation-forming reactions has been carried out through computation. Calculations at the HF-DFT hybrid Becke3LYP level were carried out on protonated 2-exo- and 2-endo-norbornanols as model substrates for 2-exo- and 2-endo-norbornyl brosylates to explore the source of the experimentally determined deuterium secondary kinetic isotope effects.

Mathematical models, Deuteron reactions

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