Journal of Thermal Analysis and Calorimetry, Vol. 88 (2007) 1, 295–299
THERMAL DECOMPOSITION OF CADMIUM SUCCINATE DIHYDRATE
Barbara MaÓecka* and Agnieszka ·cz
AGH University of Science and Technology, Faculty of Materials Science and Ceramics, Al. Mickiewicza 30, 30-059 Cracow, Poland
Thermal decomposition of cadmium succinate dihydrate, CdC4H4O4·2H2O, was studied in dynamic helium and air atmospheres by
means of simultaneous TG, DTA and MS analysis. It was found that dehydration of CdC4H4O4·2H2O takes place in the temperature
range 80–165°C and at low heating rates formation of monohydrate was stated.
The anhydrous cadmium succinate decomposes at about 350°C to metallic cadmium. The gaseous products of cadmium
succinate decomposition are CO2 and H2O. Formation of small amounts of 3-phenylpropanal and 1,7-octadiene during decomposi-
tion in helium was revealed. In helium cadmium evaporates at the temperature of decomposition and the residue consists of small
amount of elementary carbon formed in result of pyrolysis of succinate groups. In air cadmium oxidizes and the final solid product
of decomposition is CdO.
Keywords: cadmium succinate dihydrate, DTA, MS analysis, TG, thermal decomposition
Introduction
the monodentate interactions. This structure is stabi-
lised into two-dimensional polymer by hydrogen
bonds between the water molecules and the oxygen
atoms belonging to the succinate groups. The struc-
ture of Cd(H2O)2C4H4O4·0.5H2O is also described by
pentagonal dipyramid, but in this structure two crys-
tallographically independent seven-coordinate Cd at-
oms exist, chelated by succinate ligands. One of the
chelating oxygen atoms belonging to carboxyl groups
makes a bridge between two cadmium atoms, while
the other end of the same succinate ligand is used to
form three-dimensional polymer structure.
Thermal properties of cadmium salts are not often inves-
tigated due to the high toxicity of Cd. However cad-
mium salts are useful in industry, pharmacology and
analysis. Cadmium carboxylates and bicarboxylates are
used as catalysts, colorants, stabilizers [1, 2] and in
113Cd NMR spectroscopy of biological systems [3]. Re-
cently cadmium carboxylates, together with dimethyl
sulfoxide, are used as precursors of nanocrystalline CdS
for photocells and luminous paints [4]. Authors of the
present paper took up studies on thermal decomposition
of the series of cadmium carboxylates and bicarboxy-
lates to reveal the influence of cation and anions on this
process. The results on mechanism of decomposition of
cadmium acetate and malonate hydrates were published
earlier [5, 6]. In the present work we report on prepara-
tion, structural identification and thermal characteriza-
tion of cadmium succinate dihydrate.
Thermal decomposition of cadmium succinate
dihydrate was investigated in oxygen [7] and air [9]. It
was found that at temperature about 150°C, because of
dehydration, CdC4H4O4·2H2O transforms to anhydrous
and amorphous cadmium succinate. At 262°C this
amorphous product turned into crystalline CdC4H4O4.
Decomposition of CdC4H4O4 proceeded with formation
of intermediate as CdCO3 [7] or CdO·CdCO3 [9]. The
final product of decomposition is CdO.
The cadmium succinate has two stable hydrates
described in the literature
–
diaquacadmium
succinate, Cd(H2O)2C4H4O4, [7] and diaquacadmium
succinate hemihydrate, Cd(H2O)2C4H4O4·0.5H2O [8].
Both have monoclinic, polymer structure with seven-
coordinated Cd atoms. The structure of
Cd(H2O)2C4H4O4 is best described as a distorted pen-
tagonal dipyramid with the cadmium atom and five
oxygen atoms (these O atoms belong to three
succinate ligands) in the equator and two oxygen at-
oms of the water molecules out of plane. Three
succinate ligands are connected to Cd atom through
bidentate (the two of the ligands) or monodentate (the
third one) interaction. The Cd atoms are bridged by
oxygen atoms which take part in the bidentate and in
The aim of this paper is to describe the thermal
behaviour of cadmium succinate dihydrate in inert
(helium) atmosphere, determine the intermediate
product of decomposition in air as well as determine
gaseous products of decomposition.
Experimental
Material
Cadmium succinate dihydrate was prepared by mixing
a hot, aqueous solution of succinic acid, C4H6O4, and
an 15% aqueous solution of cadmium acetate,
*
Author for correspondence: bmalecka@agh.edu.pl
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Springer, Dordrecht, The Netherlands
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