Sartori The War Gases Chemistry and analysis

The values of the vapour tension and of the corresponding volatilities of dichloroethyl sulphide in the solid state are, according to Vedder :

thus highly persistent, especially on terrain covered with bushes and shrubs (see p. 12).

Dichloroethyl sulphide is very sparingly soluble in water, its solubility increasing to a certain limit with increase in temperature. According to Hopkins 1 the solubility in water is 0-033% at 0-6° C., and 0-07% at 10° C. According to French data,2 the solubility at 25°C. is 0-047%, an(i according to American data 3 0-069%.

It is, however, very soluble in various hydrocarbons4 and organic solvents, such as kerosene (in which it is soluble in all proportions at 26° C.), petrol, carbon tetrachloride, monochlorobenzene, ethyl alcohol (in absolute alcohol it is soluble in

absorbed by rubber and penetrates leather and the ordinary textile fabrics.

The following observations have been made on the degree of penetration of dichloroethyl sulphide into various materials 8 :

4THOMPSON and H. ODEEN, /. 2nd. Eng. Chem., 1920, 12, 1057.

5THOMPSON and BLACK, /. Am. Chem. Soc., 1921, 43, 877.

• SCHROTER, Dr&ger-Hefte, 1936, No. 186, 3309. 7 LINDEMANN, Yperit, Warsaw, 1929, 74.

* THEMME, Gasschutz und Luftschutz, 1936, 189, also considers the penetration of dichloroethyl sulphide into bitumen, tar, linoleum, road-making materials, etc.

228 SULPHUR COMPOUNDS

water the conversion into thiodiglycol is practically quantitative according to the equation already given.1

If, however, the amount of water is small compared with that of the dichloroethyl sulphide, for instance three times the volume of the sulphide, only a little thiodiglycol is formed, together with hydrochloric acid and a complex mixture of sulphonium chlorides, some of which form dichloroethyl sulphide with concentrated hydrochloric acid, while others do not. These latter compounds are formed principally when the ratio of water to the sulphide is very small. The only one which has been isolated is the following compoundl:

' /CHaCHA /CH2CH2OH

As to the influence on the hydrolysis of the degree of dispersion of the dichloroethyl sulphide, Wilson's 2 experiments have shown that the hydrolysis is considerably accelerated by adding alkaline solutions of sulphonated vegetable or animal oils, for example, solutions containing 3% of sulphonated corn oil and 2% sodium carbonate. These have the effect of increasing the degree of dispersion of the substance.

REACTIONS OF DICHLOROETHYL SULPHIDE IN WHICH THE SULPHUR ATOM TAKES PART

With Oxidising Agents. Like all thioethers, dichloroethyl sulphide tends to add one or two oxygen atoms and be converted into the corresponding sulphoxide or sulphone by oxidising agents like nitric acid, hydrogen peroxide, potassium permanganate, chromic acid, etc.

Dichloroethyl sulphoxide may be obtained, according to Gibson and Pope,3 by placing a drop of dichloroethyl sulphide in concentrated nitric acid (d. 1-40) at ordinary temperature. The reaction is violent, heat is evolved and a bright green liquid is formed. When this liquid is diluted with water, a white

1 DAVIES and OXFORD, /. Chem. Soc., 1931,224.

2 WILSON, /. Am. Chem. Soc., 1922, 44, 2762.

8 GIBSON and POPE, /. Chem. Soc., 1920, 117, 271.

precipitate of the sulphoxide separates. On crystallising this from 60% alcohol, colourless scales are formed which melt at 110° C. This substance is soluble in water (1-2 gm. in 100 ml. at 20° C.), in alcohol (4-3 gm. in 100 ml. at 20° C.), in ether, benzene, carbon disulphide, acetone, chloroform and mineral acids.1 Ondistilling even at reduced pressure it partly decomposes and the principal product of the decomposition is dichloroethyl sulphide.

Dichloroethyl sulphoxide has also been prepared by Steinkopf *

potassium permanganate on dichloroethyl sulphide, Steinkopf4 obtained the sulphone as colourless crystals melting at 52° C.5 and boiling at 179° to 181° C. at 14-15 mm. of mercury pressure. This compound is sparingly soluble in water (0-6 gm. in 100 ml. at 20° C., and 2-4 gm. in 100 ml. at 100° C.) and is only slightly hydrolysed. It is soluble in alcohol (7-1 gm. in 100 ml. at 20° C.), ether, chloroform, etc. Helfrich and Reid obtained the sulphone by treating the sulphoxide in the cold with a solution of chromic acid in sulphuric acid.

According to Marshall, the sulphone in contact with the skin produces vesicles and persistent ulcers. Its vapour has a lachrymatory and sometimes even a sternutatory action. This physiopathological action is not observed when working with the substance at ordinary temperatures because of its low vapour pressure.

By the action of the strongest oxidising agents,6 such as fuming

(Ber., 1920, 53, 1007) : 23 gm. 30% hydrogen peroxide are added slowly to a

allowed to stand. After reduction of the excess permanganate with sulphur

POPE, /. Chem. Soc., 1922, 121, 594.

monochloride and dichloroethyl sulphide, a compound of the following formula is obtained 1 :

a

CH2-CH2C1

that is, the same substance which is obtained from the action of chlorine on dichloroethyl sulphide. It forms white needles and is unstable at ordinary temperatures (see p. 234).

With Bleaching Powder. Dry chloride of lime reacts with dichloroethyl sulphide, acting as oxidant and chlorinating agent.2 A very violent reaction, with evolution of heat, flame and white vapours, takes place. Numerous compounds are formed : carbon dioxide, hydrochloric acid, chloroform, chloral and chlorinated substances which are not yet defined.3

According to some workers, dichloroethyl sulphoxide is also

The temperature of the reaction rises to such a point that combustible material (hay, paper, etc.) is inflamed.

By the action of chloride of lime mixed with water the action is less violent.

Bleaching powder is used to decontaminate objects which have been contaminated with mustard gas. For this purpose it is recommended that the bleaching powder be mixed to a porridge with water, or with some other powdered substance, so as to prevent the inconvenient results already mentioned, which would be caused by the violence of the reaction. In the reaction with undiluted bleaching powder, a zone of contact forms, consisting of a layer of decomposition products which protects the sulphide from further attack.5

Chloride of lime may also be employed for decontamination of the skin. In this case the violence of the reaction should be reduced by mixing the bleaching powder with water (i part of water to i part of chloride of lime) or with magnesium oxide.6

1LlBERMANN, Op. Clt.

2WIRTH, Gasschutz und Luftschutz, 1932, 2, 60.

3DESGREZ and coll., Chim. et Ind., 1921, 6, 842. With regard to the practical

aspects of decontamination with chloride of lime, see DRAGER, Gasschutz im Luftschutz, Lubeck, 1934, 98.

232 SULPHUR COMPOUNDS

The decontaminating power of the bleaching powder depends on the content of active chlorine. According to Weidner,1 in order to obtain sufficient decontaminating action, the bleaching powder should contain at least 15% active chlorine.

With Sodium Hypochlorite. On bubbling a current of carbon dioxide through a mixture of dichloroethyl sulphide and sodium hypochlorite solution, aoc'/?/?' tetrachloroethyl sulphoxide2 is formed :

/CHC1-CH2C1

OS<

NCHC1-CH2C1

This is a crystalline substance melting at 121° C.

With Iodine Trichloride. On adding a carbon tetrachloride solution of dichloroethyl sulphide to a solution of iodine trichloride also in carbon tetrachloride, an addition compound of the following formula is immediately formed 3 :

I\ /CH2CH2CJ

)S\NCH2CH2C1

In the presence of an excess of iodine trichloride or of iodine trichloride and free chlorine, dissolved in carbon tetrachloride, dichloroethyl sulphide is converted into a yellow crystalline substance of the formula :

I\ /CH2CH,C1

S

Cl// \NCH2CH2C1

This reaction may be used for the detection of dichloroethyl sulphide.

With Chloramine-T . Dichloroethyl sulphide reacts readily with chloramine-T (the sodium salt of ^-toluene sulphochloroamide, CH3—C6H4—SO2—Na=NCl) to form an additive compound of the formula :

/CH2-CH2C1 CH3-CBH4-SO2-N=S<NCH2-CH2C1

which contains a tetravalent sulphur atom. The =S=N— according to Mann and Pope 4 may be termed the " sulphilimine " group. The condensation of dichloroethyl sulphide with

3E. BOGGIO-LERA, Chim. e Industria, 1935, 334.

4MANN and POPE, /. Chem. Soc., 1922, 121, 1053.

chloramine-T takes place even in the cold ; on adding 17-1 gm. dichloroethyl sulphide to an aqueous solution of 28 gm. chloramine-T, small white crystals separate after about an hour. They melt at 144-6° C.

Chloramine-T is employed as decontaminating agent for dichloroethyl sulphide and has the advantage over bleaching powder of not producing too violent a reaction. Moreover, it is not toxic, non-irritant and keeps for a long time. It is recommended for the decontamination of clothing of linen, cambric, cotton and mixed fabrics. In decontaminating woollen materials it is necessary to avoid boiling.1

With Selenious Acid. Dichloroethyl sulphide reacts with selenious acid, reducing it to selenium :

The selenium separates in the form of an orange-yellow suspension. Selenious acid in sulphuric acid solution has been proposed by Yablich as a reaction for the detection of dichloroethyl sulphide (see p. 247).

REACTIONS OF DICHLOROETHYL SULPHIDE INVOLVING THE WHOLE MOLECULE

With Chlorine. The behaviour of dichloroethyl sulphide with chlorine was studied by Mann and Pope 2 in 1922, by Lawson and Dawson 3 in 1927, by Mumford * in 1928, and by Phillips 5 in

1929.

By the action of chlorine on dichloroethyl sulphide at ordinary temperatures, the following compounds are obtained, according to Mann and Pope :