Soman
Encyclopedia
Soman, or GD is an extremely toxic chemical substance. It is a nerve agent
, interfering with normal functioning of the mammalian nervous system
by inhibiting the cholinesterase enzyme. As a chemical weapon, it is classified as a weapon of mass destruction by the United Nations
according to UN Resolution 687. Its production is strictly controlled, and stockpiling is outlawed by the Chemical Weapons Convention
of 1993 where it is classified as a Schedule 1 substance. Soman was the third of the so-called G-series nerve agents to be discovered along with GA
(tabun), GB
(sarin), and GF
(cyclosarin).
It is a volatile, corrosive, and colorless liquid with a faint odor when pure. More commonly, it is a yellow to brown color and has a strong odor described as similar to camphor
. The LCt50
for soman is 70 mg·min/m3 in humans. It is both more lethal and more persistent than sarin
or tabun
, but less so than cyclosarin
.
GD can be thickened
for use as a chemical spray using an acryloid copolymer. It can also be deployed as a binary chemical weapon
; its precursor chemicals are methylphosphonyl difluoride
and a mixture of pinacolyl alcohol
and an amine
.
in Germany in 1944, and represented the last wartime nerve agent discovery (GF
was not found until 1949). Soman was given the identifier GD post-war (GC was already in medical use) when the information relating to soman was recovered by the Soviet Union from its hiding place in a mine. The crystal structure of soman complexed with acetylcholinesterase
was determined by Millard et al. (1999) by X-ray crystallography (PDB codes: 2wfz, 2wg0, 2wg1, and 1som).
:
MeP(O)Cl2 + MeP(O)F2 + (CH3)3 CCH(CH3)OH → MePO(F)OCH(CH3)C(CH3)3 + HCl
30% of the GL group died after the third administration of soman (0.4 LD50) and the remaining 70% died after the fourth administration of 0.5 LD50. At this cumulative dose (352ug/kg), only 10% of the SD group died, while all of the rats fed a KD and CH survived. When the cumulative dose was greater than 400ug/kg, both SD and CH groups had an approximate terminal survival value of 55%. In contrast, only one animal in the KD group died after the final soman administration (cumulative dose of 627ug/kg). 90% of KD-fed rats survived.
"Specifically, all KD animals survived a cumulative 5.0 LD50 dose of soman, whereas all glucose animals died following a cumulative 3.2 LD50 dose of soman. Not only was survival enhanced in KD animals, but there were also minimal differences in body weights compared to dietary controls injected with saline. Furthermore, KD animals exposed to soman exhibited few performance decrements on an avoidance task, and there were fewer instances of behavioral incapacitation in KD animals compared to the other diet groups."
Nerve agent
Nerve agents are a class of phosphorus-containing organic chemicals that disrupt the mechanism by which nerves transfer messages to organs...
, interfering with normal functioning of the mammalian nervous system
Nervous system
The nervous system is an organ system containing a network of specialized cells called neurons that coordinate the actions of an animal and transmit signals between different parts of its body. In most animals the nervous system consists of two parts, central and peripheral. The central nervous...
by inhibiting the cholinesterase enzyme. As a chemical weapon, it is classified as a weapon of mass destruction by the United Nations
United Nations
The United Nations is an international organization whose stated aims are facilitating cooperation in international law, international security, economic development, social progress, human rights, and achievement of world peace...
according to UN Resolution 687. Its production is strictly controlled, and stockpiling is outlawed by the Chemical Weapons Convention
Chemical Weapons Convention
The Chemical Weapons Convention is an arms control agreement which outlaws the production, stockpiling and use of chemical weapons. Its full name is the Convention on the Prohibition of the Development, Production, Stockpiling and Use of Chemical Weapons and on their Destruction...
of 1993 where it is classified as a Schedule 1 substance. Soman was the third of the so-called G-series nerve agents to be discovered along with GA
Tabun (nerve agent)
Tabun or GA is an extremely toxic chemical substance. It is a clear, colorless, and tasteless liquid with a faint fruity odor. It is classified as a nerve agent because it fatally interferes with normal functioning of the mammalian nervous system...
(tabun), GB
Sarin
Sarin, or GB, is an organophosphorus compound with the formula [2CHO]CH3PF. It is a colorless, odorless liquid, which is used as a chemical weapon. It has been classified as a weapon of mass destruction in UN Resolution 687...
(sarin), and GF
Cyclosarin
Cyclosarin or GF is an extremely toxic substance used as a chemical weapon. It is a member of the G-series family of nerve agents, a group of chemical weapons discovered and synthesized by a German team led by Dr. Gerhard Schrader. The major nerve gases are the G agents, sarin , soman, tabun, and...
(cyclosarin).
It is a volatile, corrosive, and colorless liquid with a faint odor when pure. More commonly, it is a yellow to brown color and has a strong odor described as similar to camphor
Camphor
Camphor is a waxy, white or transparent solid with a strong, aromatic odor. It is a terpenoid with the chemical formula C10H16O. It is found in wood of the camphor laurel , a large evergreen tree found in Asia and also of Dryobalanops aromatica, a giant of the Bornean forests...
. The LCt50
LD50
In toxicology, the median lethal dose, LD50 , LC50 or LCt50 of a toxin, radiation, or pathogen is the dose required to kill half the members of a tested population after a specified test duration...
for soman is 70 mg·min/m3 in humans. It is both more lethal and more persistent than sarin
Sarin
Sarin, or GB, is an organophosphorus compound with the formula [2CHO]CH3PF. It is a colorless, odorless liquid, which is used as a chemical weapon. It has been classified as a weapon of mass destruction in UN Resolution 687...
or tabun
Tabun (nerve agent)
Tabun or GA is an extremely toxic chemical substance. It is a clear, colorless, and tasteless liquid with a faint fruity odor. It is classified as a nerve agent because it fatally interferes with normal functioning of the mammalian nervous system...
, but less so than cyclosarin
Cyclosarin
Cyclosarin or GF is an extremely toxic substance used as a chemical weapon. It is a member of the G-series family of nerve agents, a group of chemical weapons discovered and synthesized by a German team led by Dr. Gerhard Schrader. The major nerve gases are the G agents, sarin , soman, tabun, and...
.
GD can be thickened
Thickening
In cooking, thickening is the process of increasing the viscosity of a liquid either by reduction, or by the addition of a thickening agent, typically containing starch....
for use as a chemical spray using an acryloid copolymer. It can also be deployed as a binary chemical weapon
Binary chemical weapon
Binary chemical weapons or munitions are chemical weapons wherein the toxic agent is not contained within the weapon in its active state, but in the form of two chemical precursors, physically separated within the weapon...
; its precursor chemicals are methylphosphonyl difluoride
Methylphosphonyl difluoride
Methylphosphonyl difluoride , also called methyl difluorophosphite, methylphosphonic difluoride, and difluoromethylphosphine oxide, is a chemical weapon precursor. It is a Schedule 1 substance in the sense of the Chemical Weapons Convention...
and a mixture of pinacolyl alcohol
Pinacolyl alcohol
Pinacolyl alcohol is a common name for 3,3-dimethyl-2-butanol, also known as pine alcohol. Pinacolyl alcohol's molecular formula is C6H14O and is a secondary alcohol....
and an amine
Amine
Amines are organic compounds and functional groups that contain a basic nitrogen atom with a lone pair. Amines are derivatives of ammonia, wherein one or more hydrogen atoms have been replaced by a substituent such as an alkyl or aryl group. Important amines include amino acids, biogenic amines,...
.
History
Soman was discovered by Richard KuhnRichard Kuhn
Richard Kuhn was an Austrian-German biochemist, Nobel laureate, and Nazi collaborator.-Early life:Kuhn was born in Vienna, Austria where he attended grammar school and high school. His interest in chemistry surfaced early; however he had many interests and decided late to study chemistry...
in Germany in 1944, and represented the last wartime nerve agent discovery (GF
Cyclosarin
Cyclosarin or GF is an extremely toxic substance used as a chemical weapon. It is a member of the G-series family of nerve agents, a group of chemical weapons discovered and synthesized by a German team led by Dr. Gerhard Schrader. The major nerve gases are the G agents, sarin , soman, tabun, and...
was not found until 1949). Soman was given the identifier GD post-war (GC was already in medical use) when the information relating to soman was recovered by the Soviet Union from its hiding place in a mine. The crystal structure of soman complexed with acetylcholinesterase
Acetylcholinesterase
"Acetylcholinesterase, also known as AChE or acetylcholine acetylhydrolase, is an enzyme that degrades the neurotransmitter acetylcholine, producing choline and an acetate group. It is mainly found at neuromuscular junctions and cholinergic nervous system, where its activity serves to terminate...
was determined by Millard et al. (1999) by X-ray crystallography (PDB codes: 2wfz, 2wg0, 2wg1, and 1som).
Synthesis
The manufacture of Soman is very similar to the manufacture of Sarin. The difference is that the isopropanol from the Sarin processes is replaced with pinacolyl alcoholPinacolyl alcohol
Pinacolyl alcohol is a common name for 3,3-dimethyl-2-butanol, also known as pine alcohol. Pinacolyl alcohol's molecular formula is C6H14O and is a secondary alcohol....
:
MeP(O)Cl2 + MeP(O)F2 + (CH3)3 CCH(CH3)OH → MePO(F)OCH(CH3)C(CH3)3 + HCl
Protective Measures
Langston and Myers tested the influence of diet on soman toxicity in rats. For this purpose, rats were fed four different diets: standard (SD), choline-enriched (CH), glucose-enriched (GL) and a ketogenic diet (KD). The doses used in this study were 0.4-0.5 of the acute 24-h LD50.30% of the GL group died after the third administration of soman (0.4 LD50) and the remaining 70% died after the fourth administration of 0.5 LD50. At this cumulative dose (352ug/kg), only 10% of the SD group died, while all of the rats fed a KD and CH survived. When the cumulative dose was greater than 400ug/kg, both SD and CH groups had an approximate terminal survival value of 55%. In contrast, only one animal in the KD group died after the final soman administration (cumulative dose of 627ug/kg). 90% of KD-fed rats survived.
"Specifically, all KD animals survived a cumulative 5.0 LD50 dose of soman, whereas all glucose animals died following a cumulative 3.2 LD50 dose of soman. Not only was survival enhanced in KD animals, but there were also minimal differences in body weights compared to dietary controls injected with saline. Furthermore, KD animals exposed to soman exhibited few performance decrements on an avoidance task, and there were fewer instances of behavioral incapacitation in KD animals compared to the other diet groups."
See also
- AChE inhibitors and substrates in ProteopediaProteopediaProteopedia is a wiki, 3D encyclopedia of proteins and other molecules..The site contains a page for every entry in the Protein Data Bank , as well as pages that are more descriptive of protein structures in general such as acetylcholinesterase, hemoglobin, and the photosystem II with a Jmol view...
- 2wfz in ProteopediaProteopediaProteopedia is a wiki, 3D encyclopedia of proteins and other molecules..The site contains a page for every entry in the Protein Data Bank , as well as pages that are more descriptive of protein structures in general such as acetylcholinesterase, hemoglobin, and the photosystem II with a Jmol view...
- 2wg0 in ProteopediaProteopediaProteopedia is a wiki, 3D encyclopedia of proteins and other molecules..The site contains a page for every entry in the Protein Data Bank , as well as pages that are more descriptive of protein structures in general such as acetylcholinesterase, hemoglobin, and the photosystem II with a Jmol view...
- 2wg1 in ProteopediaProteopediaProteopedia is a wiki, 3D encyclopedia of proteins and other molecules..The site contains a page for every entry in the Protein Data Bank , as well as pages that are more descriptive of protein structures in general such as acetylcholinesterase, hemoglobin, and the photosystem II with a Jmol view...
- 1som in ProteopediaProteopediaProteopedia is a wiki, 3D encyclopedia of proteins and other molecules..The site contains a page for every entry in the Protein Data Bank , as well as pages that are more descriptive of protein structures in general such as acetylcholinesterase, hemoglobin, and the photosystem II with a Jmol view...