Sarin

Holmstead has carried out investigations on the rate of hydrolysis of cyano-phosphorus compounds. First of all, mention may be made of the hydrolysis of diethyl phosphorocyanidate which proceeds rapidly in a buffer solution at pH 7-2 giving rise to the CN ion. Some 90 per cent hydrolysis takes place at this pH in 1 hr. Under similar conditions tabun is also hydrolysed to cyanide to the extent of about 80 per cent in 12 hr. There is a concurrent diminution of toxicity as the hydrolysis proceeds. Even in distilled water 50 per cent of the cyanide is split off in 9 hr. This instability would seem to render this compound in-effective as a toxic agent for use on a large scale. 

In acid solution, it hydrolyses rapidly to dimethylamine thus  

There is, of course, a concurrent breaking of the P—CN link because of the aqueous medium alone. 

Bleaching powder destroys tabun, but it gives rise to cyano-gen chloride, CNCl, which is also toxic. 

This ester, isopropyl methylphosphonofluoridate (X), is a colourless liquid. It is more toxic than D.F.P., but shows very similar physiological properties, intense myosis, respiratory collapse, powerful anticholinesterase activity, etc. The liquid passes rapidly through the skin. At the end of World War II, two plants were under construction in Germany for the production of the material on a large scale. 

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FLUORINECOMPOUNDS,INORGANIC - PHOSPHORUS] (Vol 11) Sarin. (See also Isopropyl methylphosphonofluoridate.)... 

S. Natansohn and V. Sarin in H. Hausner, G. Messing, and S. Hirano, eds.. Ceramic Powder Processing Science, Deutsche Keramische GeseUschaft e.V. Knfn, Germany, 1989, p. 433. 

V. K. Sarin and S. T. Buljan, in Higl Productiv. Machin. Proc. Int. Conf. High Productivity Machining New Orleans, La., May 7—9, 1985, ASM International, Metals Park, Ohio, pp. 113—120. 

VX (6,7) is estimated to be about three times as potent a respiratory agent as sarin (GB) but about a hundred times as potent as a percutaneous... 

Moreover organophosphoric acid esters have found application as insecticides (e.g. Parathion). Some derivatives are highly toxic to man (e.g. Sarin, Soman). The organophosphonates act as inhibitors of the enzyme cholinesterase by phosphorylating it. This enzyme is involved in the proper function of the parasympathetic nervous system. A concentration of 5 x 10 g/L in the air can already cause strong toxic effects to man. 

The calculated activation energy for the hydrolysis of sarin [43] on Amberlite-IRIOO is relatively low (22,000... 

The rate of hydrolysis of sarin on Dowex-50 cation exchange resin is insensitive to the stirring rate. However, with a more active catalyst (Amberlite-IRA 400), the rate constant at 20°C was 5.3, 7.5, and 8.5 h at 60,800 and 1000 revolutions/min , respectively, suggesting that film diffusion was the rate-limiting. step. Thus, the mechanism of the rate-limiting step depends on the nature of the catalyst [34]. 

Discovered in the late 1930s in Germany as improved poisonous insecticides, organophosphorus ChEIs were developed as chemical warfare agents (e.g. sarin, soman, and tabun) and were more recently employed in the 1995 terrorist attack in the Tokyo subway system [5]. 

Organophosphates are a group of pentavalent phosphorus compounds, which contain an organic group (e.g. parathion, malathion, tabun, sarin, soman). 

Sarin SK, Kumar M, Kumar R, Kazim SN, Guptan RC, Sakhuja P, Sharma BC (2005) Higher efficacy of sequential therapy with interferon-alpha and lamivudine combination compared to lamivudine monotherapy in HBeAg positive chronic hepatitis B patients. Am J Gastroenterol 100 2463-2471... 

Sarin SK, Sood A, Kumar M, Arora A, Amrapurkar D, Sharma BC, Konar A, Chawla YK, Jain RK, Nanda V, Kumar A, Hissar S, Lavate P, Lahoti D (2007) Effect of lowering HBV DNA levels by initial antiviral therapy before adding immunomodulator on treatment of chronic hepatitis B. Am J Gastroenterol 102 96-104... 

Chemical warfare agents, such as soman and sarin, sometimes termed nerve gases, are powerful anticholinesterases, which bear some resemblance in structure and properties, to the OP insecticides. A major difference from most insecticides is their high volatility. These agents were possessed by the major powers during World War II, althongh they were never employed in warfare. 

The carbamate and OP insecticides and the organophosphorous nerve gases soman, sarin, and tabun all act as anticholinesterases, and most of their toxicity is attributed to this property. The naturally occurring carbamate physostigmine, which has been used in medicine, is also an anticholinesterase. Some OP compounds can cause relatively long-lasting inhibition of the enzyme because of the phenomenon of... 

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