Propellants, Explosives, Pyrotechnics 14, 19-23 (1989) 19

Evaluation of a New Organic Azide: Hexakis( azidomethy1)benzene

E. E. Gilbert* and W. E. Voreck

Energetic Materials Division, U.S. Army Armament Research and Development Center, Dover, NJ 07801-5001 (USA)

Begutachtung eines neuen organischen Azides: Hexakis(azidomethy1)- benzol (HAB)

HAB, ein thermisch und gegen Hydrolyse stabiler Festkorper, ist aus verfigbaren Ausgangsstoffen leicht erhaltlich. Gegen Explosions- druck, Reibung, und elektrostatische Ladung ist HAB nicht sehr emp- findlich; gegen einige Arten von Schlageinwirkung ist es empfindlich, gegen andere jedoch nicht. Vorlaufigen Eindrucken zufolge mag HAB sich als Ersatz fur Bleistyphnat in nicht-scharfen Briickenziin- dern eignen, sowie als Ersatz fur Tetrazen in Zundsatzen, z.B. dem M-42 Ziinder. Leichte Zundung und hohe Abbrandgeschwindigkeit ohne Detonation deuten auf Verwendbarkeit in Anziindern hin. HAB entwickelt nicht genug Brisanz, um den Trauzl-Aluminiumblock aus- zubauchen; es erscheint deshalb ungeeignet als Ersatz fur Bleiazid in Detonatorsatzen.

Evaluation d’un nouvel azide organique: I’hexakis(azidom6thyl)ben- zene (HAB)

Le HAB est une substance solide, thermiquement stable et ne prtsentant pas de rtaction d’hydrolyse qui peut &re obtenue facile- ment a partir de produits courants. Il est peu sensible a I’onde de choc, au frottement et aux charges tlectrostatiques; il est sensible B certains types de chocs mkcaniques mais pas a d’autres. D’aprk les premiers resultats, il semblerait que le HAB puisse remplacer le styphnate de plomb dans les dktonateurs tlectriques peu sensibles, ainsi que le tetrazene dans les compositions d’amorGage, par exemple dans la fusee du type M-42. Etant facile & allumer et brillant avec une vitesse de combustion Clevte sans donner lieu a une dttonation, son emploi dans les allumeurs pourrait Ptre inttressante. La brisance de HAB n’est pas suffisante pour dtformer le bloc d‘aluminium dans I’essai d’apr&s Trauzl; il parait donc peu approprit pour remplacer l’azoture de plomb dans les compositions d’amorcage.

Summary

HAB is a thermally- and hydrolytically-stable solid, easily prepared from available raw materials. It is not highly sensitive to shock, fric- tion, or electrostatic charge, but is sensitive to some types of impact, although not to others. It shows preliminary promise for possible use as a substitute for normal lead styphnate in less-sensitive bridgewire detonators, and as a substitute for tetracene in percussion detonators, e.g. the M-42 primer. Easy ignition, and a high burning rate without detonation, suggest application as an igniter. HAB is not sufficiently powerful to dent an aluminum witness block; therefore, it would not be suitable as a replacement for lead azide as an intermediate deto- nator charge.

1. Background

Although organic azides have in the past been considered as possibly useful energetic materials, they have not as yet found application. Two such materials, cyanuric triazide and 1,3,5- triazidobenzene, were studied as possibly useful detonating explosives, but were found to be impractically sensitive(’). Recently, there has been a revival of interest in organic azides for possible use as high-energy plasticizers, propellant ingre- dients or gas generators. These include the more stable primary and secondary aliphatic azided2), for example such compounds as 1,5-diazid0-3-nitrazapentane(~) and 1,9-diaza- 2,4,6,8-tetranitr0-2,4,6,8-tetrazanonane(~). There has also been interest in aliphatic azide-containin polymers, such as poly(viny1 a~ ide ) (~ ) , glycidyl azide polyrneh (GAP), and poly- mers derived from 3,3-bis(azidomethyl) ~xe tane (~ ) . Many organic azides are easy to prepare and they may have other desirable features, such as good thermal and hydrolytic stabil- ity, high burning rates, and reduced flash.

* Author to whom correspondence should be addressed, present address: 7 Frederick Place, Morristown, NJ 07960.

0 VCH Verlagsgesellschaft mbH, D-6940 Weinheim, 1989

It occurred to us that it might be of interest to prepare and test azides derived from the easily-accessible halomethylated benzenes by reaction with sodium azide. Two of these, mono- (azidomethy1)benzene (benzylazide) and 1 ,Cbis(azidomethyl) benzene, are known(’). The former is reported to explode with flame on strong heating, and the latter is said to ,,puff off above 190”C, but to be inert in an impact test; no further tests were apparently made with these compounds. We have pre- pared the corresponding compounds with three, four, and six azidomethyl groups@); our exploratory test data on the last of these, HAB, are reported herein. This compound, C,j(CH,N&, in which all of the six positions on the benzene ring are substituted by azidomethyl groups, contains 61.8% nitrogen and belongs to the class of “planar radial” com- pounds. These have compact, symmetrical, disc-like struc- tures, resulting in high melting points, good stability, and low solubility in solvents. A series of such materials (not including the azide) has been reported(’).

2. Preparation

The following is a typical preparation of HAB: Hexakis- (bromomethy1)benzene (32.0 g - 0.05 m) was added incre- mentally over about 5 min to a magnetically-stirred mixture of sodium azide [21.0 g - 0.32 m (7% excess -mortar ground)] and dimethylformamide (150 ml) preheated to about 65 “C in a three-necked flask. A slight exotherm occurred with each increment. The suspension was then stirred for one hour at 75 “C, followed by cooling and precipitation of the product by mixing with 100 ml water. The product was suction-filtered on a 4-inch Buchner funnel and washed three times with water. The wet cake was immediately transferred to an eight-inch crystallizing dish, and then easily broken into small chunks with a plastic spatula. It was dried overnight at room tempera- ture to constant weight, and the dry chunks were easily con-

0721-3115/89/0102-0019$02.50/0

20 E. E. Gilbert and W. E. Voreck Propellants, Explosives, Pyrotechnics 13, 19-23 (1989)

verted to a snow-white powder with a plastic spatula. The yield was 20 g-20.4 (98%-100% of theory), m.p. 162-5°C (dec); IR (KBr) [cm-'1: 2100 (asym. azide) (s), 1475 (m), 1330,1250 (sym. azide) (s), 1200 (m); 1020 (m), 880 (m), 810 s, 665,570; NMR (DMSO-d6) -single peak at 4.8 ppm; elemental analysis for C , H, N agreed with theory.

Although the above procedure was not optimized, some observations were made as follows: (1) Nearly twenty other runs, starting with 0.5 g to 64 g

bromo compound, gave similar results, (2) Three other solvents gave results as follows at reflux:

acetone (17 hrs) - 98% yield; methanol (4 hrs) - a 99% yield of a slightly impure product; water (6 hrs) - little reaction,

(3) A 99% yield was obtained in one small run at room tem- perature for 4 hours using DMF as solvent.

(4) Incomplete reaction is best shown by small IR peaks for residual CH2Br groups at 1185, 790, 720, 605 and 530 [cm-'I; this is a more sensitive indication than melting point.

( 5 ) The above procedure gives a pure product (based on m.p. and IR spectrum) which is not improved by recrystalliza- tion, provided pure starting material is used, and the reac- tion is carried to completion.

(6) The wet filter cake as prepared above can be dried rapidly by washing on the filter with methanol and then sucking to dryness over half an hour. The resulting cake, however, is hard and somewhat difficult to powder.

(7) The starting compound is easily prepared by brominating he~amethylbenzene(~), which is commercially available.

3. Physical and Thermochemical Properties

3.1 Melting point

The capillary melting point of HAB is 162-5°C (uncor- rected), with darkening and gas evolution. No explosions occurred when taking melting points, even when heating was continued above that temperature. However, as noted below, more rapid heating of large quantities of HAB did lead to explosion (see below for DTA data).

3.2 Density

Calculation by Cady's method(") gives a density of 1.460 g d m l ; measurement by the pycnometric method in 95% ethanol 1.392 g/ml (15.6"). At 16000 psi (110 MPa), the mea- sured density was 1.222 g/ml and at 25000 psi (172 MPa) 1.251 g/ml.

3.3 Solubilities

Approximate solubility data for HAB are summarized in Table 1.

3.4 Thermal analysis

DTA, using the method of Harris(") at a heating rate of 2.5"C per min, showed an endotherm with an extrapolated onset temperature of 164 "C, which corresponds to the melting point, followed by an exotherm with an extrapolated onset at

Table 1. HAB Solubility Data

Solvent grad100 ml Solvent Temperature 181 ["CI

Water Methanol Isopropanol Toluene Acetone Acetone Dioxane Dioxane Tetrahydrofuran Tetrahydrofuran Dimethylformamide

<0.05 <0.05 <0.1 2.0

4 . 0 12.3 <1.0 16.0 0.7 5.3

34.0

Table 2. Autoignition Temperatures

100 65 80 95 25 56 25 95 25 67 85

Compound Temperature ["C]

Pentolite 156 Tetryl 166 HA3 173 Composition B 174 RDX 187 HMX 234

186 "C and peaking at 212 "C as decomposition occurred. From this data was calculated the activation energy (30.8 kcdmol), the value of A in the Arrhenius equation (1.3 x ld3), and the autoignition temperature, which is given in Table 2 in com- parison with that of other common explosives. It is concluded that HAB is comparable to Composition B in this test.

3.5 Heats of combustion and formation

The heat of combustion, AH, is 4841.3 caVg, as measured by hot-wire ignition of HAB powder(12) under 35 atm oxygen pressure. Ignition occurred with a loud report, as noted with other energetic materials in this experiment, but HAB gave unusually severe deformation of the container. There was no deposit of carbonaceous residue. The value of AH in 1 atm of air is 1171.4 callg; this ignition gave a substantial carbon residue. In both tests, ignition occurred easily.

The heat of formation, A@, was calculated at + 438.4 kcall mol, using the above value of AH (as determined in oxygen), and a density of 1.460 g/cm3.

4. Stability Test Data

4.1 Hydrolytic stability

HAB was unaffected by stirring with distilled water for 168 hrs at 60°C.

4.2 Action of sulfuric acid

HAB reacts immediately and violently with 96% sulfuric acid at room temperature. Reaction with 80% acid is much milder, however, and gradual addition of HAB to it, with

Propellants, Explosives, Pyrotechnics 14, 19-23 (1989)

vigorous stirring at 90 “C, can be used as a method of disposal; the HAB gradually dissolves with gas evolution and dar- kening.

Hexakis(azidomethy1)benzene (HAB) 21

zene also explodes violently when heated in a compressed metal tube(’). This may result from very rapid burning, with a correspondingly rapid pressure increase (cf. data on burning rate given below).

4.3 Effect of light

Like other organic azides, HAB gradually darkens on pro- longed exposure to sunlight; this occurs more rapidly with ultraviolet light. The formation of an IR peak at 1675 cm-’ suggests that decomposition is occurring by the following type of reaction:

-CH2N3 -+ -CH=NH + N2

4.4 Action of laser beam

A few milligrams of HAB decomposed completely to car- bonaceous material and traces of HCN (as shown by IR spec- trum) in the beam of a pulsed tuneable COz laser (1 pulse, 28 joule/cm2, focussed at 9.75 pm). No decomposition occur- red with an unfocussed beam. Although no explosion occurred in this experiment, such is considered quite possible using larger samples.

4.5 Vacuum thermal stability-test

HAB passed this test(13) (not over 5 ml gas evolved from 5.0 g sample over 40 hrs at 100°C).

4.6 Compatibility with materials of construction

HAB showed negligible reactivity at 100°C in the Vacuum Thermal Stability Test in the presence of A1 6061-T-6, stainless steel 303, low carbon steel or copper.

5. Explosive Performance Test Data

5.1 Explosion temperature tests

Data for HAB and other common explosives in the Five- Second Explosion Temperature Test(14) are given in Table 3; HAB is comparatively stable. The one-second explosive tem- perature for HAB is 317 “C.

The Five-Second Explosion Temperature Test is usually run with 40 mg of test compound; 20 mg of HAB was used in this test. Even at this low dosage, HAB showed more extensive disruption of the containing blasting cap, and more splashing of the Woods Metal from the test vessel, than RDX or other common explosives at 40 mg. 1,3,5-Triazido-2,4,6-trinitroben-

Table 3. Five-Second Explosion Temperature Test Data

Compound Temperature [“C]

PETN 237 Tetryl 242 HAB 255 RDX 273 HMX 308

5.2 Detonation velocity

The detonation velocity(”) of HAB in comparison with two other explosives is given in Table 4.

Table 4. Detonation Velocity Data

Compound Velocity [rnis] Density [g/ml]

Lead azide 5100 HAB 5773 RDX 6080

4.0 1.15 1.0

5.3 Burning rate

In this test(’6), HAl3 was pressed in seven increments into the 1.5” x 0.2” (3.8 cm x 0.5 cm) hole in brass test fixtures of the type used in the Small Scale Gap test (cf. below). Each increment was pressed at 25000 psi (172 MPa). The samples were ignited with Class 7 black powder, which was initiated with an M-100 electric match. The fuze-wire break technique was used to time the burning rate across the 1.5” (3.8 cm) column length. The data obtained are summarized in Table 5.

It is apparent that the burning rate varies from extremely fast to extremely slow, even with samples prepared similarly. This is thought to result from lack of uniformity in the pellet structure. HAB was easy to ignite, and did not detonate even at the highest burning rates. These results suggest possible use as an igniter, for example in pyrotechnic formulations. On the other hand, since it did not build up to detonation over the length of the 1.5” (3,8 cm) pellet, it is concluded that it cannot be considered as a replacement for lead azide as a booster.

Table 5. HAB Burning Rate Test Data

Test No. Rate [ d s ]

760.0 0.01 5.1

790.0

5.4 Small scale gap test

This test measures the ability of a candidate explosive to be initiated by the shock from a standard explosive (RDX) through strips of Lucite stacked to varying thickness(”). The test compound is compressed at 16000 psi (110 MPa) into a 0.2 X 1.5 inch (0.5 X 3.8 cm’) hole in a brass test fixture. Eight increments, 124 mg each, were required to fill the hole; 25 samples were prepared for test. The Lucite gap for HAB, in comparison with that of common explosives is given in Table 6 . It is concluded that HAB is not especially sensitive to shock, especially in comparison with lead azide.

22 E. E. Gilbert and W. E. Voreck Propellants, Explosives, Pyrotechnics 14, 19-23 (1989)

Table 6. Small-Scale Gap Test Data Table 8. Compositions of Reference Materials

Material Decibangs Test Density‘”) [s/mll

Composition A-5 4.616 1.70 HAB 4.51 1.222 Tetryl 4.36 1.623 PETN 2.62 1.576 Lead Azide -0.2 -

(a) All at 16,000 psi (110 MPa).

5.5 Sensitivity to electrostatic charges

In the Approaching Electrode Electrostatic Test(”), HAB appears considerably less sensitive than the other materials listed in Table 7.

Table 7. Sensitivity to Electrostatic Charge, Friction and Impact

Impact“) Compound Electro- Frictiodb) Ball Drop“) PA(d)

static‘“) [inch] or [inch] or [joule1 [gl [ml [cml

HAB 0.01 450 a 167 1 to 2 5

Lead azide 0.003 167 a 90 21.5 03.3 5 (2.5 to 5.0) (12.7)

(dextrinated) (54.6 a 8.4) (12.7) Lead azide 0.0025 81 29 20.1 a 3.5 - (RD 1333) (51.1 a 8.9)

Lead styphnate 0.000341 250 a 100 14.7 a 4.4 8

NOL 130 0.00035 - 7.2 a 2.7 -

Tetracene 0.006 17.0 a 1.0 8

(basic) (37.3 a 11.2) (20.3)

(18.3 a 6.8)

(43.2 a 2.5) (20.3) -

(a) Minimum energy in joule. (b) Grams to give 50% response.

(dl Picatinny Arsenal Impact test: 10% height, 2-kg-Hammer. (e) Height for a 7-g-steel ball impacting on a 0.5-mm-thick layer of

Inches to give 50% response (cm respectively).

explosive.

5.6 Friction sensitivity

As seen in Table 7, HAB is less sensitive to friction in the BAM Friction Test(’’) than several primary explosives. (Also, see comments below under Stab Sensitivity Test.)

5.7 Sensitivity to impact

The results from two procedures for testing im act sensitiv- ity are given in Table 7. The Ball Drop Test(’,2g shows that HAB is considerably more sensitive than the other materials. The Picatinny Arsenal (PA) Impact Test(’), on the other hand, shows that HAB is closer in sensitivity to the three other mate- rials shown.

To take advantage of its apparent impact sensitivity, HAB was then tested in the M-42 Percussion Primer cup-and-anvil assembly(’), as a possible substitute for the usual primer

Ingredient PA-101‘”’ [wt %] NOL-130(b’ [wt %]

Barium nitrate 22 20 Lead azide - 20 Tetracene 5 5 Aluminum powder 10 Antimony sulfide 10 15

(a) Used in the M-42 primer (b) Used in stab initiators.

Basic lead styphnate 53 40

-

charge, which fires at an impact of 15.4 in.oz (0.1081 N.m); its composition is given in Table 8. Surprisingly, there was no response with HAB, even at 120 in.oz (0.850 N.m) - the max- imum impact attainable with the test apparatus. No improve- ment resulted from “sensitizing” the HAB with 5% carborun- dum grit, or with 5% grit plus 1% potassium perchlorate. After checking the purity of the HAB used, and after obtain- ing similar results in duplicate tests, it was concluded that we have no explanation of these wide discrepancies in the response of HAB to impact, varying from <1 in.oz (0.007 N.m) in the Ball Drop Test to > 120 in.oz (0.850 N.m) in a M-42 Primer cup-and-anvil assembly, except possibly its comparatively low sensitivity to friction. A somewhat similar observation was made by Spear and Elischer(*’) in their evalua- tion of the impact sensitivity of 2-picryl-5-nitrotetrazole. It was found to be quite sensitive in the Rotter Impact Test, but unresponsive in the Ball and Disc Test. They attribute this to the “softness” of the organic compound in combination with the “pinching” action of the latter test, as opposed to the solid impact obtained with the Rotter apparatus.

Although HAB is of no interest as a substitute for the M-42 Primer charge as a whole, it does show promise in initial tests as a substitute for tetracene, which comprises 5% of the primer charge and functions as a sensitizer. Tetracene has the serious disadvantage of being easily hydrolyzed, which has led to malfunction of the primer after periods of storage(21). HAB, on the other hand, is stable to hydrolysis (as noted above) and functions at least as well as a sensitizer. Further tests are in progress.

5.8 Stab sensitivity test

Unlike the M-42 Primer cited above, which operates by per- cussion in a cup-and-anvil assembly, another important class of detonator is activated by the friction generated as the firing pin penetrates the charge (Stab Detonators)(’). HAB was tested for this possible use(”), either when used alone, or as a substitute for the 5% of tetracene in NOL-130, as standard stab mix (cf. Table 8). HAB did not look promising in either case, as shown by the data in Table 9. A probable explanation may be that this test depends upon the energy generated by friction, and that HAB is not strongly friction-sensitive as noted above.

5.9 Hot wire initiability test

The hot wire initiability of HAB was tested(23) in comparison with that of normal lead styphnate, which is used in bridgewire detonators. The capacitor discharge voltage, at the 50% point,

Propellants, Explosives, Pyrotechnics 1429-23 (1989)

Table 9, Stab Sensitivity Test Data(a)

Hexakis(azidornethy1)benzene (HAB) 23

( 5 ) E. E. Gilbert, J . Polym. Sci. Polym. Chem. Ed. 22, 3603 (1984). (6) E. J. Vandenberg, U.S. Patent 3,645,917 (1972); Chem. Abstr.

(7) M. B. Frankel, E. R. Wilson, J . Chem. Eng. Data26, 219 (1981). (8) E. E. Gilbert, Patent pending. (9) J. Ciric, S. L. Lawton, G. T. Kokotailo, G. W. Griffin, J . Am.

Chem. SOC. 100 (7), 2173 (1978), and references cited therein. (10) H, H. Cady, Los Alamos Scientific Laboratory Report, LA-

(11) J. Harris, Thermochimica Acta 14, 183 (1976). (12) Military Standard; “Propellants, Solid: Sampling, Examination

and Testing”; MIL-STD-286 B; Method 802.1; Heat of Explo- sion (Combustion) (Adiabatic Calorimeter Method) (1967); Department of Defense, Washington 25, D.C., 20301.

(13) Ibid; Method 403.1.3; Vacuum Thermal Stability Tests ( 9 0 T and 100°C) (1975).

(14) R. N. Rogers, Znd. Eng. Chem. Prod. Res. Dev. 1, 169 (1962). (15) I. Akst, J. Hershkowitz, “Explosive Performance Modification

by Cosolidification of Ammonium Nitrate with Fuels,” PATR 4987 (1976). A miniaturized version of this test was used.

(16) Unpublished test procedure developed by R. Velicky, U.S. Army Research and Development Center, Dover, NJ.

(17) J. N. Ayres, L. J. Montesi, R. J. Bauer, “Small Scale Gap Test Data Compilation, ” Vol. I , Change 1, Naval Ordnance Labora- tory Technical Report NOLTR 73-132, Naval Surface Weapons Center, White Oak, Silver Spring, MD (1973) pp. 1-4.

(18) M. Kirshenbaum, “Response of Primary Explosives to Gaseous Discharges in an Improved Approaching-Electrode Electrostatic Sensitivi6y Apparatus,” PATR 4955, Picatinny Arsenal, Dover, NJ (1976).

(19) J. Harris, “Friction Sensitivity of Primary Exp[osives,” Technical Report ARLCD-TR-82102, ARRADCOM, Dover, NJ (1982).

(20) R. J. Spear, P. P. Elischer, “2-Picryl-5-Nitrotetrazole: Synthesis and Explosive Properties, ” Report MRL-R-859; Materials Research Laboratory, Ascot Vale, Victoria, Australia (1982).

(21) P. P. Elischer and R. J. Spear, “A Thermal Stabiliv Test for Primary Explosive Stab Sensitizers,” Report MRL-R-918, Mate- rials Research Laboratory, Ascot Vale, Victoria, Australia (1984).

(22) W. E. Voreck, “High Velocity Stab Sensitivity Testing of M-55 Detonators,” Minutes of Defense Standardization Program held at Dover, NJ, June 1980, DSP Project No. 1390 Series, Appen- dix 11, p. 93.

(23) “Joint Services Evaluation Plan for Preferred and Alternate Explosive Fills for Principal Munitions”, Vol. IV, Section 5.7, pp. 1-19; “Hot Wire Initiability,” Report AD-A086259, National Technical Information Service, Springfield, VA, 22161.

(24) Ibid, Section 5.3, pp. 1-15, “Priming Ability”. (25) “Properties of Explosives of Military Interest, ” AMC Pamphlet

NO. 706-177, p. 69, U.S. Army Material Command, Washing- ton, DC, 20315 (1971).

(26) “Photomicrographic Examination of Explosives”, PATR 4093, pp. 50-52, Picatinny Arsenal, Dover, NJ, Aug. 1970.

76: 154730 (1972).

7760-MS (1979).

Mixture Sensitivity(b’ [ in.ozf] or [N.m]

NOL- 130“’ 0.41

HAB(~) < 2 (2.9 X lo-’)

(14.1 X lo-?) NBL-130 with I-IAB(B) 0.62 (burn)

(4.3 X 10-3) 1.23 (explode)

(8.7 x

(a) Run with standard M-55 detonator firing pins fired from an air gun. (b) In inch sunce-force for 58% fire level (newton metre, respec-

tively). (‘) Cf. Table 8 for composition of NOL-130. (dl HAB (25 mg) was pressed into an M-55 detonator cup at 70,000 psi

(483 MPa), and backed with barium nitrate at 10,ooO psi (69 MPa). (c) HAB substituted for tetracene.

for HAB was 380, compared to 203 for the styphnate; this is a safety factor in favor of HAB.

Although HAB i s not as sensitive as lead styphnate in this test, it is sufficiently so for use in less sensitive bridgewire deto- nators, such as the M-6 blasting cap. The output of both of these explosives is primarily flame; neither produced a dent in an aluminum witness block. Lead azide, on the other hand, is considerably more brisant and produces a dent under these conditions. Therefore, I-IAB would not be useful as a replace- ment for lead azide as an intermediate charge in a detonator.

5.10 Minimum priming charge test

This test was run by a standard procedure@‘). RDX (200 mg - Class A) was pressed into the battom of an aluminum blast- ing cap cup (0.238 OD (0.6 cm), with 5 mil (0.0127 cm) walls) at 1Q psi (69 kPa). Then 100 mg of loose HAB was poured in and ignited by an electric match. No dent was produced in the witness block, so the test was repeated using 100 mg, 200 rng and 300 mg HAB, all pressed to 10 psi (69 kPa). However, no dent was produced in any case. In contrast, only 50 mg of loose lead azide produces a dent(2s). This test again shows that HAB is a much less powerful explosive than lead azide.

6. References

(I) “.&zyclopedia of Explosives and Related Items,” PATR 2700,

( 2 ) E. R. Wilson, M. B. Rankel, J. Chem. Eng. Data27,472 (1982)

(3) R. L. Simmons, H. L. Young, U.S. Patent 4,450,110 (1984),

(4) R. A. Henry, W. P. Norris, U. S. Patent Application 256, 230,

Picatinny Arsenal, Dover, NJ, 1960 to 1983.

and papers cited therein.

Chem. Abstr. 101: 75314 (1985).

Chem. Abstr. 96: 165043 (1982).

Acknowledgements

We are greatly indebted to Dr. G. W. Griffin for supplying the raw material for HAB, and to Messrs. M. Kirshenbaum, A. Sutton, and R. Velicky for much of the test data.

(Received July 1, 1988 (revised); Ms 24/88)