US2536482A - Stabilized vesicant agent - Google Patents

Description

Patented Jan. 2, 1951 2,536,482 STABILIZED VESICANT AGENT William H. Wood, Arden, DeL, assignor, by mesne assignments, to the United States of America as represented by the Secretary of War No Drawing. Application December 11, 1945, Serial No. 634,408

3 Claims.

'portant, in this country, is the Levinstein proc- The product of this process is known to ess. those skilled in the art as Levinstein mustard.

Levinstein mustard is a reatively impure product and the dichlorethyl sulfide content thereof is in the neighborhood of 70%. The impurities in Levinstein mustard ar of a complex nature and have not yet been completely determined to this date but are essentially polysulfides of the composition (C1CH2CH2)2SX.

Levinstein mustard is a very effective Vesicant agent and is economical for use in chemical warfare, however, it does have the serious defect of attacking steel containers during long periods of storage. Although the exact mechanism of the chemical reaction between Levinstein mustard and steel containers is not known, it is known that mustard, stored in steel containers, becomes contaminated with iron. Levinstein mustard stored in glass containers, or in steel containers coated with a properly baked-on suitable lacquer, does not deteriorate.

For certain technical purposes it is necessary to disseminate vesicants such as mustard from airplanes. Heretofore, the effectiveness of the vesicants when sprayed from airplanes has been considerably less than the maximum effectiveness obtainable, because a large portion of the Vesicant material is broken up into a very fine mist and a correspondingly smaller fraction reaches the objective in the form of large drops. The higher the altitude and the greater the airp ane speed, the

greater is the proportion of the fine mist and the less effective the Vesicant spray.

Vesicant agents in liquid form are most effective against personnel and material in t e form of fairly large drops and the loss of eifectiveness of airplane sprays due to the formation of fine mist is very considerable. vesicants in the form of fine mists have a decreasing penetrating action through protective clothing and a smaller amount of protection is required against them. Heretol fore, it was necessary for an airplane to drop to very low altitudes (75500 ft.) and to spray at a low air speed to obtain proper sized drops in a Vesicant spray.

Another very important obstacle in the spray- .ing of vesicants from airplanes has, been the inability to aim the spray to fall upon the target with any degree of accuracy. Vesicant sprays in the form of relatively large drops can be accurately aimed but fine sprays and mists fail to hit the target area with any degree of precision.

The same general principles also apply to the dissemination of vesicants by artillery shell. The use of high explosive charges to burst the shell results in the creation of a fine mist and consequent dispersion of the Vesicant.

It has therefore been found to be necessary to thicken the Vesicant agents in order to obtain proper drop size and to eliminate the loss of agent, the loss of accuracy, and the necessity for projecting the spray from low altitudes at low plane speeds. The addition of certain polymeric materials to Vesicant agents in order to thicken the agent to obtain the required properties has been proposed. However, I have discovered that Vesicant agents thus thickened have the defect of decreasing in viscosity when the agent is contaminated with iron.

I have discovered that in iron-contaminated mustard containing a polymeric thickener there is formed a complex of low solubility between the polymeric thickener and the iron, which precipitates and lowers the viscosity of the supernatant mustard below that required for its dissemination in proper drop size.

Since mustard is normally stored in steel containers both before and after thickening, contamination with iron, always occurs and lowering of viscosity due to the above described reaction is encountered.

I have discovered that this serious defect can be remedied by the addition of certain stabilizers to the mustard either before or after thickening, in order to prevent the precipitation of the ironthiekener complex and to thus maintain the desired viscosity of the Vesicant agent.

I have found that heterocyclic aromatic nitrogen bases of any degree of purity are suitable as stabilizers for thickened mustard.

Any of the crude aromatic nitrogen bases or fractions of crude bases obtained from coal tar or petroleum, or pure bases such as pyridine, quinoline, and picoline may be used. Ordinarily, an amount of nitrogen base equal to 2% of the weight of the mustard is sufiicient. This amount will neutralize all t e iron in mustard containing up to 1% iron, calculated as ferrous chloride. If more than 1% iron is present, proportionally larger amounts, e. g., up to 5% of nitrogen bases, may be used. When mixing in the plant, it is preferable to add the nitrogen base to the mustard first, to prevent precipitation of the iron-thickener complex when the thickener is added. When mixing in the field, the nitrogen base may be added either to the thickener solution or to the mustard, the thickener and mustard then being combined. Whatever the mixing method employed, the nitrogen base may be added either to the thickener solution or to the mustard, the thickener and mustard then being combined. Whatever the mixing method employed, the nitrogen base may be used in conjunction with non-aromatic amines, such as hexamethylenetetramine, which are effective anti-corrosion agents for mustard. These nitrogen bases havebeen tested in mustard, thickened with methyl methacrylate polymer and methly methacrylatemethyl acrylate interpolymer, and they arealso eifective in mustard containing any other poly.- meric thickener, e. g., polystyrene.

This invention contemplates compositions comprising iron-contaminated mustard containing a polymeric thickener soluble therein, and a small amount of a heterocyclic aromatic nitrogen base, i. e., a nitrogen base in which the nitrogen is part of an aromatic ring, 1. e., a ring containing conjugated double bonds. Nitrogen bases of this type have been found to be particularly eifective in preventing the iron normally present in ordinary mustard (particularly that stored in steel containers) from altering, undesirably; the viscosity characteristics of the thickened composition. This is of significance since, if the iron is not removed or deactivated; it will form a complex of low solubility with the polymeric thickener and precipitate as :a sludge, particularly at low temperatures. The precipitation of the iron-thickener complex re- 7 moves the thickener and thus lowers the viscosity Example I.-FieZd-mia:ing process A steam-jacketed iron vessel fitted with a reflux condenser and mechanical stirrer is charged with 652 parts of benzene and 87 parts of quincline residue (from distillat on of quinoline from coal tap-contains high boiling nitrogen bases of ouinoline type), and 33 parts of pulverized methi yl methacrylate polymer sheeting are added with stirring. The temperature of the mixture is raised to 50-55 C. and agitation continued at this temperature until a product of constant viscosity is obtained, about 4 to 5 hours being required. This solution, which will have a viscosity in the range of 8 to 25 stokes at 25 C., is suit.- able for mixing with mustard in the field. In thecase of Levinstein mustard containing, e. g., LS-0.6% iron (calculated as ferrous chloride), 'l5iparts of the solution is added to 85"parts-of mustard and the mixture agitated gently for 1'5-20 minutes atroom temperature. The resulting smooth solution has a viscosity of'about Example II.-Plant mixing process A vessel equipped with a mechanical stirrer and means for heating is charged with 1586 parts of mustard of the quality used'in Example 1, "32 parts of a mixture of pyridine bases, and 32 parts of pulverized methyl methacrylate' polymer sheeting are added. The mixture is stirred atf40 to 50C. for 3 hours, then cooled to room. 2, 9

. 4 temperature and stirred overnight. The resulting smooth solution has a viscosity of 4.44 stokes at 10 C., with no sludge formation, whereas a control composition containing no pyridine base forms a sludge immediately when cooled to 10 C.

Attempts have been made to stabilize thickened Levinstein mustard by the addition of a non-aromatic heterocyclic amine but the results were not satisfactory. The only amines Which I have found to be eifective for this purpose are the heterocyclic aromatic nitrogen basis which contains a conjugate double bond system.

Accordingly, an object of my invention is to stabilize thickened mustard gas in order to maintainproper viscosity. Another object of this invention is to provide a practical and effective means of stabilizing Levinstein mustard so that it can be thickened and so that the viscosity of the thickened agent can be controlled in'order that proper drop size may be obtained upon dissemination of the agent.

My invention, by the addition of a small amount of a heterocyclic aromatic amine, prevents the precipitation of iron-thickener complex and thus maintains the desired viscosity of agent.

The nature of this invention having been broadly outlined above and the preferred sinbodiments specifically pointed out, it will beapparent to those skilled in the art that certain modifications and additional formulations can be employed. Accordingly, it is intended that the foregoing descriptive material be interpreted as illustrative and not in a limiting sense.

Iclaim:

1. A composition of matter comprising Levinstein mustard containing from about 0.5% to 0.6% of iron calculated as ferrous chloride, thickened with a polymeric material selected fromthe group consisting of methyl methacrylate polyusers and of methyl-methacrylate-acrylate interpolymers and stabilized with from'about 2% to about 5% of a compoundselected from the group consisting of pyridine, quinoline and piccline, said composition having a viscosity of about a 3. .A'composition of matter comprising'about 1586 parts by weight of Levinstein mustardconta-ining about i).5-0.6% of iron calculated as ferrous chloride, about 32 parts by weight of pyridine bases, and about 32 parts by weight of methyl methacrylate polymer, said composition of matter having a viscosity of about 4.44 stokes at 10 C. with no sludge formation.

WILLIAM H. woon.

aernnsncns crrnn The following references are of record in the file o th s pate t:

UNITED STATES P ATENTS Number Name Date 2,260,420 Young Oct. 28, 1941 Hum Feb. 28, 1950

Claims (1)

1. A COMPOSITION OF MATTER COMPRISING LEVINSTEIN MUSTARD CONTAINING FROM ABOUT 0.5% TO 0.6% OF IRON CALCULATED AS FERROUS CHLORIDE, THICKENED WITH A POLYMERIC MATERIAL ELECTED FROM THE GROUP CONSISTING OF METHYL METHACRYLATE POLYMERS AND METHYL-METHACRYLATE-ACRYLATE INTERPOLYMERS AND STABILIZED WITH FROM ABOUT 2% TO ABOUT 5% OF A COMPOUND SELECTED FROM THE GROUP CONSISTING OF PYRIDINE, QUINOLINE AND PICOLINE, SAID COMPOSITION HAVING A VISCOSITY OF ABOUT 0.42 STROKE AT 10* C. WITH NO SLUDGE FORMATION.