U.S. patent application number 12/542409 was filed with the patent office on 2009-12-10 for mono amine and diamine derivatives of cl-20.
This patent application is currently assigned to The Secretary of State for Defence. Invention is credited to Anthony John BELLAMY, Peter GOLDING, Alistair J. MACCUISH.
Application Number | 20090306381 12/542409 |
Document ID | / |
Family ID | 9953808 |
Filed Date | 2009-12-10 |
United States Patent
Application |
20090306381 |
Kind Code |
A1 |
GOLDING; Peter ; et
al. |
December 10, 2009 |
Mono Amine and Diamine Derivatives of CL-20
Abstract
The invention describes the synthesis of novel mono-amine and
di-amine derivatives of hexa-nitro-hexaazaisohex-awurtzitane
(CL-20). The synthesis is effected by the novel use of
fluoroacylating compounds to protect the secondary amine groups of
acylated precursors to CL-20 against nitrolysis. In so doing the
mono-amine and di-amine derivatives of CL-20 are rendered and which
in turn may be subsequently utilised as intermediates to generate
further novel derivatives with differing physical and chemical
properties to the parent compound. Formula (I), wherein:-- X.dbd.H,
and Y.dbd.H or NO.sub.2. ##STR00001##
Inventors: |
GOLDING; Peter; (Reading,
GB) ; MACCUISH; Alistair J.; (Portree, GB) ;
BELLAMY; Anthony John; (Swindon, GB) |
Correspondence
Address: |
JOHN S. PRATT, ESQ;KILPATRICK STOCKTON, LLP
1100 PEACHTREE STREET, SUITE 2800
ATLANTA
GA
30309
US
|
Assignee: |
The Secretary of State for
Defence
London
GB
|
Family ID: |
9953808 |
Appl. No.: |
12/542409 |
Filed: |
August 17, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10547260 |
Aug 29, 2005 |
7592448 |
|
|
PCT/GB04/00844 |
Mar 1, 2004 |
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12542409 |
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Current U.S.
Class: |
544/345 |
Current CPC
Class: |
C06B 25/34 20130101;
C07D 487/22 20130101; C07D 487/18 20130101; Y02P 20/55
20151101 |
Class at
Publication: |
544/345 |
International
Class: |
C07D 495/14 20060101
C07D495/14 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 28, 2003 |
GB |
0304555.6.7 |
Claims
1-45. (canceled)
46. A compound of formula (I) ##STR00005## wherein X is H, and Y is
H or NO.sub.2.
47. An explosive comprising the compound of claim 46.
48. A synthetic precursor to explosive compounds or explosive
compositions comprising the compound of claim 46.
49. A precursor to derivatives to poly-nitro-hexaazaisowurtzitanes
comprising the compound of claim 46.
50. A compound of formula (III) ##STR00006## wherein R.sub.1 and
R.sub.2 are independently selected from: C.sub.1-C.sub.10 alkyl,
C.sub.1-C.sub.10 alkylaryl, --CH.sub.2--C.sub.6H.sub.5,
C.sub.1-C.sub.10 polyethers, C.sub.1-C.sub.10 fluorinated
polyethers, C.sub.1-C.sub.10 fluorinated alkyl,
CH.sub.2--C.sub.6F.sub.5, COR' where R'.dbd.C.sub.1-C.sub.10 alkyl,
--COCl.sub.3, --COCCl.sub.3, CONHR'', where R''.dbd.H,
C.sub.1-C.sub.10 alkyl, --COCl.sub.3, --COCCl.sub.3,
CONHCO.sub.2C.sub.2H.sub.5, C(O)C.sub.mF.sub.2mC.sub.pH.sub.2p+1,
wherein m and p are integers and are independently chosen from the
range 1 to 19 and wherein m+p is less than or equal to 20, and
COCF.sub.3.
Description
[0001] The present invention relates to the synthesis of CL-20
derivatives.
[0002] The explosive 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexa aza
isowurtzitane, known as CL-20, is an explosive with a high energy
density, but is too sensitive for some applications. In its pure
form, it is vulnerable to fracture, thus releasing CL-20 powder and
dust which can cause accidental explosions.
[0003] In order to reduce the likelihood of such an event, crystals
of the explosive are coated with a binding agent. The binding agent
allows the explosive composition to be worked into a desired shape
and decreases its sensitivity. However, the interactions between
the explosive and the binding agent are weak, in certain
circumstance, in which case the coating will tend to separate from
the CL-20 crystals.
[0004] A solution is to mix CL-20 with a less sensitive, yet still
explosive, compound in order to reduce the sensitivity of the
mixture. In such manner CL-20 has been mixed with
dinitrotetraoxadiazacyclododecane (TEX) to give a mixture with a
lower sensitivity than CL-20 (K. E. Lee et al., "An insensitive
alternative to pressed explosive LX-14", pg. 38, National Defense
Industrial Association, 2000, Insensitive Munitions and Energetic
Materials Technology, Nov. 27-30, 2000, San Antonio, Tex.).
[0005] Another solution is to seek to modify the chemical structure
of CL-20 whilst retaining the nitrohexaazaisowurtzitane residue.
This has until hitherto remained an unresolved problem due to the
inability to find routes to generating precursor derivatives of
CL-20.
[0006] The applicant has solved this problem through the chemical
synthesis of mono-amine and di-amine derivatives of CL-20 through
the use of selective protection against strong nitrolysing reagents
by fluoroacylating compounds thereby providing a means for the
subsequent generation of further chemically modified derivatives.
The applicant describes herein new penta-nitrohexaazaisowurtzitane
derivatives and tetra-nitro-hexaazaisowurtzitane derivatives of
CL-20. The synthetic route enables selective nitration of a
protected poly-nitrohexaazaisowurtzitane residue thereby exposing
on deprotection free amine sites for subsequent chemical
derivatisation.
[0007] Wardle and Hinshaw in UK Patent Application 2333292 A state
that the nitration of 2,6,8,12-tetraacetyl-2,4,6,8,10,12-hexa aza
iso wurtzitane leads to 2,6,8,12-tetra nitro-2,4,6,8,10,12-hexa aza
isowurtzitane. The applicants have been unable to substantiate the
claims provided therein and note that the authors of GB 2333292 A
provide no experimental details as to how to synthesise this
compound. Comparative examples are provided below.
[0008] Chung et al. in J. Heterocyclic Chem., vol. 37, 1647, 2000
disclose that the nitration of
2,6,8,10,12-pentaacetyl-2,4,6,8,10,12-hexaazaisowurtzitane
according to the method described in GB 2333292 A leads to the
generation of CL-20. This is confirmed by the applicant in the
comparative examples provided below. The comparative examples
provide supporting evidence that the nitration claimed by Wardle
and Hinshaw cannot be done. If Wardle and Hinshaw were correct the
nitration undertaken as shown in the comparative examples would
have given rise to the penta-nitro derivative rather than the
hexa-nitro derivative. This was not observed.
[0009] H. Bazaki et al. in Propellants, Explosives, Pyrotechnics
23, 333-336 (1998) (at p. 333 para 2 and p. 334, para. 3.1)
disclose that the preparation of AC-HNIW using a nitrating agent
and a precursor synthesised from hexabenzyl hexaazaisowurtzitane
(synthesised according to the a method in JP 08,208,655)
manufacture yields PNIW a mono-amino-pentanitro-hexa
azaisowurtzitane (the mono-amine derivative referred to herein) as
an impurity. The paper however provides no enabling disclosure in
terms of the generation and isolation of the compound (PNIW) nor
indeed the process for generating it.
[0010] Hamilton et al. have suggested the use of nitrolysis of
2,6,8,12-tetraacetyl-2,4,6,8,10,12-hexaazaisowurtzitane to form the
di-amine derivative
2,6,8,12-tetranitro-2,4,6,8,10,12-hexaazaisowurtzitane (ICT
conference on Energetic Materials, Karlsruhe, Germany, 2000, 21-1
to 21-8). The applicants however have been unable to generate the
di-amine derivative according to their suggested route. Comparative
examples are provided below.
[0011] Wang and Chen have provided a theoretical study only of the
heat of formation of the N-nitro derivatives of
hexaazaisowurtzitane Huoyao Jishu (1993), 9(2), 35-43.
[0012] Therefore to the knowledge of the applicant there has been
no prior synthesis of the mono-amine and diamine derivatives stated
herein.
[0013] Accordingly compounds of formula (I) are provided:
##STR00002##
[0014] wherein:--
[0015] X.dbd.H, and
[0016] Y.dbd.H or NO.sub.2
[0017] The compounds of formula (I) are explosives per se or can be
used as precursors and/or intermediates to the preparation of
explosives and compositions thereof. Impact sensitivity studies
(Rotter Impact Test, 5 Kg) indicate that the mono-amine derivative
has a Figure of Insensitiveness value of approx. 16 and the
di-amine has a value of approx. 12.
[0018] It is the introduction of the free amine groups at either
one or both of the n-4 and n-10 positions on the
poly-nitro-hexaazaisowurtzitane residue that enables the residue to
be subsequently modified using relatively straight forward
chemistry in order to generate derivatives of CL-20 with different
chemical and physical properties to the parent molecule.
[0019] In order to demonstrate that derivatives may be synthesised
from compounds of formula (I) by reactivity at the n-4 and n-10
sites specific examples are provided below. The structural
possibilities are of course extremely extensive although the
applicant has ascertained that the extend of derivatisation
chemistry is in fact more limited than might have been expected by
the skilled man.
[0020] Poly-nitro derivatives synthesised from compounds of formula
(I), will be energy rich on account of the high stoichiometric
ratio of nitro groups within the compound. These derivatives may
not however be explosive materials in their own right but will have
modified chemical and physical properties in comparison to CL-20
from which they are derived.
[0021] In a further application and building upon the concept of
the energetic nature of the derivatives. It is clear that the
derivatives may be chemically combined with inert binding agents
such as hydroxyl terminated polybutadiene (HTPB) or energetic
binding agents such as poly-(3-nitratomethyl-3-methyloxetane) known
as poly-NIMMO to form new explosive compositions. Again these new
compositions will have modified explosive behaviour in comparison
to CL-20 per se.
[0022] A synthetic route to compounds of formula (I) starting from
compounds of formula (II) is provided:
[0023] wherein formula (II) comprises:
##STR00003##
[0024] X.dbd.Y.dbd.H
[0025] or,
[0026] X.dbd.Ac and Y.dbd.H
[0027] Ac.dbd.COCH.sub.3, COCH.sub.2R where R.dbd.C.sub.1-C.sub.10,
alkyl (linear branched), --CH.sub.2--C.sub.6H.sub.5,
C.sub.1-C.sub.10 arylalkyl).
[0028] and wherein the synthetic route comprises the sequential
steps of:
[0029] (1) fluoroacylation to protect the non-acylated secondary
amine group(s) at the n-4 and/or n-10 positions, followed by
[0030] (2) nitrolysis of the product of step (1), followed by
[0031] (3) deprotection by solvolysis of the product of step
(2).
[0032] The synthesis of the starting material of formula (II) may
be found in WO9623792 and EP 0753519.
[0033] Step (1) is performed by reacting at least one of the
non-acetylated secondary amine groups (at positions n-4 and n-10)
with a fluoroacylating reagent. In a specific embodiment the
fluorinated acyl reagent may be a tri-fluoroacylating compound such
as trifluoroacetic anhydride or a mixture of trifluoroacetic acid
and trifluoroacetic anhydride or a pentafluorinated anhydride such
as pentafluoropropionic anhydride or CF.sub.3COCl.
[0034] The trifluoroacetyl group when used as a protecting group
for the nitrogen atoms at the n-4 and n-10 positions provides
excellent protection against nitrolysis for hexa aza isowurtzitane
compounds. Indeed the use of trifluoroacylation as a means of
generating a protecting group to the nitrogen atom of the free
amine groups enables the synthesis of the formula (I) compounds to
be derived by this route.
[0035] It is found that fluoroacylation may be achieved in an
unselective manner or a selective manner according to the choice of
fluoroacylating reagent. This in turn may be used to select the
amine stoichiometry of the ultimate end product. Trifluoroacetic
acid has been found to fully fluoroacylate the di-amine derivate of
formula (II) whereas a mixture of trifluoroacetic acid and
trifluoroacetic anhydride has been found to selectively
fluoracetylate at only one of the n-4 or n-10 secondary amines.
[0036] Step (2) is performed by the nitrolysis of the product of
step (1) using concentrated nitric and concentrated sulphuric acids
or other nitrolysing agents such as nitric acid/oleum. The skilled
man will appreciate that other well known nitrolysing reagents such
as but not limited to N.sub.2O.sub.5 (dinitrogen pentoxide) as well
as NOBF.sub.4 and NO.sub.2BF.sub.4 would equally effectively carry
out this nitrolysis.
[0037] Step (3) is performed by solvolysis of the compound formed
in step (2) using an alcohol such as ethanol (and optionally sodium
acetate) however solvolysis could equally be achieved through use
of any alcohol such as methanol or propanol as well as water. The
skilled man will appreciate that solvolysis could also be achieved
by using any combination of a carboxylic acid salt with an alcohol
such as for example sodium propionate in ethanol.
[0038] In industrial practice it may be commercially desirable to
commence synthesis of either the mono-amine derivative or the
di-amine derivative from a single starting material. In the case
where a compounds of formula I having X.dbd.Y.dbd.H is the starting
material, a means of generating either the tetra-nitro derivative
or the penta-nitro derivative may be occasioned by complete or
selective solvolysis respectively.
[0039] In order to bring about complete solvolysis of the
tetra-nitro derivative sodium acetate (or other carboxylic acid
salt) is required to effect solvolysis (i.e. stronger conditions
are required)
[0040] Solvolysis of the penta-nitro derivative does not require
sodium acetate (or other carboxylic acid salt). If it is desired to
effect selective solvolysis of the tetra nitro derivative then only
ethanol or other alcohol should be used.
[0041] Further, in the case where X.dbd.Y.dbd.H the above three
step synthetic pathway leads to the formation of either the
tetra-nitro-hexaazaisowurtzitane derivative (tetra-nitro
derivative) or the penta-nitro derivative according to the strength
of the acylating reagent. The use of a strong fluoroacylating
reagent such as trifluoroacetic anhydride will fully acylate the
di-amine starting material whereas use of a weaker fluoroacylating
reagent such as trifluoroacetic acid and trifluoroacetic anhydride
will only partially acylate the di-amine to produce the mono-amine.
In the case of the former, subsequent nitrolysation and solvolysis
will generate the penta-nitro derivative whereas in the case of the
latter the tetra-nitro derivative will be generated.
[0042] Again, and in the case where in formula (I) X.dbd.Y.dbd.H,
an alternative means of generating the penta-nitro derivative is to
introduce a further acylation step into the synthetic pathway prior
to step (1). In this manner the di-amine starting product is
converted to the mono-amine acetylated intermediate (i.e. X.dbd.H,
Y.dbd.Ac).
[0043] Accordingly there is provided a further acylation step prior
to step (1) to form the acylated derivative wherein the
tetra-acylated di-amine starting material is acylated to form a
penta-acylated mono-amine intermediate.
[0044] The acylation step may be conveniently performed by reacting
the compound of formula I having X.dbd.Y.dbd.H with an acetylating
reagent such as acetic anhydride and acetic acid (AcOH/Ac.sub.2O).
The skilled man will appreciate that other common acylation agents
such as acyl anhydrides, acid anhydrides and acid chlorides, could
equally be used to effect this reaction.
[0045] An alternative means of generating the penta-nitro
derivative where in formula (I) both X.dbd.Y.dbd.H, is to introduce
a further solvolysis step (step 5) followed by a further nitrolysis
step (step 6) between steps (2) and (3).
[0046] Accordingly there is provided a further two steps to the
reaction synthesis, wherein after step (2) but prior to step (3)
the following two sequential steps are introduced:
[0047] (5) the product of step (2) is selectively deprotected by
solvolysis, followed by
[0048] (6) nitrolysis of the product of step (5).
[0049] Selective deprotection at Step (5) may be achieved through
the use of ethanol however selective deprotection by solvolysis
could equally be achieved through the use of any alcohol such as
methanol or propanol as well as water.
[0050] Step (6) may be achieved through the use of concentrated
nitric and sulphuric acids or other nitrolysing agents such as
nitric acid/oleum. The skilled man will appreciate that other
nitrolysing reagents such as N.sub.2O.sub.5 or NOBF.sub.4 and
NO.sub.2BF.sub.4 would equally effectively carry out this
nitrolysis.
[0051] The compounds of formula (I) may be used as intermediates or
precursors for the production of compounds derived from the
poly-nitro-hexaazaisowurtzitane residue. The free amine groups at
the n-4 and/or n-10 positions enables these amine sites to
participate in substitution and addition reactions with other
reagents.
[0052] Such derived compounds may be explosive in their own right
or non-explosive but in most instances they will be sufficiently
energetic to be incorporated into materials of use as
explosives.
[0053] The applicants that the possibility of deriving products
from formula (I) is more limited in scope than might at first be
expected as these compounds are less reactive than might at first
have been expected. For example the mono-amine and di-amine
derivatives have been found not to react with alkyl halides or
phenyl halides such as benzyl bromide. Moreover, acetylation has
required the presence of sulphuric acid.
[0054] Accordingly compounds of formula (III) are provided:
##STR00004##
[0055] wherein:
[0056] R.sub.1 and R.sub.2 are independently selected from:
[0057] C.sub.1-C.sub.10 alkyl, C.sub.1-C.sub.10 alkylaryl,
CH.sub.2--C.sub.6H.sub.5,
[0058] C.sub.1-C.sub.10 polyethers, C.sub.1-C.sub.10 fluorinated
polyethers, C.sub.1-C.sub.10 fluorinated alkyl,
CH.sub.2--C.sub.6F.sub.5,
[0059] COR' where R'.dbd.C.sub.1-C.sub.10 alkyl, COCl.sub.3,
COCCl.sub.3
[0060] CONHR'', where R''.dbd.H, C.sub.1-C.sub.10 alkyl,
COCl.sub.3, COCCl.sub.3
[0061] C(O)C.sub.mF.sub.2mC.sub.pH.sub.2p+1, wherein m and p are
integers and are independently chosen from the range 1 to 19 and
wherein m+p is less than or equal to 20
[0062] COCF.sub.3
[0063] A synthetic route to compounds of formula (III) starting
from compounds of formula (I) is provided comprising reacting a
compound of formula (I) with an acyl halide (such as for example an
acyl bromide or an acyl chloride).
[0064] The acyl halide may comprise C.sub.1-C.sub.10 alkylacyl
halides, C.sub.1-C.sub.10 alkylaryl acyl halides, CH.sub.2-arylacyl
halide, and R-acyl halides where R comprises
[0065] C.sub.1-C.sub.10 polyethers, C.sub.1-C.sub.10 fluorinated
polyethers, C.sub.1-C.sub.10 fluorinated alkyl,
CH.sub.2-fluorinated phenyl,
[0066] COR' where R'.dbd.C.sub.1-C.sub.10 alkyl, COCl.sub.3,
COCCl.sub.3 CONHR'', where R''.dbd.H, C.sub.1-C.sub.10 alkyl,
COCl.sub.3, COCCl.sub.3
[0067] C(O)C.sub.mF.sub.2mC.sub.pH.sub.2p+1, wherein m and p are
integers and are independently chosen from the range 1 to 19 and
wherein m+p is less than or equal to 20 and COCF.sub.3.
[0068] In a specific embodiment the alkylacyl halide may be acetyl
chloride.
[0069] A synthetic route to compounds of formula (III) starting
from compounds of formula (I) is provided comprising reacting a
compound of formula (I) with an acyl anhydride.
[0070] The acyl anhydride may comprise C.sub.1-C.sub.10
alkylacylanhydride, C.sub.1-C.sub.10 alkylarylacylanhydride,
CH.sub.2-arylacylanhydride, and R-acylanhydrides where R comprises
C.sub.1-C.sub.10 polyethers, C.sub.1-C.sub.10 fluorinated
polyethers, C.sub.1-C.sub.10 fluorinated alkyl,
CH.sub.2-fluorinated phenyl, as well as R acyl anhydrides where R
comprises:
[0071] COR' where R'.dbd.C.sub.1-C.sub.10 alkyl, COCl.sub.3,
COCCl.sub.3 CONHR'', where R''.dbd.H, C.sub.1-C.sub.10 alkyl,
COCl.sub.3, COCCl.sub.3
[0072] C(O)C.sub.mF.sub.2mC.sub.pH.sub.2p+1, wherein m and p are
integers and are independently chosen from the range 1 to 19 and
wherein m+p is less than or equal to 20 and COCF.sub.3.
[0073] In a specific embodiment the acyl anhydride may be acetic
anhydride.
[0074] A further synthetic route to compounds of formula (III)
starting from compounds of formula (I) is provided comprising
reacting the compounds of formula (I) with an isocyanate.
[0075] In a specific embodiment the isocyanate may be
N-(chlorocarbonyl)isocyanate or trichloroacetyl isocyanate.
[0076] In a further embodiment after reacting a compound of formula
(III) with an isocyanate the product may be further reacted with a
chlorocarbonyl acetate and an alcohol to form a urethane derivative
of hexaazaisowurtzitane.
[0077] In a specific embodiment alcohol may be methanol or
ethanol.
[0078] The invention will now be described by way of example and
with reference to the following figures of which:
[0079] FIG. 1 shows a synthetic route in accordance with the
present invention for the production of
2,6,8,12-tetranitro-2,4,6,8,10,12 hexaazaisowurtzitane. This
synthetic route is entitled reaction scheme 1.
[0080] FIG. 2 shows a synthetic route in accordance with the
present invention for the production of
2,6,8,10,12-pentanitro-2,4,6,8,10,12-hexaazaisowurtzitane. This
synthetic route is entitled reaction scheme 2.
[0081] FIG. 3 shows an alternative synthetic route in accordance
with the present invention for the production of
2,6,8,10,12-pentanitro 2,4,6,8,10,12-hexaazaisowurtzitane. This
synthetic route is entitled reaction scheme 3.
[0082] FIG. 4 shows an alternative route synthetic route in
accordance with the present invention for the production of
2,6,8,10,12-pentanitro 2,4,6,8,10,12-hexaazaisowurtzitane. This
synthetic route is entitled reaction scheme 4.
[0083] FIG. 5 shows a synthetic route to the acetylation of either
the mon-amine or di-amine derivatives using trichloroacetic
anhydride. These reactions must be catalysed by the addition of
conc. sulphuric acid.
[0084] FIG. 6 shows a synthetic route to an amide derivative of
CL-20 starting from the di-amine derivative and using an isocyanate
as reagent.
[0085] FIG. 7 shows a synthetic route to an amide chloride or an
amide (by further methanolysis) starting from the mono-amine
derivative and using an isocyanate as reagent.
[0086] FIG. 8 shows a synthetic route to an amide chloride or an
amide (by further methanolysis) starting from the di-amine
derivative and using an isocyanate as reagent.
[0087] FIG. 9 shows a synthetic route to an amide starting from
either the mono-amine or the di-amine and using an isocyanate as
reagent to generate the mono-amide or di-amide respectively.
[0088] FIG. 10 shows how CL-20 may be generated by nitrolysis of
the diamine.
SYNTHESIS OF COMPOUNDS OF FORMULA (I)
Reaction Scheme 1
(a) Synthesis of 2,6,8,12-tetra nitro-2,4,6,8,10,12-hexa aza
isowurtzitane
[0089] The reaction comprises three steps:
[0090] (1) the preparation of
2,6,8,12-tetraacetyl-4,10-bis(trifluoroacetyl)-2,4,6,8,10,12-hexaazaiso
wurtzitane (B) from
2,6,8,12-tetraacetyl-2,4,6,8,10,12-hexaazaisowurtzitane (A),
[0091] (2) the nitration of
2,6,8,12-tetraacetyl-4,10-bis(trifluoroacetyl)-2,4,6,8,10,12-hexaazaiso
wurtzitane (B) to form
2,6,8,12-tetranitro-4,10-bis(trifluoroacetyl)-2,4,6,8,10,12-hexaazaisowur-
tzitane (C) and
[0092] (3) the removal of the two trifluoroacetyl groups from
2,6,8,12-tetranitro-4,10-bis(trifluoroacetyl)-2,4,6,8,10,12-hexaazaisowur-
tzitane (C) to form
2,6,8,12-tetranitro-2,4,6,8,10,12-hexaazaisowurtzitane (D).
(1) Preparation of
2,6,8,12-tetraacetyl-4,10-bis(trifluoroacetyl)-2,4,6,8,10,12-hexaazaisowu-
rtzitane (B)
[0093] Compound A (6.0 g) was suspended in trifluoroacetic
anhydride (30 ml) and stirred at 38.degree. C. for 48 hours. An
aliquot removed and analysed after 24 hours indicated that the
reaction was complete at that stage. Excess anhydride was removed
on a rotary evaporator to leave a pink-white solid. The solid was
dissolved in chloroform and evaporated to dryness, this process
then being repeated. The resulting solid was dried under vacuum at
50.degree. C. for 8 hours, giving 9.62 g, 102% crude yield.
[0094] NMR and IR analysis indicated that the resulting solid was
compound (B).
[0095] .sup.1H NMR (DMSO-d6): .delta.62.06 (broad s, 12.4H,
4.times.COCH.sub.3), 6.63-7.00 ppm (m, 6.0H, 6.times.CH).
[0096] .sup.19F NMR: .delta. 66.52 and 66.88 ppm.
(2) Preparation of
2,6,8,12-tetranitro-4,10-bis(trifluoroacetyl)-2,4,6,8,10,12-hexaazaiso
wurtzitane (C)
[0097] A nitrating acid was prepared by the dropwise addition of
30% SO.sub.3 fuming sulphuric acid (5.0 ml) to 99.5% nitric acid
(30.0 ml). An ice/water bath was used to keep the temperature of
the reaction mixture below 15.degree. C. during the addition
process. The mixed acid was then cooled to 5.degree. C. before the
rapid addition with vigorous stirring of crude compound B (7.0 g)
via a solids funnel. When all of compound B had dissolved, the
solution was heated to 50.degree. C. for 4 hours. TLC analysis of a
sample at this point indicated the presence of uncer-nitrated
products, so heating was continued at 60.degree. C. for a further
1.5 hours. The solution was removed from the heat and drowned in
500 ml of an ice/water mixture. The precipitate that formed was
removed by filtration, washed with water until washings were
neutral, then dried overnight in a vacuum dessicator to leave a
fine white solid (6.59 g, 92% crude yield).
[0098] NMR and IR analysis indicated that the resulting solid was
compound C.
[0099] .sup.1H NMR (DMSO-d6): .delta.7.31-7.41 (m, 3.6H,
4.times.CH), 8.01 ppm (s, 2.0H, 2.times.CH)
[0100] .sup.19F NMR: .delta. 67.24 to 66.7 ppm (m).
(3) Preparation of 2,6,8,12-tetranitro-2,4,6,8,10,12-hexa aza
isowurtzitane (D)
[0101] Crude compound (C) (0.8 g) was added to a pre-prepared
solution of sodium acetate (140 mg) in dry ethanol (14 ml). A
precipitate formed immediately after the crude compound (C) had
dissolved, and a yellow colouration was observed in the mixture.
Stirring was continued for a further 10 minutes, then the
precipitate was filtered off, washed with water and dried in a
vacuum dessicator overnight to leave a white solid (303 mg, 58.7%
yield)
[0102] NMR and IR analysis indicated that the resulting solid was
compound (D). DSC (10 K/min) indicated onset of decomposition at
183.degree. C. There was no explosive exotherm using these DSC
conditions. This indicates that compound (D) is a thermally stable
explosive, relative to CL-20.
[0103] .sup.1H NMR (DMSO-d6): .delta.5.44 (s, 1.9H, 2.times.NH),
6.28 (s, 4.1H, 4.times.CH), 7.57 ppm (s, 2.0H, 2.times.CH).
[0104] .sup.13C NMR (acetone-d6): .delta.72.48, 72.98 ppm.
[0105] 1H-13C correlation: 5.44 ppm (H-4, H-10) uncoupled, 6.28
(H-3, H-5, H-7, H-9) coupled to 72.48 9C-3, C-5, C-7, C-9), 7.57
ppm 9H-1, H-11) coupled to 72.98 (C-1, C-11).
Reaction Scheme 2
(b) Synthesis of 2,6,8,10,12-pentanitro-2,4,6,8,10,12-hexa aza iso
wurtzitane
[0106] The reaction comprises four steps:
[0107] (1) the preparation of
2,6,8,10,12-pentaacetyl-2,4,6,8,10,12-hexaazaisowurtzitane (E) from
2,6,8,12-tetraacetyl-2,4,6,8,10,12-hexaazaisowurtzitane (A);
[0108] (2) the preparation of
2,6,8,10,12-pentaacetyl-4-trifluoroacetyl-2,4,6,8,10,12-hexaazaiso
wurtzitane (F) from
2,6,8,10,12-pentaacetyl-2,4,6,8,10,12-hexaazaisowurtzitane (E);
[0109] (3) the nitration of
2,6,8,10,12-pentaacetyl-4-trifluoroacetyl-2,4,6,8,10,12-hexaazaiso
wurtzitane (F) to form
2,6,8,10,12-pentanitro-4-trifluoroacetyl-2,4,6,8,10,12-hexaazaiso
wurtzitane (G) and
[0110] (4) the removal of the trifluoroacetyl group from
2,6,8,10,12-pentanitro-4-trifluoroacetyl-2,4,6,8,10,12-hexa
azaisowurtzitane (G) to form
2,6,8,10,12-pentanitro-2,4,6,8,10,12-hexaazaisowurtzitane (H).
(1) Preparation of 2,6,8,10,12-pentaacetyl-2,4,6,8,10,12-hexa aza
iso wurtzitane from 2,6,8,12-tetraacetyl-2,4,6,8,10,12-hexa
azaisowurtzitane
[0111] A suspension of compound A (1.0 g) in a mixture of glacial
acetic acid (15 ml) and acetic anhydride (10 ml) was stirred at
60.degree. C. for 12 hours. Excess acetic acid/anhydride mixture
was removed on a rotary evaporator at 60.degree. C. The remaining
reaction mixture was dried under vacuum at 60.degree. C. for 6
hours to leave a white solid. This solid was slurried in methanol
(200 ml) at 60.degree. C. and filtered hot. The remaining solids in
the filter were recovered and extracted in a similar manner with
two further portions of hot methanol. The extracts were combined
and the methanol was removed on the rotary evaporator and the
remaining off-white solid dried under vacuum at 50.degree. C. (6.7
g, 99.5% crude yield, 302-304.degree. C. melting point (DSC, ex
methanol).
[0112] NMR and IR analysis indicated that the resulting solid was
compound (E).
[0113] .sup.1H NMR (DMSO-d.sub.6): .delta.1.90-2.04 (m, 12.0H,
4.times.COCH.sub.3), 2.18-2.31 (m, 3.1H, COCH.sub.3), 4.66-4.85 (m,
0.8H, NH), 5.55-5.58 (m, 1.9H, 2.times.CH), 6.21-6.77 ppm (m, 4.0H,
4.times.CH).
(2) Preparation of
2,6,8,10,12-pentaacetyl-4-trifluoroacetyl-2,4,6,8,10,12-hexaazaiso
wurtzitane from
2,6,8,10,12-pentaacetyl-2,4,6,8,10,12-hexaazaisowurtzitane.
[0114] Crude compound (E) (3.0 g) was stirred in trifluoroacetic
anhydride (12 ml) at 38.degree. C. for 48 hours. The resulting
clear solution was evaporated to dryness, the resulting solid being
redissolved in chloroform and evaporated to dryness twice more. The
solid was dried under vacuum at 50.degree. C. to leave a
pinkish-white solid (3.3.8 g, 90% crude yield).
[0115] NMR and IR analysis indicated that the resulting solid was
compound (F).
[0116] .sup.1H NMR (DMSO-d.sub.6): .delta.1.94-2.09 (m, 12.5H,
4.times.COCH.sub.3), 2.28-2.36 (m, 3.6H, 1.times.COCH.sub.3),
6.45-7.08 ppm (m, 6.0H, 6.times.CH).
[0117] .sup.19F NMR: .delta.67.66 and 66.86 ppm.
(3) Preparation of 2,6,8,10,12-pentanitro-4-trifluoroacetyl-2,4,6,
8, 10,12-hexaazaiso wurtzitane from 2,6,8,10,12-penta
acetyl-4-trifluoroacetyl-2,4,6,8,10,12-hexa aza iso wurtzitane
[0118] A nitrating mixture was formed by the dropwise addition of
30% SO.sub.3 fuming sulphuric acid (6.0 ml) to 99.5% nitric acid
(13.0 ml). The temperature was kept below 15.degree. C. during the
addition by immersion of the reaction vessel in a water/ice bath.
The mixed acid was cooled to 5.degree. C. before the rapid
addition, with vigorous stirring, of crude compound F (2.0 g) via a
solids funnel. When the solid had completely dissolved, the flask
was heated at 60.degree. C. for 3 hours. The reaction mixture was
allowed to cool before being drowned in an ice/water mixture (200
ml). The flask was washed out with two portions of water
(2.times.50 ml). The dense white precipitate was filtered off,
washed with water until the washings were neutral, and dried
overnight in a vacuum dessicator (1.2 g, 58% crude yield).
[0119] MNR and IR analysis indicated that the resulting solid was
compound (G).
[0120] .sup.1H NMR (DMSO-d.sub.6): .delta.7.54-7.97 (m, 2.0H,
2.times.CH), 8.12 (s, 1.6H, 2.times.CH), 8.29 ppm (d, J=7 Hz, 1.4H
2.times.CH).
[0121] .sup.19F NMR: 67.99 ppm.
[0122] TLC analysis of the crude material indicated that CL 20 was
a major contaminant. NMR studies indicated that approximately 37%
of the crude product was CL-20.
(4) Preparation of 2,6,8,10,12-pentanitro-2,4,6,8,10,12-hexa aza
iso wurtzitane (H) from
2,6,8,10,12-pentanitro-4-trifluoroacetyl-2,4,6,8,10,12-hexaazaisowurtzita-
ne (G).
[0123] Crude compound (G) (2.0 g) was dissolved in dry ethanol (2
ml) and stirred at room temperature for 48 hours, during which time
the solution developed a yellow colouration. The solvent was
removed by rotary evaporation and the resulting solid dried under
vacuum at 50.degree. C. to leave a yellow solid (1.2 g). TLC
analysis of the solid suggested that it consisted of two major
components, one of which was CL-20. A portion of the product was
resolved by column chromatography, using a 40 cm nylon column of 2
cm diameter packed with silica gel (Merck Kieselgel 60 F.sub.254),
using a 3:2 mixture of n-heptane/ethyl acetate as eluent. After
development, the column was cut-up and the products extracted from
the silica gel.
[0124] MNR and IR analysis indicated that the purified solid was
compound (H).
[0125] .sup.1H NMR (DMSO-d.sub.6): .delta.5.99 (broad s, 0.8H, NH),
6.67-6.72 (m, 2.0H, 2.times.CH), 7.88 (s, 1.9H, 2.times.CH), 7.94
ppm (d, J=8 Hz, 2H, 2.times.CH).
[0126] .sup.13C NMR: 71.19, 73.25, 74.21 ppm.
[0127] .sup.1H-.sup.1H correlation (COSY45): 5.99 (H-4) coupled to
6.67-6.72 (H-3, H-5), 6.67-6.72 coupled to 7.94 (H-9, H-11).
[0128] 3H-13C correlation: 6.67-6.72 coupled to 73.25, 7.88 coupled
to 74.21 ppm, 7.94 coupled to 71.19.
[0129] DSC (10 K/min) of the purified solid recorded the onset of
an explosive decomposition exotherm at 168.degree. C., indicating
that compound (H) is an explosive compound.
Reaction Scheme 3
(c) Synthesis of 2,6,8,10,12-pentanitro-2,4,6,8,10,12-hexa aza iso
wurtzitane
[0130] FIG. 3 shows an alternative synthetic route for the
production of compound H. It involves more steps than the route of
FIG. 2, but is more reagent-efficient. The reaction comprises five
steps viz.
[0131] (1) the preparation of 2,6,8,12-tetraacetyl-4,10-bis(tri
fluoroacetyl)-2,4,6,8,10,12-hexaazaiso wurtzitane (B) from
2,6,8,12-tetraacetyl-2,4,6,8,10,12-hexaazaisowurtzitane (A);
[0132] (2) the preparation of 2,6,8,12-tetranitro-4,10-(bis) tri
fluoroacetyl-2,4,6,8,10,12-hexaazaiso wurtzitane (C) from
2,6,8,12-tetraacetyl-4,10-bis(trifluoroacetyl)-2,4,6,8,10,12-hexaazaiso
wurtzitane (B);
[0133] (3) the preparation of
2,6,8,12-tetranitro-4-trifluoroacetyl-2,4,6,8,10,12-hexaazaisowurtzitane
(J) from
2,6,8,12-tetranitro-4,10-(bis)trifluoroacetyl-2,4,6,8,10,12-hexa-
azaisowurtzitane (C);
[0134] (4) the preparation of
2,6,8,10,12-pentanitro-4-trifluoroacetyl-2,4,6,8,10,12-hexaazaiso
wurtzitane (G) from
2,6,8,12-tetranitro-4-trifluoroacetyl-2,4,6,8,10,12-hexa aza iso
wurtzitane (J), and
[0135] (5) the preparation of
2,6,8,10,12-pentanitro-2,4,6,8,10,12-hexaazaisowurtzitane (H) from
2,6,8,10,12-pentanitro-4-trifluoroacetyl-2,4,6,8,10,12-hexaazaisowurtzita-
ne (G).
[0136] Steps (1) and (2) above correspond to steps (1) and (2) of
the method described in relation to reaction scheme 1 above.
(3) Preparation of
2,6,8,12-tetranitro-4-trifluoroacetyl-2,4,6,8,10,12-hexazaisowurtzitane
from
2,6,8,12-tetranitro-4,10-(bis)trifluoroacetyl-2,4,6,8,10,12-hexaazai-
sowurtzitane.
[0137] Compound (C) (2.0 g) was dissolved in dry ethanol (10 ml)
and stirred at room temperature for 48 hours. The excess ethanol
was removed by rotary evaporation to leave a yellow solid which was
dried under vacuum at 50.degree. C. for 6 hours (1.73 g, 105%).
[0138] NMR and IR analysis indicated that the solid was compound
J.
(2) Preparation of
2,6,8,10,12-pentanitro-4-trifluoroacetyl-2,4,6,8,10,12-hexaazaiso
wurtzitane from 2,6,8,12-tetra
nitro-4-trifluoroacetyl-2,4,6,8,10,12-hexazaisowurtzitane.
[0139] Compound (J) (1.0 g) was added quickly with vigorous
stirring to an ice-cooled mixture of 30% SO.sub.3 fuming sulphuric
acid (0.2 ml) and 99.5% nitric acid (3.0 ml). The mixture was
allowed to warm slowly to room temperature and then stirred for 4
hours. The reaction mixture was then drowned in an ice/water
mixture (100 ml) and the white precipitate which formed was removed
by filtration and washed with several large portions of water
before being dried overnight in a vacuum dessicator (0.96 g, crude
yield 87%).
[0140] NMR and IR analysis indicated that the solid was compound
(G).
[0141] .sup.1H NMR (d.sub.6-acetone): 7.70-7.87 (m, 2.6H,
2.times.CH), 8.15 (s, 2.1H, 2.times.CH), 8.26 ppm (d, J=7 Hz, 2.0H,
2.times.CH),
[0142] .sup.13C NMR (d.sub.6-acetone): 71.21, 73.26, 74.22 ppm.
[0143] .sup.19F NMR (d.sub.6-acetone): 68.41 ppm.
(3) Preparation of 2,6,8,10,12-pentanitro-2,4,6,8,10,12-hexa
azaisowurtzitane from
2,6,8,10,12-pentanitro-4-trifluoroacetyl-2,4,6,8,10,12-hexaazaisowurtzita-
ne.
[0144] Compound (G) (0.50 g) was dissolved in dry ethanol (10.0 ml)
and stirred at room temperature for 48 hours. The solution was then
evaporated to dryness and the resulting yellowish solid was dried
under vacuum at 50.degree. C. for 6 hours (0.45 g).
[0145] NMR analysis of the solid indicated that the solid was
predominantly compound (H).
[0146] .sup.1H NMR (acetone-d.sub.6): 5.96 (s, 0.8H, NH), 6.66-6.71
(m, 2.0H, 2.times.CH), 7.84 (2.1H, 2.times.CH), 7.93 ppm (d, J=8
Hz, 2H, 2.times.CH).
[0147] TLC and NMR studies indicated that the main contaminants
were CL 20 (about 10% of the final product) and compound (J).
[0148] The reaction method of FIG. 2 was found to be reagent
inefficient, especially the preparation of compound (E) from
compound (A) and the subsequent preparation of compound (F). The
final nitration product was found to contain almost 40% CL 20 as an
impurity.
[0149] It was discovered that nitration of compound (B), conducted
in an identical manner to the nitration used in relation to the
reaction scheme of FIG. 2, gives a product which is almost entirely
free of the two over-nitration products CL-20 and
pentanitro-trifluoroacetyl-2,4,6,8,10,12-hexaazaisowurtzitane. This
suggests that the N--COCF.sub.3 group is stable under the harsh
nitration conditions employed and that the COCF.sub.3 group is an
effective protecting group in nitration reactions. It seems likely
that the CL 20 contaminant in the nitration product of compound (F)
is a result of the presence of compound (E) in the crude starting
material (B).
Reaction Scheme 4
(D) Synthesis of 2,6,8,10,12-penta nitro-2,4,6,8,10,12-hexa aza iso
wurtzitane from 2,6,8,12-tetra acetyl-2,4,6,8,10,12-hexa aza iso
wurtzitane.
[0150] The reaction comprises three steps:
[0151] (1) the preparation of
2,6,8,12,tetraacetyl-4-trifluoroacetyl-2,4,6,8,10,12-hexaazaisowurtzitane
(K) from 2,6,8,12-tetraacetyl-2, 4, 6, 8,
10,12-hexaazaisowurtzitane (A).
[0152] (2) Preparation of
2,6,8,10,12-pentanitro-4-trifluoro-2,4,6,8,10,12-hexaazaisowurtzitane
(G) from
2,6,8,12-tetraacetyl-2,6,8,12-tetraacetyl-4-trifluoroacetyl-2,4,6,8,-
10,12-hexa aza isowurtzitane (K).
[0153] (3) Preparation of 2,6,8,10,12-pentanitro-2,4,6,8,10,12-hexa
azaisowurtzitane (H) from
2,6,8,10,12-pentanitro-2,4,6,8,12-trifluoroacetyl-2,4,6,8,10,12-hexaazais-
owurtzitane (G).
(1) the preparation of
2,6,8,12,tetraacetyl-4-trifluoroacetyl-2,4,6,8,10,12-hexaazaisowurtzitane
from 2,6,8,12,tetraacetyl-2,4,6,8,10,12-hexaazaisowurtzitane.
[0154] Compound (A) (3.0 g) was stirred in trifluoroacetic acid (25
ml) before the addition of trifluoroacetic anhydride (10 ml). The
reaction mixture was stirred at room temperature for 24 hours. The
excess of trifluoroacetic acid/anhydride mixture was removed on the
rotary evaporator to leave a viscous liquid. Methanol (5 ml) was
added dropwise to the liquid, and then the volatile components were
removed on the rotary evaporator to leave a white solid. This solid
was dissolved in methanol (10 ml) and refluxed for 4.5 hours; a
white solid precipitated from the solution as the reflux
progressed. The methanol was then evaporated from the suspension
and the resulting solid dried under vacuum at 50.degree. C. [2.85
g, 74.0% crude yield, 292.degree. C. melting point (DSC, ex
methanol)].
[0155] NMR and IR analysis indicated that the resulting solid was
compound (K).
(2) Preparation of
2,6,8,10,12-pentanitro-4-trifluoro-2,4,6,8,10,12-hexaazaisowurtzitane
from
2,6,8,12-tetraacetyl-2,6,8,12-tetraacetyl-4-trifluoroacetyl-2,4,6,8,-
10,12-hexaazaisowurtzitane.
[0156] A nitrating mixture was prepared by the dropwise addition of
30% SO.sub.3 fuming sulphuric acid (0.4 ml) to 99.5% nitric acid
(3.0 ml). The temperature was kept below 15.degree. C. during the
addition by immersion of the reaction vessel in an ice/water bath.
The reaction vessel was kept in the ice/water bath during the rapid
addition, with vigorous stirring, of crude compound K (500 mg). The
reaction mixture was then heated at 70.degree. C. for 3 hours
(after which time TLC analysis indicated that the reaction was
complete). The reaction mixture was allowed to cool before being
drowned in an ice/water (100 ml) bath. The precipitate was filtered
off, washed with water until the washings were neutral and dried
overnight in a vacuum dessicator (390 mg, 69% yield).
[0157] TLC analysis indicated that the resulting solid was compound
(G).
(3) Preparation of 2,6,8,10,12-pentanitro-2,4,6,8,10,12-hexa
azaisowurtzitane from
2,6,8,10,12-pentanitro-2,4,6,8,12-trifluoroacetyl-2,4,6,8,10,12-hexaazais-
owurtzitane.
[0158] Crude compound (G) was dissolved in dry ethanol (10 ml) and
stirred at room temperature for 48 hours. The solution was
evaporated to dryness and the resulting yellowish solid was dried
under vacuum at 50.degree. C. for 6 hours (331 mg, 105% crude
yield).
[0159] TLC and NMR analysis indicated that the solid was
predominantly compound (H), with CL-20 as the main contaminant.
Synthesised Derivatives
[0160] The following reaction schemes demonstrate specific
embodiments as to how the compounds of formula (III) may be derived
from compounds of formula (I).
Reaction Scheme 5
[0161] WN.sub.5H: 2,6,8,10,12-pentanitro-2,4,6,8,10,12-hexa aza iso
wurtzitane.
[0162] WN.sub.5A:
4-acetyl-2,6,8,10,12-pentanitro-2,4,6,8,10,12-hexa aza iso
wurtzitane
Acetylation of WN.sub.5H; Formation of WN.sub.5A
[0163] WN.sub.5H (50 mg) was suspended in acetyl chloride (1.0 ml)
and conc. sulphuric acid (two drops) was added. The reaction
mixture was stirred at room temperature for 8 min, during which
time the suspended material dissolved. The reaction mixture was
then poured onto crushed ice (30 mg) and allowed to stand for 45
min. The precipitate was collected by filtration and washed with
water until the washings were neutral, then dried overnight in a
vacuum dessicator (42 mg, 76% crude yield).
[0164] IR (KBr disc): 1703.8 cm-1 (CO stretch)
[0165] .sup.1H NMR (acetone-d6): 2.49 (s, 3.00H), 7.52-7.71 (m,
1.0H) and 8.03-8.33 ppm (m, 4.80H)
[0166] .sup.13C NMR (acetone-d6): 20.49, 67.53, 71.60, 72.37, 74.88
and 169.29 ppm.
Acetylation of WN.sub.4H.sub.2; Formation of WN.sub.4A.sub.2
[0167] WN.sub.4H (20 mg) was suspended in acetic anhydride (2.0 ml)
and conc. sulphuric acid (1 drop) was added. All of the suspended
solids immediately dissolved. The solution was stirred at room
temperature for 24 h. TLC analysis at this stage indicated that no
starting material remained and that a single new product (higher
R.sub.f) had formed. The reaction was drowned in ice/water (50 ml),
the precipitate was filtered off and washed with water. Yield 21 mg
(after drying).
[0168] .sup.1H NMR (acetone-d6): .delta. 2.46 (s, 6.51H), 7.30
(m)+7.42 (m) (2.11H), 7.85 (s)+7.96 ppm (m) 4.00H).
[0169] .sup.13C NMR (acetone-d6): 66.2, 67.5, 70.2, 71.6, 74.7,
169.8 ppm.
Reaction Scheme 6
[0170] WN.sub.4H.sub.2: 2,6,8,12-tetranitro-2,4,6,8,10,12-hexa aza
iso wurtzitane.
[0171] WN.sub.5A:
4,10-diacetyl-2,6,8,12-tetranitro-2,4,6,8,10,12-hexa aza iso
wurtzitane.
Reaction of WN.sub.5H with EtNCO; Formation of WN.sub.5(CONHEt)
[0172] WN.sub.5H (200 mg) anhydrous CuCl.sub.2 (5-10 mg) and EtNCO
(1.0 ml) were dissolved in acetonitrile (4.0 ml). The solution was
heated at 55.degree. C. for 20 h, the volatile components were
rotary evaporated and the residue was transferred to a separating
funnel with water (2.times.5 ml) and EtOAc (2.times.5 ml). The
aqueous layer was extracted with more EtOAc (2.times.20 ml), the
extracts were combined and washed with water, and then
concentrated. rying gave a yellow solid (263 mg). A sample (20 mg)
of the crude WN.sub.5(CONHEt) was column purified (5 cm "Trikonex"
flash tube supplied by Fisher) using 3/2 (vol) n-heptane/EtOAc as
eluent. The low R.sub.f components were recovered and re-columned
(Trikonex) using 1/2 n-heptane/EtOAc.
[0173] .sup.1H NMR (acetone-d6): .delta. 1.13 (t 3.94H), 3.28 (q,
2.10H), 6.73 (br s, 0.99H, NH), 7.67 (d, J=8.0 Hz 2.21H) 7.99 (s,
1.99H), 8.08 ppm (d, J=8.0 Hz, 2.00H)
[0174] .sup.13C NMR (acetone-d6): 15.1, 36.8, 71.1, 71.3, 74.8
ppm.
Reaction Scheme 7
[0175] EtNCO: N-ethyl isocyanate.
[0176] WN.sub.5(CONHEt):
4-(N-ethylcarboxamido)-2,6,8,10,12-pentanitro-2, 4,
6,8,10,12-hexaazaisowurtzitane.
[0177] WN.sub.5 (CONH.sub.2):
4-carboxamido-2,6,8,10,12-pentanitro-2,4,6,8,10,12-hexa aza
isowurtzitane
Reaction of WN.sub.5H with Cl.sub.3CCONCO; Formation of
WH.sub.5(CONHCOCCl.sub.3)
[0178] (a) WN.sub.5H (30 mg) was dissolved in acetonitrile (3.0 ml)
in a nitrogen-flushed flask. The solution was stirred at 60.degree.
C. Trichloroacetyl isocyanate (0.2 ml) was added by syringe via the
septum cap and stirring was continued for 4 h. The volatile
components were removed by rotary evaporation to give a
yellow/orange, sticky solid. Trituration with first DCM and then
Et.sub.2O failed to cause crystallisation, the material being
soluble in both solvents. The sample was dried under vacuum at
50.degree. C. for a prolonged period. TLC analysis of the isolated
material showed that all of the starting material had reacted and
that a new product had been formed (possibly a single spot at low
R.sub.f, but badly tailed). The .sup.1H NMR spectrum confirmed that
the starting material was absent, and that the cage structure had
been retained (all main signals below 7 ppm). There were only 3
peaks in the .sup.13C spectrum.
[0179] .sup.1H NMR (acetone-d.sub.6): .delta. 7.50 (br s, 1.66H),
7.65 (d, J=7.7 Hz, 2.08H), 7.85 (br s, 1.19H), 8.10 (s, 1.56H),
8.19 (m, 1.51H), 8.36 ppm (s, 1.00H).
[0180] .sup.13C NMR (acetone-d.sub.6): 71.3, 71.7, 72.2, 75.0,
75.1, 150.2 ppm.
[0181] (b) WN.sub.5H (1.0 g) was dissolved in acetonitrile (10.0
ml) and stirred under N.sub.2. Trichloroacetyl isocyanate (0.3 ml)
was added by syringe via the septum cap. The solution was stirred
at room temperature for 20 min, before the volatile components were
removed by rotary evaporation. TLC analysis of the residue showed
the presence of a large amount of starting material. The procedure
was repeated with a further quantity of Cl.sub.3CCONCO (0.2 ml) The
.sup.1H NMR spectrum of the final product was virtually identical
to that from the previous reaction.
Methanolysis of WN.sub.5(CONHCOCCl.sub.3); Formation of
WN.sub.5(CONH.sub.2)
[0182] WN.sub.5(CONHCOCCl.sub.3) was dissolved in MeOH (10.0 ml),
conc. sulphuric acid (5 drops) was added and the solution was
refluxed for 2 h. The excess of solvent was removed by rotary
evaporation and the residue washed into a separating funnel with
water and ethyl acetate. The organic phase was removed, combined
with EtOAc extracts (2.times.10 ml) of the aqueous portion and then
washed with water (2.times.20 ml). The EtOAc was rotary evaporated
and the remaining yellow solid was dried under vacuum (0.524 g).
TLC analysis indicated that several components were present
including HNIW (as an impurity from the starting material). A
sample (30 mg) was purified on a Trikonex column (3/2
n-heptane/EtOAc) to remove HNIW (contaminant in WN.sub.5H).
[0183] .sup.1H NMR (acetone-d.sub.6): .delta. 6.49 (br s, 1.86H,
NH), 7.69 (d, J=8.0 Hz, 2.37H), 8.00 (s, 2.01H), 8.11 ppm (d, J=8.0
Hz, 2.00H)
[0184] .sup.13C NMR (acetone-d6): 70.9, 71.4, 74.8, 154.9 ppm.
Reaction Scheme 8
[0185] Cl.sub.3CCONCO: N-trichloroacetyl isocyanate
[0186] WN.sub.4 (CONH.sub.2).sub.2:
4,10-bis(carboxamido)-2,6,8,12-hexaazaisowurtzitane.
[0187] WN.sub.5 (CONHCOCl.sub.3): 4-(N-trichloroacetyl
carboxamido)-2,6,8,10,12-penta
nitro-2,4,6,8,10,12-hexaazaisowurtzitane.
[0188] WN.sub.4(CONHCOCCl.sub.3).sub.2:
4,10-bis(N-trichloroacetylcarboxamido)-2,6,8,12-tetra
nitro-2,4,6,8,10,12-hexaazaisowurtzitane.
Reaction of WN.sub.4H.sub.2 with Cl.sub.3CCONCO; Formation of
WN.sub.4(CONHCOCCl.sub.3).sub.2
[0189] WN.sub.4H.sub.2(400 mg) was stirred in acetonitrile (2.0 ml)
under N2 and trichloroacteyl isocyanate (400 mg) was stirred in
acetonitrile (2.0 ml) under N.sub.2 and trichloroacetyl isocyanate
(0.10 ml) was added by syringe via a septum cap. Complete
dissolution occurred within approx. 3 min, but stirring was
continued for a further 7 min. The volatile components were then
removed by rotary evaporation to leave a yellow film. This was
dried under vacuum at 50.degree. C., during which time it
crystallised to leave a very light yellow solid, 258 mg.
[0190] .sup.1H NMR (acetone-d6): 7.52 9s with br base, 4.00H), 7.87
(br s, 0.91H), 7.97 ppm (s, 1.75H).
[0191] .sup.13C NMR (acetone-d.sub.6): 70.6, 74.8, 92.7, 150.5,
150.6, 160.0, 160.1 ppm.
Methanolysis of WN.sub.4(CONHCOCCl.sub.3).sub.2; Formation of
WN.sub.4(CONH.sub.2).sub.2
[0192] WN.sub.4(CONHCOCCl.sub.3).sub.2 (30 mg) was dissolved in
MeOH (3.0 ml), conc. sulphuric acid (2 drops) was added and the
solution was refluxed for 7.5 h. The solvent was removed by rotary
evaporation and water (3.0 ml) was added to the remaining thick
film. The solid red precipitate which formed was filtered off.
Washing with water revealed that this material was water-soluble.
It was left in solution overnight then extracted with EtOAc
(3.times.30 ml). The organic extract was combined and washed with
water (2.times.20 ml). The extract was evaporated to dryness and
dried under vacuum to leave a pale orange solid (21 mg).
[0193] NMR (acetone-d.sub.6): 6.46 (br s, 3.46H, NH), 7.44 (s,
4.00H), 7.79 ppm (s, 1.92H).
Reaction Scheme 9
[0194] ClCONCO: N-chlorocarbonyl isocyanate.
[0195] WN.sub.5(CONHCOOEt):
4-(N-ethoxycarbonylcarboxamido)-2,6,8,10,12-pentanitro-2,4,6,8,10,12-hexa-
azaisowurtzitane.
Reaction Of WN.sub.5H with (i) CLCONCO (ii) EtOH; Formation of
WN.sub.5 (CONHCOOEt)
[0196] WN.sub.5H (50 mg) was dissolved in anhydrous acetonitrile
(1.0 ml) under nitrogen. N-(chlorocarbonyl)isocyanate (0.20 ml) was
added by syringe via the septum, and the solution was stirred at
room temperature for 90 min. The volatile components were removed
by rotary evaporation and the residue was allowed to react with
EtOH (1.0 ml). The excess of EtOH was evaporated to leave a viscous
liquid, which did not solidify on standing (2 h). Drying under
vacuum at 60.degree. C. finally caused solidification of some of
the material; some remained as a viscous film (103 mg). A sample
was purified on a Trikonex column (3/2 n-heptane/EtOAc) to remove
HNIW (contaminant in WH.sub.5H).
[0197] .sup.1H NMR: (acetone-dr): .delta. 1.24 (t, 12.81) 4.14 (q,
7.90H), 7.65 (d, J=8.0 Hz, 2.02H), 8.03 (S, 1.99H), 8.14 (d, J=7.9
Hz, 2.00H), 9.10 ppm (br s, 1.22H, NH).
[0198] .sup.13C NMR (acetone-1): 14.6, 63.0, 71.4, 71.5, 75.0,
151.4, 151.9, 152.8 ppm
Reaction Scheme 10
[0199] WN.sub.4 (CONHCOOEt) 2:
4,10-bis(N-ethoxycarbonylcaroxamido)-2,6,8,10,12-tetranitro-2,4,6,8,10,12-
-hexaazaisowurtzitane.
Reaction of WN.sub.4H.sub.2 with (i) ClCONCO, (ii) EtOH; Formation
of WN.sub.4 (CONHCOOEt).sub.2
[0200] WN.sub.4H.sub.2 (50 mg) was suspended in anhydrous
acetonitrile (1.0 ml) under N.sub.2. N-(chlorocarbonyl) isocyanate
(0.20 ml) was added by syringe via the septum cap. The suspension
cleared almost immediately to leave a pale yellow solution which
was stirred at room temperature for 10 min. The volatile components
were removed by rotary evaporation to leave a viscous liquid, to
which ethanol (1.0 ml) was added. An exotherm was observed, and a
white precipitate formed rapidly. The excess EtOH was evaporated to
leave a yellow solid. The .sup.1H NMR spectrum of the material
exhibited the typical hexaazaisowurtzitane methine signals in a
ratio of 2:1. The presence of N--H appeared to be confirmed by
FTIR.
[0201] .sup.1H NMR: (acetone-d.sub.6): .delta. 1.22 (t, 7.67H) 4.17
(q, 4.80H), 7.42 (s, 3.99H), 7.85 (s, 2.00H), 9.50 ppm (br s,
1.50H, NH).
[0202] .sup.13C NMR (acetone-d.sub.6): 14.5 62.9, 70.6, 74.8,
151.9, 152.8 ppm.
Reaction Scheme 11
[0203] WN4(NO)2:
4,10-dinitro-2,6,8,12-tetranitro-2,4,6,8,10,12-hexa aza iso
wurtzitane.
Reaction of WH.sub.4H.sub.2 with N.sub.2O.sub.4; Formation of
WN.sub.4(NO).sub.2
[0204] WN4(NO)H: 4-nitroso-2,6,8,12-tetranitro-2,4,6,8,10,12-hexa
aza isowurtzitane
[0205] WN.sub.4H.sub.2 (25 mg) was suspended in HOAc (1.0 ml)
before the addition of N.sub.2O.sub.4 (0.75 ml). The reaction
mixture was stirred at room temperature for 20 h, at which point
TLC showed no starting material remained. The main spot (high
R.sub.f) was assumed to be WN.sub.4 (NO)H and a very faint spot at
lower R.sub.f was assumed to be WN.sub.4 (NO)H. The solid was
removed by filtration. The filtrate gave no further precipitation
on drowning in ice/water. The NMR spectrum of the solid confirmed
that the new product was neither WN.sub.4(NO)H nor HNIW, and most
probably WN.sub.4(NO)H.
[0206] .sup.1H NMR (acetone-d6): .delta. 7.96 (s, 1.00H), 8.10 (s,
2.00H), 8.22 (m, 1.14H), 8.28 (m, 1.11H), 8.54 ppm (s, 0.94H)
[0207] .sup.13C NMR (acetone-d6): 61.6, 62.4, 73.5, 74.7, 74.9 (w),
75.2, 75.7 ppm (w).
Comparative Analysis
[0208] The comparative examples below and the synthetic routes of
FIGS. 1,2 and 3 use
2,6,8,12-tetraacetyl-2,4,6,8,10,12-hexaazaisowurtzitane (compound
A) as a starting material. The production of compound A is detailed
in International Patent Application WO9623792 and European Patent
EP 0753519.
COMPARATIVE EXAMPLE 1
[0209] Attempts were made to nitrate
2,6,8,12-tetraacetyl-2,4,6,8,10,12-hexaazaisowurtzitane (compound
A) to form 2,6,8,12-tetranitro-2,4,6,8,10,12-hexaazaisowurtzitane
(compound D).
[0210] Compound A (100 mg) was dissolved in concentrated sulphuric
acid (0.45 ml), and cooled to 0.degree. C. Nitric acid (90 or 99.5
wt %, 4 or 6 equivalents) was added. The solution was maintained at
0.degree. C. for the required period and then poured onto ice (10
g). The precipitated solid was filtered off, washed with water and
dried. The product was analysed by thin layer chromatography and
.sup.1H NMR spectroscopy. TLC indicated the number of components in
the product mixture and identified
2,4,6.8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20)
when present. NMR indicated the proportion of the N-acetyl groups
that remained un-nitrolysed, the content of CL-20 and the presence
of NH groups. The following experimental results are
representative.
Experiment 1 (Using 90 Wt % Nitric Acid, 4 Equivalents, Held at
0.degree. C. for 20 Hours).
[0211] The product was largely
2-acetyl-4,6,8,10,12-pentanitrohexaazaisowurtzitane, with approx.
15% CL-20. About 22% of the N-acetyl groups remained
un-nitrolysed.
Experiment 2 (Using 99.5 Wt % Nitric Acid, 4 Equivalents, Held at
0.degree. C. for 4 Hours)
[0212] Product contained approx. 3% CL-20 with about 39% of the
N-acetyl groups remained un-nitrolysed.
Experiment 3 (Using 99.5 Wt % Nitric Acid, 4 Equivalents, Held at
0.degree. C. for 23 Hours)
[0213] Product contained approx. 56% CL-20. About 5t of the
N-acetyl groups remained un-nitrolysed, the majority of this
material comprised of 2-acetyl-4,6,8,10,12-pentanitro hexaazaiso
wurtzitane.
[0214] There was no NMR evidence that NH groups were present. This
indicates that 2, 6, 8,12-tetranitro-2,4,6,8,10,12-hexais
owurtzitane (compound D) was not present in the product of the
reaction.
COMPARATIVE EXAMPLE 2
[0215] Attempts were made to nitrate
2,6,8,12-tetraacetyl-2,4,6,8,10,12-hexaazaisowurtzitane (compound
A) to form 2,6,8,12-tetranitro-2,4,6,8,10,12-hexaazaisowurtzitane
(compound D) based on the methodology of Hamilton et al. (ICT
Conference on Energetic Materials, Karlsruhe, Germany, 2000, 21-1
to 21-8), varying the nitration conditions suggested by Hamilton in
order to try to obtain compound (D). Compound A (175 mg) was
dissolved in a cooled mixture of concentrated sulphuric acid
(0.0072 ml) and 99.5 wt % nitric acid (0.50 ml) and immediately
heated to 85.degree. C. After the required period the solution was
cooled and added to ice (5 g). The precipitate solid was filtered
off, washed with water and dried. The product was analysed by thin
layer chromatography and .sup.1H NMR spectroscopy.
[0216] The following experimental results are representative.
Experiment 1 (Held at 85.degree. C. for 30 Mins)
[0217] Product contained about 57% CL-20, with about 15% of the
N-acetyl groups being un-nitrolysed.
Experiment 2 (Held at 85.degree. C. for 5 Mins)
[0218] Product contained about 1% CL-20, with about 57% of the
N-acetyl groups being un-nitrolysed. There was no NMR evidence that
NH groups were present. This indicates that
2,6,8,12-tetranitro-2,4,6,8,10,12-hexaazaisowurtzitane (compound D)
was not present in the product of the reaction.
[0219] It has thus been shown that it has hitherto not been
possible to produce 2,6,8,12-tetranitro-2,4,6,8,10,12-hexaazaiso
wurtzitane (compound D) using the methods of the prior art.
* * * * *