โ Scribed by Y. Gonen; L. A. Rajbenbach; A. Horowitz
No coin nor oath required. For personal study only.
The kinetics of the gamma radiation induced free radical chain decomposition of BrCH2CN in liquid cyclohexane (RH) was investigated over the temperature range of 60-170ยฐC. In addition competitive experiments in the presence of CC1, were carried out between 80 and 180ยฐC. For the reactions
the following Arrhenius expressions were derived : log ka/(2k4)"2 (11/2/(mol . sec)l@) = 4.07 f 0.35 -(11.96 f 0.63)le log ka/kh = -0.699 zk 0.167 + (2.69 f 0.31)/8
where 0 = 2.303RT in kcal/moI. The effect of CN substitution on the activation energies of reactions (2) and ( ) was evaluated based on the present and previously published results. The CN group effect on halogen atom abstraction [reaction (2)) is discussed in terms of inductive and enthslpic factors.
The differences Es -E(CH3 + RH) and E(CC12CN + RH) -E(CC18 + RH), which yield : % value of about 5.5 kcal/mol, are considered to reflect the cyano stabilization effect a t the radical center confirming D(CHz(CN)-H) -93 kcal/mol.
๐ SIMILAR VOLUMES
The kinetics of the gamma-radiation-induced free radical chain reaction in solutions of C2C13F in cyclohexane (RH) was investigated over a temperature range of 87.5-200ยฐC. The following rate constants and rate constant ratios were determined for the reactions: log k2b/kza = (-0.03 f 0.15) -(2.39 f
The kinetics and mechanism of the free-radical chain dechlorination of CZCIS, C~CISH, and sym-CzCl4Hz in EtgSiH were investigated over a wide temperature range. The propagation step of the dechlorination of chloroethanes (C&I,H+r) proceeds by the following reactions: (2) C1+ EtsSiH -HCI + EtaSi An
chemical shift difference (A8 = 2.4-2.9 ppm) between the axial (Ha) and equatorial (He) protons of the cis-methylene group. In contrast, the corresponding chemical shift difference of the trans-methylene groxp is much smaller (A% = 1-1.4 PPm). R 4-Bromoheptane 2-Bromoheptane 2-Bromooctane
The relative yields of cyclohexyl radical in pulse-irradiated liquid cyclohexane and cyclohexane solutions containing negatwe (C02) and positive charge scavengers (cis-and trans-decalin) are measured via time-resolved EPR. Charge scavenging has a negligible effect on radical production. A mechanism