2370-13-0Relevant articles and documents
Convincing Evidence, Not Involving Cyclizable Radical Probes, That the Reaction of LiAlH4 with Hindered Alkyl Iodides Proceeds Predominantly by a Single Electron Transfer Pathway
Ashby,Welder, Catherine O.
, p. 3542 - 3551 (1997)
Previous workers have maintained that evidence for the radical nature of the reaction of LiAlH4 with sterically hindered alkyl iodides is due to radical initiation by impurities followed by a halogen atom radical chain process involving the cyclizable alkyl iodide probe and that the reduction of the C-I bond actually proceeds by an SN2 pathway. In order to resolve the validity of this explanation, 1-iodo-2,2-dimethylhexane (the saturated counterpart of the cyclizable probe), which is not capable of this halogen atom radical chain process, was allowed to react with LiAlD4. The reduction product, 2,2-dimethylhexane, contained only 4-76% deuterium depending on the conditions of the reaction. This result is consistent with the reaction proceeding by a SET process via a radical intermediate and is inconsistent with an SN2 pathway. We have determined the influence of the nature of the reaction on the type of reactor surface (Pyrex, Teflon, stainless steel, and quartz) used in the reaction. We have also studied the influence of AlD3 (a byproduct in the reduction) in the mechanistic evaluation of this reaction.
Alkane Functionalization on a Preparative Scale by Mercury-Photosensitized Cross-Dehydrodimerization
Brown, Stephen H.,Crabtree, Robert H.
, p. 2946 - 2953 (2007/10/02)
Alkanes can be functionalized with high conversions and in high chemical and quantum yields on a multigram scale by mercury-photosensitized reaction between an alkane and alcohols, ethers, or silanes to give homodimers and cross-dehydrodimers.The separation of the product mixtures is often particulary easy because of a great difference in polarity of the homodimers and cross-dimers.It is also possible to bias the product composition when the ratio of the components in the vapor phase is adjusted by altering the liquid composition.This is useful either to maximize chemical yield or to ease separation by favoring the formation of the most easily separated pair of compounds.The mechanistic basis of the reaction is discussed and a number of specific types of syntheses, for example of 2,2-disubstituted carbinols, are described in detail.The selectivity of cross-dimerization is shown to exceed that for homodimerization and reasons are discussed.Relative reactivities of different compounds and classes of compound are MeOHp-dioxanecyclohexane1,3,5-trioxacyclohexaneethanolisobutaneTHFEt3SiH.The observed selectivities generally parallel those for homodimerization, reported in the preceding paper, but certain differences are noted, and reasons for the differences are proposed.The bond-dissociation energy of Et3SiH is estimated from the reactivity data to be 90 kcal/mol.Eleven new carbinols are synthesized.
