STUDIES OF CAGE REACTIONS .2. COMBINATION OF CH3 RADICALS AND OF CH3 AND CF3 INTO CF3CH3
STUDIES OF CAGE REACTIONS .2. COMBINATION OF CH3 RADICALS AND OF CH3 AND CF3 INTO CF3CH3
复制标题
DOI：
10.1021/ja01004a013
复制
发表时间：
1968-01-01
影响因子：
15
通讯作者：
SZWARC, M
中科院分区：
文献类型：
--
作者：
CHAKRAVORTY, K;PEARSON, JM;SZWARC, M
研究了CH3N=NCH3在4种不同温度下，在8种溶剂中光解生成的甲基自由基的笼式结合反应。结合概率p(CH_3)=C_2HVN2由Noyes的处理得到，即对于每种溶剂，L/p(CH_3)是‘/2/’的线性函数，尽管不同的溶剂得到的谱线略有不同。结果表明，CH3自由基在每次碰撞中结合的几率是CF3自由基的三到五倍。这可能是因为与CF3相比，CH3的自转速度更快。与先前的研究一样，log P(CH3)=log{(C2H6/N2)/[1-(COHE/N2)]}对1；T被发现是线性的，并且所有溶剂获得的线条再次彼此平行。GB c-ED(形式“活化能”的差异)的这种恒定是惊人的。而对于CF3自由基的反应，Gb“-Gbd=-2.6±0.1kcal/mole。CH3和CF3在CH3CF3中的混合笼状组合表现出相似的特征；p(CH3，CF3)和Gb(CH3，CF3)介于CH3和CF3的同种组合和各自的GB c-GB d=-2.1kcal/mole之间。
Cage combination of methyl radicals formed by photolysis of CH3N= NCH3 was investigated in eight solvents at four different temperatures. The probability of combination p (CH3)= C2HVN2 was accounted for by Noyes’ treatment; ie, l/p (CH3) is a linear function of'/2/for each solvent, although slightly different lines were obtained for different solvents. The results led to theconclusion that the probability of combination, a, on each collision is three to five times as high for CH3 radicals as for CF3 radicals. This may be accounted for by the higher rate of rotation of CH3 when compared with CF3. As in the previous study, log P (CH3)= log {(C2H6/N2)/[1—(CoHe/N2)]} vs. 1; T is found to be linear, and the lines obtained for all the solvents are again parallel to each other. This con-stancy of£ c— Ed (the difference of formal “activation energies”) is striking. Its value is—1.6±0.2 kcal/mole for CH3 cage combination, whereas for the reaction of CF3 radicals£„—£ d=—2.6±0.1 kcal/mole. The mixed cage combination of CH3 and CF3 into CH3CF3 shows similar features; p (CH3, CF3) and£(CH3, CF3) are between those found for the homocombinations of CH3 and of CF3 and the respective£ c—£ d=—2.1 kcal/mole.