Oohashi K, Morikawa N
Radioisotopes. 1984 Sep;33(9):601-5. doi: 10.3769/radioisotopes.33.9_601.
The T-for-H substitution reaction was studied in the recoil tritium reactions with toluene in C6F6-moderated systems. The moderator-free control experiment showed an approximately uniform labeling in the aromatic ring, with a slightly enhanced reactivity in the ortho- and para-positions (o: 41%, m: 38%, p: 21%) and showed a preference for ring tritiation over methyl group tritiation (23 relative to the corresponding ring assumed as a standard (= 100)). The addition of hexafluorobenzene progressively changed the uniform distribution to a marked ortho- and para-orientation and decreased the relative tritium activity of the methyl group. If the C6F6/PhCH3 mole ratio is 204, the tritium distribution in the ring is o: 53%, m: 22%, p: 25% and the methyl group activity is reduced to 2. The data show the existence of the threshold energy of side chain tritiation and that the selective aromatic ring tritiation is given by increasing contribution of the reactions of tritium atoms having lower energy than the threshold energy.
在C6F6慢化体系中，研究了反冲氚与甲苯反应中的T-H取代反应。无慢化剂的对照实验表明，芳环上的标记大致均匀，邻位和对位的反应活性略有增强（邻位：41%，间位：38%，对位：21%），并且显示出芳环氚化优于甲基氚化（相对于假定为标准的相应环，甲基氚化的相对活性为23（=100））。六氟苯的加入逐渐将均匀分布变为明显的邻位和对位取向，并降低了甲基的相对氚活性。如果C6F6/PhCH3摩尔比为204，环中氚的分布为邻位：53%，间位：22%，对位：25%，甲基活性降至2。数据表明存在侧链氚化的阈能，并且选择性芳环氚化是由能量低于阈能的氚原子反应的贡献增加所致。
