A Critical Review of H-Atom Transfer in the Liquid Phase: Chlorine Atom, Alkyl, Trichloromethyl, Alkoxy, and Alkylperoxy Radicals

Abstract

This review covers hydrogen-atom transfer from carbon-hydrogen bonds in organic compounds to chlorine atom, methyl, ethyl, trichloromethyl, t-butoxy and alkylperoxy radicals in the liquid phase. Rate constant data are presented-iri 38 tables. Literature is covered throu,gh most of 1972. The review is divided into six sections; an introduction plus five sections each dealing with specific radicals. Hydrogen-atoIn trander to chlorine Iltom Ilrp pre!':f>ntp{l :I!': rpbtivp ratp eon",tant",_ For hydrogen-atom transfer to methyl, ethyl, trichloromethyl, and t-butoxy radicals, both relative and absolute rate constants are tabulated. For alkylperoxy radicals only absolute rate constants are listed. Each absolute rate constant ha.s a tabulated set of rate parameters where A has been assigned and E derived from the Arrhenius equation.

Solvent Effects on the AIBN Forced Degradation of Cumene: Implications for Forced Degradation Practices

“…However, the situation is markedly different for the reaction of highly nucleophilic radicals, such as peroxy and alkoxy radicals. Hendry et al21 have reported the hydrogen abstraction rates between the tert ‐butoxy radical and a number of common organic compounds, and cyanoalkanes such as acetonitrile are among the slowest reactions reported—more than an order of magnitude slower than ethers and only slightly faster than alkanes. A number of groups have taken advantage of the relative inertness of acetonitrile with respect to oxidation by polar radicals to use it as a reaction solvent.…”

The kinetic regularities, products, and mechanism of the thermal decomposition of dimethyldioxirane. The contribution of molecular and radical reaction channels

“…(27). Substitution of expressions (36) and (37) into Eq. (33) gives at'ter simple rearrangements the expression for the rate of ia consumption:…”

Artifacts Generated During Azoalkane Peroxy Radical Oxidative Stress Testing of Pharmaceuticals Containing Primary and Secondary Amines

“…All 1D and 2D data were collected at 298 K using a Bruker-Biospin 5 mm BBFO probe on a AVANCE III NMR spectrometer (Bruker-Biospin, Billerica, Massachusetts) operating at 500 MHz for milligram scale samples or using a Bruker-Biospin 5 mm TCI cryoprobe on a AVANCE III NMR spectrometer operating at 600 MHz for a submiligram sample. The following data were collected: 1D proton, 1D carbon, 1 H-1 H gradient COSY (correlation spectroscopy), 1 H-13 C multiplicity edited HSQC (heteronuclear single quantum coherence), and 1 H- 13 spectrum and the 1D carbon spectra were referenced using the TMS signal, set to 0.00 ppm. NMR spectra can be found in the Supporting Information.…”

“…The long‐lived azoalkane‐derived peroxy radicals may therefore encounter drug molecules from which they may abstract H atoms, but may also readily undergo recombination/decomposition as shown in Scheme . Characteristic to tertiary peroxy radicals, the recombination/decomposition of the azoalkane peroxy radicals leads to the undesired formation of alkoxy radicals, estimated to react 10 4 –10 5 times faster with organic substrates, than the corresponding peroxy radicals . As a result, the selectivity of the test for weakly bound H atoms is lost, as the drug may preferentially react with alkoxy radicals at a variety of sites within the drug molecule.…”

“…Characteristic to tertiary peroxy radicals, the recombination/decomposition of the azoalkane peroxy radicals leads to the undesired formation of alkoxy radicals, estimated to react 10 4 -10 5 times faster with organic substrates, than the corresponding peroxy radicals. 13 As a result, the selectivity of the test for weakly bound H atoms is lost, as the drug may preferentially react with alkoxy radicals at a variety of sites within the drug molecule. For drug compounds with little reactivity toward peroxy radicals, the reaction with alkoxy radicals therefore produces false positive test results.…”