Si-PETN

The molecules pentaerythritol tetranitrate (PETN, 2) and its silicon analogue (Si-PETN, 3) provide a striking example of the consequences that can follow from a 1,3 intramolecular interaction [37]. PETN is a well known explosive, quite sensitive to impact dropping a 2.5 kg mass upon it from a height of just 14 cm has a 50% probability of producing detonation [62]. However Si-PETN, prepared only recently [63], is reported to be so remarkably more sensitive that impact is not even needed touching with a spatula is sufficient to cause explosion ... 

In an effort to understand this difference in sensitivity between PETN and Si-PETN, Liu et al. analyzed computationally several possible initial steps in the explosive decompositions of these molecules [64]. Eor PETN, the energetically-preferred possibilities were O-NO2 rupture and HONO elimination these were both found to have energy barriers of about 39 kcal/mol. For Si-PETN, the analogous... 

The computed activation energy for this was 32 kcal/mol [64], which is less than for any of the other processes investigated for either PETN or Si-PETN. In addition, this rearrangement is overall quite exothermic, with a predicted AE of about —45 kcal/mol, and therefore can provide energy for further decomposition. In the case of PETN, on the other hand, the corresponding process has a much higher activation barrier of about 80 kcal/mol. 

The fact that the rearrangement in Eq. 16.4 is available for initiating the decomposition of Si-PETN but not PETN was cited by Liu et al. as the reason for the vastly greater sensitivity of the former [64]. But why does Si-PETN rearrange in this manner so much more readily than PETN One factor, as Liu et al. pointed out, is likely to be the greater size of the silicon atom compared to carbon, which facilitates the expansion of its coordination sphere from four to five during the transition from 12 to 13. 

A second factor was brought out by a detailed analysis of the analogous rearrangements of the molecules 14 and 15, used as models for PETN (2) and Si-PETN (3) to shorten the... 

Study of the effects of charge diam, crystal dimensions 8t nature of the gas present on the velocity of deton of crystd expls, such as PETN 2) A. Parisot 8t P. Lafitte, ComptRend 18eCongrlntemlChimlnd (Nancy, France), Sept-Oct 1938, 930-36 Si CA 33, 6049(1939) (Influence of cartridge diam on the vel of deton of expls) 3) Anon, La Chimica. e l ln-dustria 21, 546(1939) 8t SS 35, 83(1940) (Influence of charge diam on the deton velocity)... 

Solubilities v si sol in w more sol in acetone than PETN more sol in coned nitric acid than PETN in sol in coned sulfuric acid Temperature of Explosion (Detonation) 3240° vs 3920° for PETN (Ref 2)... 

CA 69, 98129w(1968) [Conditioning particulate materials for use in org expls, is described. Solid pulverulent materials (such as RDX, PETN or AN) suitable for suspension in melted org expls (such.as TNT) were treated before dispersion, to make them wet and disperse better, with.= 1 liq or solid org Si compd (such as methylchloro-silane of the general formula R1R3R3R4Si,... 

CA 41, 6047(1947) (Equation of state for gases at extremely high.temperatures from the hydrodynamic theory of detonation) (Data ealed by various. equations is presented for RDX, PETN, TNT, Tetryl, PA, AmmP, LA Si Mr and correlated with sunila. data cbtd... 

Zr hydride is also used in pyrot formulations. Ellem (Ref 7, p 354) reports on a conductive primer mixt contg fine Zr (15), Zr hydride (30), Pb dioxide (20), Ba nitrate (15) and PETN (20%), while both he (p 379) and Weingarten Knapp (Ref 3) detail the following formula for a pressed-on first fire for illuminating flares Si (20),... 

TNBzlN is an expl about as powerful as tetryl (ca 126-7% TNTby Ballistic Mortar Test) and si less sensitive to impact than PETN. It possesses adequate stability and favorable oxygen balance to CO C7H4N40g - 7C0+2H20 + 2NZ... 

Its expl and other props, given in R.efs 2,3,4 5), are as follows Ballistic Mortar Value (Power) 127%TNT Explosion Temperature ignites ca 340°, but does not expl even at 360° (same as for TNT) Friction Sensitivity- si less sensitive than RDX Heat of Combustion, Qc 769.8 kcal/mole Heat of Explosion, Qe 272.6 kcal/mole Heat of Formation, 27.8 kcal/mol Hygroscopicity- increase in wt at 100% RH 0.09% vs 0.03% for TNT not hygroscopic at 90% RH Impact Sensitivity, detd by BurMinesApp No 5- si less sensitive than PETN 75° International Heat Test loss of wt in 48 hrs 0.1% vs 0.2% for TNT Power- see Ballistic Mortar Value and Trauzl Value Stability. Thermal at 100°- no expln in 300+ mins(same as for TNT) Stability, Thermal at 2 35°- methyl violet turned salmon pink in 30 mins vs 300+ mins for TNT Temperature of Explosion 3885°K Trauzl Test Value 135% TNT ... 

V. Treatment with Diphenylamine Reagent. See item E under colorimetric reagents and Charts A Si B. A yel color indicates the presence of one of the expls TNT, TNAns, HNDPhA, PA, AmmPic or DNPh viol, blue or black color indicates DNT, DNB, DINA, Tetryl, PETN, RDX, EDNA, EDD or AN red color indicates o-MNN... 

Majrich Sorm (Ref 14, p 338) give brisance values based on the lead plate cutting test on other brisance tests. They compare these values with those calcd by Kast s formula. Their lead plate cutting test data showed si higher brisance values for RDX than for PETN... 

Summarizing the above impact sensitivity results one can conclude that RDX is si more sensitive than Tetryl and si less sensitive than PETN... 

Brit abbr for Azide-Styphnate-Aluminum. It refers to LA, LSt Si A1 mixts which are used as priming compns in detonators having Tettyl or PETN as the base chge [McAdam Westwater fl958). 52l... 

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