Evidence for the formation of anhydrous zinc acetate and acetic anhydride during the thermal degradation of zinc hydroxy acetate, Zn_5(OH)_8(CH_3CO_2)_2 centre dot 4H_2O to ZnO

摘要

Zinc hydroxy acetate, Zn_5(OH)_8(CH_3CO_2)_2 centre dot 4H_2O, has been prepared by the precipitation method. It has been demonstrated by FTIR analysis that, contrary to previous reports, the interaction of the acetate anion with the matrix cation is ionic. TG analysis, mass spectral analysis of the evolved gases, and in situ variable temperature PXRD and FTIR analysis have shown that decomposition of the material to ZnO involves the formation of Zn_5(OH)_8(CH_3CO_2), Zn_3(OH)_4(CH_3CO_2)_2 and anhydrous zinc acetate (Zn(CH_3CO_2)_2) as some of the acetate-containing intermediate solid products. The acetate anion is finally lost, at temperatures below 400 deg C, as acetic anhydride, (CH_3CO)_2O.