Improved method for the preparation of 1,1-dimethyl-3-arylureas using chlorocarbonylsulfenyl chloride

Article abstract of DOI:10.1080/00397911.2010.530374

A convenient procedure for preparing some arylureas having herbicidal properties is reported. The method has two steps: (1) reaction of arylamine with chlorocarbonylsulfenyl chloride in the presence of nonpolar solvent to produce aryl carbonylsulfenyl chloride and (2) reaction with dimethylamine in a two-phase reaction catalysed by phase-transfer catalyst to produce the corresponding aryl ureas. Taylor & Francis Group, LLC.

Full text of DOI:10.1080/00397911.2010.530374

This article was downloaded by: [Pennsylvania State University]
On: 10 June 2012, At: 21:47
Publisher: Taylor & Francis
Informa Ltd Registered in England and Wales Registered Number: 1072954 Registered
office: Mortimer House, 37-41 Mortimer Street, London W1T 3JH, UK
Synthetic Communications: An
International Journal for Rapid
Communication of Synthetic Organic
Chemistry
Publication details, including instructions for authors and
subscription information:
http://www.tandfonline.com/loi/lsyc20
Improved Method for the Preparation
of 1,1-Dimethyl-3-arylureas Using
Chlorocarbonylsulfenyl Chloride
K. Adeppa a , D. C. Rupainwar a & Krishna Misra b
a U.P. Technical University, Lucknow, India
b Indian Institute of Information Technology, Jhalwa Campus,
Allahabad, India
Available online: 17 Aug 2011
To cite this article: K. Adeppa, D. C. Rupainwar & Krishna Misra (2012): Improved Method for
the Preparation of 1,1-Dimethyl-3-arylureas Using Chlorocarbonylsulfenyl Chloride, Synthetic
Communications: An International Journal for Rapid Communication of Synthetic Organic Chemistry,
42:5, 714-721
To link to this article: http://dx.doi.org/10.1080/00397911.2010.530374
PLEASE SCROLL DOWN FOR ARTICLE
Full terms and conditions of use: http://www.tandfonline.com/page/terms-and-conditions
This article may be used for research, teaching, and private study purposes. Any
substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing,
systematic supply, or distribution in any form to anyone is expressly forbidden.
The publisher does not give any warranty express or implied or make any representation
that the contents will be complete or accurate or up to date. The accuracy of any
instructions, formulae, and drug doses should be independently verified with primary
sources. The publisher shall not be liable for any loss, actions, claims, proceedings,
demand, or costs or damages whatsoever or howsoever caused arising directly or
indirectly in connection with or arising out of the use of this material.

Synthetic Communications1, 42: 714–721, 2012
Copyright # Taylor & Francis Group, LLC
ISSN: 0039-7911 print=1532-2432 online
DOI: 10.1080/00397911.2010.530374
IMPROVED METHOD FOR THE PREPARATION
OF 1,1-DIMETHYL-3-ARYLUREAS USING
CHLOROCARBONYLSULFENYL CHLORIDE
K. Adeppa,1 D. C. Rupainwar,1 and Krishna Misra2
1U.P. Technical University, Lucknow, India
2Indian Institute of Information Technology, Jhalwa Campus,
Allahabad, India
GRAPHICAL ABSTRACT
Abstract A convenient procedure for preparing some arylureas having herbicidal properties
is reported. The method has two steps: (1) reaction of arylamine with chlorocarbonylsulfe-
nyl chloride in the presence of nonpolar solvent to produce aryl carbonylsulfenyl chloride
and (2) reaction with dimethylamine in a two-phase reaction catalysed by phase-transfer
catalyst to produce the corresponding aryl ureas.
Keywords Arylureas; carbonylation; chlorocarbonylsulfenyl chloride; isoproturon;
p-cumidine
INTRODUCTION
A series of dimethylamine substituted aryl urea derivatives (1) are well-known
commercial herbicides. Some of these herbicides shown in Fig. 1 [e.g., isoproturon
(1a), fenuron (1b), monuron (1c), diuron (1d), and metoxuron (1e)] have been
produced on an industrially large scale.
Several methods for the synthesis of aryl urea derivatives (1a–e) have been
reported in the literature. Initially in the early fifties,[1] these were developed as
industrial herbicides, and several are still on the market. Subsequently, these were
also used in the other agricultural applications.[2–7] There is a considerable amount
of literature available, especially patents, dealing with a wide variety of procedures
for the preparation of arylurea derivatives, and the majority of the procedures can
be classified into five groups: (a) phosgenation of primary arylamines with the for-
mation of the corresponding aryl isocyanates and their subsequent reaction in situ
Received May 3, 2010.
Address correspondence to Krishna Misra, Indo-Russian Center for Biotechnology, Indian
Institute of Information Technology, Allahabad 211002, India. E-mail: krishnamisra@hotmail.com,
kkmisra@yahoo.com
714

IMPROVED PREPARATION OF ARYLUREAS
715
Figure 1. Some commercially available herbicides.
with anhydrous dimethylamine,[8,9] (b) reactions of aryl isocynates with anhydrous
dimethylamine,[10–14] aqueous dimethylamine[15–17] or dimcarb,[18] (c) reactions of
primary arylamines with dimethylcarbamoyl chloride,[19–24] (d) transamidation of
urea with primary arylamines and subsequent transamidation of the resultant pro-
ducts with dimeth ylamine,[25,26] transamidation of diarylureas with dimethyl-
amines,[27–30] and the transamidation of dimethylurea with primary arylamines,[27]
and (e) oxidative–reductive carbonylation of nitriarenes and dimethylamine with
carbon monoxide as catalyst.[17,31,33]
The present study aims to elaborate a novel economically and commercially
viable method for the preparation of dimethylamine substituted aryl urea derivatives
having the general formula 1. In the present communication, the arylamines are first
reacted with chlorocarbonylsulfenyl chloride in ethylene dichloride under a nitrogen
atmosphere. The resulting aryl carbonylsulfenyl chlorides react with dimethylamine
in a two-phase reaction using a phase-transfer catalyst to produce corresponding
arylureas.
RESULTS AND DISCUSSION
In the present work, carbonylation of p-cumidine with chlorocarbonylsulfenyl
chloride (1:1.04 M) at ꢀ85 ꢁC over 2 h under N2 atm. was followed by condensation
with aqueous solution of dimethylamine in two phase reaction using different
solvents and different phase-transfer catalysts at ꢀ65 ꢁC over 5 h (Table 1). The
maximum yield obtained was 95% when ethylene dichloride was used as a solvent
and triethylbenzylammonium (TEBA) was used as phase-transfer catalyst.
In the case of p-cumidine, changing the molar ratio with respect to chlorocarbo-
nylsulfenyl chloride from 1:1.04 to 1:1.73 M (entry 2; Table 1) lowered the yield from
95% to 35%, indicating an unfavorable effect on enhancing concentration of chloro-
carbonylsulfenyl chloride. A change in molar ratio of phase-transfer catalyst TEBA
(0.22 mM) against p-cumidine (1 M) to 0.05 mM: 1.0 M and 0.10 mM: 1.0 M (entries
3 and 4; Table 1) lowers the yield from 95% to 36% and 66% respectively, indicating

716
K. ADEPPA, D. C. RUPAINWAR, AND K. MISRA
Table 1. Effect of phase transfer catalyst (PTC) and solvents in the synthesis of Isoproturon (1a) [molar
ratio of p-cumidine: chlorocarbonylsulfenylchloride 1:1.04]
Entry
Phase transfer catalyst
Solvent
Yeild (%)
1
2
Triethylbenzylammonium chloride (0.22 mM)
Triethylbenzylammonium chloride (0.15 mM)
Triethylbenzylammonium chloride (0.05 mM)
Triethylbenzylammonium chloride (0.10 mM)
Triethylene diamine (0.22 mM)
Ethylene dichloride
Ethylene dichloride
Ethylene dichloride
Ethylene dichloride
Ethylene dichloride
Ethylene dichloride
Ethylene dichloride
Tetrahydrofuron
95
35ꢂ
36
66
45
85
20
52
76
28
38
3
4
5
6
Dimethyl amino pyridine (0.22 mM)
without catalyst
7
8
Triethylbenzylammonium chloride (0.22 mM)
Triethylbenzylammonium chloride (0.22 mM)
Triethylbenzylammonium chloride (0.22 mM)
Triethylbenzylammonium chloride (0.22 mM)
9
N-Methyl pyrrolidine
Dimethyl sufoxide
Dimethyl formamide
10
11
ꢂReaction using p-cumidine: chlorocarbonylsulfenyl chloride 1.0 M:1.73 M.
the significant effect of phase-transfer catalyst concentration on the yield. A change of
phase-transfer catalyst from TEBA to triethylene diamine and dimethylamino pyri-
dine (entries 5 and 6; Table 1) lowered the yield from 95% to 45% and 85% respect-
ively, while without catalyst (entry 7; Table 1) the yield was only 20%, suggesting
TEBA as the most favorable phase-transfer catalyst.
A change of solvent from ethylene dichloride to tetrahydrofuran, N-methyl
pyrrolidine, dimethylsulfoxide, and dimethylformamide (entries 8–11; Table 1) low-
ered the yields to 52%, 76%, 28%, and 38%, respectively, suggesting ethylene dichlor-
ide as the most favorable solvent.
Table 2. Reaction conditions for synthesis of dimethylamine substituted aryl urea herbicides (1a–e)
Ratio Time
2=ccsc (h)
Ratio Time
3=DMA (h)
Yield (%)y
Entry
1.
Arylamine
2
3
1
(purity, %)p Mp (ꢁC)
Lit.32
2a 1:1.04
2
3a 1:1.04
5
1a 94 (98.45)
158–158.5 155–156
2.
3.
2b 1:1.15
2c 1:1.10
4
2
3b 1:1.20
3c 1:1.80
12 1b 90 (96.25) 133.8–134 131–134
8
5
1c 92 (95.40)
1d 88 (94.00)
173–174
–
4.
5.
2d 1:1.20
2e 1:1.05
4
8
3d 1:1.15
3f 1:1.20
154–154.5 153–155
125–126.5 126–127
12 1e 90 (96.00)
2: arylamine (2a: para cumidine; 2b: aniline; 2c: para chloroaniline; 2d: 3,4-dichloroaniline; 2e:
3-chloro-4-methoxy aniline); ccsc: chlorocarbonylsulfenyl chloride; 1: dimethylamine substituted arylureas
1a: Isoproturon; 1b: Fenuron; 1c: Monuron; 1d: Diuron; 1e: Metoxuron.
yYields of the isolated products.
pPurity determined by GC.

IMPROVED PREPARATION OF ARYLUREAS
717
Scheme 1. General method for the preparation of dimethylamine substituted arylurea herbicides (1a–e):
(1a) Isoproturon; (1b) Fenuron; (1c) Monuron; (1d) Diuron; (1e) Metoxuron (Commercial names of
herbicides).
Other arylamines (2b–e) were similarly reacted using ethylene dichloride as
solvent and TEBA as phase-transfer catalyst, while changing the other reaction
conditions (Table 2).
The mechanism of this two-step reaction has been given in Scheme 1. The
arylamine acts as nucleophile and attacks the carbonyl carbon of chlorocarbonyl-
sulfenyl chloride, yielding the intermediate arylcarbonylsulfenyl chloride (3), the
carbonyl carbon of which is further attacked by nucleophilic nitrogen of dimethyl-
amine, yielding arylureas (1a–e).
CONCLUSION
A convenient, cost-effective synthetic method for the preparation of dimethyl
amine substituted arylurea herbicides (1a–e) has been developed. The reaction occurs
under mild conditions in which the carbonylation of aryl amines (2a–e) with chlor-
ocarbonylsulfenyl chloride has been carried out followed by reaction with aqueous
dimethylamine, powerfully assisted by the phase-transfer reagent TEBA and ethyl-
ene dichloride as a solvent. The optimal conditions for the synthesis of different ary-
lurea herbicides have been reported. Insertion of a carbonyl group without using
carbon monoxide gas is an advantage of this method.
EXPERIMENTAL
All chemicals (p-cumidine, aniline, 4-chloroaniline, 3,4-dichloroaniline,
3-chloro-4-methoxy aniline, ethylene dichloride, tetrahydrofuron, dimethylsulfoxide,
dimethyl formamide, dimethylaminopyridine, TEBA, triethylene diamine) were pur-
chased from Merck, India, and perchloromethyl mercaptan was doneted by India
Pesticides, Lucknow, India. Melting points were determined on a paramount digital
melting-point instrument, and gas chromatographic (GC) analyses were performed
on a Thermo Fischer GC model GC-1000. 1H NMR spectra were obtained on a Bru-
ker Avance 400 spectrometer. Mass and exact mass spectra were recorded on a
Perkin-Elmer mass spectrometer.

718
K. ADEPPA, D. C. RUPAINWAR, AND K. MISRA
General Procedure for the Synthesis of 3-(4-Isopropyl-
phenyl)-1,1-dimethylurea (Isoproturon, 1a)
Chlorocarbony sulfenyl chloride (34 g, 0.26 M) was added dropwise over
45–50 min to a stirred solution of p-cumidine (34 g, 0.25 M) in ethylene dichloride
(200 ml) under vigorous reflux in a nitrogen atmosphere. The reaction was mildly
exothermic, and the progress of the reaction was monitored by GC. After the
addition, the reaction mixture was maintained at ꢀ85 ꢁC for an additional 2 h
followed by distillation of ethylene dichloride (50 ml) under a vacuum to remove dis-
solved hydrochloric acid. The reaction mixture was diluted with ethylene dichloride
(100 ml) and phase-transfer catalyst triethylbenzylammonium chloride (0.05 g,
0.22 M), sodium chloride (15 g, 0.24 M) and antifoaming agent turkyredoil (0.1 g)
were added. A 10% aqueous solution of dimethylamine (120 g, 0.27 M) was added
dropwise at 60–65 ꢁC over 1 h. The progress of the reaction was monitored by GC.
After the addition, the reaction mixture was maintained for an additional 5 h, fol-
lowed by filtration and layer separation. The organic layer was collected, dried over
sodium sulfate, and concentrated under a vacuum. The crude product was quenched
in a pool of cold ethanol followed by crystallization, filtration, and drying to obtain
colorless needles of 3-(4-isopropyl-phenyl)-1,1-dimethylurea (isoproturon, 1a, Fig. 2);
yield: 49.60 g (94%); 98.45% purity (GC), mp: 158–158.5 ꢁC (lit.[32]).
1NMR (200 MHz)18: d ¼ 1.22 (d, J ¼ 6.6 Hz, 6H, 2 ꢃ CH3), 2.79–2.92 (m, 1H,
CH), 3.01 (S, 6H, 2 ꢃ CH3), 6.40 (br s, 1H, NH). 7.14 (d, J ¼ 8.8 Hz, 2H, 2 ꢃ ArH),
7.28 (d, J ¼ 8.8 Hz,2H, 2 ꢃ ArH).
MS (EI, 70 ev): m=z (%) ¼ 206 (61) [Mþ], 192 (5), 191 (35), 161 (7), 147 (6), 146
(53), 128 (8), 91 (10), 72 (100), 45 (6).
3-Phenyl-1,1-dimethylurea (Fenuron, 1b)
Yield: 42.65 g (90%); 96.25% purity (GC), colorless needles, mp: 133.5–134 ꢁC
(lit.[32]).
1NMR (200 MHz)[17,18]: d ¼ 2.99 (s, 6H, 2 ꢃ CH3), 6.51 (br s, 1H, NH), 7.01
(appt, J ¼ 7.2 Hz, 1H, ArH), 7.26 (t, J ¼ 7.6 Hz, 2H, 2 ꢃ ArH), 7.38 (d, J ¼ 7.6 Hz,
2H, 2 ꢃ ArH).
MS (E1, 70 ev): m=z (%) ¼ 164 (57) [Mþ], 119 (11), 91 (5), 72 (100) 65 (7).
3-(4-Chlorophenyl)-1,1-dimethylurea (Monuron, 1c)
Yield: 45.65 g (92%), 95.4% purity (GC), colorless needles, mp: 173–174 ꢁC
(lit.[32]).
Figure 2. Preparation of Isoproturon.

IMPROVED PREPARATION OF ARYLUREAS
719
1NMR (200 MHz)[17,18]: d ¼ 3.00 (s, 6H, 2 ꢃ CH3), 6.40 (br s, 1H, NH), 7.21 (d,
J ¼ 8.8 Hz, 2H, 2 ꢃ ArH), 7.31 (d, J ¼ 8.8 Hz, 2H, 2 ꢃ ArH).
MS (E1, 70 eV): m=z (%) ¼ 198 (30) [Mþ], 153 (9), 73 (6), 72 (100)).
3-(3,4-Dichlorophenyl)1,1-dimethylurea (Diuron, 1d)
Yield: 51.50 g, (88%), 94% purity (GC), colorless needles, mp: 154–154.5 ꢁC
(lit.[32]).
1NMR (200 MHz)[17,18]: d ¼ 3.00 (s, 6H, 2 ꢃ CH3), 6.42 (br s, 1H, NH),
7.19–7.21 (m, 1H, ArH), 7.22–7.30 (m, 1H, ArH), 7.59 (s, 1H,ArH).
MS (E1, 70 ev): m=z (%) ¼ 232 (17) [Mþ], 189 (11), 187 (18), 124 (10), 73 (6), 72
(100), 44 (7).
3-(3-Chloro-4-methoxy-phenyl)1,1-dimethylurea (Metoxuron, 1e)
Yield: 60.50 g, (92%), 96% purity (GC), colorless needles, mp: 125–126.5 ꢁC
(lit.[32] 124–127 ꢁC).
1NMR (400 MHz)[17,18]: d ¼ 3.05 (s, 6H, 2 ꢃ CH3), 6.95 (dr s, 1H, NH), 7.17
(m, 1H, ArH), 7.34 (d, 1H, ArH).
Chlorocarbonylsulfenylchloride[34]
Trichloromethanesulfenyl chloride (294 ml, 500 g, 2.7 mol) was taken in a 2 L
reaction flask equipped with reflux condenser, thermometer, and stirrer. A mixture
of water (54 ml, 3.0 M) in concentrated sulfuric acid (620 ml) was added dropwise
over 3 h. The heterogenous mixture was vigorously stirred for 6 h at 45–50 ꢁC as
HCl evolved and then stirred overnight at 25 ꢁC to ensure complete conversion of
perchloromethylmercaptan (trichloromethane sulfenyl chloride) (PCMM) to chlor-
ocarbonyl sulfenyl chloride (CCSC). The progress of the reaction was monitored by
GC. The upper phase (280 g, 80%) was separated and distilled through a column, bp
98–101 ꢁC (lit.[34] bp 98 ꢁC) to provide typically 230 g (65%) of the clear light yellow
liquid of chlorocarbonylsulfenyl chloride.
ACKNOWLEDGMENTS
The authors gratefully acknowledge the Center for Biomedical Magnetic
Resonance (CBMR; SGPGIMS), Lucknow, for NMR spectra and the Central
Drug Research Institute (CDRI), Lucknow, for mass spectra. One of the authors
(K. Adeppa) is grateful to India Pesticides Limited, Lucknow, for financial support.
REFERENCES
1. Bucha, H. C.; Todd, C. W. 3-(p-Chlorophenyl)-1–1dimethylurea: A new herbicides.
Science 1951, 114, 493–494.
2. Grayson, M.; Eckroth, D. Herbicides. In Kirk-Othmer: Encyclopedia of Chemical
Technology, 3rd ed.; Wiley: New York, 1980; vol. 12, pp. 319–324.
3. Peterson, U. In Houben-Weyl-Hagemann Methods of Organic Chemistry, 4th ed.; Thieme:
Stuttgart, 1983; vol. E4, pp. 334–367.

720
K. ADEPPA, D. C. RUPAINWAR, AND K. MISRA
4. Vishnyakova, T. P.; Golubeva, A.; Glebova, E. V. Substituted ureas, method of synthesis
and application. Russ. Chem. Rev. 1985, 54, 249–261.
5. Petersen, H. In Ullmann’s Encyclopedia of Industrial Chemistry, 5th ed.; Wiley: Hoboken,
NJ, 1996; vol. A27, pp. 355–365 .
6. Tafesh, A. M. Weiguny, A. Review of the selective catalytic reducation of aromatic nitro
compound into aromatic amines, isocyanates, carbamates, and ureas using CO. J. Chem.
Rev. 1996, 96, 2035–2052.
7. Artuso, E.; Degani, I.; Fochi, R.; Magistris, C. Preparation of mono-, di-, and trisub-
stituted ureas by carbonylation of aliphatic amines with S,S-dimethyl dithiocarbonate.
Synthesis 2007, 3497–3506.
8. Todd, C. W. E. I. Preparation of 3-(halophenyl)-1-(methyl or ethyl) ureas and herbicidal
compositions and application. U.S. Patent 2655445, 1953.
9. Searle, N. E. E. I. Weed control composition and method of preparation. U.S. Patent
2764478, 1956.
10. Scherer, O.; Horlein, G.; Schonowsky, H. Preparation of urea derivatives and their use as
herbicides. U.S. Patent 3937726, 1976.
11. Spatz, D. M.; Cross, B. Preparation of para-phenylalkoxy phenyl urea and thiourea com-
pounds and their herbicidal use. U.S. Patent 4289903, 1981.
12. Koenig, K. H.; Schwendemann, V.; Schirmer, U.; Liesner, M.; Wuerzer, B. Process for the
preparation of halogenoalkylphenyl ureas and their use in combating undesired plant
growth. DE Patent 3213375, 1983.
13. Haeberle, N.; Oeltze, H.; Brader, L. Process for the preparation of urea derivatives. DE
Patent 3638753, 1988.
14. Haug, M.; Santel, H. J.; Schmidt, R. R.; Strang, H. Process for the preparation of
difluorophenyl urea derivatives and their use as herbicides. DE Patent 3800269, 1989.
15. Ciba Geigy, A. G. Method of selectively combating weeds with 4-isopropyl phenyl ureas.
GB Patent 1407587, 1975. Chem. Abstr. 1976, 84, 4711.
16. Sales, R.; Barquets, L.; Perez Esteban, R.; Martin Recio, A.; Gayo, H. ES Patent 520096,
1984.
17. Wang, X.; Mei, J.; Lu, S. Method of synthesizing isoproturon using dimethyl amine water
solution. CN Patent 1597663, 2005; Chem. Abstr. 2006, 144, 191981 .
18. Schroth, W.; Andersch, J.; Schaedler, H. D.; Spitzner, R. Chem. Ztg. 1989, 113, 261–271.
19. Goldhamer, D. L.; Onyszkkewyez, M.; Wilson, A. Preparation of aryl urea derivatives.
Tetrahedron Lett. 1968, 38, 4077–4080.
20. CIBA Ltd. Process for the manufacture of arylureas. GB Patent 1152892, 1969.
21. Ihara Chemical Industry Co. Ltd., Kumiai Chemical Industry Co., Ltd. Process for the
preparation of urea derivatives and herbicide comprising it as active ingredient. JP Patent
56053645, 1981.
22. Seckinger, K. Process for the preparation of urea derivatives. DE Patent 300154, 1983.
23. Takematsu, T.; Fukuoka, D.; Takahashi, K.; Hashimoto, I. Novel urea derivatives:
Process for the production thereof and herbicides. WO Patent 8700840, 1987.
24. Camps, M.; Anaya Riba Garcia, M. J. Method for obtaining carbamoyl chlorides and
procedure for use in the preparation of substituted monoarylureas. ES Patent 2027074,
1992.
25. Jones, R. L. Preparation of alkyl-aryl urea. U.S. Patent 2768971, 1956.
26. Wu, Z.; Guo, D.; Zou, Z. Synthetic method of herbicide isoproturon, C.N. Patent
1063279, 1992.
27. Werther, R. H.; Korntner, H.; Auer, E.; Thoonhofer, K. Process for the preparation of
pure asymmetric disubstituted ureas. Patent Application EP 427963, 1991.
28. Yang, Y.; Lu, S. Substitution reaction of N,N0-diphenylurea by amines to unsymmetric
phenylureas. Org. Prep. Proced. Int. 1999, 31, 559–576.

IMPROVED PREPARATION OF ARYLUREAS
721
29. Yang, Y.; Lu, S. Process for synthesizing unsymmetrically substituted urea herbicides.
C.N. Patent 1276368, 2000.
30. Wang, X.; Li, P.; Yuan, X.; Lu, S. Selenium-catalyzed carbonylation of nitroarenes to
symmetrical 1,3-diaryl ureas under solvent-free condition. J. Mol. Catal. A: Chem.
2006, 253, 261–264.
31. Tietz, H.; Schwetlick, K. L.; Schoebel, H. J.; Herbig, H.; Lankau, H. J. Process for the
preparation of phenyl ureas. D.D. Patent 227700, 1985.
32. Dictionary of Organic Compounds, ver. 15.2 [CD ROM]; Chapman & Hall: London, 2007.
33. Mizuno, T.; Kino, T.; Ito, T.; Miyata, T. T. Synthesis of aromatic urea herbicides by the
selenium-assisted carbonylation using carbon monoxide with sulfur. Synth. Commun.
2000, 30, 1675–1688.
34. Weiss, W. Process for the preparation of chlorocarbonylsulfenyl chloride. German Patent
1224720, 1964.