物理化学学报 >> 1988, Vol. 4 >> Issue (04): 356-360.doi: 10.3866/PKU.WHXB19880406

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MINDO/3研究胞嘧啶异构体间异构化反应——Ⅱ. N1-氢-4-氨基-2-羰基胞嘧啶与4-氨基-2-羟基胞嘧啶异构化反应

洪三国; 冯文林; 傅孝愿   

  1. 北京师范大学化学系
  • 收稿日期:1986-12-15 修回日期:1987-04-13 发布日期:1988-08-15
  • 通讯作者: 傅孝愿

MINDO/3 STUDY OF THE TAUTOMERIC REACTION OF THE TAUTOMERS OF CYTOSINE: Ⅱ. The tautomeric reaction of N1-H-4-NH2-2-oxo-cytosine and 4-NH2-2-OH-cytosine

Hong Sanguo; Feng Wenlin; Fu Xiaoyuan   

  1. Quantum Chemistry Laboratory; Department of Chemistry; Beijing Normal University
  • Received:1986-12-15 Revised:1987-04-13 Published:1988-08-15
  • Contact: Fu Xiaoyuan

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摘要： 本文报导用半经验方法研究N_1-氢-4-氨基-2-羰基胞嘧啶与4-氨基-2-羟基胞嘧啶异构化反应。MINDO/3能量梯度法优化孤立体系的全部自由度, 计算得ΔE=36.79 kJ mol~(-1),内酰胺型比醇式内酰胺型稳定。限定分子体系在同一平面内, 用MINDO/3中的Powell法优化过渡态的几何构型, 计算得正反应活化势垒为204.08 kJ mol~(-1), 逆反应活化势垒为167.30 kJ mol~(-1)。从IRC途径分析了该异构化反应的物理实质。

Abstract: The molecular structure of 4-NH_2-2-OH-cytosine (for short, Lactim) has been optimized by MINDO/3. The Lactam is more stable than Lactim by ΔE=36.79 kJ mol~(-1). The geometric parameters of the transition state of the tautomeric reaction has been optimized by Powell's procedure which is contained in the MINDO/3 program. The reaction pathway of the Lactam <=> Lactim has been studied by Fukui's IRC theory. The activation energy of the forward reaction is 204.08 kJ mol~(-1) while it is 167.30 kJ mol~(-1) for the backward reaction.