Formation of a Copper-Sorbitol Complex in Copper Sulfate-Sorbitol Systems

食品のミネラルに関する一連の研究の一部として,今回は銅－ソルビット錯体について研究した結果を報告する。すなわち,CuSO4－ソルビット反応系における銅－ソルビット錯体の生成を,分光光度法と電位差滴定法で確認した。そして,この錯形成に対する,反応系の銅/ソルビット比およびPHの影響を調べ,pH12以上の強アルカリ条件下で銅3:ソルビット1の組成比を持つ錯体ができることを確かめた。さらに,この錯形成によって,アルカリ溶液中での銅イオン加水分解重合を阻止すること,およびソルビット1モルは銅3モル比までこの効果を示すことがわかった。

これらの実験結果に基づいて,銅に結合するソルビットの配位基について若干の考察を加えた。

Only a few investigations have been reported on the copper-sorbitol complex, and especially very little is known about the states of this complex in aqueous solutions. Accordingly, the formation of the complex has been investigated spectrophotometrically and potentiometrically with CuSO4-sorbitol systems. The copper-sorbitol complex was formed under strongly alkaline conditions above the critical point (pH 9.5～10.6) and it was estimated to have a composition of 3:1 in the molar ratio of copper to sorbitol. Moreover, the complex was ascertained to exist in a state of polymers under pH conditions below the critical point. From the examination of the solubility of the complex, it was found that formation of the soluble copper-sorbitol complex or the insoluble one occurred under pH conditions above or below the critical point, respectively. The relationship between the solubility and the chemical structure of the complex was discussed in this paper, and a model has been proposed.