| Résumé | Di-tert-butylmethyl, B2CH, and a wide variety of related radicals, e.g., B3C, B2CCH2C6H5, B2CCH2P-(O)(OEt)2, etc., are extremely long lived when compared with less highly substituted alkyl radicals. They show no sign of dimerizing even at low temperatures. At ambient temperatures these radicals decay with first-order kinetics and Arrhenius parameters for these reactions are reported. The decay mechanism could not be unequivocally established but it is believed to be either a β scission (e.g., B2CH → B(H)C=CMe2 + Me·) or a 1,3-intramolecular hydrogen atom transfer (e.g., B2CH → BCH2CMe2CH2). At low temperatures most B2CCH2R radicals decay with second-order kinetics, presumably yielding the disproportionation products, B2CHCH2R and B2C=CHR. |
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