Sixteen 4-arylthiazol-2(3H)-ones (3) were synthesised by cyclisation of α-thiocyanatoacetophenones (1) in acid solution. They appear to prefer greatly the oxo tautomeric forms. In CCl4 solution an equilibrium between the free CO bond and a “dimeric” hydrogen-bonded form exists in which the latter predominates. Several IR and NMR (1H, 13C and 15N) spectral properties are shown to correlate with Hammett σ-values and/or atomic Mulliken charges and bond orders, the latter being estimated by PM3 or AM1 semiempirical methods. The electron-impact mass spectra were also recorded and the fragmentation mechanisms interpreted in terms of the energetics of the ionic species. In addition, the geometric and electronic properties of 4-phenylthiazol-2(3H)-one (3a)
and the related benzothiazol-2(3H)-one (4) based on ab initio HF/6-31 G* calculations are compared with each other.
通过在酸性溶液中环化α-
硫氰基
苯乙酮(1),合成了16种4-芳基
噻唑-2(3H)-酮(3)。它们似乎更倾向于氧代互变异构形式。在
CCl4溶液中,自由羰基键与“二聚”氢键形式之间存在平衡,其中后者占优势。有几种红外和核磁共振(1H、13C和15N)光谱特性与H
AMmett σ值和/或原子Mulliken电荷及键级相关联,后者通过PM3或
AM1半经验方法估算。还记录了电子冲击质谱,并根据离子物种的能量学解释了裂解机制。此外,基于从头算HF/6-31G*计算,比较了
4-苯基噻唑-2(3H)-酮(3a)及相关
苯并噻唑-2(3H)-酮(4)的几何和电子性质。