Journal of Molecular Structure
Microwave assisted synthesis of biarlys by CeC coupling reactions
with a new chitosan supported Pd(II) catalyst
*
Talat Baran , Ayfer Mentes¸
Department of Chemistry, Faculty of Science and Letters, Aksaray University, 68100 Aksaray, Turkey
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 16 April 2016
Received in revised form
In this study a new type chitosan-based support has been produced for Pd(II) catalyst and its catalytic
performance in Suzuki CeC reactions has been studied under microwave irradiation without using any
solvent. The chemical identification of the catalyst was performed using TG/DTG, FTIR, UVeVis ICP-OES,
SEM/EDAX, C NMR, molar conductivity, XRD and magnetic moment techniques. The performance of
this new Pd(II) catalyst was studied in Suzuki CeC reactions. The Pd(II) catalyst exhibited a good catalytic
26 May 2016
13
Accepted 26 May 2016
Available online 30 May 2016
performance in very short time (4 min) by giving high TONs and TOFs with low amount of the catalyst
(
0.015 mol%). The catalyst also had reusability and did not lose its activity until six runs.
Keywords:
Suzuki CeC reactions
Chitosan
©
2016 Elsevier B.V. All rights reserved.
Schiff base
Reusability
1. Introduction
renewable natural polymers [14].
This study reports prepare of a new biopolymer supported Pd(II)
catalyst. The chemical structure of the Pd(II) catalyst was illumi-
Chitosan is one of the abundant biopolymer in nature and it has
13
excellent properties such as non-toxicity, biodegradability, renew-
ability, and biocompatibility [1,2]. Mechanical strength, chemical
stability can be improved by producing its derivatives can through
free amino and hydroxyl groups [3,4]. Chitosan modifications, such
as carboxymethyl, Schiff base, phosphorylation, and sulfation,
result in its enhanced solubility and functionality [5e7]. Especially,
nated using TG/DTG, C NMR, XRD, FTIR, SEM-EDAX, magnetic
susceptibility, UVeVis and conductivity measurements. In addition,
the performance of the catalyst was explored in cross-coupling
reactions by using microwave heating. The results of the catalytic
tests revealed that the catalyst possessed high catalytic activity. In
addition, the Pd(II) catalyst yielded higher TON, TOF and reaction
yields in synthesis of biaryl compounds by using a fast and clean
technique.
2
reaction of eNH groups present on chitosan with reactive ketones
or aldehydes gives Schiff base and this modification has been used
in many applications in the literature due to its chemical and bio-
logical properties [8,9].
2. Experimental
Palladium catalysts play a vital role in Suzuki CeC coupling
reactions of biaryl compounds [10]. Different homogenous or
heterogeneous palladium catalyst systems were developed for
coupling reactions in the past decades [11,12]. Particularly, the
microwave irradiation system has been extensively used in CeC
coupling reactions due to its easier workup, short reaction time,
and higher reaction yield [13]. There is a great demand for new
biopolymer (cellulose, chitosan, zeolite, and silica) supported
heterogeneous catalysts in CeC coupling reactions due to their
having high metal adsorpsiyon capacity, cheapness, and being
2
.1. Instrumentation
FT-IR spectra of chitosan, SL, CCSL and the catalyst were per-
formed on a Perkin Elmer Spectrum 100 FTIR spectrophotometer.
Thermal stability of the products was studied on an EXSTAR S11
ꢀ
7300 (nitrogen atmosphere; heating range: 30e650 C). The sur-
face morphology of the products was examined on a QUANTA-FEG
50 ESEM. The analyses of palladium and chloride ions on the
2
catalyst were done using an EDAX-Metek. X-ray diffractions chi-
tosan, CSSL and Pd(II) catalyst were recorded on a Rigaku D max
ꢀ
2000 system (at 40 kV, 30 mA and 2
q
with a scan angle:5e50 ).
Palladium ion content of the catalyst was analyzed by using Perkin
Elmer Optima 2100 DV Inductively Coupled Plasma (ICP) Optical
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022-2860/© 2016 Elsevier B.V. All rights reserved.
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