Jaroslav Včelák

Laser-powered homogeneous decomposition of tert.-butylamine

Abstract The title reaction shows a preference for carbon-nitrogen bond over carbon-carbon bond cleavage and is depicted by a different reaction scheme from that reported earlier for the hot-wall decomposition, which favours the cleavage of the carbon-carbon bond. The new mechanism was verified by simulation of kinetic curves.

Organosilicon compounds : LXIX. Electrophilic chlorination of benzylfluorosilanes☆

Abstract The orientating effects of silylmethyl groups of the type (CH 3 ) 3− n F n SiCH 2 ( n = 0−3) in electrophilic chlorination of C 6 H 5 CH 2 (CH 3 ) 3− n SiF n have been measured. Ferric chloride and iodine were used as catalysts. All the groups are o - and p - directing, and this is explained in terms of hyperconjugation between the methylene hydrogens and the aromatic ring. The competition method was used to determine the reactivities of these compounds relative to benzene. With the exception of the compound with n = 3, the members of the series are more reactive than benzene. The reactivities are interpreted mainly in terms of the inductive effects of the silylmethyl groups, though these may be modified by ( p → d ) interaction in the SiF bonds.

SUBSTITUENT EFFECTS IN DEHALOGENATION OF ARYL BROMIDES WITH Naalh2(OCH2CH2OCH3)2

Kinetics of dehalogenation of the bromobenzenes 4-RC6H4Br (R=F, Cl, H, CH3, CH3O and N(CH3)2) with the title hydride (SDMA) and with SDMA in the presence of Co(acac)2 have been examined. The rate constants of the debromination were correlated with Hammett substituent constants σp and E1/2 reduction potentials of the bromobenzenes. ρ values (+4.3 for SDMA reduction and +1.9 for the Co-catalyzed debromination) imply a negative charge concentration effect in transition states of both debrominations. Differences in the course of these reactions are discussed.