Russian Journal of Applied Chemistry, 2011, Vol. 84, No. 10, pp. 1826−1829.
Pleiades Publishing, Ltd., 2011.
Original Russian Text © N.V. Dolgopyatova, V.Yu. Novikov, I.N. Konovalova, 2011, published in Zhurnal Prikladnoi Khimii, 2011, Vol. 84, No. 10, pp. 1734−1738.
AND POLYMERIC MATERIALS
Inﬂ uence of the Degree of Deacetylation on the Rate of Acid
Degradation of Chitin and Chitosan
and on the Yield of D(+)-Glucosamine Hydrochloride
N. V. Dolgopyatova
, V. Yu. Novikov
, and I. N. Konovalova
Murmansk State Technical University, Murmansk, Russia
Knipovich Polar Research Institute of Marine Fishery and Oceanography, Murmansk, Russia
Received August 4, 2010
Abstract—The dependence of the rate of acid degradation of chitin and chitosan on the degree of deacetylation
Chitin is one of the main raw materials for commercial
production of D(+)-glucosamine hydrochloride,
a valuable substance for medical purposes . Many
drugs and biologically active additives contain this
monosaccharide as base material.
With the aim to increase the yield of D(+)-glucosamine
hydrochloride, we studied the inﬂ uence exerted by the
degree of chitin deacetylation on the rate and extent of
the acid degradation of chitin.
It was noted in [2, 3] that glycoside bonds in the
deacetylated monomeric unit of partially deacetylated
chitin (or chitosan) undergo acid degradation at lower
rate than do the same bonds in the acetylated unit (see
This is due to the fact that the amino group at the C
atom, charged positively under the conditions of acid-
catalyzed hydrolysis, decreases the electron density at
the glycoside center, thus destabilizing the intermediate
carbocations. At the same time, acetylation of the amino
group at the C
atom accelerates the hydrolysis of glyco-
sides owing to an increase in the electron density on the
reaction center as a result of the anchimeric assistance
effect of the N-acetyl group. This results in stabilization
of the carbocations, increasing the probability of their
formation and of the subsequent hydrolysis and hence
accelerating the rate of the glycoside bond cleavage. It
should be noted that quantitative kinetic characteristics
of these processes are not discussed in the literature.
It was found previously  that the acid degradation
rate drastically decreases with an increase in the initial