1070-4272/03/7601-0017$25.00C2003 MAIK [Nauka/Interperiodica]
Russian Journal of Applied Chemistry, Vol. 76, No. 1, 2003, pp. 17!19. Translated from Zhurnal Prikladnoi Khimii, Vol. 76, No. 1,
2003, pp. 18!20.
Original Russian Text Copyright + 2003 by Mitrofanova.
AND INDUSTRIAL INORGANIC CHEMISTRY
Complex Formation of Calcium Ions and Monosubstituted
Succinic Acid Derivatives in Aqueous Solutions
G. V. Mitrofanova
Mining Institute, Kola Scientific Center, Russian Academy of Sciences, Apatity, Murmansk oblast, Russia
Received September 25, 2002
Abstract-Complex formation of calcium ions with succinic acid monoamide and methyl hydrogen succinate
at 25oC and ionic strength I = 0.3 (KCl) was studied by pH-potentiometric titration. The stability constants of
the complexes were determined.
Fatty acid collecting agents used for dressing of
phosphorus-containing ores are obtained from vege-
table raw materials. They are insufficiently effective
for flotation of ores with complicated mineralogical
composition, especially under conditions of water
recycling. One of promising ways for the development
of effective collecting agents that are less sensitive
to the salt composition of the pulp liquid phase is the
use of compounds containing two different functional
Nitrogen- or oxygen-containing monosubstituted
succinic acid derivatives are of interest in this respect
. They are readily available owing to high reac-
tivity of the anhydride ring in reactions of the an-
hydride with methanol or ammonia.
The pulp liquid phase formed during dressing of
apatite (a calcium-containing mineral) contains a sig-
nificant amount of calcium ions, which strongly affect
the flotation process. Therefore, it was important to
estimate stability of calcium compounds in aqueous
solutions of succinic acid monoamide and monoester.
The complex formation of unsubstituted succinic acid
with calcium ions was studied in , and the stability
constants of the resulting compounds were deter-
The aims of this work were to estimate the effect of
amidation or esterification of one of carboxy groups in
succinic acid on the stability of calcium salts and to
determine the constants of Ca(II) complex formation
with succinic acid monoamide and monomethyl ester.
Methyl hydrogen succinate  and succinic acid
monoamide were prepared by the reactions of succinic
anhydride with methanol and ammonia, respectively.
Succinic acid monoamide was recrystallized three
times from ethanol and dried under reduced pressure.
Methyl hydrogen succinate was used without addi-
tional purification. The compounds synthesized were
identified by melting points and neutralization equiv-
alents (see table).
The Ca(II) complex formation with monosubsti-
tuted derivatives of succinic acid was studied by
pH-potentiometric titration. The experimental condi-
tions were the same as in the earlier study of Ca(II)
complex formation with unsubstituted succinic acid
: 25oC and ionic strength I = 0.3 supported by KCl.
The ionization constants B of the compounds HL
under consideration, which are required to calculate
the complex formation constants, were determined
previously under the same conditions .
The pH was measured with glass and silver chlor-
ide electrodes on an I-120.1 pH meter with an ac-
curacy of +0.01 pH unit.
The concentration of monosubstituted succinic acid
derivatives was 0.103 0.15 M, and the concentration
of the added Ca(NO
solution, 0.1 M. The concen-
ration ratios Ca(II) : HL were 1 : 5 and 1 : 3.
Characteristics of monosubstituted succinic acid derivatives
³ mp, oC ³ Neutralization, mol-equiv
³ found ³  ³ found ³ calculated
Methyl hydro-³ 57 ³ 58 ³ 131.3 ³ 132.1
gen succinate ³³³ ³
Succinic acid ³ 156 ³ 157 ³ 116.2 ³ 117.0
monoamide ³³³ ³