undertaken. Pyrimidyl-pyrimidyledene equilibrium has been found in the case of 5-substituted 2-pyrimidyl-cyanoacetic esters. Unsymmetrically substituted pyrimidyl-2-methanes form two types (1-NH and 3-NH) of ylidene tautomers, which differ in ring proton spin coupling constants. The effect of substituents in the pyrimidine ring and of the solvent on tautomeric equilibrium are discussed. A drastic effect
进行了
嘧啶-2-
甲烷中互变异构平衡的研究。在5-取代的2-
嘧啶基-
氰基
乙酸酯的情况下,已发现
嘧啶基-
嘧啶基亚烯平衡。不对称取代的
嘧啶基-2-
甲烷形成亚烷基互变异构体的两种类型(1-NH和3-NH),其环质子自旋偶联常数不同。讨论了
嘧啶环中的取代基和溶剂对互变异构平衡的影响。酸(CF 3 COOH)产生了巨大的影响,酸将平衡移向碱性更高的亚烷基互变异构体。研究了互变异构平衡的热力学和动力学特性以及机理。