Full text of DOI:10.1080/10426507.2017.1287182

Phosphorus, Sulfur, and Silicon and the Related Elements
ISSN: 1042-6507 (Print) 1563-5325 (Online) Journal homepage: http://www.tandfonline.com/loi/gpss20
Synthesis of N-Phenylphosphoramidothioic
Dichloride
Zhuo Zeng, Meng-Qiu Li, Qiu-Lin Deng, Wen-Jie Guo, Shao-Bo Wang, Yi-Bing
Wu & Hui-Wei Liao
To cite this article: Zhuo Zeng, Meng-Qiu Li, Qiu-Lin Deng, Wen-Jie Guo, Shao-Bo Wang, Yi-Bing
Wu & Hui-Wei Liao (2017): Synthesis of N-Phenylphosphoramidothioic Dichloride, Phosphorus,
Sulfur, and Silicon and the Related Elements, DOI: 10.1080/10426507.2017.1287182
To link to this article: http://dx.doi.org/10.1080/10426507.2017.1287182
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Synthesis of N-Phenylphosphoramidothioic Dichloride
Zhuo Zeng, Meng-Qiu Li, Qiu-Lin Deng, Wen-Jie Guo, Shao-Bo Wang, Yi-Bing Wu, Hui-
Wei Liao*
Department of Materials Science and Engineering, Southwest University of Science and
Technology, Mianyang 621010, China
Corresponding author Email: liaohw6709@163.com
Abstract
N-Phenylphosphoramidothioic dichloride was successfully synthesized from the reaction of
thiophosphoryl chloride and phenylamine. Ammonia was used as acid-binding agent in the
reaction. The product was fully characterized by IR, NMR (1H, 13C and 31P), and EA. Under the
optimized conditions, the overall yield was 85%. There are many advantages for this synthesis
method such as simple synthesis procedure, low cost of production, and few by-products.
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Keywords
N-Phenylphosphoramidothioic dichloride; acid-binding agent; organophosphorus;
thiophosphoryl chloride
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Introduction
Organophosphorus compounds have attracted considerable interest of chemists worldwide for
their excellent biological activity; many phosphorylated derivatives of them were used as
pesticides, insecticides, fungicides, and urease inhibitors1 and have been widely applied in
medicinal chemistry, pharmacochemistry and agriculture. The outstanding biological activity of
the phosphoryl group drives our interest to further expand the scopes of phosphorylated
compounds to apply to various fields.
In agriculture we always apply various synthetic nitrogen fertilizers to improve the uptake of
+
nitrogen. But the fertilizers such as urea are easily hydrolyzed to NH4 ions, which causes in the
respective zones high pH and conductivity due to NH3 volatilization.2 The urease inhibitors such
as N-(n-butyl) thiophosphorictriamide (NBPT) have shown a highly efficiency in reducing NH3
losses from surface-applied urea and increasing the yield of nitrogen uptake.3 A number of
urease inhibitors have been reported.4,5 N-Phenyl thiophosphorictriamide (NPPT) is a derivative
of NBPT and the critical step for its synthesis is the preparation of N- phenyl
phosphoramidothioic dichloride (NPPD). NPPD is also a valuable intermediate with important
application in the synthesis of dichlorophosphinothioyl derivatives,6,7 oligonucleotide
phosphorodithioates,8 and phosphorus containing flame retardants.9,10 The synthesis of NPPD
has been reported in the literature.8,11-13 In this paper we report a synthetic route to NPPD using
ammonia as acid-binding agent (Scheme 1).
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Results and Discussion
The pesticide intermediate NPPD was synthesized by nucleophilic substitution reaction of
thiophosphoryl chloride with phenylamine. The structure of NPPD was confirmed by FTIR
(Figure 1). The stretching vibration of C---H and P---Cl was observed at 3041 cm1 and 580
cm1, respectively. The peaks at 1597 and 1497 cm1 were attributed to the framework vibration
of the benzene ring and the absorption bands at 751 cm1 and 688 cm1 corresponded to the
vibration of a singly substituted benzene ring. The peaks at 3250-3400 cm1 can be assigned to
N---H stretching14 and the peak 1597 cm1 was associated with the bending absorption mode of
N---H. There is a weak absorption band at about 760-800 cm1, which may be associated with
the stretching mode of P = S. Because of the effect of electronic effect of chlorine, the stretching
absorption of P = S was observed higher wave numbers than that reported in the literature (580--
750 cm1)6,15
.
The 1H NMR spectrum (400 MHz, CDCl3) of NPPD was also shown in Figure 1. The signal
of the NH proton was observed at δ = 5.30 ppm and the signals of the aromatic protons were
observed between 6.94 and 7.20 ppm. The 13C{1H} NMR spectrum (100 MHz, CDCl3) of NPPD
is shown in Figure 2. The signals at δ = 119.6, 123.0 and 129.5 ppm are attributed to the ortho,
para and meta carbon atoms of the benzene ring, respectively. The NMR signal of the ipso
carbon atom is observed at δ = 139.2 ppm.
The purity of NPPD was also confirmed by its 31P NMR (200 MHz, CDCl3) spectrum
illustrated in Figure 2. There was only one 31P resonance observed at δ = 42.6 ppm.
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Experimental
Materials
Unless otherwise noted, all reagents used (phenylamine, benzene, tetrahydrofuran, methanol,
petroleum ether, ethanol, and ethyl acetate) were commercially available (Chengdu Kenong
reagent Co., Chengdu, China), and were used without further purification. Thiophosphoryl
chloride (97 wt %) was obtained from Chengdu Xiya reagent Co., (Chengdu, China); ammonia
(99.99 vol %) was obtained from Messer gas Co..
Characterization
FTIR spectrum was recorded with a Spectrum One infrared spectrophotometer (PE, USA)
using KBr pellets. 1H, 13C and 31P NMR spectra were obtained with a Bruker Avance NMR
spectrometers (Bruker, Suisse). Elemental analysis was performed with a Varian EL CUBE
elemental analyzer (Elementar Analysensysteme GmbH, Germany). The melting point was
determined using an Optimelt OPM100 apparatus.
Preparation of NPPD
Phenylamine was dried by refluxing with calcium hydroxide for 4-6 h and then and distilled
after standing for 12 h; tetrahydrofuran was refluxed overnight with sodium and diphenylketone
as tracer agent for water removing. Thiophosphoryl chloride was freshly distilled before use. A
solution of 29.50 g thiophosphoryl chloride in 47.90 g of tetrahydrofuran was cooled to 0-5°C in
a 500 mL three-necked round bottom flask which was set in a cryogenic cooling circulation
machine (DL-4020, Ningbo Scientz biotechnology Co., Ltd, China), after the flask is flushed
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with nitrogen. Then a solution of 22.70 g phenylamine in 33.60 g of tetrahydrofuran was added
dropwise into the flask with constant stirring. After all of the phenylamine solution were added,
the reaction mixture was kept about 2.5 h at the same temperature until a white emulsion showed
up. By thin layer chromatography (TLC) we could see that the reaction of the thiophosphoryl
chloride was complete. During the process, ammonia was bubbled into the system intermittently
with appropriate velocity. After filtering the solvent was removed at reduced pressure and a solid
was obtained. The solid was dried in vacuum and dissolved in an appropriate amount of ethyl
acetate with stirring in the ultrasonic cleaning machine (SB-5200DTN, Ningbo Scientz
Biotechnology co., Ltd, China); it took about 2 min to dissolve. Through lowering temperature
the pure product precipitated as a white solid, which was filtered and dried (33.1 g, yield 84.7%).
Elemental analysis: Calcd for NPPD: C 31.77, H 2.64, N 6.21, S 14.21%; Found: C 31.85, H
2.65, N 6.19, S 14.15%. M. p.: 41 C.
Conclusion
In summary, we have developed a large scale synthesis of NPPD by using thiophosphoryl
chloride and phenylamine. The reaction proceeds under very mild reaction conditions and NPPD
can be obtained in good yield.
Acknowledgment
We are grateful to the National Science and Technology Support Program [2014BAB15B02].
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Figure 1 IR and 1H NMR spectrum of NPPD
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Figure 2 13C and 31P NMR spectrum of NPPD
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Scheme 1 Synthesis of NPPD
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