A New Route for the Synthesis of Methylene Dibenzoate by Using

A New Route for the Synthesis of Methylene Dibenzoate by Using

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Current Organic Chemistry, 2013, 17, 79-82
79
A New Route for the Synthesis of Methylene Dibenzoate by Using An Ionic Liquid
Natalya V. Likhanova,a Irina V. Lijanova,*b Laura P. Morelos Alvarado,b Marcos Martínez García,c Simón
Hernández-Ortegac and Octavio Olivares Xometl.d
a
Instituto Mexicano del Petróleo, Dirección de Investigación y Posgrado, Eje Central Lázaro Cárdenas No. 152, Col. San Bartolo
Atepehuacan, México D.F., CP 07730, México
b
Instituto Politécnico Nacional, CIITEC, Cerrada Cecati S/N, Colonia Santa Catarina, Azcapotzalco, CP 02250, México D.F.,
México
c
Instituto de Química, Universidad Nacional Automona de México, Cd. Univesitaria, Circuito Exterior, Coyoacán, CP 04510, México
D.F., México
d
Facultad de Ingeniería Química, Benemérita Universidad Autónoma de Puebla, Av. San Claudio y 18 Sur, Col. San Manuel, Ciudad
Universitaria, Puebla, CP 72570, México
Abstract: Ionic liquids are often used together with dichloromethane in different reactions. This combination can be problematic because
the use of ionic liquids with a carboxylic acid as an anion and dichloromethane can lead to the formation of methylene diesters. The reaction of trioctylmethylammonium benzoate with dichloromethane was studied, where the ionic liquid acted as reactant, solvent and catalyst. The molecular structure of methylene dibenzoate was determined by X-ray crystallography.
Keywords: Dichloromethane, Ionic liquids, Metilenedibenzoates, Synthesis.
INTRODUCTION
One of the tasks in contemporary chemistry is the development
of new chemical products with minimum damage to the
environment. Until now, most chemical reactions have been carried
out in molecular solvents. For a long time, most of our
understanding of chemistry has been based upon the behavior of
molecules in the solution phase in solvents [1,2]. The toxic and
volatile organic solvents used in the chemical industry always
breaches the green chemistry spirit [3]. These last 15 years,
however, a new class of solvent has been recognized — ionic liquids. These solvents are often fluid at room temperature, and
consist entirely of ionic species. Ionic liquids have been widely
researched as possible ‘green’ replacements for organic solvents;
they have no vapor pressure and therefore may be easier to
efficiently reuse them than organic solvents [4,5].
An ionic liquid is quite different from traditional organic solvents because it cannot be easily purified by distillation due to its
very low volatility. Ionic liquids are generally immiscible with
many organic solvents, especially when the latter are nonpolar like
hexane; whereas some may be miscible with polar solvents like
dichloromethane, cyclohexane, terahydrofuran and many others.
Same ionic liquids could be extracted into CH2Cl2 for their purification [6]. Dichloromethane is sometimes added to reduce the viscosity of the ionic liquid [7].
Sometimes it is very desirable to have a reaction medium,
where a component could be multifunctional: solvent and reagent at
the same time. From a chemical point of view, the main potential
benefits of using ionic liquids are the improvement of both reaction
rates and chemo- and regioselectivities in comparison with other
organic solvents. They have many fascinating properties which
make them of fundamental interest to all chemists, since both the
* Address correspondence to this author at the Instituto Politécnico Nacional, CIITEC,
Cerrada Cecati S/N, Colonia Santa Catarina, Azcapotzalco, CP 02250, México D.F.,
México; Tel: +52 55 91758382; Fax: +52 55 91758380;
E-mail: irinalijanova @yahoo.com.mx
1875-5348/13 $58.00+.00
thermodynamics and kinetics of reactions carried out in ionic liquids are different from those in conventional molecular solvents,
and then the chemistry is different and unpredictable at our current
state of knowledge. Recently, the ionic liquids have been used as
catalysts [8-11] for processes like oligomerization, alkylation and
regioselective synthesis [12]. Jairton Dupont et al. demonstrated for
the first time that room-temperature imidazolium ionic liquids are
not only a suitable medium for the preparation and stabilization of
transition-metal nanoparticles but also ideal for the generation of
recyclable biphasic hydrogenation systems [13]. The immiscibility
of ionic liquids with either water or organic solvents allows them to
be used in two-phases systems [12]. Ionic liquids are generally
thought to have another advantage where they display a low coordination tendency; however, direct experimental evidence of this is
still missing. Fundamental studies on the coordination behavior of
ionic liquids with several materials such as metal clusters, oxide
nanoparticles and coordination complexes are required in order to
understand this area more clearly [14]. Different organic reactions,
including alkylation [15] and transesterification [16] have been
reported to proceed in dichloromethane and ionic liquids, at room
temperature, with excellent yields and selectivity.
We have discovered that ionic liquids with carboxylic acid as
an anion can be neither used in reactions where dichloromethane is
present nor purified with this solvent because it leads to the formation of methylenediesters through a biphasic catalysis reaction,
where ionic liquid acts as prime material, solvent and catalyst.
Herein, we report our results on the use of a room-temperature
ionic liquid named trioctylmethylammonium benzoate for the formation of methylene dibenzoate (MDB) whose X-ray diffraction
analysis is reported for the first time in this work.
RESULTS AND DISCUSSION
Most of the synthetic methods to prepare derivatives of methylene dibenzoates start from substituted chloromethylbenzoate and
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