1070-4272/05/7810-1718 + 2005 Pleiades Publishing, Inc.
Russian Journal of Applied Chemistry, Vol. 78, No. 10, 2005, pp. 1718!1719. Translated from Zhurnal Prikladnoi Khimii, Vol. 78, No. 10, 2005,
Original Russian Text Copyright + 2005 by Protopopov, Kon’shin, Chemeris.
Acylation of Aspen Wood and Cellulose with p-Aminobenzoic
Acid in Trifluoroacetic Acid and Thionyl Chloride
A. V. Protopopov, V. V. Kon’shin, and M. M. Chemeris
Polzunov Altai State Technical University, Barnaul, Russia
Received November 15, 2004; in final form, September 2005
Abstract-Cellulose esters with p-aminobenzoic acid were prepared.
Cellulose esters find growing use in industry due to
their characteristics (e.g., light and weather resistance,
hydrophobicity, and low processing temperature) and
the renewability of raw materials for their production
. Esters of cellulose with aromatic amino acids (e.g.,
p-aminobenzoic acid) may exhibit biological activity;
it is well known that all amino acids and their deriv-
atives are biologically active substances. Cellulose by
itself, as a matrix-carrier, is biologically inert and has
sorption characteristics . Therefore, new methods
for synthesis of cellulose esters are of interest.
Synthesis and characteristics of cellulose esters
containing aromatic substitutes have not been system-
atically studied, although some representatives (cel-
lulose benzoate and phenylacetate) have been synthe-
sized using chlorides of the corresponding acids 
and trifluroacetic anhydride  as acylating agents.
Here, we suggest a method for preparing cellulose de-
rivatives with the use of p-aminobenzoic acid (p-ABA),
starting directly from pretreated aspen wood [lignocel-
lulose material (LCM)], and describe the procedures
of analysis for the content of the bound amino acid.
Acylated derivatives of LCM (ALCM) were formed
by the reaction of LCM with an acylating mixture
containing p-ABA, trifluoroacetic acid (TFAA), and
thionyl chloride (TC), with continuous stirring at con-
stant temperature. Synthesis of ALCM can be repres-
ented by the scheme
COOH + SOCl
+ ROH 7776
where ROH is cellulose or LCM.
ALCM was synthesized in a round-bottomed flask,
into which p-ABA and TFAA were introduced.
The mixture was kept at a required temperature, after
that TC was added and the mixture was kept at the
same temperature p-ABA chloride was formed. To
the resulting acylating mixture we added air-dry aspen
wood (content of a-cellulose 64.8, lignin 35.2 wt %),
which was preliminarily extracted and prehydro-
lyzed to remove extractive substances and hemicel-
luloses. The reaction product, ALCM, was precipi-
tated into ethanol, washed, and dried to air-dry state.
Cellulose produced by the Priozersk Paper and Pulp
Plant (content of a-cellulose 96 wt %) was acylated
under the similar conditions to obtain acylated cel-
Bound p-ABA was determined by the Kjeldahl
The degree of substitution of hydroxyls by p-ABA
in the resulting products was evaluated by chemical
analysis for nitrogen in percent relative to the cellu-
lose weight; the amount of converted hydroxy groups
of cellulose c
was also evaluated:
= 7777777 ,
N 0 8.571n 0 100
= 77777 ,
M 3 1.19n
17n 0 100
where N is the content of bound nitrogen (wt %);
= 8.571N, content of p-aminobenzoate groups
(wt %); 8.571, coefficient equal to the ratio of molec-
ular weight of p-aminobenzoate group to the atomic
weight of nitrogen; n, number of acyl groups in
p-ABA, n =1;c
, amount of acylated hydroxyl
groups (wt %); and M, molecular weight of LCM or