论文部分内容阅读
通过利用热力学循环估测气相均裂键能 (BDE)的方法 ,考察了 48个含N H键的化合物 (GNHG′)的BDE数值 ,较系统地研究了双取代基对氮自由基热力学稳定性的影响 .结果表明 ,氮自由基上的双取代基效应的表现形式与碳自由基有所不同 .一般来说 ,由于饱和效应 ,第 2个取代基对自由基稳定性的影响会有所减弱 ;但当带有可形成三电子键的供电子基 (如 ,NH2 ,OH等 )或可形成“离域通道”的拉电子基 (如 ,Ph3 P+)时 ,双取代基会对氮自由基发生协同作用 ,即产生“协稳定效应” .
The BDE values of 48 NHH-bonded compounds (GNHG ’) were investigated by thermodynamic cycling estimation of the mean bond energy (BDE). The thermodynamic stability of the two substituents on nitrogen radicals was systematically investigated The results showed that the diradical effect on the nitrogen radicals was different from that of carbon radicals.In general, the effect of the second substituent on the stability of free radicals was weakened due to the saturation effect. However, when a donor has an electron donating group (eg, NH2, OH, etc.) that can form three electron bonds or an electron withdrawing group (eg, Ph3P +) that forms a “delocalized channel” Synergy, that is, “co-stabilization effect.”