9-羟基苯并萘酮分子内氢传递过程的理论计算

借助MNDO、AM 1、HF/ 3 2 1G、HF/ 6 31G 量子化学理论计算方法 ,对 9 羟基苯并萘酮 (9 HPO)的分子内氢传递过程进行了理论探讨 ,并与X射线衍射的结构数据作了比较。发现 :1 .A构型的 9 HPO比B构型的更稳定 ,两个等同的A可以通过分子内氢传递相互转化 ,反应的过渡态就是B .2 .B是一种严格对称的平面构型 ,它的H电荷和偶极矩都较A增大 ,所以分子内氢传递速率在极性溶剂中将加快。3.共轭在 9 HPO分子内氢传递反应中起了重要的作用。 4.对于类似分子IHT的计算 ,先用半经验方法或小基组的从头计算方法优化结构 ,再用大基组的从头计算方法计算单点能可以得到较好的结果。

Theoretical Calculation on Intramolecular Hydrogen Transfer Process of 9-Hydroxyphenalen-1-one

Various quantum chemical methods, including MNDO, AM1, HF/3-21G, HF/6-31G~**, were employed to investigate the intramolecular hydrogen transfer (IHT) process of 9-hydroxyphenalen-1-one (9-HPO), the result was compared with X-ray structure data. The following facts were found. i) A is more stable than B, and the two equivalent tautomers(A and C) of 9-HPO can tautomerize through IHT. B is the transition state for IHT of 9-HPO. ii) B was in a symmetrical plane. The charge of hydrogen and molecular dipole moment of B are higher than that of A, so the IHT rate will be accelerated in polar solvents. iii) Conjugation is very important for the IHT of 9-HPO. iv) To calculate the IHT of 9-HPO and other similar molecules, the following procedure could be applicable and economic: at first,by using the semiempirical method or ab initio method with smaller basis set to optimize the molecular structure, and then ab initio method with large basis set to calculate the single point energy.