PETN

Overview
PETN (pentaerythritol tetranitrate, also known as pentrite, or rarely and primarily in German as nitropenta) is one of the most powerful high explosives known, with a relative effectiveness factor (R.E. factor) of 1.66. It is more sensitive to shock or friction than TNT or tetryl, and it is never used alone as a booster. It is primarily used in booster and bursting charges of small caliber ammunition, in upper charges of detonators in some land mines and shells, and as the explosive core of detonation cord.

PETN is also used as a vasodilator, similar to Glyceryl trinitrate (pharmacology). The medicine for heart diseases, "Lentonitrat", is pure PETN.

Properties
The velocity of detonation of PETN at a density of 1.7 g/cm³ is 8,400 meters per second. The heat of explosion is 5,862 kilojoules per kilogram, or 1.5 times that of TNT.

PETN's formula is C(CH2ONO2)4. Its theoretical maximum crystal density is 1.773 g/cm³. It melts at 141 °C.

As a pollutant in the environment
PETN does not occur naturally, so the production of this kind of compound without detonation may lead to contamination of the environment. PETN is subject to biodegradation in untreated or unpreserved urine and feces. There also have been some reports of its degradation by bacteria, whose PETN reductase denitrates PETN into trinitrates and then dinitrates (French et al., 1996). The last compound shown in the pathway, pentaerythritol dinitrate, is degraded further to unknown products.

Production
PETN's preparation involves the nitration of pentaerythritol with a mixture of concentrated nitric and sulfuric acid. The preferred method of nitration is the ICI method, which utilizes concentrated nitric acid (98%+) alone, as mixed acid can create unstable sulfonated by-products.

C(CH2OH)4 + 4HNO3 &rarr; C(CH2ONO2)4 + 4H2O

History
Penthrite was first synthesized in 1891 by Tollens and Wiegand by nitration of pentaerythritol. In 1912, after being patented by the German government, the production of PETN started. PETN was used by the German army in World War I. PETN is also one of the ingredients in Semtex plastic explosive.

Additional Resources

 * Cooper, Paul W., Explosives Engineering, New York: Wiley-VCH, 1996. ISBN 0-471-18636-8