Sartori The War Gases Chemistry and analysis

Since the war several other homologues of methyl chlorosulphonate have been prepared and studied,1 for instance :

Propyl Chlorosulphonate

NC1

which is obtained by the action of sulphuryl chloride on rc-propyl alcohol. It boils at 70° to 72° C. at a pressure of 20 mm.

Also halogenated derivatives of ethyl Chlorosulphonate:

Chloroethyl Chlorosulphonate

OCH2 • CH2C1

obtained by the action of sulphuryl chloride on glycol chlorohydrin, boils at 101° C. at 23 mm. pressure and has an odour similar to that of chloropicrin.

Bromoethyl Chlorosulphonate

/OCH2CH2Br £>U2v.

NC1

obtained by the action of sulphuryl chloride on glycol bromohydrin, boils at 100° to 105° C. at 18 mm. pressure.

These three compounds are powerful lachrymators.

Several analogous compounds have also been prepared, such as methyl fluorosulphonate and ethyl fluorosulphonate. These are liquids with ethereal odours, having both lachrymatory and toxic properties. The ethyl derivative has greater lachrymatory power than the methyl.2

Further, a chlorinated derivative of dimethyl sulphate has been prepared, dichloromethyl sulphate (see p. 257). This is a colourless liquid boiling at 96° to 97° C. at 14 mm. of mercury. Unlike dimethyl sulphate, this compound is completely destitute of toxic power.3

Chlorosulphonic acid was used as a war gas in small quantities in the war of 1914-18 by the French and also by the Germans, but

1 W. STEINKOPF and coll., Ber., 1920, 53, 1144 ; R. LEVAILLANT, Contpt. rend.,

1928, 187, 730.

1 j. MEYER and G. SCHRAMM, Z. anorg. Chem., 1932. 206, 27. 3 FUCHS and KATSCHER, Ber., 1927, 60, 2293.

258 SULPHUR COMPOUNDS

Chlorosulphonic acid also reacts with dimethyl sulphate to form methyl chlorosulphonate 1 :

It reacts with monochloromethyl chloroformate, forming monochloromethyl chlorosulphonate 2 :

a colourless liquid, boiling at 49° to 50° C. at a pressure of 14 mm. mercury and having a density of 1-63 at room temperature. It is sparingly soluble in water with partial decomposition. It is soluble in the common organic solvents. It strongly irritates the mucous membranes (Fuchs and Katscher).

The lethal concentration for man at 30 minutes' exposure is 6,000-8,000 mgm. chlorosulphonic acid per cu. m. of air (Lindemann).

/Cl

so/

XC1

Sulphuryl chloride was chiefly prepared during the war for the manufacture of methyl and ethyl chlorosulphonates, but was occasionally employed also in admixture with cyanogen chloride, phosgene or chloropicrin (Prentiss).

PREPARATION

It may be obtained by heating chlorosulphonic acid to 180° C. under pressure. The following reaction takes place :

In the presence of suitable catalysts, such as salts of mercury, this reaction may be carried out at lower temperatures : at about 70° C. and ordinary pressure.

1 R. LEVAILLANT and L. SIMON, Compt. rend., 1919, 169, 234 ; C. BOULIN,

Com.pt. rend., 1919, 169, 338.

* KRAFT and ALEXEJEV, /. Obscei Khim., Ser. A., 1932, 2, 728.

260 SULPHUR COMPOUNDS

Iodine in the presence of aluminium chloride reacts with sulphuryl chloride in several ways : to form iodine monochloride if the sulphuryl chloride is insufficient:

S02C12 + I2 = 2IC1 -f SO2;

or if the sulphuryl chloride is in excess, to form iodine trichloride :

3S02C12 + I2 = 2IC13 + 3S02.

By the action of hydriodic acid on sulphuryl chloride sulphur dioxide, hydrochloric acid, sulphur and iodine are formed.1

On heating to 200° C. with sulphur, sulphur monochloride and dichloride are formed. This reaction takes place at ordinary temperatures in presence of aluminium trichloride.

Sulphuryl chloride usually behaves as a chlorinating agent.

In presence of excess of the alcohol, methyl sulphate is formed :

/OCH3

2 CH8OH + S02C12 = S02< + 2 HC1 NOCH3

or else methyl chloride and methyl sulphuric acid :

/OCH3

3 CH3OH + S02C12 = 2 CH3C1 + SO2< + H2O

XOH

It also reacts with ethylene chlorohydrin, forming chloroethyl chlorosulphonate 3:

/OCH2CH2C1

SO2Cla + C1-CH2-CH2OH = S02( -f HC1

NC1

a liquid boiling at 101° C. at a pressure of 23 mm. and having a

1 BESSON, Compt. rend., 1896, 122, 467.

8 R. McKEE, U.S. Pat. 1641005/1927.

8 W. STEINKOPF and coll., Ber., 1920, 53,1144 ; R. LEVAILLANT, Compt. rend. 1928, 187, 730.

density of 20° C. of 1-552. It is stable during storage and has an odour like that of chloropicrin ; it causes lachrymation.

On continuing the heating, the reaction proceeds further and j8j8' dichloroethyl sulphate is formed l :

This is a colourless, inodorous liquid which distils without decomposition only under reduced pressure. The boiling point is 154° C. at 8 mm. mercury pressure. Its S.G.at 20° C. is 1-4622. On cooling it forms a crystalline mass, melting at 11° C. and insoluble in water. It is hydrolysed neither by water nor ammonia.

Liquid sulphuryl chloride has a slight corrosive action on iron, but is without action on lead.

The importance of this compound as a war gas is almost nil; it had a very limited use during the war mixed with dimethyl sulphate.

PREPARATION

In the laboratory it is prepared by the action of methanol on chlorosulphonic acid. Accordingto Claesson,2 the chlorosulphonic acid is placed in a small flask, which is fitted with a tap-funnel and externally cooled with ice. Water-free methyl alcohol, previously distilled from lime, is slowly introduced in quantity stoichiometrically equivalent to the chlorosulphonic acid. As each drop of alcohol comes into contact with the chlorosulphonic acid, hydrochloric acid is evolved. At the end of addition of the alcohol the flask is heated gently while a current of dry air is passed through in order to remove the hydrochloric acid dissolved in the mixture. The product obtained contains about 90% methyl sulphuric acid.

PHYSICAL AND CHEMICAL PROPERTIES

Methyl sulphuric acid is an oily liquid which may be cooled to —30° C. without solidifying. On heating to 130° to 140° C. it

1 NEKRASSOV and KOMISSAROV, /. prakt. Chem., 1929, 123, 160 ; R. LEVAILLANT, Compt. rend., 1928,187, 730.

1 CLAESSON, /. prakt. Chem., 1879, [2]19, 240.

262 SULPHUR COMPOUNDS

decomposes almost quantitatively into dimethyl sulphate and sulphuric acid :

It is sparingly soluble in water and alcohol. In anhydrous ether it dissolves in all proportions.

It reacts with methyl chloroformate to form dimethyl sulphate

With monochloromethyl chloroformate it reacts to form methyl chlorosulphonate2:

industrial manufacture from methanol and chlorosulphonic acid when the esterification is incomplete. Dimethyl sulphate mixed with chlorosulphonic acid was used by the French under the name of "Rationite."

Dimethyl sulphate, before being employed as a war gas, was used in industry as a methylating agent for amines and phenols. In recent years it has also been employed as a catalyst in the preparation of cellulose esters.3

PREPARATION

It may be obtained by the decomposition of methyl sulphuric acid at high temperatures and in vacua :

* Brit. Pat. 306531/1929.

DIMETHYL SULPHATE: PREPARATION 263

or by the action of methyl alcohol on sulphuryl chloride :

or else by the esterification of fuming sulphuric acid with methyl alcohol :

Guyot and Simon,1 employing oleum containing 60% SO3 in the last method have obtained a very high yield of dimethyl sulphate (about 90%).

Recently a method of preparation has been worked out based on the reaction between methyl nitrite and methyl chloro-

LABORATORY PREPARATION

In the laboratory it is preferable to prepare dimethyl sulphate by Ullmann's method,3 that is, by the action of methyl alcohol on chlorosulphonicacid.

100 gm. chlorosulphonicacid are placed in a 200 ml. distillation flask which is closed with a rubber stopper containing two holes. Through one of the holes passes a thermometer and through the other a tap-funnel of the " Bulk " type 4 containing 27 gm. water-free methyl alcohol. The exit tube of the distillation flask is connected with a wash-bottle containing a little sulphuric acid, and the exit from this leads to a second bottle partly filled with water which serves to absorb the hydrochloricacid formed in the reaction.

The contents of the flask are cooled to — 10° C. by means of a freezing mixture and then the methyl alcohol allowed to enter from the tap-funnel, regulating the rate of addition so that the evolution of hydrochloric acid is not too violent. During the addition of the alcohol, the contents of the flask are repeatedly

1 GUYOT and SIMON, Compt. rend., 1919, 169, 795.

capillary bent in a crook for 5-10 mm. at the end. The stem, which should reach almost to the bottom of the flask, should be filled with methyl alcohol before the reaction commences.