Three polarographic reduction waves, which appear when dehydro-L-ascorbicacid (DAA) is treated with o-phenylenediamine (OPD) in acetate buffer, pH 3.6, were renivestigated by comparing with those of the synthesized products from DAA and OPD. A reaction scheme of DAA with OPD is presented and the characteristics of the reactions are discussed.
Oxidation of ascorbic acid by copper(<scp>II</scp>) and the ferrocenium ion in acetonitrile–water mixtures
作者:Brian G. Cox、Wojciech Jedral、Josefina Palou
DOI:10.1039/dt9880000733
日期:——
Measurements are reported on the rates of oxidation of ascorbicacid (H2A) by copper(II) and the ferrocenium cation [Fe(C5H5)2]+ in mixtures of water and acetonitrile. The stabilisation of Cu+ by acetonitrile results in a rapid increase in E⊖ for Cu2+–Cu+ and a simple, irreversible reaction between copper(II) and ascorbicacid to form copper(I) and dehydroascorbic acid upon addition of small amounts of acetonitrile
报道了在水和乙腈的混合物中,铜(II)和二茂铁阳离子[Fe(C 5 H 5)2 ] +对抗坏血酸(H 2 A)的氧化速率的测量结果。Cu的稳定+通过在乙腈中的快速增加的结果Ë ⊖对Cu 2+ -Cu +和一个简单的,铜(之间的不可逆反应II)抗坏血酸和以形成铜(我)和在水中加入少量乙腈后的脱氢抗坏血酸。速率常数对酸的依赖性与单阴离子[Cu II(HA)] +和二价阴离子[Cu II A]的络合物的参与相一致,前者随着溶剂中乙腈含量的增加而变得相对更为重要。讨论了速率常数的溶剂依赖性与混合物中铜(II)和铜(I)的溶剂化有关,并建议主要的影响是在初始电子转移过程中形成的铜(I)的溶剂化过程。氧化还原电位,Ë为的[Fe(C 5 H ^ 5)2 ] + – [Fe(C 5 H 5)2 ],以及在相同条件下测量的典型外层氧化剂二茂铁对抗坏血酸的氧化速率,并将其与铜(II)进行比较。)–铜(I)系统。
Studies on dehydro-l-ascorbic acid 2-arylhydrazone 3-oximes: Conversion into substituted triazoles and isoxazolines
作者:Mohamed Ali El Sekily、Sohila Mancy、Bernard Gross