An efficient synthesis of polymethylene-bis-aroyl thiourea derivatives under the condition of phase-transfer catalysis

Article abstract of DOI:10.1080/10426500490473456

Reaction of polymethylene diamine with aroyl chloride and ammonium thiocyanate under the condition of solid-liquid phase-transfer catalysis using polyethylene glycol-400 (PEG-400) as the catalyst yielded polymethylene-bis- aroyl thiourea derivatives 3a-q

Full text of DOI:10.1080/10426500490473456

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Phosphorus, Sulfur, and Silicon and the Related
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AN EFFICIENT SYNTHESIS OF POLYMETHYLENE-BIS-
AROYL THIOUREA DERIVATIVES UNDER THE CONDITION
OF PHASE-TRANSFER CATALYSIS
You-Ming Zhang a , Tai-Bao Wei a , Liang Xian a & Li-Ming Gao a
a Department of Chemistry, Northwest Normal University , Lanzhou, Gansu, P.R. China
Published online: 16 Aug 2010.
To cite this article: You-Ming Zhang , Tai-Bao Wei , Liang Xian & Li-Ming Gao (2004) AN EFFICIENT SYNTHESIS OF
POLYMETHYLENE-BIS-AROYL THIOUREA DERIVATIVES UNDER THE CONDITION OF PHASE-TRANSFER CATALYSIS, Phosphorus,
Sulfur, and Silicon and the Related Elements, 179:10, 2007-2013, DOI: 10.1080/10426500490473456
To link to this article: http://dx.doi.org/10.1080/10426500490473456
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Phosphorus, Sulfur, and Silicon, 179:2007–2013, 2004
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ISSN: 1042-6507 print / 1563-5325 online
DOI: 10.1080/10426500490473456
AN EFFICIENT SYNTHESIS OF
POLYMETHYLENE-BIS-AROYL THIOUREA
DERIVATIVES UNDER THE CONDITION
OF PHASE-TRANSFER CATALYSIS
You-Ming Zhang, Tai-Bao Wei, Liang Xian, and Li-Ming Gao
Department of Chemistry, Northwest Normal University,
Lanzhou, Gansu, P.R. China
(Received November 20, 2003; accepted March 6, 2004)
Reaction of polymethylene diamine with aroyl chloride and ammonium
thiocyanate under the condition of solid–liquid phase-transfer catal-
ysis using polyethylene glycol-400 (PEG-400) as the catalyst yielded
polymethylene-bis-aroyl thiourea derivatives 3a–q in good-to-excellent
yield. The products have been characterized by analytical and spectral
(IR and H1 NMR) data.
Keywords: PEG-400; Phase transfer catalysis; polymethylene-bis-
aroyl thiourea; synthesis
INTRODUCTION
A number of 1,3-disubstituted thiourea derivatives are associated with
various kinds of biological activities. Some thioureas have been found
to be useful as herbicides, insecticides, and plant-growth regulators.1
In view of these observations and in continuation of our earlier work
on the synthesis and biological activity of thiourea derivatives,2–5 we
now report a convenient and efficient method for the preparation
of polymethylene-bis-aroyl thiourea derivatives under the condition
of solid–liquid phase-transfer catalysis using polyethylene glycol-400
(PEG-400) as phase-transfer catalyst.
Aroyl chloride (1) obtained by the reaction of aromatic acid with
thionyl chloride was treated with ammonium thiocyanate under the
Financial support of this work by the Natural Science Foundation of China
(No. 20371040) and the Foundation (No. 02-18) of Northwest Normal University are
acknowledged.
Address correspondence to T.-B. Wei, Department of Chemistry, Northwest Normal
University, Lanzhou, 730070, Gansu, P. R. China. E-mail: keiichu@nwnu.edu.cn
2007

2008
Y.-M. Zhang et al.
condition of solid–liquid phase-transfer catalysis using 3% PEG-400 as
the catalyst to give the corresponding aroyl isothiocyanate (2). With-
out isolation, compound 2 was treated with polymethylene diamine
to afford polymethylene-bis-aroyl thiourea derivatives (3) in good-to-
excellent yield (Scheme 1).
SCHEME 1
RESULTS AND DISCUSSION
Acyl isothiocyanates have been prepared under liquid–liquid phase-
transfer catalysis using tetrabutylammonium bromide as the catalyst,
which after isolation reacted with aniline to give the corresponding
thiourea derivatives.6 However, in the presence of water, hydrolysis of
the aroyl chloride may occur, and the yield of the acyl isothiocyanate
is decreased. Parekh has reported that acyl chloride reacts with dif-
ferent phenylthioureas to yield N1-acyl-N3-arylthioureas, but long re-
action times and high temperature are required.7 Jirman8 has also
reported that substituted benzoyl chloride reacts with N1-acetyl-N3-
arylthioureas to give the corresponding acylthiourea derivatives; how-
ever, long reaction times, high temperature, and the preparation of N1-
acetyl-N3-arylthioureas are required. Other methods9 for preparation
of acylthioureas have also been reported, but none of them was com-
pletely satisfactory for our purpose. Consequently, we have conducted
our reaction under solid–liquid phase-transfer catalysis conditions us-
ing PEG-400 as the catalyst. It was found that the acyl chloride was
quantitatively converted to the corresponding acyl isothiocyanate. This
intermediate was then treated with polymethylene diamines to give the
thiourea derivatives 3 in high yield.
In searching for the best conditions, the condensation of benzoyl chlo-
ride (4) with ammonium thiocyanate in methylene dichloride in the
presence of a phase-transfer catalyst was studied at room temperature
in detail. Instead of the isolation of the formed benzoyl isothiocyanate
(5), the reaction mixture was quenched by the addition of aniline (6) af-
ter 1 h. The added 6 gives rise to the formation of N-phenyl benzamide
(7) and N1-benzoyl-N3-Phenyl thiourea (8) from the starting benzoyl

Polymethylene-bis-aroyl Thiourea Derivatives
2009
chloride 4 and the resulting benzoyl isothiocyanate (5), respectively
(Scheme 2).
SCHEME 2
Without a phase-transfer catalyst, no reaction was observed and 4
was recovered as phenyl benzamide 7. Among the catalysts studied,
18-crown-6 and tetrabutylammonium bromide led to good results; how-
ever, polyethylene glycol derivatives appeared as the best catalysts, and
we used PEG-400 to perform the experiments described below. Other
quatermary ammonium salts tested, 15-crown-5, DB-15-crown-5, and
cyclodextrins such as α-, β-, and γ -CD are not effective. The results are
summarized in Table I.
TABLE I Effect of Catalyst on the Yield of
N1-benzoyl-N3-phenyl thiourea (8) and N-phenyl benzamide (7)
Yield (%)
Run
Catalyst
7a
8b
1
2
3
4
5
6
7
8
18-crown-6
15-crown-5
DB-15-crown-5
α-CD
β-CD
γ -CD
0
82
85
83
76
81
0
0
0
0
0
81
90
82
83
92
85
0
0
0
0
0
PEG-400
PEG-600
98
98
96
92
91
0
0
0
0
0
9
PEG-2000
PEG-6000
Bu4NBr
PhCH2NBu3Cl
PhCh2NMe3Cl
PhCh2NMe3NO3
Me4NCl
10
11
12
13
14
15
16
no PTC
am.p. of 7 is 162–163◦C (Lit.10 163–164◦C).
bm.p. of 8 is 146–148◦C (Lit.6148◦C).

2010

Polymethylene-bis-aroyl Thiourea Derivatives
TABLE III Spectral Data for Compounds 3a–q
2011
Product
IR (KBr) cm−1
1H NMR (δ) ppm
3a
3420, 3232 (NH); 1665 (CO)
and 1154 (CS)
3418, 3221 (NH); 1670 (CO)
and 1151 (CS)
3.98 (t, 4H, CH2); 7.36–7.98 (m, 10H, C6H5);
10.95 (s, 2H, NH); 11.31 (S, 2H, NH).
1.70 (t, 4H, CH2); 3.68 (t, 4H, CH2);
7.45–7.92 (m, 10H, C6H5); 10.91 (s, 2H,
NH); 11.02 (s, 2H, NH).
1.45 (t, 4H, CH2); 1.65 (t, 4H, CH2); 3.60 (t,
4H, CH2); 7.45–7.93 (m, 10H, C6H5); 10.89
(s, 2H, NH); 11.01 (s, 2H, NH).
3b
3c
3238 (NH); 1667 (CO) and
1151 (CS)
3d
3e
3169 (NH); 1693 (CO) and
1182 (CS)
3245 (NH); 1691 (CO) and
1178 (CS)
3.98 (t, 4H, CH2); 7.47–7.54 (m, 8H, C6H5);
10.71 (s, 2H, NH); 11.35 (s, 2H, NH).
1.71 (t, 4H, CH2); 3.67 (t, 4H, CH2);
7.47–7.96 (m, 8H, C6H5); 10.96 (s, 2H,
NH); 11.07 (s, 2H, NH).
3f
3320 (NH); 1694 (CO) and
1180 (CS)
1.43 (t, 4H, CH2); 1.65 (t, 4H, CH2); 3.57 (t,
4H, CH2); 7.48–7.98 (m, 8H, C6H5); 10.72
(s, 2H, NH); 11.73 (s, 2H, NH).
3g
3h
3223 (NH); 1690 (CO) and
1170 (CS)
3213 (NH); 1691 (CO) and
1173 (CS)
3.96 (t, 4H,CH2); 7.46–7.58 (m, 8H,C6H5);
10.81 (s, 2H, NH); 11.37 (s, 2H, NH).
1.07 (t, 4H, CH2); 3.68 (t, 4H, CH2);
7.48–7.98 (m, 8H, C6H5); 10.98 (s, 2H,
NH); 11.09 (s, 2H, NH).
3i
3j
3k
3l
3220, 1690 (NH); 1690 (CO)
and 1172 (CS)
1.43 (t, 4H, CH2); 1.65 (t, 4H, CH2); 3.62 (t,
4H, CH2); 7.45–7.98 (m, 8H, C6H5); 10.85
(s, 2H, NH); 11.77 (s, 2H, NH).
3.63 (t, 6H, CH3); 3.82 (t, 4H, CH2);
6.96–7.98 (m, 8H, C6H5); 10.90 (s, 2H,
NH); 11.03 (s, 2H, NH).
1.69 (t, 4H, CH2); 3.63 (, 6H, CH3); 3.84;
6.96–7.97 (m, 8H, C6H5); 10.90 (s, 2H,
NH); 11.03 (s, 2H, NH).
1.50 (t, 4H, CH2); 1.60 (t, 4H, CH2); 3.60 (t,
4H, CH2); 3.80 (S, 6H, CH3); 6.9–7.95 (m,
8H, C6H5); 10.95 (s, 2H, NH); 11.03 (s, 2H,
NH).
3342, 3265 (NH); 1660 (CO)
and 1172 (CS)
3403, 3221 (NH); 1668 (CO)
and 1165 (CS)
3296, 3220 (NH); 1655 (CO)
and 1158 (CS)
3m
3n
3o
3406, 3219 (NH); 1673 (CO)
and 1154 (CS)
3.96 (t, 4H, CH2); 6.72–7.87 (m, 6H, furan3,
4,5-H); 10.91 (s, 2H, NH); 11.77 (s, 2H,
NH).
1.68 (t, 4H, CH2); 3.82 (t, 4H, CH2);
6.90–7.85 (m, 6H, furan3, 4,5-H); 10.93 (s,
2H, NH); 11.53 (s, 2H, NH).
1.46 (t, 4H, CH2); 1.62 (t, 4H, CH2); 3.58 (t,
4H, CH2); 6.54–7.79 (m, 6H, furan3,
4,5-H); 10.81 (s, 2H, NH); 11.72 (s, 2H, NH)
3.92 (t, 4H, CH2); 7.58–8.52 (m, 8H, C6H5);
10.80 (s, 2H, NH); 11.31 (s, 2H, NH).
1.43 (t, 4H, CH2); 1.64 (t, 4H, CH2); 3.65 (t,
4H, CH2); 7.66–8.70 (m, 8H, C6H5); 10.74
(s, 2H, NH); 11.72 (s, 2H, NH).
3317, 3262 (NH); 1675 (CO)
and 1162 (CS)
3326, 3217 (NH); 1688 (CO)
and 1175 (CS)
3p
3q
3291, 3211 (NH); 1685 (CO)
and 1158 (CS)
3359, 3218 (NH); 1673 (CO)
and 1159 (CS)

2012
Y.-M. Zhang et al.
With the above results in hand, we have prepared seventeen
polymethylene-bis-aroyl thioureas by the reaction of polymethylene
diamines with aroyl chloride and ammonium thiocyanate under the
condition of solid–liquid phase-transfer catalysis in the presence of
catalytic amounts of PEG-400. The results obtained are reported in
Table II.
In summary, this is a facile and convenient method for the synthe-
sis of polymethylene-bis-aroyl thiourea derivatives under solid–liquid
phase-transfer catalysis conditions, with the advantages of mild con-
ditions, simple operation, short reaction times, and high yield over
the reported method. The catalyst PEG-400 is inexpensive, relatively
nontoxic, highly stable, and easily available.
EXPERIMENTAL
General
All melting points were determined in open capillary tubes and are
uncorrected.
IR spectra were recorded using KBr pellets on an Alpha Centauri
1
Fourier transform infrared (FT IR) Spectrophotometer and H NMR
spectra on Bruker AC-80 instrument, DMSO-d6 was used as the solvent
and TMS as internal standard. The chemical shifts are expressed as δ.
Elemental analyses were performed with a PE-2400 CHN instrument.
General Procedure for the Preparation
of Polymethylene-bis-aroyl Thioureas (3)
Powdered ammonium thiocyanate (1.14 g, 15 mmol), aroyl chloride
(1.41 g, 10 mmol), PEG-400 (0.18 g, 3% with respect to ammo-
nium thiocyanate) and methylene dichloride (25 ml) were placed in
a dried round-bottomed flask containing a magnetic stirrer bar and
stirred at room temperature for 1 h. Then a solution of polymethy-
lene diamine (4.5 mmol) in methylene dichloride (10 ml) was added
dropwise over 0.5 h, and the mixture was stirred for 1 h. The cor-
responding polymethylene-bis-aroyl thiourea (3) precipitated immedi-
ately. The product was filtered, washed with water to remove inorganic
salts, dried, and recrystallized from DMF-EtOH-H2O to give the title
compounds (3).
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