The Barrier to Rotation around N−O Bonds in 4-Substituted N-Isopropoxythiazole-2(3H)-thiones and in N-Isopropoxy-2(1H)-pyridinethione
作者:Jens Hartung、Rainer Kneuer、Michaela Schwarz、Markus Heubes
DOI:10.1002/1099-0690(200112)2001:24<4733::aid-ejoc4733>3.0.co;2-p
日期:2001.12
Activation parameters [lg A, Ea, ΔH‡, ΔS‡] for the barriers to rotation around N−O bonds in N-Isopropoxy-2(1H)-pyridinethione (1) and two 4-substituted N-isopropoxythiazole-2(3H)-thiones 2 and 3 were determined by variable-temperature NMR spectroscopy [1H (600 MHz) and 13C (150 MHz)] in the temperature range 125−273 K. The measured ΔG‡200 values increase from 29 ± 2 kJ mol−1 (1) to 42 ± 7 kJ mol−1
N-异丙氧基-2(1 H)-吡啶硫酮(1)和两个4-取代的N-异丙氧基噻唑中N-O键周围旋转障碍的活化参数[lg A,E a,ΔH ‡,ΔH ‡,ΔS ‡ ] -2(3 H)-硫酮2和3是通过在125-273 K的温度范围内通过可变温度NMR光谱法[ 1 H(600 MHz)和13 C(150 MHz)]确定的。测得的ΔG ‡ 200值从29±2 kJ mol -1(1)至42±7 kJ mol -1(2)和46±1 kJ mol -1(3)。所观察到的旋转障碍中硫酮的排名1,2,和3是通过在空间拥塞旁边的差异来解释Ñ -烷氧基的取代基。