L-苏糖酸及其金属化合物的红外光谱研究

制备了高纯度的L-苏糖酸及其与钙、镁、锰、钴、镍和锌的化合物,用化学分析和元素分析确定了它们的组成;通过红外光谱分析研究,确定金属离子与L-苏糖酸的羰基氧配位,同时与羧基脱质子配位,而醇羟基质子不解离,金属离子为sp~3杂化,配位数为4。

FTIR Studies of L-threonic Acid and Its Metal Compounds

Highly pure solid compounds, such as L-threonic acid, calcium L-threonate, magnesium L-threonate, manganese L-threonate, cobalt L-threonate, nickel L-theronate, and zinc L-threonate, were prepared, wherein, L-threonic acid was obtained from calcium L-threonate by strong acid type ion exchange process, calcium L-threonate or zinc L-threonate was prepared by alcohol extracting the concentrated filter liquor of the reaction of Vc, H2O2 and CaCO3 or ZnCO3 , the reminder of the compounds were synthesized using alcohol extracting the concentrated solution derived from the reaction of L-threonic acid solution, prepared by double decomposition reaction of calcium L - threonate with oxalic acid, and superfluous MgO, MnCO3, Co2 (OH)2CO3 and Ni2 (OH)2CO)3. The compositions of the compounds were determined by chemical and elemental analysis, and these compounds have the formula M(C4H7O5 )2. nH2O (M = Ca, Zn, n=0; M=Mg, Mn, Co, n = l; M = Ni, n =2).The purity of the compounds was 99.60% by HPLC. The IR spectra of the complexes were similar with each other but different from that of L-threonic acid. The characteristic absorption peaks of water were not observed in those of calcium L-threonate or zinc L-threonate, which showed that the molecule of water was not involved in the complexes. Further analyses indicate that M2 in the compounds coordinated to oxygen atom of the carboxy group, while the proton of the carboxyl group was dissociated and the proton belonging to hydroxyl was not M2 coordinated to L-threonic acid through the sp3 hybrizated fashion. It was assumed that the coordination number of M2 was 4.