1118-10-1Relevant articles and documents
Electon-Transfer, Halogen-Metal Exchange and Direct Processes in Formal Nucleophilic Substitutions on Alkyl Halides by Trimethyltinsodium
Smith, Gary F.,Kuivila, Henry G.,Simon, Reyna,Sultan, Leslie
, p. 833 - 839 (2007/10/02)
Formal nucleophilic substitutions have been studied by simple trapping techniques designed to separate and estimate contributions of reactions proceeding by way of free radicals, by way of anions, and by way of geminate or synchronous processes.Reactions of trimethyltinsodium with organic halides in tetrahydrofuran at 0 deg C were examined, using dicyclohexylphosphine for trapping free radicals and tert-butylamine for free anionoids.Among 22 halides included in this study nine have been shown to involve two or all three of the mechanistic pathways.Primary chlorides reacted predominantly by a direct mechanism (SN2, geminate reaction of intermediates, or multicenter process).Branching, as in isobutyl and neopentyl, led to contributions from electron-transfer (free radical) and halogen-metal exchange (anionoid) mechanisms.Secondary bromides reacted predominantly by the ET process (major) and HME (minor) while the relative contributions from these were reversed in importance with the iodides.Triethylcarbinyl chloride reacted exclusively by elimination while the bromide reacted by ET alone or in competition with elimination. 1- and 2-bromoadamantanes reacted by ET, and 1-chloroadamantane showed no reaction after 10 days at -4 deg C.
REACTIONS OF TRIMETHYLTINSODIUM WITH ALKYL HALIDES. EFFECTS OF STRUCTURE AND SOLVENT ON COURSE OF REACTION AND REACTIVITY
Kuivila, Henry G.,Reeves, William G.
, p. 801 - 808 (2007/10/02)
The reactions of eleven alkyl chlorides and bromides with trimethyltinsodium have been examined.It has been found that primary and secondary halides react smoothly and rapidly to provide good yields of substitution products in THF and TG at Oo.The reaction is less satisfactory for allyl bromide and unsatisfactory for cinnamyl chloride and tertiary halides.Trimethyltinsodium and 2-chlorobutane react with second order kinetics.Relative reactivities of the halides have been determined in the two solvents and are discussed.Lithium, sodium and potassium as counterions yielded the same results in the reaction of the trimethyltinalkils with primary, secondary and tertiary butyl bromides in THF.