116 Synthetic Routes to Nitrate Esters
O
H 3 C CH 2 ONO 2
HO O
H 3 C CH 2 ONO 2
H
n
122
Poly[NIMMO]
43
(NIMMO)
Figure 3.54
3-Nitratomethyl-3-methyloxetane (NIMMO) (43) is synthesized from the selective nitration
of the hydroxy group of 3-hydroxymethyl-3-methyloxetane with dinitrogen pentoxide in an
inert solvent.36aThe cationic polymerization of NIMMO using an initiator system of boron
trifluoride and a diol yields the energetic polymer poly[NIMMO] (122).^37 Poly[NIMMO]
generated by this process is a viscous liquid with a very low sensitivity to impact and well
suited for use as an energetic binder for rocket propellants and plastic bonded explosives
(PBXs). The synthesis and scale-up of NIMMO and its polymerization to poly[NIMMO] was
pioneered by chemists at DERA (British Defense Evaluation and Research Agency). Chemists
at DERA have also developed a plastic bonded explosive called CPX-413 which is based on
poly[NIMMO]/HMX/NTO/plasticizer and is ranked as an extremely insensitive detonating
substance (EIDS).
O
O
R
O
OH
ONO 2 O 2 NO
H
ONO 2
O
nn
123
Poly[GLYN]
19
(GLYN)
Figure 3.55
Glycidyl nitrate (GLYN) (19) is synthesized in high yield and purity from the selective nitra-
tion of glycidol with dinitrogen pentoxide in an inert solvent.^35 ,^36 The cationic polymerization
of glycidyl nitrate is more difficult than the polymerization of NIMMO and requires a strong
mineral acid like tetrafluoroboric acid.^37 The product, poly[GLYN] (123), is a low molecu-
lar weight hydroxy-terminated pre-polymer which reacts with diisocyanates to give energetic
polyurethane polymers.^164 Willer and co-workers^165 have reported on an improved process
for producing poly[GLYN] which is well suited for use as an oligomer in solid high-energy
compositions. Willer and co-workers^166 have also described the use of low molecular weight
poly[GLYN] for use as an energetic plasticizer. In this context, poly[GLYN] has a number of ad-
vantages over traditional nitrate ester plasticizers, including: low volatility, lowTg(∼− 40 ◦C),
excellent miscibility with the binder and decreased plasticizer mobility. On the basis of perfor-
mance and the ease with which poly[GLYN] is prepared via dinitrogen pentoxide technology,
it seems likely that it will prove to be a world leader in the field of energetic polymers.
Recent interest has turned to nitrated cyclodextrin polymers (poly-CDN) for potential use
in insensitive and minimum smoke producing propellants.^167 The synthesis, purification and
characterization of the following polymers was studied in detail:^168
(1) r-Cyclodextrin polymer cross-linked with 1-chloro-2,3-epoxypropane.
(2) r-Cyclodextrin polymer cross-linked with 4,4′-methylene-bis(phenyl isocyanate).