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<tens,00 van Romburgh,0G and Davis and Allen00 obtained methyl-

picramide. When refluxed in xylene solution, tetryl gives off nitrous fumes and is converted into a tarlike mass from which picric acid and methylpicramide may be isolated, along with a third, unidentified, buff-colored finely crystalline substance which melts at 240.5°. If pure tetryl is kept at 100°, it gives off nitrous fumes and a small quantity of formaldehyde, and yields after 40 days a mass which remains semi-liquid at ordinary temperature. By heating at 125° it is converted into a viscous liquid after about the same number of hours.

At ordinary temperatures tetryl appears to be perfectly stable. Current methods of purification insure the absence of occluded acid. It is more powerful and more brisant than TNT and picric acid, though distinctly more sensitive to shock, and is probably the best of all the common explosives for use in boosters and reinforced detonators. Koehler reports pressures in the mano-metric bomb (density of loading = 0.3) and temperatures produced by the explosions, as follows:

Pressure: Kilos per

Square Centimeter Temperature, °C.

Tetryl 46S4 2911

Picric acid 3638 2419

TNT 3749 2060

TNB 3925 2356

Aranaz reports that the explosion of tetryl produces a temperature of 3339°. Tetryl is slightly more sensitive than picric acid, and considerably more sensitive than TNT, in the drop test. Experimenting with a 5-kilogram weight, Koehler found that a drop of 150 cm. caused the detonation of tetryl 10 times out of 10 trials, a drop of 100 cm. 9 times out of 10, of 50 cm. 5 times out of 10, and of 40 cm. 3 times out of 10. Martin has determined the minimum charges of various primary explosives necessary for the detonation of TNT and tetryl. The explosives were loaded into detonator capsules, and the initiators were compressed upon them at a pressure of 1100 kilos per square centi-meter. ^g^

Minimum Charoe for Detonation of

TNT Tetryl

Mercuric fulminate 0.36 0.29

Silver fulminate 0.095 0.02

Cadmium fulminate 0.11 0.008

Mercurous azide 0.145 0.045

Silver azide 0.07 0.02

Lead azide 0.09 0.025

Cadmium azide 0.04 0.01

With each of the initiators which was tried, tetryl was more easily detonated than TNT. Taylor and Cope have determined the minimum charges of fulminate-chlorate (90:10) necessary to cause the complete detonation of various mixtures of TNT and tetryl, as follows:

Mixture of TNT-Tetryl Weight of Initiator, Grams

100 0 0.25

90 10 0.22

80 20 0.21

50 50 0.20

0 100 0.19

"Ethyl Tetryl." 2,4,6-Trinitrophenylethylnitramine

The ethyl analogue of tetryl was first prepared by van Rom-burgh, who procured it both by nitrating monoethylaniline and by nitrating diethylamide, and reported that it melts at 96°. The present writer has found that the pure material, recrystal-lized twice from nitric acid (d. 1.42) and once from alcohol,

4 melts at 94°. It is comparable to tetryl in its chemical reactions and in its explosive properties.

"Butyl Tetryl." 2,4,6-Trinitrophenyl-n-butylnitramine

The n-butyl analogue of tetryl has been prepared by two methods: (a) by condensing 2,4-dinitrochlorobenzene with n-butylamine to form 2,4-dinitro-n-butylaniline,103 and by the nitration of this product; and (b) by the nitration in one step of n-butylaniline. The pure substance crystallizes from alcohol in

103 Pure 2,4-dinitro-?i-butylaniline crystallizes from alcohol in deep yellow or orange needles, m.p. 92.5-93.0°.

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