ISSN 1070-4272, Russian Journal of Applied Chemistry, 2007, Vol. 80, No. 2, pp. 341!343. + Pleiades Publishing, Ltd., 2007.
Original Russian Text + O.V. Sibikina, E.V. Novikova, A.A. Iozep, L.I. Iozep, N.G. Tikhomirova, L.S. Kozhevnikova, 2007, published in Zhurnal
Prikladnoi Khimii, 2007, Vol. 80, No. 2, pp. 342!344.
Reaction between Dextran Polyaldehyde and Iron(III)
O. V. Sibikina, E. V. Novikova, A. A. Iozep, L. I. Iozep,
N. G. Tikhomirova, and L. S. Kozhevnikova
St. Petersburg State Academy of Pharmaceutical Chemistry, St. Petersburg, Russia
Received June 27, 2006
Abstract-The reaction of dextran polyaldehyde with iron(III) chloride was studied. The dependences of
content in the resulting complex on the number of aldehyde groups in polysaccharide and pH of
the solution were found.
Metal complexes with polysaccharides and their
derivatives are of growing importance in medicine and
pharmacy. For instance, polypher is well known as
a blood substitute . New blood substitutes with
hemostimulating and antianemic function, Rondfer-
rin, Spaceferron, Neorondex, and Microdez, which
are complexes of dextran with Fe
, respectively [2, 3], differ from the existing
analogues in good bio- and hemocompatibility and
more pronounced and prolonged action. Magnetic
complexes based on polysaccharide derivatives with
Fe, Ca, Zn, Co, Ni, and Cu oxides are used in roent-
genologic studies . These complexes are very
stable during prolonged storage and are not toxic,
when introduced in blood as X-ray contrast sub-
stances. In this context, we studied reactions of dex-
tran polyaldehyde (DPA) with iron(III).
Dextran polyaldehyde was prepared by oxidation
of dextran with sodium meta-periodate, separated,
and analyzed as in . Samples containing 0.553
0.84 mol of aldehyde groups per mole of the mono-
meric fragment (C
) were used.
The reaction of DPA with iron(III) chloride was
performed in water at 18323oC; 1.233.6 mol of salt
was taken per mole of aldehyde groups: 0.2 g DPA
was dissolved in 3 ml of 0.043 0.48 M NaOH within
30 min, and then 2 ml of a 5315 wt % FeCl
in 0.1 M HCl was added. On doing so, the reaction
mixture immediately became reddish-brown. The re-
action product was precipitated with acetone, filtered,
washed with acetone (to remove iron chloride) and
ethyl ether, and dried in a vacuum at a residual pres-
sure of 20325 mm Hg at 61oC.
The compound synthesized is beige amorphous
powder soluble in water and insoluble in ethanol,
acetone, and ethyl ether. The complex is fairly stable;
it does not decompose during reprecipitation from
aqueous solution or dialysis for 24 h at pH < 7.
The IR spectra of DPA and of iron(III) complex
with DPA strongly differ in the intensity of absorp-
tion bands. In the spectrum of the complex, bands at
137031420 and 1620 cm
are substantially stronger
than those in the DPA spectrum, suggesting a consid-
erably larger amount of the aldoenol form in the first
case. In addition, there is no band at 1270 cm
longing to hydrated aldehyde group in the spectrum
of the complex.
A peak at 321 nm is observed in the UV spec-
trum of the complex in 0.1 M HCl, in contrast to
the initial substances which do not absorb light in
this spectral range. Similar absorption at 310 nm in
the spectra of DPA alkaline solutions is attributed
to aldoenol fragments.
The spectrum of the DPA complex with iron(III)
compared to that of the Fe(III) salt solution of
the same concentration, exhibits a new peak at 5103
520 nm. In the spectrum of the initial DPA, this peak
is absent. The reaction product was characterized
by the degree of substitution, C
(number of iron
ions per monosaccharide unit), which was calculated
from the results of determination of the iron con-
tent by potentiometric titration with ascorbic acid 
and spectrophotometrically with sulfosalicylic acid
in ammonia solution . The values of C
by these two methods differ by no more than 2%.
The degree of substitution varied from 0.11 to 0.32.