ISSN 1070-4272, Russian Journal of Applied Chemistry, 2008, Vol. 81, No. 4, pp. 597!602. + Pleiades Publishing, Ltd., 2008.
Original Russian Text + A.M. Ivanov, E.A. Grechushnikov, 2008, published in Zhurnal Prikladnoi Khimii, 2008, Vol. 81, No. 4, pp. 559 !564.
AND INDUSTRIAL INORGANIC CHEMISTRY
Effect of Solvent Nature on the Reaction of Metallic Iron
with Benzoic Acid in a Bead Mill
A. M. Ivanov and E. A. Grechushnikov
Kursk State Technical University, Kursk, Russia
Received February 22, 2007
Abstract-Results of an experimental study of the influence exerted by the solvent nature on the reaction
rate, achieved degree of acid expenditure, selectivity with respect to salts of iron(II) and (III), and phase
state of the reaction mixture in a single-stage reaction of iron with benzoic acid and atmospheric oxygen in
the presence of a stimulating iodine additive are presented.
Iron(III) and (II) benzoates are rather widely used
in various industries .
Commonly, these salts are obtained by one of
the following three methods: (i) exchange interaction
of iron salts and mineral acids with sodium benzoate
or by a direct reaction of an iron oxide with benzoic
acid in the temperature range 1253260oC in the pres-
ence of an organic dispersing agent ; (ii) reaction
of benzoic acid with the metal nitrate in the presence
of an inert organic solvent, followed by addition to
the reaction mixture of ammonia and(or) amine, and(or)
tetraalkylammonium hydroxide at a temperature of
203 40oC and pressure of (1350) 0 10
and (iii) direct electrosynthesis . These methods
require certain auxiliary substances and rather severe
conditions and yield by-products that need utilization.
Moreover, some of these methods cannot be perform-
ed in a single stage.
It was of interest to obtain iron benzoates in a sin-
gle-stage process in accordance with the stoichio-
metric overall equations (HA stands for carboxylic
2Fe + 4HA + O
4Fe + 12HA + 3O
i.e., with atmospheric oxygen as an oxidizing agent,
crushed iron or its alloys (including those of waste
origin) as a reducing agent, and also an organic sol-
vent and iodine (the latter as a stimulating additive).
By now, iron(II) and (III) formates and acetates have
been synthesized by this method . The process
occurs in a single technological stage to give the tar-
get product mainly in the form of a suspension easily
separated by filtration. The filtrate containing dissolv-
ed products of conversion of the stimulating additive
and iron salts is recycled and thereby requires neither
separation, nor repeated utilization.
The overall processes (1) and (2) are heterogeneous,
complex, and multistage. Their principal stages are
the following :
Fe + I
+ 4HA + O
+ 12HA + 3O
and also [17, 18]
+ 4HA 6 4FeA
Fe + 2FeA
Together, stages (3) + (4), (3) + (5) or (3) + (4) + (5)
constitute cyclic processes of consumption and forma-
tion of iodine, and just this circumstance is the reason
why it is used as a catalyst.
The main purpose of the liquid phase is the trans-
port function. The place where the basic stages occur
is the iron surface onto which the reactants are de-