3531-48-4Relevant academic research and scientific papers
Surface organometallic chemistry on metals: Controlled hydrogenolysis of Me4Sn, Me3SnR, Me2SnR2, MeSnBu 3 and SnBu4 (R = methyl, n-butyl, tert-butyl, neopentyl, cyclohexyl) onto metallic rhodium supported on silica
Taoufik, Mostafa,Cordonnier, Marie-Anne,Santini, Catherine C.,Basset, Jean-Marie,Candy, Jean-Pierre
, p. 1531 - 1537 (2007/10/03)
The controlled hydrogenolysis of MexSnR4-x (0 ≤ x ≤ 4; R = methyl, n-butyl, tert-butyl, neopentyl, cyclohexyl) onto Rh/SiO 2 is followed by quantitative and qualitative analysis of evolved gases. Only MeH and RH are detected in the evolved gases. There is hydrogenolysis of the Sn-C bonds without any C-C bond hydrogenolysis, leading to formation of grafted organometallic fragments. Using various organotin compounds, MexSnR4-x, it has been possible to determine the regioselectivity of the hydrogenolysis of the Sn-C bonds. The initial selectivity is inversely proportional to the steric bulk of the alkyl group: tBu xR4-x (symmetry D3h), in which the bulkiest group, e.g., R, is away from the surface could explain these results. This surface five-coordinate tin species could eliminate an alkyl group, generally a methyl group, thus decreasing the steric bulk around the tin, into the equatorial plane of D3h, via a concerted hydrogen transfer-elimination mechanism to give Rh-SnMex-1R4-x. Then, in the successive steps of the hydrogenolysis, the bulkiest group, R, would be eliminated.
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.
Estimation of Electron-Transfer Contributions in Reactions of Alkyl Bromides with (Trimethyltin)sodium
Kuivila, Henry G.,Smith, Gary F.
, p. 2918 - 2919 (2007/10/02)
Estimates of the minimum degrees of electron-transfer contributions to the mechanisms of reaction of primary, secondary, and tertiary bromides with (trimethyltin)sodium have been obtained by the use of dicyclohexylphosphine as a free-radical trap.
