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Theoretical Study on Gas‐phase Pyrolytic Reactions of N ‐Ethyl, N ‐Isopropyl and N‐t ‐Butyl Substituted 2‐Aminopyrazine
Author(s) -
LiPing Chen,
SanGuo Hong
Publication year - 2003
Publication title -
chinese journal of chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.28
H-Index - 41
eISSN - 1614-7065
pISSN - 1001-604X
DOI - 10.1002/cjoc.20030210208
Subject(s) - chemistry , isopropyl , pyrolytic carbon , density functional theory , ab initio , gas phase , computational chemistry , atom (system on chip) , ab initio quantum chemistry methods , transition state , medicinal chemistry , crystallography , molecule , pyrolysis , organic chemistry , catalysis , computer science , embedded system
Density functional theory (DFT) and ab initio methods were used to study gas‐phase pyrolytic reaction mechanisms of iV‐ethyl, N‐ isopropyl and N‐t ‐butyl substituted 2‐aminopyrazine at B3LYP/6–31G* and MP2/6–31G*, respectively. Single‐point energies of all optimized molecular geometries were calculated at B3LYP/6–311 + G(2d,p) level. Results show that the pyrolytic reactions were carried out through a unimolecular first‐order mechanism which were caused by the migration of atom H(17) via a six‐member ring transition state. The activation energies which were verified by vibrational analysis and correlated with zero‐point energies along the reaction channel at B3LYP/6–311 + G(2d,p) level were 252.02 kJ. mo −1 ( N ‐ethyl substituted), 235.92 kJ‐mol −1 ( N‐t ‐isopropyl substituted) and 234.27 kJ‐mol −1 ( N‐t ‐butyl substituted), respectively. The results were in good agreement with available experimental data.