Inorganic Chemistry Communications
Sodium borohydride reduction of aldehydes catalyzed by an
oxovanadium(IV) Schiff base complex encapsulated in the nanocavity
of zeolite-Y
a,
a
b,
Saeed Rayati ⁎, Elaheh Bohloulbandi , Saeed Zakavi ⁎
a
Department of Chemistry, K.N. Toosi University of Technology, P.O. Box 16315-1618, Tehran 15418, Iran
Department of Chemistry, Institute for Advanced Studies in Basic Sciences (IASBS), Zanjan 45137-66731, Iran
b
a r t i c l e i n f o
a b s t r a c t
Article history:
Selective reduction of a wide range of aromatic and aliphatic aldehydes to the corresponding alcohols with NaBH4
was achieved in the presence of an oxovanadium(IV) Schiff base complex encapsulated in the nanopores of ze-
olite Y (VOL-Y). For most of the aldehydes, a conversion of 100% was observed after less than 5 min. High
chemoselectivity of the reduction for aldehydes over ketones was verified by a competitive reduction between
Received 11 December 2014
Received in revised form 29 January 2015
Accepted 2 February 2015
Available online 3 February 2015
4-methylbenzaldehyde and acetophenone.
©
2015 Elsevier B.V. All rights reserved.
Keywords:
Reduction
Aldehyde
Ketone
Heterogeneous catalyst
Zeolite-Y
Schiff base
The reduction of aldehydes and ketones is one of the most
reliable and efficient methods to obtain the corresponding alcohols
as key intermediates for synthesis of pharmaceuticals, agrochemi-
cals, polymers and new materials [1,2]. Sodium borohydride is
the reagent of choice for the reduction of aldehydes and ketones to
compounds for the transhydrogenation of carbonyl groups. In this
study, catalytic activity of an oxovanadium(IV) Schiff complex en-
capsulated in nanopores of zeolite-Y (VOL-Y) for the reduction of al-
4
dehydes and acetophenone with NaBH is reported.
The Schiff base ligand derived from 2,4-dihydroxyacetophenone and
2,2′-dimethylpropane-diamine and its oxovanadium(IV) complex were
prepared and immobilized in nanocavity of zeolite-Y as reported previ-
ously (See S1) [11]. NaBH reduction of aromatic and aliphatic alde-
4
hydes to their corresponding alcohols catalyzed by VOL-Y was studied
(Table 1). Aldehydes were reduced rapidly with 0.5 molar equivalents
alcohols in protic solvents [3]. However, the reactivity of NaBH
4
can be enhanced by carrying out the reaction in the presence of
transition-metal catalysts or co-reagents [4]. Optically active cobalt
and manganese Schiff base complexes have been used as efficient
4
catalysts for the reduction of ketones and imines with NaBH [5].
Also, the metal complexes of Schiff bases were used extensively in
oxidation of organic compounds [6–8]. The reduction of ketones
was also carried out using zeolites and MCM-41 anchored Schiff
base complexes of transition metals under heterogeneous condi-
tions [9]. The use of heterogeneous catalysts offers several advan-
tages over the homogeneous systems, such as ease of recycling
and recovery and enhanced stability. In spite of the extensive use
of oxovanadium(IV) Schiff base complexes [10] for the oxidation
of organic substrates, there is no report on the utilization of these
4
of NaBH in MeOH at room temperature. The yields are high to excellent
(74–100%). While the reduction of 4-chlorobenzaldehyde in the pres-
ence of VOL-Y led to complete reduction of the aldehyde to the corre-
sponding alcohol, running the reaction in absence of the catalyst gave
the product a yield of 25%. Accordingly, the catalyst plays a major role
in the reduction of the aldehydes to alcohols. In the presence of the cat-
alyst, conversions of ca. 100% were obtained for most of the aldehydes.
According to Table 1, similar reactivities were found for the aromatic
and aliphatic aldehydes. Also, the introduction of different substituents
on the phenyl ring of the former had little effect on the reactivity of the
aldehydes. On the other hand, little steric effects were observed for –OH
and –Br groups substituted at the ortho position with respect to the al-
dehyde moiety.
⁎
387-7003/© 2015 Elsevier B.V. All rights reserved.
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