Chemical Warfare Essay, Research Paper

Chem Warfare

It was not until the early 1930’s that German

chemists observed that organo-phosphorus

compounds could be poisonous. In 1934, Dr

Gerhard Schrader, a chemist at IG Farben, was

given the task of developing a pesticide. Two

years later a phosphorus compound with

extremely high toxicity was produced for the first

time. According to contemporary regulations,

discoveries with military implications had to be

reported to the military authorities, which was also

done with Schrader’s discovery. This phosphorus

compound, given the name tabun, was the first of

the substances later referred to as nerve agents. A

factory for production of the new CW agent was

built and a total of 12 000 tonnes of tabun were

produced during the years 1942-1945. At the end

of the war the Allies seized large quantities of this

nerve agent. Up to the end of the war, Schrader

and his co-workers synthesized about 2 000 new

organo-phosphorus compounds, including sarin

(1938). The third of the "classic" nerve agents,

soman, was first produced in 1944. These three

nerve agents are known as G agents in the

American nomenclature. The manufacture of sarin

never started properly and up to 1945 only about

0.5 tonne of this nerve agent was produced in a

pilot plant. Immediately after the war, research

was mainly concentrated on studies of the

mechanisms of the nerve agents in order to

discover more effective forms of protection against

these new CW agents. The results of these efforts

led, however, not only to better forms of

protection but also to new types of agents closely

related to the earlier ones. By the mid-1950’s a

group of more stable nerve agents had been

developed, known as the V-agents in the

American nomenclature. They are approximately

ten-fold more poisonous than sarin and are thus

among the most toxic substances ever synthesized.

The first publication of these substances appeared

in 1955. The authors, R. Ghosh and J.F.

Newman, described one of the substances, known

as Amiton, as being particularly effective against

mites. At this time, intensive research was being

devoted to the organo-phosphorus insecticides

both in Europe and in the United States. At least

three chemical firms appear to have independently

discovered the remarkable toxicity of these

phosphorus compounds during the years

1952-53. Surprisingly enough, some of these

substances were available on the market as

pesticides. Nonetheless, they were soon

withdrawn owing to their considerable toxicity also

to mammals. In the United States, the choice fell in

1958 on a substance known by its code name VX

as suitable as a CW agent of persistent type.

Full-scale production of VX started in April 1961

but its structure was not published until 1972.

Physical and Chemical Properties The most

important nerve agents included in modern CW

arsenals are: ? Tabun, O-ethyl

dimethylamidophosphorylcyanide, with the

American denomination GA. This nerve agent is

the easiest to manufacture. Consequently, it is

more likely that developing countries start their

CW arsenal with this nerve agent whereas

industrialized countries consider tabun to be

out-of-date and of limited use. ? Sarin, isopropyl

methylphosphonofluoridate, with the American

denomination GB, a volatile substance mainly

taken up through inhalation. ? Soman, pinacolyl

methylphosphonofluoridate, with the American

denomination GD, a moderately volatile substance

which can be taken up by inhalation or skin

contact. ? Cyclohexyl methylphosphonofluoridate,

with the American denomination GF, a substance

with low volatility which is taken up through skin

contact and inhalation of the substance either as a

gas or aerosol. ? O-ethyl

S-diisopropylaminomethyl

methylphosphonothiolate, better known under the

American denomination VX, a persistent

substance which can remain on material,

equipment and terrain for long periods. Uptake is

mainly through the skin but also through inhalation

of the substance as a gas or aerosol. The formulae

for some nerve agents are: ? Tabun, GA:

(CH3)2N-P(=O)(-CN)(-OC2H5) ? Sarin, GB:

CH3-P(=O)(-F)(-OCH(CH33)2) ? Soman, GD:

CH3-P(=O)(-F)(-CH(CH3)C(CH3)3 ? GF:

CH3-P(=O)(-F)(cyklo-C6H11) ? VX:

CH3-P(=O)(-SCH2CH2N[CH(CH3)2]2)(-OC2H5)