ISSN 1070-4272, Russian Journal of Applied Chemistry, 2008, Vol. 81, No. 7, pp. 1305!1307. + Pleiades Publishing, Ltd., 2008.
Original Russian Text + M.V. Efanov, A.I. Galochkin, V.A. Novozhenov, 2008, published in Zhurnal Prikladnoi Khimii, 2008, Vol. 81, No. 7,
Synthesis of Mixed Wood Esters
M. V. Efanov, A. I. Galochkin, and V. A. Novozhenov
Research Institute of Wood Thermoplastics, Altai State University, Barnaul, Russia
Received February 5, 2008
Abstract-A new procedure was developed for preparing mixed esters of lignocarbohydrate materials.
Transformations of aspen wood in the course of its acylation with a mixture of acetic anhydride with
aliphatic carboxylic acid under the conditions of mechanochemical activation in the presence of ammoni-
um sulfate as catalyst were studied.
Acylation of wood is a promising direction of its
chemical modification. Wood acylation products are
soluble in organic solvents. They exhibit hydrophob-
ic and thermoplastic properties and are bioresistant.
These physicochemical properties determine possible
application fields of wood acylation products .
The use of acylated wood as a thermoplastic
binder for preparing composite materials with a
mineral or wood filler allows preparation of wood
boards with good physicomechanical and hydro-
phobic properties. This is favored by high thermo-
plasticity of acylated wood and its good adhesion to
mineral and especially organic substances (wood).
Procedures have been developed for preparing
esters from wood mechanochemically activated in
the presence of catalysts by acylation with a mixture
of acetic anhydride (AAn)with a carboxylic acid at
1003130oC for 436 h. These procedures have cer-
tain drawbacks: long synthesis time (up to 6 h),
elevated temperature, and high consumption of
acylating agents (up to 10 mol)[3, 4].
A more efficient mechanochemical procedure for
acylation of lignocarbohydrate materials with acetic
anhydride or a mixture of acetic anhydride and a
carboxylic acid in the presence of ammonium sulfate
as catalyst was developed previously [5, 6]. In this
study we examined the composition and properties
of products obtained by mechanochemical acylation
of aspen wood.
Mechanochemical acylation of vegetable raw
materials was performed as follows: A reactor of
a vibration mill (IV 98B commercial vibrator, fre-
quency 2800 min
)with 15 steel rods (10 0 100 mm)
was charged with a 2.0-g portion of air-dry sawdust
of a lignocarbohydrate material, and acetic anhy-
dride and a monobasic saturated carboxylic acid
containing three to six C atoms in the molecule were
added (0.335 mol per mole of OH groups of the raw
material). The temperature in the reaction chamber
was maintained at 25oC with a thermostat. The reac-
tor was charged with 5330% ammonium sulfate
(based on the raw material), and the mixture was
subjected to intense mechanical milling for 0.533h.
Then the products were unloaded, separated from
the milling bodies, washed with water to remove
the acids and catalyst, and dried to constant weight.
The content of bound acyl groups was determined
by saponification of the samples of acylated ligno-
carbohydrate materials with a 0.5 N alcoholic solu-
tion of NaOH, followed by determination of the free
carboxylic acids by GLC with an internal reference
. The solubility of wood acylation products in
chloroform was determined by the procedure de-
scribed in  fir cellulose acetates.
We examined how the time of the mechanochem-
ical synthesis at an acetic anhydride amount of
1 mol per mole of OH groups of wood affects the
content of bound carboxylic acids and the solubility
of the acylation products in chloroform.
Experiments showed (Table 1)that, as the time
of mechanochemical acylation is made longer, the
content of bound acetic (AAc)and butyric (BAc)
acids in the products and their solubility in chloro-
form regularly increase.
Table 2 shows that, with an increase in the molar