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The free‐radical reaction of tri‐ n ‐butyltin hydride with peroxides
Author(s) -
Brokenshire J. L.,
Ingold K. U.
Publication year - 1971
Publication title -
international journal of chemical kinetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.341
H-Index - 68
eISSN - 1097-4601
pISSN - 0538-8066
DOI - 10.1002/kin.550030405
Subject(s) - chemistry , benzene , radical , reaction rate constant , reactivity (psychology) , hydrogen peroxide , alkyl , hydride , peroxide , medicinal chemistry , decomposition , photochemistry , hydrogen , organic chemistry , kinetics , medicine , physics , alternative medicine , pathology , quantum mechanics
Rate constants for the tri‐ n ‐butyltin radical ( Sn · ) induced decomposition of a number of peroxides have been measured in benzene at 10°C. The values range from ∼100 M −1 sec −1 for di‐ t ‐butyl peroxide to 2.6 × 10 7 M −1 sec −1 for di‐ t ‐butyl diperoxyisophthalate. The majority of the peroxides, including diethyl peroxide, diacetyl peroxide, and t ‐butyl peracetate, have rate constants of ∼10 5 M −1 sec −1 . It is shown that di‐ n ‐alkyl disulfides are ten times as reactive toward Sn · as di‐ n ‐alkyl peroxides, although the exothermicities of these reactions are ∼15 and ∼39 kcal/mole, respectively. The enhanced reactivity of the disulfides is attributed to the easier formation of an intermediate or transition state with 9 electrons around sulfur, compared with an analogous species with 9 electrons around oxygen. The following bond strengths (kcal/mole) have been estimated: D [ Sn OR] = 77; D [ Sn H] = 82; D [ Sn SR] = 83; and D [ Sn OC(O)R] = 86, where R = alkyl. Rate constants for reaction of Sn · with some benzyl esters have also been measured. It has been found that t ‐butoxy radicals can add to benzene and abstract hydrogen from benzene at ambient temperatures.