New microemulsions for oxidative decontamination of mustard gas analogues and polymer-thickened half-mustard

Article abstract of DOI:10.1039/b003671o

Chemical decontamination of toxic compounds (warfare agents and pesticides) is of increasing importance. In this study, we report the oxidation of mustard gas analogues in microemulsion media. A first formulation, very well-suited for stock-pile destruction, allows a fast, quantitative and chemoselective oxidation of the analogues. In a second formulation, the choice of microemulsion components used allowed us to study the oxidation of a polymer-thickened half-mustard (2-chloroethylphenyl sulfide), opening the field of application of these microemulsions to on-site decontamination. These results confirm both the efficiency and potential of microemulsions for mustard gas destruction/decontamination in essentially aqueous systems.

Full text of DOI:10.1039/b003671o

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New microemulsions for oxidative decontamination of mustard gas
analogues and polymer-thickened half-mustard
Ferdinand Gonzaga,* Emile Perez, Isabelle Rico–Lattes and Armand Lattes
L aboratoire des Interactions Mole
UMR 5623), Universite Paul Sabatier, 118 route de Narbonne, 31062 T oulouse cedex, France.
culaires et Reactivite Chimique et Photochimique (CNRS
  

E-mail: ferdinan=helen.ups-tlse.fr
Received (in Montpellier, France) 4th May 2000, Accepted 3rd July 2000
First published as an Advance Article on the web 4th October 2000
Chemical decontamination of toxic compounds (warfare agents and pesticides) is of increasing importance. In this
study, we report the oxidation of mustard gas analogues in microemulsion media. A Ðrst formulation, very
well-suited for stock-pile destruction, allows a fast, quantitative and chemoselective oxidation of the analogues. In a
second formulation, the choice of microemulsion components used allowed us to study the oxidation of a
polymer-thickened half-mustard (2-chloroethylphenyl sulÐde), opening the Ðeld of application of these
microemulsions to on-site decontamination. These results conÐrm both the efficiency and potential of
microemulsions for mustard gas destruction/decontamination in essentially aqueous systems.
Formulation de nouvelles microe
dÏun demi-moutarde adsorbe sur polyme
toxiques de guerre) est dÏune importance croissante. Dans cette e
soufres modeles de lÏyperite en milieu microemulsion. Dans un premier temps, une formulation particulie
bien adaptee a la destruction de stocks dÏyperite est decrite: celle ci permet une oxydation rapide, quantitative et
chimioselective des modeles du toxique. Une deuxieme formulation nous a ensuite permis de realiser lÏoxydation
dÏun modele tres proche de lÏyperite (le demi-moutarde 2-chloroethylphenyl sulfure) formule sur polymere, ouvrant
ainsi le champ dÏapplication de nos systemes a la decontamination sur site. Ces resultats demontrent encore une fois
lÏefÐcacite et le potentiel des microemulsions pour la destruction de lÏyperite en mileu majoritairement aqueux.
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mulsions pour la de
re. La decontamination chimique de compose
tude, nous decrivons lÏoxydation de compose
rement
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contamination par oxydation dÏanalogues soufre
s de lÏyperite et
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s toxiques (pesticides ou
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Bis(2-chloroethyl) sulÐde, known as mustard gas or yperite, is
a chemical warfare agent Ðrst used in World War I. Large
amounts of this compound are still stockpiled throughout the
world. The compound attacks mucous membranes, skin, eyes
and the respiratory tract and is an alkylating agent that is
lethal even at low doses.1 Until the 1980Ïs, yperite was mainly
destroyed by incineration. However, this incurs the additional
hazard of transportation to the incineration site and release of
toxic compounds during the process. Safer methods are
required for the in situ destruction of the compound. Since the
corresponding sulfoxide (Scheme 1) is relatively harmless, we
studied here its degradation by oxidation. However, oxidation
may also give rise to the sulfone, which is somewhat toxic.2
A method for rapid detoxiÐcation that favours production
of the sulfoxide is thus required. Oxidation in a basic reaction
medium can also allow the detoxiÐcation of mustard gas:
elimination of HCl by the chlorosulfoxide and/or the chloro-
sulfone leads to the corresponding vinyl sulfoxide and/or vinyl
sulfone, which are harmless compounds. Various oxidising
agents have been used for this decontamination reaction,
including hypochlorites,3 peracids of the oxone type,4 oxaziri-
dines,5 peroxides6 or magnesium monoperoxyphthalate
In
a
recent review of the hydrolysis of toxic
organophosphorus compounds,8 we described the advantages
of organised molecular systems as reaction media. There
appear to have been few studies on the use of such media for
the degradation of sulfur-containing compounds, although
they appear to o†er considerable advantages for rapid and
chemoselective reactions. Drago et al. reported the advantages
of phase transfer for oxidation of sulfur compounds with
sodium hypochlorite,9 while Lion and colleagues employed
MMPP successfully both with and without surfactant.7
Menger and Elrington employed a microemulsion to form the
sulfoxide of the half-mustard Cl-CH CH -S-CH CH with
2
2
2
3
sodium hypochlorite.10 Menger and Rourk later described the
formulation of microemulsions able to simultaneously destroy,
via oxidative and hydrolytic mechanisms, simulants of three
chemical warfare agents.11
We have recently shown that micellar or mixed micellar
media (water ] structured polar solvent) are well-suited for
the hydrolysis of toxic organophosphorus compounds.12
Glycerol was used for the hydrolysis reaction. In another
study on the oxidation of mustard gas analogues,13 we selec-
ted formamide, which we had previously used to produce col-
loidal media.14 In this respect, Chen and Reymond
demonstrated the high reactivity of a mixture of hydrogen
peroxide and formamide for the oxidation of alkenes.15 They
postulated the formation of small amounts of performic acid,
which is used up as it is generated in situ.
(
MMPP).7 MMPP was used in the present experiments.
In an analogous system, we replaced the rather unstable
hydrogen peroxide with MMPP. A micellar medium consist-
ing of a cetylpyridinium chloride and waterÈformamide binary
system (50 : 50 v/v) allowed the quantitative oxidation of the
half-mustard 2-chloroethyl sulÐde by MMPP with 99% sul-
foxide production.16 These examples indicate the suitability of
Scheme 1 Oxidation products of yperite.
DOI: 10.1039/b003671o
New J. Chem., 2001, 25, 151È155
151
This journal is ( The Royal Society of Chemistry and the Centre National de la Recherche ScientiÐque 2001

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organised aqueous media for the decontamination of mustard
gas.
50 : 50, v/v). The resulting pseudo-ternary phase diagram is
presented in Fig. 1.
However, mustard gas is often ““thickenedÏÏ by mixing with
È10% of a polymer thickener.3 The thickened agent is more
viscous and adheres better to surfaces than the neat agent,
making it more difficult to remove. The possible presence of a
thickener in the poison adds a signiÐcant constraint to the
design of a decontamination medium.
We report here the development of new decontaminant
microemulsions. A microemulsion is an isotropic and optically
transparent dispersion of oil in water (O/W) or water in oil
The microemulsion zone is sufficiently large to be used for
the oxidation process. Moreover, solubilisation of more than
20% oil can be achieved in a homogeneous medium. So, large
quantities of the toxin (or its model compound) can be neu-
tralised, limiting the volume of microemulsion required.
We retained the following formulation for the oxidation
tests: 60% of the pseudo-constituent (coTAÈTA) with a
weight ratio of 2; 30% of the binary system waterÈformamide
(50 : 50 v/v); 10% of the model compound. This formulation
is visualised by point A on the phase diagram.
5
(
W/O), where the ““oilÏÏ is a hydrocarbon (or an organic
solvent). Such chemical systems form spontaneously when
water (a structured polar solvent) or a mixture of structured
polar solvents, a surfactant (noted TA), a cosurfactant (noted
coTA, generally a low molecular weight alcohol) and a hydro-
carbon are mixed in speciÐc proportions. Microemulsions,
The three model substrates were oxidised in the formulation
described above. MMPP was used stoichiometrically with
regard to the model substrate (the molar ratio
sulÐde : MMPP was kept constant and equal to 0.55; MMPP
is a di-oxidant, so 1.1 equiv. were used for 1 equiv. of the
analogue). The experimental conditions of stock-pile destruc-
tion allow us to control the relative stoichiometry of the oxidi-
sing agent and of the mustard gas; in contrast, the amounts
and the concentrations of the toxin are unknown in battleÐeld
decontamination. In this case, the problem is more difficult to
resolve: decontaminant solutions are often used in excess, so
over-oxidation can occur. Our results are summarised in
Table 1.
with dispersed droplets averaging 50È500 A in diameter,
Ž
remain clear indeÐnitely. Microemulsions allow greater oil
solubilisation than micellar solutions, and thus a better solu-
bilisation of the toxin. Furthermore, the presence of an
organic solvent in these systems could permit the solu-
bilisation of the thickened agent.
Two types of microemulsions were developed: one very
well-suited to stock-pile destruction (formulation A), and a
second, in which the choice of components used allowed us to
study the oxidation of a polymer-thickened half-mustard,
opening the Ðeld of application of this microemulsion to
on-site decontamination (formulation B).
The analysis of these results shows that the three model
substrates
are
oxidised
quantitatively
(or
nearly
quantitatively), whatever the microemulsion used (aqueous or
binary solvent system): minimal observed conversion is 98%.
The selectivity in favour of sulfoxide is excellent: no more
than 6% sulfone is produced, and only 1% sulfone is formed
Results and discussion
Formulation A: microemulsion for stock-pile destruction
First let us describe the constituents of the microemulsion.
The continuous phase of microemulsion A was water or the
binary system waterÈformamide (50 : 50 v/v). We used
cetylpyridinium chloride (CPCl) as surfactant (we had already
used it in micellar solutions) because it promotes localisation
of both MMPP and formamide (the oxidising system) at the
micellar interface via the following mechanisms: by exchange
of the counter-ion Cl~ and the perphthalate ion for MMPP,
and for formamide, by preferential solvation (with respect to
water) of the pyridinium head.17 Butanone was used as cosur-
factant; no oxidation of this compound by MMPP can occur
under the conditions used.
The success of chemical decontamination in micellar solu-
tions was found to depend largely on the lipophilicity of the
model compounds (evaluated by the log P parameter) and
their corresponding sulfoxides. The reactivity and selectivity of
the reaction were related to the localisation of the di†erent
substrates in the microheterogeneous medium. p-
Methoxyphenyl methyl sulÐde (1), thioanisole (2) and the half
mustard 2-chloroethyl phenyl sulÐde (3) (log P \ 3 for these
three compounds) appeared to be suitable compounds to
model the degradation of yperite.16 So, we used these com-
pounds as simulants in the oxidation reaction in micro-
emulsions where they acted as the oil of the system. Indeed,
according to the ““molecular economy principleÏÏ, postulated
by our laboratory,14a we chose to retain compounds having
several functions: here, the model substrate to be oxidised
constituted the microemulsion oil.
Fig. 1 Pseudo-ternary phase diagram of the CPClÈbutanoneÈ
thioanisoleÈbinary solvent (waterÈformamide, 50 : 50 v/v) system.
Table
1 Oxidation of the model substrates in microemulsion
medium by MMPPa
Microemulsion
Aqueous
Binary systemb
Model
substrates
Yield/%c Select.c Yields/%c Select.c
p-CH O-C H -SCH
100
100
98
95 : 5
96 : 4
96 : 4
99
100
98
94 : 6
99 : 1
95 : 5
3
6
4
3
C H -SCH
6
5
3
C H -SCH CH Cl
6
5
2
2
a All reactions were carried out at 25 ¡C for 1 h. The molar ratio
MMPP : substrate was kept constant and equal to 0.55. b WaterÈ
formamide (50 : 50 v/v). c Yields and selectivity (molar ratio
sulfoxide : sulfone) were determined by HPLC after calibration using
an internal standard. The uncertainty of the results is evaluated at
In order to obtain a pseudo-ternary phase diagram, we
retained a cosurfactant : surfactant weight ratio of 2; the
microemulsion oil chosen was thioanisole, and the third con-
stituent was the binary solvent system (waterÈformamide;
^2%.
152
New J. Chem., 2001, 25, 151È155

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in the oxidation of thioanisole by the binary solvent system
microemulsion.
The previous results (formulation A) being more than satis-
factory, we chose to conserve, as well as possible the best for-
mulation studied, but adapted to battleÐeld conditions:
(i) cetylpyridinium chloride as surfactant;
(ii) butan-1-ol as cosurfactant; this compound leads to a larger
(compared to butanone) microemulsion zone in the phase
diagram;
The microemulsion medium has a marked inÑuence on the
oxidation reaction: Ðrst, it allows total solubilisation of the
model substrates (as opposed to micellar solutions, where the
model substrates form emulsions in the aqueous or binary
system continuous phase); then, the preferential location at
the interface of the oxidising agent (MMPP and formamide)
and of the model substrates leads to a better contact between
the reactants that favours the Ðrst oxidation (leading to
sulfoxide); Ðnally, the more hydrophilic sulfoxide is expelled
into the continuous phase, preventing further oxidation. Note
here that the microemulsion allows fast reaction times: in 3.5
min (time required to dissolve MMPP in the reaction
medium), thioanisole oxidation is complete; the results (yield
and selectivity) were unchanged after 1 h reaction.
Formulation A is therefore very efficient: it allows fast and
quantitative oxidation of various mustard gas analogues, with
strong sulfoxide selectivity. We can also add that all the
reagents used are cheap, available on the laboratory and the
industrial scales and do not require particular conditions for
their utilisation.
(iii) water as continuous phase; no formamide was used
because of its toxicity;
(iv) benzyl chloride as oil; this solvent dissolves the polymer
efficiently (up to 5.8% weight), has a low freezing point ([43
to [39 ¡C), which is an advantage for low-temperature use,
has low toxicity and has previously been used by Bartram and
colleagues as a substitute for N-cyclohexyl-2-pyrrolidone in
the U.S. Army D.A.M. (decontamination agent multipurpose)
formulation.18 Benzyl chloride is, however, a reactive material,
so only war equipment and materials can be detoxiÐed on the
battleÐeld by the microemulsions described here (it cannot be
used for skin decontamination).
The resulting pseudo-ternary phase diagram is presented in
Fig. 2. It shows a large microemulsion zone, which could
allow us to work in direct microemulsion (water as continuous
phase; left part of the diagram) or inverse microemulsion
(benzyl chloride as continuous phase; right part of the
diagram). The main advantage resides in the quantity of oil
that can be dissolved in water-rich formulations: for example,
We then modiÐed the formulation: our goal being a system
to permit on-site detoxiÐcation of mustard gas (and not stock-
pile destruction), and more particularly destruction of
polymer-thickened mustard gas.
1
5
5% benzyl chloride dissolves in a formulation containing
0% water. However, the decontaminating system must be
Formulation B: microemulsion for decontamination of
polymer-thickened agent
essentially aqueous, because large quantities of organic
solvent are susceptible to damage painted surfaces, plastics,
rubbers, etc.
Mustard gas and Soman (3,3-dimethyl-2-butylmethylphos-
phonoÑuoridate) are often formulated with 5 to 10% (by
weight) of an organic polymer. For example, Paraloid K125, a
methylethylbutyl methacrylate copolymer of high molecular
weight, developed by Rohm & Haas, is used to thicken such
toxic agents.3 We thus used K125 in order to prepare the
model substrate (10% by weight with regard to the half-
mustard).
The polymer has multiple roles: (i) it controls the rheology
of toxin scattered by the weaponÏs explosion; (ii) its higher
viscosity makes it adhere better to surfaces, so the toxin is
more difficult to remove, extending its action; (iii) Ðnally,
because of its organic nature, the polymer prevents solu-
bilisation of the toxin in most aqueous decontaminant solu-
tions. It was observed that upon contact with water, a
polymer Ðlm can form at the interface between the thickened
agent and water: this prevents the thickened agent from dis-
solving into the decontaminant solution.3 The presence of a
thickener in the poison adds constraints to the conception of
an efficient decontamination medium.
Finally, a useful formulation must be largely aqueous, and
be able to accept the addition of 10% by weight of the sub-
strate without phase separation, in order to be efficient in the
battleÐeld (this constraint is necessary to preserve a micro-
emulsion at the time of the application of our system on the
polymer-thickened toxin). Table 2 shows the behaviour of
many phase diagram points before and after addition of 10%
(by weight) half-mustard.
We have therefore performed the oxidation tests at points
E, H and K. In a comparative way, we used a stoichiometric
amount of MMPP with regard to the half-mustard, as pre-
viously described for formulation A. The oxidation reaction
being stoichiometric, large weights of peracid must be used in
battleÐeld decontamination. However, the water-rich micro-
emulsions described here (minimum 40% by weight of water)
allow solubilisation of large amounts of MMPP. We can also
compare the e†ect of an increasing quantity of oil on the oxi-
dation of thickened half-mustard, the amount of water
remaining between 40 and 50% by weight. Half-mustard and
polymer-thickened half-mustard were oxidised in the formula-
tions described above. The results obtained are listed for com-
parison in Table 3.
The choice of mustard gas analogue was critical: indeed,
the model must present a lipophilicity near that of yperite,
and must also allow similar solubilisation of the polymer
(
Paraloid K125). The rheology and the behaviour of the
couple polymer/model substrate must be as near as possible
to those of the thickened mustard gas. With p-methoxyphenyl
methyl sulÐde and thioanisole, the polymer does not present
the same solubilisation characteristics, being insufficiently
soluble. In contrast, the half-mustard 2-chloroethyl phenyl
sulÐde seems to mimic the thickened mustard gas satisfacto-
rily: the polymer Ðrst expands, then dissolves.
The relative proportion of polymer with regard to the half-
mustard was set at 10% by weight: in these proportions only
part of the polymer was solubilised, the rest being present in
an elastic and very viscous form.
In order to be efficient, the microemulsion must contain two
essential components: an organic solvent able to solubilise
both toxin and polymer, and a decontaminating agent that
reacts with the toxin and neutralises it. MMPP was again
used.
Fig. 2 Pseudo-ternary phase diagram of the CPClÈbutan-1-olÈ
benzyl chlorideÈwater system.
New J. Chem., 2001, 25, 151È155
153

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Table 2 Behaviour of some phase diagram formulations after addi-
tion of 10% (by weight) of the half-mustard 2-chloroethyl phenyl
sulÐde
addition of the toxin, the toxin acting as a diluent that Ðlls the
excess volume of the polymer, or (ii) polymer-toxin inter-
actions, which create steric hindrance and decrease the seg-
mental mobility of the polymer.19 Similar behaviour could be
postulated for the half-mustard 2-chloroethyl phenyl sulÐde,
which has a structure resembling that of yperite.
Composition
Physical state after
half-mustard addition
Points
[coTAÈTA]ÈoilÈwater
A
B
C
D
E
F
G
H
I
25 : 5 : 70
30 : 5 : 65
35 : 5 : 60
40 : 5 : 55
45 : 5 : 50
30 : 10 : 60
35 : 10 : 55
40 : 10 : 50
35 : 15 : 50
40 : 15 : 45
45 : 15 : 40
Phase separation
Phase separation
Phase separation
Microemulsion
Microemulsion
Phase separation
Phase separation
Microemulsion
Phase separation
Microemulsion
Microemulsion
These results show that microemulsions are well-suited for
the oxidative destruction of polymer-thickened half-mustard.
Despite difficult experimental conditions: 10% by weight of
polymer with regard to the toxin, whereas 3 to 5% only are
generally used, and a small quantity of decontaminant micro-
emulsion was used with regard to the thickened-polymer half-
mustard (weight of microemulsion used only 10 times the
weight of thickened half-mustard, whereas large amounts are
used in on-site decontamination), the microemulsion devel-
oped remained efficient: with 10% oil formulation, more than
J
K
a By weight with a Ðxed cosurfactantÈsurfactant ratio of 2 (also by
weight).
85% of the model substrate was oxidised, of which 85% was
in the form of the sulfoxide.
Conclusion
For half-mustard oxidation, the same results were obtained
as with the previously described microemulsion (formulation
A). Yields were over 95% and selectivity in favour of the sul-
foxide remained important (less than 10% sulfone produced).
These results therefore conÐrm the efficiency of micro-
emulsions as reaction media for mustard gas analogue oxida-
tion.
For oxidation of the polymer-thickened half-mustard, we
note that sulÐde conversion decreased by 10 to 15%, and the
proportion of sulfoxide obtained decreased by 10 to 15%, with
a corresponding increase in sulfone production. These results
can be interpreted by considering the physical state of the
half-mustard: one part, accessible, is incorporated in the
microemulsion oil droplets, and then converted into the corre-
sponding sulfoxide. Another part of the sulÐde, however, is
trapped in the polymer. Competition occurs between the oxi-
dation of the sulfoxide already formed and the less available
sulÐde fraction: the proportion of sulfone produced then
increases.
The MMPP consumed for sulfoxide oxidation is lacking at
the end of the reaction, no longer permitting quantitative oxi-
dation of the sulÐde, as observed in the absence of thickener.
We can also note that the percentage of oil used in the
microemulsion weakly inÑuences the yield and selectivity of
the reaction. So, 5% (and even better 10%) could be sufficient
to allow extraction of half-mustard from the polymeric phase
into the microemulsion phase.
Another e†ect can decrease solvation of the K125 polymer
by benzyl chloride; it is assumed that sulfur mustard restricts
the mobility of polymeric chains by acting as an anti-
plasticising agent. Antiplasticisation results from one or both
of the following e†ects: (i) a decrease in free volume upon
In this study, we developed new decontaminant micro-
emulsions. The systems were shown to be well-suited for selec-
tive oxidation of mustard gas analogues.
Firstly, we formulated systems where the model substrate
was also the microemulsion oil: this strategy could be applied
to the oxidation of stock-piled mustard gas. Indeed, the oxida-
tion of the simulants in microemulsion media is fast (oxidation
of thioanisole was complete in 3.5 min), quantitative and
highly chemoselective (sulfoxide production of up to 99%).
Total solubilisation of the simulants, preferential location at
the micellar interface of both oxidising agent and model sub-
strates and expulsion of the sulfoxide produced into the con-
tinuous phase explain the efficiency observed.
Secondly, we developed a microemulsion for on-site decon-
tamination, and particularly for oxidation of polymer-
thickened half-mustard. The formulation was efficient: despite
the difficult experimental conditions we imposed (10%
polymer with regard to the toxin, low amount of micro-
emulsion used), oxidation of 2-chloroethylphenyl sulÐde
occurred with 85% conversion and suitable chemoselectivity
(no more than 15% of sulfone was produced). The relative
speeds of simulant solubilisation (which requires sufficient sol-
vation of the polymer, and which is thus a slow phenomenon)
and oxidation (relatively faster) are responsible for the lower
yields and selectivity: a fraction of the MMPP being used for
oxidation of the freshly produced sulfoxide rather than for
oxidation of the polymer-trapped sulÐde.
Nevertheless, these results demonstrate both the efficiency
and potential of microemulsions for mustard-gas destruction/
decontamination in essentially aqueous systems.
Materials and methods
Table 3 Oxidation of half-mustard and polymer-thickened half-
mustard in various microemulsion formulationsa
Chemicals
p-Methoxyphenyl methyl sulÐde (97%), thioanisole (99%), 2-
chloroethyl
Polymer-
thickened
phenyl
sulÐde
(98%)
and
MMPP
Formulation
E
Half-mustard
half-mustard
(monoperoxyphthalic acid, magnesium salt hexahydrate, 80%)
were purchased from Aldrich. Cetylpyridinium chloride
monohydrate (99%) and formamide (99.5%) were obtained
from Acros. Butanone ([99.5%) and benzyl chloride (99.5%)
were purchased from Fluka. Butan-1-ol ([99.5%) was pur-
chased from Prolabo. We thank Rohm & Haas (France) for a
sample of Paraloid K125.
Yield %b
Select.b
Yield %b
Select.b
Yield %b
Select.b
96
95 : 5
95
90 : 10
97
81
80 : 20
86
84 : 16
84
(
5% OIL)
H
(
10% OIL)
K
(
15% OIL)
97 : 3
87 : 13
a All reactions were carried out at 25 ¡C for 1 h. The molar ratio
MMPP : substrate was kept constant and equal to 0.55. b Yields and
selectivity (molar ratio sulfoxide : sulfone) were determined by HPLC
after calibration using an internal standard. The uncertainty of the
results is evaluated at ^2%.
Pseudo-ternary phase diagrams
Formulation A. We used thioanisole as oil to plot the phase
diagram, and the weight ratio cosurfactantÈsurfactant
(pseudo-constituent) was 2. The pseudo-ternary phase
154
New J. Chem., 2001, 25, 151È155

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diagram was obtained by titrating several mixtures of pseudo-
constituent and oil with the binary solvent system (waterÈ
formamide, 50 : 50, v/v) until transparency, as described
previously.20
For the other model substrates (p-methoxyphenyl methyl
sulÐde and 2-chloroethyl phenyl sulÐde), we only checked that
the microemulsions were obtained in the retained formulation
by substituting thioanisole with the other mustard-gas simu-
lants.
of the polymer by the simulant), 5.380 g of previously pre-
pared microemulsion (0.717 g CPCl; 1.434 g butan-1-ol; 0.538
g benzyl chloride and 2.690 g water; formulation H) and 0.964
g of 80% MMPP (1.95 ] 10~3 mol; 0.55 equiv.) were added.
One hour later, the reaction medium was treated and analysed
in the same way as formulation A.
References
1
S. M. Somani, in Chemical W arfare Agents, ed. S. M. Somani,
Formulation B. The same procedure was used, except that
the surfactantÈcosurfactantÈoil (benzyl chloride) mixture was
titrated with water.
San Diego, 1992, ch. 2, pp. 13È50.
2
(a) F. A. Davis, R. H. Jenkins and S. G. Yocklovich, T etrahedron
L ett., 1978, 52, 5171; (b) J. R. Anslow, D. A. Karnofsky, B. Valja-
ger and H. W. Smith, J. Pharmacol. Exp. T her., 1948, 93, 1.
Y. C. Yang, J. A. Baker and J. R. Ward, Chem. Rev., 1992, 92,
1729, and cited references.
3
4
Oxidation in formulation A
A. Leblanc, L. Fosset, G. Magnaud, M. Desgranges, H.
SentenacÈRoumanou, C. Lion, C. Charvy and A. Mohri, Phos-
phorus Sulfur Silicon, 1993, 79, 141.
The procedure used is illustrated by thioanisole oxidation: a
mixture of 0.703 g (5.67 ] 10~3 mol; 1 equiv.) of thioanisole,
2.812 g of butanone, 1.406 g of CPCl and 2.109 g of the binary
5
Y. C. Yang, L. L. Szafraniec and W. T. Beaudry, J. Org. Chem.,
1
990, 55, 3664.
solvent system (waterÈformamide; 50 : 50, v/v) was stirred
magnetically in a round-bottom Ñask. This mixture is homo-
geneous, in accordance with the phase diagram. Then, 1.928 g
6
7
R. S. Drago, Coord. Chem. Rev., 1992, 117, 185.
G. Delmas, M. Desgranges, C. Lion, M. Magnaud and H.
SentenacÈRoumanou, Fr. Pat. C2676368, 1991.
(
3.90 ] 10~3 mol; 0.55 equiv.) of 80% MMPP is introduced
8
9
0
B. Segues, E. Perez, I. RicoÈLattes, M. Riviere and A. Lattes,
Bull. Soc. Chim. Fr., 1996, 133, 925.
rapidly. One hour later, residual MMPP is neutralised by
excess NaHCO ; the mixture is extracted with chloroform
J. H. Ramsden, R. S. Drago and R. Riley, J. Am. Chem. Soc.,
3
1
989, 111, 3958.
(
3 ] 50 mL) and the solvent evaporated under reduced pres-
1
F. M. Menger and A. R. Elrington, J. Am. Chem. Soc., 1991, 113,
sure. The residue is taken up in 50 mL chloroform in a grad-
uated Ñask. One milliliter of this solution is added to a 25 mL
graduated Ñask along with 1 mL standard stock solution of
benzophenone and made up to the mark with chloroform.
The resulting solution is then analysed by HPLC as pre-
viously described.16 Sulfoxides, sulfones and starting sulÐdes
9
621.
1
1
1
2
F. M. Menger and M. J. Rourk, L angmuir, 1999, 15, 309.
P. Eychenne, I. RicoÈLattes, E. Perez and A. Lattes, New J.
Chem., 1995, 19, 193.
13 F. Gonzaga, E. Perez, I. RicoÈLattes and A. Lattes, C. R. Acad.
Sci., Ser. IIc, 1998, 1, 209.
1

4
(a) A. Lattes and I. RicoÈLattes, C. R. Acad. Sci., Se

r. IIb, 1997,
24, 575; (b) I. RicoÈLattes, Recent Res. Dev. Org. Chem., 1998, 2,
42 and references therein.
(
eventually) only were detected by HPLC. No evidence for
3
2
vinyl sulfoxide and/or vinyl sulfone production was found.
The microemulsionÏs pH was not determined: it might be
slightly acidic (because of the inÑuence of the MMPP).
1
5
Y. Chen and J. L. Reymond, T etrahedron L ett., 1995, 23, 4015.
16 F. Gonzaga, E. Perez, I. RicoÈLattes and A. Lattes, L angmuir,
1999, 15, 8328.
However,
microemulsions
being
microheterogeneous
17
18
19
20
X. Auvray, T. Perche, C. Petipas, R. Anthore, M. J. Marti, I. Rico
and A. Lattes, L angmuir, 1992, 8, 2671.
(
continuous phase, interface, micellar core), it is always diffi-
cult to determine exactly the pH parameter.
Y. Wei, J. Wang, G. Wei, C. T. Tang, W. Wang and P. W.
Bartram, J. Dispersion Sci. T echnol., 1996, 17, 307.
L. V. R. Murthy, S. Banerjee, B. Singh and R. S. Chauhan, J.
Appl. Polym. Sci., 1997, 65, 731.
Oxidation in formulation B
F. Gonzaga, Ph.D. Thesis, Universite Paul Sabatier, Toulouse,

A
mixture of 0.489 g of 2-chloroethyl phenyl sulÐde
France, 2000; I. Danielsson, M. R. Hakala and M. Jorpes-
Friman, in Solution Chemistry of Surfactants, ed. K. L. Mittal,
IBM Corporation, Hopewell Junction, New York, 1979, vol. 2,
pp. 659È671.
(
(
2.835 ] 10~3 mol; 1 equiv.) and 0.049 g of K125 polymer
10% by weight with respect to the toxic) is introduced in a
round-bottom Ñask; 10 min later (time for optimum solvation
New J. Chem., 2001, 25, 151È155
155