631-65-2Relevant academic research and scientific papers
Silylaminyl Radicals. Part 2. Free Radical Chain Halogenation of Hydrocarbons using N-Halogenobis(trialkylsilyl)amines
Cook, Malcolm D.,Roberts, Brian P.,Singh, Karamjit
, p. 635 - 644 (2007/10/02)
The liquid-phase halogenation of a number of hydrocarbons and of 1-chlorobutane by N-halogenobis(trialkylsilyl)amines has been studied using product analysis techniques.The reactions take place by free radical chain mechanisms which involve the propagation steps generalised in equations (A) and (B) (X=Br or Cl).At 353 K, the molar reactivities of toluene (benzylic C-H) and cyclohexane towards (R3Si)2N+RH(R3Si)2NH+R (A) R+(R3Si)2NXRX+(R3Si)2N (B) (Me3Si)2N are approximately equal and toluene is 5.2 times more reactive than perdeuteriotoluene.The relative rates of hydrogen abstraction by (Me3Si)2N and (ButMe2Si)2N from the primary, secondary, and tertiary C-H groups in 2-methylbutane show that the silylaminyl radicals are not only highly reactive but also sterically demanding.Thus, at 333 K the average primary C-H reactivity is 0.6 times that of the tertiary C-H towards attack by (Me3Si)2N, but 4.2 times that of the tertiary C-H towards attack by the more bulky (ButMe2Si)2N.Silylaminyl radicals are much more reactive in hydrogen abstraction than are analogous dialkylaminyl radicals and this difference is interpreted in terms of thermodynamic and polar effects which arise because of the ?-donor-?-acceptor nature of the trialkylsilyl substituent.
Selectivity in the Halogenation of Hexane by Tertiary Aminium Radicals from the Photodecomposition of N-Halogenoammonium Perchlorates
Fuller, Steven E.,Smith, John R. Lindsay,Norman, Richard O. C.,Higgins, Raymond
, p. 545 - 552 (2007/10/02)
The photochlorination of hexane with tertiary N-chloroammonium perchlorates in trifluoroacetic acid gives monochlorohexanes in high yield and with a striking preference for the 2-isomer.It is shown that free-radical chains are involved in which hydrogen-atom abstraction is by tertiary aminium radicals.The marked preference for 2- compared with 3-chlorination is attributed mainly to the bulky aminium radical attacking the relatively more accessible 2-position; an alternative explanation involving a reversible hydrogen-atom abstraction is ruled out.The magnitude of the primary deuterium kinetic isotope effect in these photochlorinations gives information about the dependence of the extent of C-H bond breakage in the transition state on the structure of the abstracting aminium radical.
Studies on Sulphochlorination of Paraffins. IX. Regularities of the Sulphochlorination of Branched-chain Paraffins
Estel, D.,Mateew, K.,Pritzkow, W.,Schmidt-Renner, W.
, p. 262 - 268 (2007/10/02)
In the cases of 2-methylbutane and 2-methylpentane the formation of tertiary sulphochlorides in the sulphochlorination of the parent hydrocarbons could be established by means of 13C-n.m.r.-spectroscopy.The relative rates of the various C-H-bonds in 2-methylbutane, 2-methylpentane and 3-methylpentane in the sulphochlorination reaction were determined.The relative rates of the tertiary C-H-bonds in the sulphochlorination were considerably lower than the corresponding values for the chlorination of the branched-chain paraffins.
(E-Z)-ISOMERISATION OF CHLOROOLEFINS
Prochazka, Milos,Adamcova, Jindriska,Palecek, Milos
, p. 1388 - 1400 (2007/10/02)
Equilibrium constants for the (E-Z)-isomerisation of the compounds R-CH=CH-Cl were determined and the experimental values compared with energy differences, calculated by the CNDO/2 method.
