4325-49-9Relevant articles and documents
Solvolysis of 1,1-dimethyl-4-alkenyl chlorides: Evidence for π-participation
Malnar, Ivica,Juric, Sandra,Vrcek, Valerije,Gjuranovic, Zeljka,Mihalic, Zlatko,Kronja, Olga
, p. 1490 - 1495 (2002)
Tertiary 1,1-dimethyl-4-alkenyl chloride (1) solvolyzes with significantly reduced secondary β-deuterium kinetic isotope effect (substrate with two trideuteromethyl groups) and has a lower entropy and enthalpy of activation than the referent saturated analogue 4 (kH/kD = 1.30 ± 0.03 vs kH/kD = 1.79 ± 0.01; ΔΔH? = -9 kJ mol-1, ΔΔS? = -36 J mol-1 K-1, in 80% v/v aqueous ethanol), indicating participation of the double bond in the rate-determining step. Transition structure 1-TS computed at the MP2(fc)/6-31G(d) level of theory revealed that the reaction proceeds through a late transition state with considerably pronounced double bond participation and a substantially cleaved C-Cl bond. The doubly unsaturated compound 3 (1,1-dimethyl-4,8-alkadienyl chloride) solvolyzes with further reduction of the isotope effect, and a drastically lower entropy of activation (kH/kD = 1.14 ± 0.01; ΔS? = -152 ± 12 J mol-1 K-1, in 80% v/v aqueous ethanol), suggesting that the solvolysis of 3 proceeds by way of extended π-participation, i.e., the assistance of both double bonds in the rate-determining step.
Reactions of Saturated and Unsaturated Tertiary Alkyl Halides and Saturated Secondary Alkyl Iodides with Lithium Aluminum Deuteride. Convincing Evidence for a Single-Electron-Transfer Pathway
Ashby, E. C.,Welder, Catherine O.
, p. 7707 - 7714 (2007/10/03)
Reactions of saturated secondary and tertiary alkyl halides with LiAlH4 (LAH) and LiAlD4 (LAD) have been carried out, and convincing evidence for a single-electron-transfer (SET) pathway has been obtained. Reactions involving saturated alkyl halides with LAD provide a model system in which a halogen-atom radical chain process is not possible, and therefore, the observation of large quantities (in some cases >90 percent) of protium in the reduction product provides strong evidence for a radical intermediate and a SET pathway. Specifically, the reaction of 2-iodooctane (10) with LAD produced octane with a deuterium content as low as 21 percent. Also, the reaction of the tertiary halide 2-iodo-2-methylheptane (15) with LAD produced 2-methylheptane (16) with a deuterium content as low as 8 percent. The effect of stoichiometry, halogen type, and reaction vessel surface on these reactions was studied. Reaction of the unsaturated tertiary halide 6-iodo-6-methyl-1-heptene (25) with LAD was also studied and was found to proceed predominantly by a SET process involving a halogen-atom radical chain process. The possibility of a carbocation intermediate in all of these reactions is discussed.
Geminale Dialkylierung von Ketonen mit Grignard-Verbindungen und Methyltitan(IV)-chloriden
Reetz, Manfred T.,Westermann, Juergen,Steinbach, Rainer
, p. 931 - 933 (2007/10/02)
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