Efficient oxidation of sulfur mustard and its simulants using N-tert-butyl-N-chlorocyanamide

Article abstract of DOI:10.1080/00397910600640370

N-tert-Butyl-N-chlorocyanamide reacts with sulfur mustard instantaneously to give a corresponding nontoxic sulfoxide in quantitative yield. The transformation is selective and takes place in semi-aqueous medium (CH ₃CN/H₂O, 1:1), even at subzero temperatures. Copyright Taylor & Francis Group, LLC.

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Efficient Oxidation of Sulfur
Mustard and Its Simulants using
N‐tert‐Butyl‐N‐chlorocyanamide
Vinod Kumar a & M. P. Kaushik a
a Process Technology Development Division , Defence Research and
Development Establishment , Gwalior, India
Published online: 22 Sep 2006.
To cite this article: Vinod Kumar & M. P. Kaushik (2006) Efficient Oxidation of Sulfur Mustard and Its
Simulants using N‐tert‐Butyl‐N‐chlorocyanamide, Synthetic Communications: An International Journal for
Rapid Communication of Synthetic Organic Chemistry, 36:16, 2385-2388, DOI: 10.1080/00397910600640370
To link to this article: http://dx.doi.org/10.1080/00397910600640370
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Synthetic Communicationsw, 36: 2385–2388, 2006
Copyright # Taylor & Francis Group, LLC
ISSN 0039-7911 print/1532-2432 online
DOI: 10.1080/00397910600640370
Efficient Oxidation of Sulfur Mustard and
Its Simulants using N-tert-Butyl-
N-chlorocyanamide
Vinod Kumar and M. P. Kaushik
Process Technology Development Division, Defence Research and
Development Establishment, Gwalior, India
Abstract: N-tert-Butyl-N-chlorocyanamide reacts with sulfur mustard instantaneously
to give a corresponding nontoxic sulfoxide in quantitative yield. The transformation is
selective and takes place in semi-aqueous medium (CH3CN/H2O, 1:1), even at subzero
temperatures.
Keywords: Decontamination, N-tert-butyl-N-chlorocyanamide, simulants, sulfoxides,
sulfur mustard
INTRODUCTION
Bis(2-chloroethyl) sulfide, also known as sulfur mustard, HD, or yperite, is a
potential chemical warfare agent first used in World War I. Large amount of
this compound are still stockpiled throughout the world. Mustard is potential
fatal vesicant that damages skin, eyes, and the respiratory track.[1] High
toxicity of mustard is associated with the ability of the S22CH222CH222Cl
group to alkylate protein and other components of living things. 2-Chloro-
ethyl ethyl sulfide (CEES) and 2-chloroethyl phenyl sulfide (CEPS) also
contain this group and effectively simulate sulfur mustard. Until the 1980s,
mustard was mainly destroyed by incineration. However, this incurs the
additional hazards of transportation to the incineration site and release of
toxic compounds during the process. Various oxidizing agents have also
Received in the USA January 24, 2006
Address correspondence to M. P. Kaushik, Process Technology Development
Division, Defence Research and Development Establishment, Jhansi Road, Gwalior
MP 474002, India. E-mail: mpkaushik@rediffmail.com
2385

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V. Kumar and M. P. Kaushik
Scheme 1.
been used for the decontamination reaction such as hypochlorites,[2] peracids
of the oxone type,[3] oxaziridines,[4] peroxides,[5] magnesium peroxyphthalate
(MMPP),[6] and microemulsion reaction media.[7] More recently, methods of
photocatalytic gas-phase destruction[8] and catalytic aerobic oxidation[9] of
mustard simulant CEES have also been investigated. Among all these
methods, hypochlorites and DS2[2] (diethylenetriamine 70 % þ
ethyleneglycol, monomethyl ether 28% and 2% sodium hydroxide) are fre-
quently used for decontamination of mustard, but there are some disadvan-
tages in using bleach as a decontaminant because a large amount of bleach
is required for the oxidation of the agents, and most important, both are
corrosive to many surfaces. Also, bleach is not effective at low temperatures.
RESULTS AND DISCUSSION
During the course of our study on chemical transformations of some organic
compounds with N-tert-butyl-N-chlorocyanamide 2,[10] we discovered that the
quantitative conversion of sulfides to their corresponding sulfoxides 3 occurs
efficiently. The oxidation took place between 0–358C with ease (Scheme 1).
With a ratio of 1 : 1 for substrate/oxidant, the major product was the corre-
sponding sulfoxides 3 with no evidence of sulfones formation. The results
are summarized in Table 1. tert-Butyl cyanamide 4 was recovered in quantitative
Table 1. Selective oxidation of mustard and its simulants in CH3CN/H2O (1:1) by 2
Entry
Substrate
Product
Yield (%)a
1
Cl-CH2-CH2-S-C2H5
97
2
3
Cl-CH2-CH2-S-Ph
(Cl-CH2-CH2-)2S
95
95
(Cl-CH2-CH2-)2S55O
Note: All products had satisfactory spectroscopic data and were compared with
authentic samples.
aIsolated yield.

Oxidation of Sulfur Mustard
2387
Scheme 2. Mechanism of sulfoxides formation of SM and its simulants.
yield and was recycled to obtain the reagent 2. The sulfur in mustard is believed
to be oxidatively less reactive than that in alkyl sulfide, essentially because of the
presence of two large electron-withdrawing chlorine atoms; however, our
observation revealed that 2 was capable of oxidizing these sulfides smoothly.
The stability of 2 was also evaluated with respect to chlorine content.
Oxidant was indeed very stable at 358C for 6 months.
The mechanism of sulfoxide formation is shown in Scheme 2.
EXPERIMENTAL
Sulfur mustard (caution: highly toxic) and its stimulant were prepared by
known methods. N-tert-Butyl-N-chlorocyanamide was synthesized by the
reported method.[11]
Oxidation Procedure
N-tert-Butyl-N-chlorocyanamide (1.0 mmol) was added slowly to a stirred
solution of sulfides (1.0 equiv.) in acetonitrile–water (1 : 1) (10 mL). After
completion of reaction, as monitered by gas chromatography, water (10 mL)
was added to reaction mixture which was then extracted with methylenechlor-
ide gas chromatography (GC) (3 ꢀ 10 mL). The organic layer was washed
with water (2 ꢀ 10 mL), and dried over anhydrous Na2SO4, and evaporated.
The residue was crystallized with methylene chloride–light petroleum to
give the sulfoxides.
In summary, oxidative decontamination of sulfur mustard and its
simulants using N-tert-butyl-N-chlorocyanamide has been described. N-tert-
butyl-N-chlorocyanamide–based preparations can be used as effective decon-
tamination formulations for sulfur mustard, even at lower temperatures where
other methods become inoperable, because the reaction of oxidant 2 and sulfur
mustard is instantaneous at two different temperatures (210 to þ358C).
ACKNOWLEDGMENT
We thank K. Sekhar, director, DRDE, Gwalior, for his keen interest and
encouragement.

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V. Kumar and M. P. Kaushik
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