Asian Journal of Chemistry; Vol. 27, No. 10 (2015), 3564-3566
A
SIAN
J
OURNAL OF HEMISTRY
C
Preparation and Characterization of Primary Amines by Potassium
Borohydride-Copper Chloride System from Nitriles
1
1
1,2,*
HAN JIANG , JIALEI HU , XINLIANG XU2,* and YIFENG ZHOU
1Zhejiang Provincial Key Laboratory of Biometrology and Inspection & Quarantine, College of Life Science, China Jiliang University, Xiasha,
Hangzhou 310018, Zhejiang Province, P.R. China
2Zhejiang Apeloa Medical Tehnology Co. Ltd., Dongyang 322118, Zhejiang Province, P.R. China
*Corresponding authors: E-mail: xl.xu@apeloajiayuan.com; zhouyifeng@cjlu.edu.cn; jh66hz@163.com
Received: 3 November 2014;
Accepted: 4 March 2015;
Published online: 22 June 2015;
AJC-17303
Nitriles undergo reduction to primary amines under optimized conditions at 50 °C using 0.25 equiv of copper chloride and 3.0 equiv of
potassium borohydride in 80 % isopropanol. The aromatic and aralkyl nitriles could be effectively reduced in yield ranging from 60 to
90 %.
Keywords: Nitrile, Reduction, Potassium borohydride, Copper chloride.
INTRODUCTION
EXPERIMENTAL
The prevalence and extensive use of amines as starting
materials for plastics, agrochemicals and dyes in industry make
it an important functional group in organic chemistry1. The
reduction of nitriles into the corresponding amines is a very
important method, because of the ready commercial availability2.
There are a number of different methods for this conversion,
including catalytic hydrogenation3, LiAlH4 reduction4, sodium
borohydride reduction5, etc.
As is known, sodium horohydride in combination with
transition metal have been developed to reduce nitriles. In 1988
Itsuno et al.6 used NaBH4-ZrCl4 reducing nitriles and obtained
good effect. The NaBH4-CoCl2 reagent system effectively
reduces the nitriles in good yields in hydroxylic as well as non-
hydroxylic solvents7. The halogenides, sulfates, carboxylates
of nickel, iridiumm, rhodium, osmium and platinum were also
used along with NaBH4 in several applications8. Sodium
borohydride-I2 can also reduce nitriles9.
Interestingly, potassium borohydride-metal salt system
also has the similar role, even though the reducing power of
potassium borohydride is rather limited. Here, we would like
to report a simple and efficient reduction condition of pota-
ssium borohydride and redily available cupric salts. The reac-
tion can be carried out in alcoholic solvents as well as in the
mixture of alcoholic solvent and water which makes the work
up process quite simple.
All reagents are purchased without further purification.
The 1H NMR spectra was recorded in DMSO-d6 on a Bruker
400 (400 MHz) spectrometer. The chemical shifts of 1H NMR
spectra are reported relative to TMS (δ 0.00) as the internal
standard. GC was carried out withAgilent 6890N coupled with
a FID detector using HP-5 column.
General procedure for the reduction of nitrile by KBH4
and CuCl2: To a 10 mL round-bottomed flask was added 2-(4-
chlorophenyl)acetonitrile (0.1 5 g, 1 mmol), KBH4 (0.17 g, 3
mmol), CuCl2 (0.03 g, 0.25 mmol) and 80 % isopropanol (1.6
mL isopropanol and 0.4 mL water). The reaction completed in
8 h at 60 °C as evidenced by TLC (DCM:MeOH 10:1). The
reaction mixture was cooled to 25 °C and removed the solvent.
Ethyl acetate (5 mL) was added to the residue, washed with
water (1 mL) and brine (1 mL). The organic layer were dried with
anhydrous Na2SO4, filtered and evaporated in vacuo to afford
the crude product. The crude product was determined by GC.
2-(4-Chlorophenyl)ethanamine (Table-3, entry 1):
Yellowish oil, 90 % yield, 1H NMR (400 MHz, DMSO-d6) δ
2.68 (s, 2H), 3.19 (m, 2H), 7.24 (d, 2H), 7.34 (d, 2H); APCI-
MS: found m/z 156.00.
2-(3-Chlorophenyl)ethanamine (Table-3, entry 2):
Yellowish oil, 78 % yield, 1H NMR (400 MHz, DMSO-d6) δ
1.77 (s,2H), 1.89 (m, 2H), 2.75 (m, 2H) 7.24 (m, 4H); APCI-
MS: found m/z 156.02.