Article: Soman

Soman
Discovery
Discovered by	Richard Kuhn
Discovered in	1944
Chemical characteristics
Chemical name	3-(fluoro-methyl-phosphoryl)oxy- 2,2-dimethyl-butane
Chemical family	Fluorinated organophosphorus compound
Chemical formula	C7H16FO2P
NFPA Rating	1 4 1
Boiling point	198 °C
Freezing/melting point	−42 °C (−44 °F)
Vapor pressure	0.40 mmHg (53 Pa) at 25 °C
Vapor relative density (air=1)	6.3
Solubility in water	Moderate
Density at 25 °C	1.022 g/cm3
Appearance and color	When pure, colorless liquid with fruity odor. With impurities, amber or dark brown, with oil of camphor odor

Soman, also known by its NATO designation GD (O-Pinacolyl methylphosphonofluoridate) is an extremely toxic substance whose sole application is as one of the world's most dangerous military weapons. It is a nerve agent, interfering with normal functioning of the mammalian nervous system. As a chemical weapon, it is classified as a weapon of mass destruction by the United Nations according to UN Resolution 687, and its production is strictly controlled and stockpiling outlawed by the Chemical Weapons Convention of 1993. 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 colourless liquid with a faint odour when pure. More commonly, it is a yellow to brown color and has a stronger odour described as 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.

Alternative names

Soman is occasionally referred to names other than soman or GD:

• Phosphonofluoridic acid, methyl-, 1, 2, 2-trimethylpropyl ester
• Pinacolyl methylphosphonofluoridate
• 1,2,2-Trimethylpropyl methylphosphonofluoridate
• Methylpinacolyloxyfluorophosphine oxide
• Pinacolyloxymethylphosphonyl fluoride
• Pinacolyl methanefluorophosphonate
• Methylfluoropinacolylphosphonate
• Fluoromethylpinacolyloxyphosphine Oxide
• Methylpinacolyloxyphosphonyl fluoride
• Pinacolyl methylfluorophosphonate
• 1,2,2,-Trimethylpropoxyfluoromethylphosphine oxide

History

Soman was discovered by Richard Kuhn 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.