The novel candidate high energy insensitive explosive; 2,5-diamino-3,6-
dinitropyrazine (ANPZ-i) (10) has been prepared in acceptable overall yield.
ANPZ-i was synthesised by the nitration of 2,5-diethoxypyrazine (149, R=Et)
using nitronium tetrafluoroborate (NO2
-) in sulfolane and the subsequent
amination of 2,5-diethoxy-3,6-dinitropyrazine (150, R=Et) under autoclave
conditions. Oxidation studies towards the dioxide derivative of ANPZ-i, 2,5-
diamino-3,6-dinitropyrazine-1,4-dioxide (PZDO) (11), were unsuccessful. The
synthesis of existing high explosives; 2,6-diamino-3,5-dintropyrazine (ANPZ)
(95) and 2,6-diamino-3,5-dinitropyrazine-1-oxide (PZO) (9) has been scaled up to
produce approximately 25 g batches of material.
A number of novel nitrations using NO2
- have been carried out on a range of
chloro-, methyl- and hydroxy-functionalised quinoxalines and quinazolines.
A range of novel functionalisations have been carried out on the platform
molecule 2,4-diamino-6,8-dinitroquinazoline (61) giving rise to 2,4-diamino-6,8-
dinitroquinazoline-1,3-dioxide (141) (di-N-oxidation product), 2,4,7-triamino-6,8-
dinitroquinazoline (142) (monoamination product) and 2,4,6,8-tetraaminoquinazoline
(143) (dihydrogenation product).
Detonics molecular modelling was carried out on the following target molecules:
2,5-diamino-3,6-dinitropyrazine-1,4-dioxide (PZDO) (11), 2,5,8-triamino-3,6,7-
trinitroquinoxaline-1-oxide (151) and 2,5,7-triamino-4,6,8-trinitroquinazoline-1-
oxide (138). The detonation velocity of the new explosive molecule; 2,5-
diamino-3,6-dinitropyrazine (ANPZ-i) (10) was calculated and it was found to be
a similar value to that obtained experimentally for the existing high explosive
RDX (5). Calculation by molecular modelling of the steric energies of ANPZ
(95), PZO (9), ANPZ-i (10) and PZDO (11) gave a quantitative assessment of the
difficulty in oxidising ANPZ-i to give PZDO.
Extensive analysis of carbon-13 NMR spectroscopy shift values was carried out
for approximately twenty nitrogen heterocyclic compounds. Comparison of shift
values indicated consistency in the interpretations.
On-line literature searches have shown that the following compounds prepared in
this project are new: 2,3,6-trichloro-5-nitroquinoxaline (120), 2,3-dimethoxy-6,7-
dinitroquinoxaline (128), 2,3,6-trichloroquinoxaline-1-oxide (133), 2,4-diamino-
6,8-dinitroquinazoline-1,3-dioxide (141), 2,4,7-triamino-6,8-dinitroquinazoline
(142) and 2,5-diamino-3,6-dinitropyrazine (ANPZ-i) (10). Furthermore, new
synthetic routes have been used in the preparation of the following compounds:
2,3-dichloro-5-nitroquinoxaline (118), 2,3,6,7-tetrachloro-5-nitroquinoxaline
(123), 2-hydroxy-6-nitroquinoxaline (127), 2-hydroxy-3-methyl-6-
nitroquinoxaline (126) and 2,5-diethoxy-3,6-dinitropyrazine (150, R=Et).