疏水-亲脂相互作用对化学反应性的影响 7: 十四元和十八元环的邻基参与

本工作研究了不同链长的ω-取代羧酸对硝基苯酯p-NO2-C6H4OCO(CH2)n-1Y(简称n-Y,n=17,13,11;Y=SH,H,OH,Br和SCH3)在Me2SO-H2O溶剂体系(有机溶剂体积组成分数φ=0.40,0.45,0.50,0.55)中的水解动力学,观察到疏水-亲脂作用影响下,由于13-SH和17-SH长链分子自身绕曲,可以实现十四元环和十八元环的大环邻基参与,至于11-SH的水解,则观察不到十二元环的邻基参与.因此,这些受物的邻基助效确与链长有关.溶剂组成对此现象也有影响.

The effect of hydrophobic-lipophilic intgeractions on chemical reactivity 7: The neighboring group participations on fourteen- and eighteen-membered ring

Hydrolytic rate constants of p-nitrophenyl esters of w-substituted straight chain acids with various chain lengths [4-O2NC6H4O2C(CH2)n-1R (R = H, OH, SH, Br, SMe; n = 11, 13, 17)] were measured in f = 0.40, 0.45, 0.50, 0.55 Me2SO-H2O mixtures These data demonstrate that for the long-chain substrates 13-SH and 17-SH, hydrophobic-lipophilic forces can bring about 14-membered ring and 18-membered ring neighboring group participations in aggregating solvents. Twelve-membered ring participation has not been observed for 11-SH, indicating that tendencies towards self-coiling and aggregating parallel each other.