ISSN 0012-5008, Doklady Chemistry, 2009, Vol. 425, Part 1, pp. 57–59. © Pleiades Publishing, Ltd., 2009.Original Russian Text © S.S. Novikov, 2009, published in Doklady Akademii Nauk, 2009, Vol. 425, No. 1, pp. 60–62.

57

In the 20th century, most of the conventionalammunition used the energy of the standard explo-sives C

a

H

b

O

c

N

d

, such as trinitrotoluene (TNT)C

6

H

2

CH

3

(NO

2

)

3

, hexogen (RDX) (CH

2

NNO

2

)

3

, octo-gen (HMX) (CH

2

NNO

2

)

4

, and nitroglycerine powders(NG) C

3

H

5

(ONO

2

)

3

. Hundredths of organic explosivesare described in reference books, encyclopedic dictio-naries, and numerous articles. Some of such publica-tions [1–3] suggest that there emerges a new generationof powerful organic explosives.

The presence of explosophorous functional groupsC–NO

2

, O–NO

2

, N–NO

2

and others in the molecule ofan explosive indicates that this explosive may be deto-native.

The explosives C

a

H

b

O

c

N

d

in the solid state aremolecular crystals. Of the greatest practical interest arecrystalline modifications with the maximal density

ρ

ofa single crystal.

A detailed review of methods for calculating the det-onation velocities of condensed explosives was madeby Aizenshtadt [4], who used an idealized scheme ofexplosive reaction

ë

a

H

b

O

c

N

d

= (

d

/2)

N

2

+ (

b

/2)H

2

O

+ (

c

/2 –

b

/4)CO

2

+ (

a

+

b

/4 –

c

/2)C.

The existing methods for calculating the density ofthe molecular crystals C

a

H

b

O

c

N

d

are empirical andhave limited predicting ability.

The ideal detonation velocity

D

at the maximal den-sity

ρ

of the single crystal of a given individual explo-sive C

a

H

b

O

c

N

d

takes a single value and is a characteris-tic physicochemical constant of the substance. Themaximal detonation velocities of explosives arereached at their maximal single-crystal densities. Forcyclic and polycyclic organic compounds, the detona-

tion velocities are maximal at

ρ

= 2.0 g/cm

3

. The natu-ral upper limit (scale) of the density of these com-pounds can be considered the diamond density3.51 g/cm

3

. Another convenient natural density scale isthe density of fulminic acid CHON. Within each classof explosives, the ones containing fully nitro substi-tuted compounds, such as tetranitromethane C(NO

2

)

4

,hexanitroethane C

2

(NO

2

)

6

, and hexanitrobenzeneC

6

(NO

2

)

6

, have the highest detonation characteristics.

In particular, hexanitrobenzene C

6

(NO

2

)

6

at themaximal density 2.0 g/cm

3

has a detonation velocity of

D

= 9.5 km/s. Until recent years, this

D

value was con-sidered maximal for stable secondary explosives, butthere is evidence that, for another explosive,

D

=9.93 km/s [2].

The existing theories of detonation of condensedexplosives [4–7] do not allow one to calculate the deto-nation velocities of these explosives from the initialdata on the structure and properties of their molecules.

Numerous methods for calculating

D

are onlyempirical. Using them for predicting the properties ofnew synthesized or computer-designed substancesrequire serious analysis and substantiation.

It is necessary to develop new (nonempirical) meth-ods for calculating the ideal detonation velocity foraccurate computer design and prediction of propertiesof explosives.

The classical theory of detonation of condensedexplosives [8] does not permit one to calculate the det-onation velocities of these explosives from the data onthe structure and properties of their molecules.

In recent decades, a number of new promising poly-cyclic explosives have been synthesized, among whichskeletal compounds, in particular, nitrocubanes,nitroadamantanes [9], and polynitroisowurtzitanes[10], are of prime importance. The compound CL20(HNIW) with the gross formula C

6

H

6

N

12

O

12

and thechemical name 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazatetracyclododecane has a higher density of

ρ

=2.04 g/cm

3

(table) and higher detonation velocity than

The Natural Upper Limit of the Ideal Detonation Velocityof the Condensed Explosives

S. S. Novikov

Presented by Academician A.A. Berlin July 1, 2008

Received July 8, 2008

DOI:

10.1134/S001250080903001X

Semenov Institute of Chemical Physics, Russian Academy of Sciences, ul. Kosygina 4, Moscow, 119991 Russia

CHEMISTRY

58

DOKLADY CHEMISTRY

Vol. 425

Part 1

2009

NOVIKOV

1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane (octo-gen).

CL20 is a relatively new polycyclic nitramine withthe cage–lattice molecular structure. CL20 was firstsynthesized in 1987 by Nilson at the Naval Air Weap-ons Station China Lake, California, United States.

The CL20 molecular structure consists of anisowurtzitane cage with one nitro group bound to eachnitrogen atom (figure).

Although CL20 is chemically similar to the well-known monocyclic nitramines RDX and HMX, CL20has much better characteristics owing to specific fea-tures of the cage structure.

The table illustrates the effect of the cage structureowing to high density and a significant increase in theheat of formation because of additional ring stress.

The density and ideal detonation velocity of a vir-tual explosive, a nitro derivative of CL20 with the for-mula (CNO

2

NNO

2

)

6

, were estimated. The estimatesshowed that the density and detonation velocity of suchan explosive exceed these characteristics for CL20.

Modern methods of computer-assisted organic syn-thesis [11] show great promise for searching for newhigh-energy condensed systems C

a

H

b

O

c

N

d

. In combi-nation with the existing empirical methods for calculat-ing

ρ

and

D

, this simplifies the design of a new genera-tion of powerful high-energy explosives.

A review and systematic analysis of a database of com-positions and physicochemical and detonation propertiesof individual condensed explosives C

a

H

b

O

c

N

d

were per-formed.

Relevant literature was analyzed, systematizationand qualitative analysis of published empirical methodsfor calculating the ideal detonation velocity were made,and the potential of using these methods for calculatingthe detonation velocities of skeletal polynitramines wasevaluated.

A preliminary survey and analysis of the state of theart in empirical and semiempirical methods for calcu-lating the density of the molecular crystals C

a

H

b

O

c

N

d

were carried out, and the calculation error limits wereestimated.

The structures of the possible molecules of stableexplosives under certain minimal constraints form afinite countable set.

Modern computer-assisted organic synthesis soft-ware opens wide possibilities for computer design ofnew organic compounds. Owing to this, it becomes fea-sible to enumerate all the elements of this set. In quitereasonable computation time, this enumeration withdetailed identification of each element of the set isachievable in the near future.

Of fundamental interest is the problem of calculat-ing the absolute upper limit

D

(

ρ

) of the ideal detona-tion velocities of various explosives stable under stan-dard external conditions. The accurate formulation ofthis problem was analyzed, and approaches to solvingthis problem were formulated.

Estimates show that the

D

values for nitro and azidoderivatives of CL20 are near the natural upper limit ofthe detonation velocities of all the possible explosivesC

a

H

b

O

c

N

d

.

REFERENCES

1.

Energeticheskie kondensirovannye sistemy

(EnergeticCondensed Systems), Zhukov, B.P., Ed., Moscow:Yanus-K, 1999.

2. Eremenko, L.T. and Nesterenko, D.A.,

XI simpozium pogoreniyu i vzryvu

(Proceedings of XI Symposium onCombustion and Explosion), Chernogolovka, 1996,pp.

43–49.

3. Golfier, M., Graindorge, H., Longevialle, Y., andMace,

H., New Energetic Molecules and Their Applica-tions in Energetic Materials,

Java Aspect Components

,1998, vol. 3.

N N

N N

N N

NO2O2N

NO2

NO2

O2N

O2N

2,4,6,8,10,12-Hexanitro-2,4,6,8,10,12-hexaazatetracy-clododecane.

Characterization of polycyclic and cage–lattice modifications of nitramines

Characteristic

HMX RDX CL20

Gross molecular formula

C

4

H

8

N

8

O8 C3H6N6O6 C6H6N12O12

Molecular weight, g/mol 296 222 438

Polymorphic modification β – γ, α, β, εDensity, g/cm3 1.91 1.81 1.92, 1.97, 1.99, 2.04

Enthalpy, kJ/mol +88 +70 +372

Oxygen balance, % –21.61 –21.61 –10.95

DOKLADY CHEMISTRY Vol. 425 Part 1 2009

THE NATURAL UPPER LIMIT OF THE IDEAL DETONATION VELOCITY 59

4. Aizenshtadt, I.N., Fiz. Goreniya Vzryva, 1976, vol. 12,no. 5, pp. 754–758.

5. Pepekin, V.I. and Lebedev, Yu.A., Dokl. Akad. NaukSSSR, 1977, vol. 234, no. 6, pp. 1391–1394.

6. Dremin, A.N., Savrov, S.D., Trofimov, B.S., and Shve-dov, K.K., Detonatsiionnye volny v kondensirovannykhsredakh (Detonation Waves in Condensed Media), Mos-cow: Nauka, 1970.

7. Mader, C.L., Numerical Modeling of Detonation, Berke-ley: Univ. of California, 1979. Translated under the titleChislennoe modelirovanie detonatsii, Moscow: Mir,1985.

8. Zel’dovich, Ya.B. and Kompaneets, A.S., Teoriya deto-natsii (Detonation Theory), Moscow: Fizmatgiz, 1955.

9. Golfier, M., Graindorge, H., Longevialle, Y., andMace, H., New Energetic Molecules and Their Applica-tions in Energetic Materials, Java Aspect Components,1998, vol. 3.

10. Pivina, T.S., Shcherbukgin, V.V., Molchanova, M.S., andZefirov, N.S., Propellants, Explosives, Pyrotecnics,vol. 20, pp. 144–146.

11. Clark, T., A Handbook of Computational Chemisty,Chichester: Wiley, 1985. Translated under the titleKomp’yuternaya Khimiya, Moscow: Mir, 1990.