Asian Journal of Chemistry; Vol. 32, No. 5 (2020), 1082-1086
A
SIAN
J
OURNAL OF HEMISTRY
C
Preparation of Salicylic Nitrile through Direct Catalytic Dehydration of
Salicylamide with Immobilized Phosphoric Acid as Catalyst
1,2
1,*
1
1
SHU-FENG YAO , ZHAO-SHENG CAI , XU-JUAN HUANG and LAN-XUAN SONG
1School of Chemistry and Chemical Engineering, Yancheng Institute of Technology, Yancheng, 224051, Jiangsu Province, P.R. China
2Institute of Chemical Industry of Forest Products, CAF, Nanjing 210042, Jiangsu Province, P.R. China
*Corresponding author: E-mail: jsyc_czs@163.com
Received: 24 November 2019;
Accepted: 26 December 2019;
Published online: 29 April 2020;
AJC-19838
Salicylic nitrile was prepared through direct catalytic dehydration of salicylamide under high temperature using immobilized phosphoric
acid as catalyst. The catalytic performances of different catalysts were evaluated according to the analytic results of GC-MS, and the
feasibility about the preparation of salicylic nitrile by direct catalytic dehydration of salicylamide was investigated according to the
composition of product determinated by GC analysis (area nomalization). Experimental results indicated the comprehensive property of
silica gel supported phosphoric acid was the best one among all of the catalysts utilized in this study. When the temperature of catalyst bed
was 480 10º and silica gel supported phosphoric acid was utilized as catalyst, the conversion ratio of salicylamide was 88.79%, the
selectivity to salicylic nitrile was 97.97% and the yields of salicylic nitrile could up to 86.99%. Meanwhile, the experimental results
showed the increase of temperature of catalyst bed could result in the increase of the conversation of salicylamide, but much more by-
product could be formed when the temperature of catalyst bed was too high.
Keywords: Salicylamide, Salicylic nitrile, Catalytic dehydration, Immobilized phosphoric acid, Selectivity.
example, the dehydrants for conversing salicylaldoxime or
salicylamide to salicylic nitrile usually related with toxic
compounds including phosgene or bis(trichloromethyl)carbo-
nate, the yields for preparing salicylic nitrile through catalytic
ammoxidation of o-cresol is usually at a lower level, and the
hydroxylation of halogenated benzonitrile needs to be carried
out with harsh condition.
In order to avoid these disadvantages in present method
for preparing salicylic nitrile, herein, a method for the synthesis
of salicylic nitrile from salicylamide through direct catalytic
dehydration with immobilized phosphoric acid as catalyst is
reported.
INTRODUCTION
The importance of salicylic nitrile as pharmaceutical and
agricultural intermediates has been well established. For example,
salicylic nitrile could be utilized for the synthesis of bunitrolol,
one of β-recepter bolockers for the treatment of arrhythmia,
angina and hypertension [1]. Salicylic nitrile could also be
utilized for the preparation of azoxystrobin, one of the efficient
agricultural fungicides with broad-spectrum and ability of
intaking absorption [2]. Meanwhile, salicylic nitrile has obtained
important application in the production of some perfumes and
liquid crystal materials, etc. [3].
There are several methods applied for preparing salicylic
nitrile, such as dehydration of salicylaldoxime in the presence
of dehydrant [4-8], selective oxidation of benzonitrile [9], iso-
merization of 1,2-benzisoxazole [10], catalytic ammoxidation
of o-cresol [11,12], dehydration of salicylamide in the presence
of dehydrant [13-16], cyanylation of methyl salicylate [17]
and hydroxylation of halogenated benzonitrile [18], etc. But,
all of the above methods have disadvantage in some extent, for
EXPERIMENTAL
All reagents were of analytical reagents and used without
further purification. Salicylamide (99%, industrial product),
phosphoric acid, absolute ethanol, artificial zeolite (chemically
pure), silica gel (GF254, TLC), aluminium oxide), molecular
sieve (3Å), silicon dioxide and zirconium dioxide (CP) were
procured from Sigma-Aldrich, USA.
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