查尔酮缩氨基硫脲类希夫碱的合成与表征

由苯甲醛、对二甲氨基苯甲醛和苯乙酮通过Claisen-Schmidt缩合反应合成反应中间体查尔酮和对二甲氨基查尔酮。用查尔酮和对二甲氨基查尔酮与氨基硫脲为原料,在弱酸性条件下经过羟醛缩合反应合成查尔酮缩氨基硫脲希夫碱和对二甲氨基查尔酮缩氨基硫脲希夫碱。通过元素分析、红外光谱、气相色谱／质谱联机分析及核磁共振氢谱对所合成的化合物进行表征。研究结果表明:C＝C的伸缩红外光谱吸收峰和烯烃上C—H的伸缩及面外振动红外光谱吸收峰分别出现在1 644～1 651,3 020～3 034,988～998 cm-1处,表明所合成的希夫碱为反式异构体。C＝S的红外光谱吸收峰在1219～1221 cm-1处,低于其特征波数1 230～1 253 cm-1;且伯胺上的质子的化学位移相对于仲胺大幅度向低场移动;推测希夫碱之间存在分子间氢键作用,且C＝S主要以酮式存在。

Synthesis and characterization of Schiff bases derived from chalcone and thiosemicarbazide

The intermediates including chalcone and 4-dimethylaminochalcone were synthesized from benzaldchyde, 4-dimethylamino-benzaldchyde and hypnone by Claisen-Schmidt reaction. And then using chalcone and 4-dimethylaminochalcone with thiosemicarbazide as raw material, two novel Schiff bases comprising thiosemicarbazone were synthesized by aldol condensation under the faintly acid condition. The compounds were characterized by elemental analysis, infrared, GC-MS and ^1HN1VIR. The results show that in the infrared spectra of C=C and alkene C--H there are absorption peaks at 1 644-1 651, 3 020-3 034, 988-998 cm^-1, respectively, indicating that the two Schiff bases are trans-isomerization. In the infrared spectra of C= S there are absorption peaks at 1 219-1 221 cm^-1, lower than its characteristic frequency at 1 230-1 253 cm^-1, and the chemical shifts of primary amine to low magnetic field occur greatly in reference to that of secondary amine, which indicates the molecules is combined with intermolecular hydrogen bonds and concludes that C= S exists mainly in the form ofketo tautomer.