Cyclosarin or GF (cyclohexyl methylphosphonofluoridate) is an extremely
toxic
Toxicity is the degree to which a chemical substance or a particular mixture of substances can damage an organism. Toxicity can refer to the effect on a whole organism, such as an animal, bacterium, or plant, as well as the effect on a subst ...
substance used as a
chemical weapon
A chemical weapon (CW) is a specialized munition that uses chemicals formulated to inflict death or harm on humans. According to the Organisation for the Prohibition of Chemical Weapons (OPCW), this can be any chemical compound intended as ...
nerve agent
Nerve agents, sometimes also called nerve gases, are a class of organic chemistry, organic chemicals that disrupt the mechanisms by which nerves transfer messages to organs. The disruption is caused by the blocking of acetylcholinesterase (ACh ...
s, a group of
chemical weapons
A chemical weapon (CW) is a specialized munition that uses chemicals formulated to inflict death or harm on humans. According to the Organisation for the Prohibition of Chemical Weapons (OPCW), this can be any chemical compound intended as ...
discovered and synthesized by a German team led by Gerhard Schrader. The major nerve gases are the G agents,
sarin
Sarin (NATO designation GB nerve_agent#G-series.html" ;"title="hort for nerve agent#G-series">G-series, "B" is an extremely toxic organophosphorus compound.soman (GD), tabun (GA), and the V agents such as VX. The original agent, tabun, was discovered in Germany in 1936 in the process of work on organophosphorus
insecticide
Insecticides are pesticides used to kill insects. They include ovicides and larvicides used against insect eggs and larvae, respectively. The major use of insecticides is in agriculture, but they are also used in home and garden settings, i ...
s. Next came sarin, soman and finally, cyclosarin, a product of commercial insecticide laboratories prior to
World War II
World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...
.
As a
chemical weapon
A chemical weapon (CW) is a specialized munition that uses chemicals formulated to inflict death or harm on humans. According to the Organisation for the Prohibition of Chemical Weapons (OPCW), this can be any chemical compound intended as ...
, it is classified as a
weapon of mass destruction
A weapon of mass destruction (WMD) is a biological, chemical, radiological, nuclear, or any other weapon that can kill or significantly harm many people or cause great damage to artificial structures (e.g., buildings), natural structures ( ...
by the
United Nations
The United Nations (UN) is the Earth, global intergovernmental organization established by the signing of the Charter of the United Nations, UN Charter on 26 June 1945 with the stated purpose of maintaining international peace and internationa ...
. Pursuant to
UN Resolution 687
United Nations Security Council Resolution 687 was adopted on 3 April 1991. After reaffirming resolutions United Nations Security Council Resolution 660, 660, United Nations Security Council Resolution 661, 661, United Nations Security Council Re ...
its production and stockpiling was outlawed globally by the
Chemical Weapons Convention
The Chemical Weapons Convention (CWC), officially the Convention on the Prohibition of the Development, Production, Stockpiling and Use of Chemical Weapons and on their Destruction, is an arms control treaty administered by the Organisation for ...
(CWC) of 1993, although Egypt, Israel, North Korea and South Sudan have not ratified the CWC (thus not outlawing their own stockpiling of chemical weapons).
Chemical characteristics
Like its predecessor
sarin
Sarin (NATO designation GB nerve_agent#G-series.html" ;"title="hort for nerve agent#G-series">G-series, "B" is an extremely toxic organophosphorus compound.organophosphate
In organic chemistry, organophosphates (also known as phosphate esters, or OPEs) are a class of organophosphorus compounds with the general structure , a central phosphate molecule with alkyl or aromatic substituents. They can be considered ...
nerve agent. Its physical characteristics are, however, quite different from those of sarin.
At
room temperature
Room temperature, colloquially, denotes the range of air temperatures most people find comfortable indoors while dressed in typical clothing. Comfortable temperatures can be extended beyond this range depending on humidity, air circulation, and ...
, cyclosarin is a colorless liquid whose odor has been variously described as sweet and musty, or resembling
peach
The peach (''Prunus persica'') is a deciduous tree first domesticated and Agriculture, cultivated in China. It bears edible juicy fruits with various characteristics, most called peaches and the glossy-skinned, non-fuzzy varieties called necta ...
es or
shellac
Shellac () is a resin secreted by the female Kerria lacca, lac bug on trees in the forests of India and Thailand. Chemically, it is mainly composed of aleuritic acid, jalaric acid, shellolic acid, and other natural waxes. It is processed and s ...
. Unlike sarin, cyclosarin is a ''persistent'' liquid, meaning that it has a low
vapor pressure
Vapor pressure or equilibrium vapor pressure is the pressure exerted by a vapor in thermodynamic equilibrium with its condensed phases (solid or liquid) at a given temperature in a closed system. The equilibrium vapor pressure is an indicat ...
and therefore evaporates relatively slowly, at only about 1/69th the rate of sarin and 1/20th that of water.
Also unlike sarin, cyclosarin is
flammable
A combustible material is a material that can burn (i.e., sustain a flame) in air under certain conditions. A material is flammable if it ignites easily at ambient temperatures. In other words, a combustible material ignites with some effort ...
, with a
flash point
The flash point of a material is the "lowest liquid temperature at which, under certain standardized conditions, a liquid gives off vapours in a quantity such as to be capable of forming an ignitable vapour/air mixture".
The flash point is somet ...
of 94 °C (201 °F).
History
First synthesized during
World War II
World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...
as part of
Nazi Germany
Nazi Germany, officially known as the German Reich and later the Greater German Reich, was the German Reich, German state between 1933 and 1945, when Adolf Hitler and the Nazi Party controlled the country, transforming it into a Totalit ...
's chemical weapons research on organophosphate compounds after their military potential was recognized, cyclosarin was also studied later in the
United States
The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...
and
Great Britain
Great Britain is an island in the North Atlantic Ocean off the north-west coast of continental Europe, consisting of the countries England, Scotland, and Wales. With an area of , it is the largest of the British Isles, the List of European ...
in the early 1950s as part of a systematic study of potential nerve agents. It was never selected for
mass production
Mass production, also known as mass production, series production, series manufacture, or continuous production, is the production of substantial amounts of standardized products in a constant flow, including and especially on assembly lines ...
, however, due to its precursors being more expensive than those of other G-series nerve agents such as sarin (GB).
To date, Iraq is the only nation known to have manufactured significant quantities of cyclosarin for use as a chemical agent and to deploy it in battle. During the
Iran–Iraq War
The Iran–Iraq War, also known as the First Gulf War, was an armed conflict between Iran and Iraq that lasted from September 1980 to August 1988. Active hostilities began with the Iraqi invasion of Iran and lasted for nearly eight years, unti ...
(1980–1988), the Iraqis used sarin and cyclosarin together as a mixture. This was likely done to obtain a more persistent chemical agent as well as in response to an existing embargo placed on alcohol precursors for sarin.
Munitions
Binary weapons
Like other nerve agents, cyclosarin can be shipped in binary munitions.
A cyclosarin binary weapon would most likely contain methylphosphonyl difluoride in one capsule, with the other capsule containing a mixture of cyclohexylamine and
cyclohexanol
Cyclohexanol is the organic compound with the formula HOCH(CH2)5. The molecule is related to cyclohexane by replacement of one hydrogen atom by a hydroxyl group. This compound exists as a deliquescent colorless solid with a camphor-like odor, whi ...
.
GB-GF mixtures
Iraq
Iraq, officially the Republic of Iraq, is a country in West Asia. It is bordered by Saudi Arabia to Iraq–Saudi Arabia border, the south, Turkey to Iraq–Turkey border, the north, Iran to Iran–Iraq border, the east, the Persian Gulf and ...
fielded munitions filled with a mixture of GB (sarin) and GF (cyclosarin). Tests on mice indicated that GB-GF mixtures have a relative toxicity between GF and GB.