红外伏吸法研究抗坏血酸在水溶液和离子液体1-乙基-3-甲基咪唑四氟硼酸盐中的电化学行为

Investigation of Electrochemical Behavior of Ascorbic acid in Water Solution and in Ionic Liquid 1-Ethyl-3-Methyl Imidazolium Tetrafluoroborate by Fourier Transform Infrared Voltabsorptometry

采用电化学及红外伏吸法研究了抗坏血酸(AA)在水溶液和离子液体1-乙基-3-甲基咪唑(EMIMBF4)中的电化学行为。AA在EMIMBF4中与在水溶液中一样,不可逆氧化成脱氢抗坏血酸(DHAA)。现场红外光谱结果表明,DHAA在水中迅速发生水解反应,而在EMIMBF4中则较稳定。在EMIMBF4中,AA的羰基峰出现在1739cm-1处,DHAA的羰基峰出现在1785cm-1处,它们相比于游离态的羰基发生了红移。原因可能是AA和DHAA与EMIMBF4间易形成氢键,或者是AA自身形成了氢键,DHAA以二聚体的形态存在。

Electrochemical behavior of ascorbic acid（AA） in water solution and in ionic liquid 1-ethyl-3-methyl imidazolium tetrafluoroborate（EMIMBF4） was studied by electrochemistry and in situ FTIR voltabsorptometry.AA was oxidized to dehydro-ascorbic acid（DHAA） in water solution and ionic liquid.The in situ FTIR spectra suggest that DHAA exists stably in ionic liquid,but hydrolyzes in water solution.In ionic liquid,the carbonyl peak of AA is 1739 cm-1,and DHAA is 1785 cm-1,in comparison with the dissociative carbonyl peak,both of which show Einstein shift.The possible reason is the hydrogen bonds forming between AA and EMIMBF4,DHAA and EMIMBF4,or DHAA may exist as a dimer.