Chemistry of High Energy Materials

Chemistry of High Energy Materials
R.A. Rodriguez
Baran GM
2012-08-18
History of Explosives
7th century A.D.- "Greek Fire" petroleum distillate used by
Byzantines of Constantinopole
High Energy Materials
13th century - black powder (aka gunpowder) Chinese alchemists
Non-explosive materials
Explosives
18th century - black powder composition became standardized:
KNO3/charcoal/sulfur (75/15/10 w/w)
19th century - NH4NO3 replacement for KNO3 in black powder
1846 - Italian Chemist Ascanio Sobrero invented nitroglycerin (NG)
High Explosives
Low Explosives
[detonate]
1° Explosives
2° Explosives
[detonate by ignition]
- Lead azide
- Tetrazene
[need detonator]
- TNT
- RDX
[deflagrate-burn rapidly]
Propellants
- Black powder
- liquid/solid
Pyrotechnics
- Fireworks
- Color/flash/sound
Organic Chemistry of Explosives by J.P. Agrawal and R.D. Hodgson
Prof. Thomas Klapotke - Ludwig-Maximilians-Universität München - Germany
Chair of inorganic chemistry
Dr. Michael A. Hiskey - Los Alamos National Laboratory
What makes an explosion?
1863 - German chemist Julius Wilbrand invented 2,4,6-trinitrotoluene (TNT)
originally used as a yellow dye. Potential as an explosive not appreciated
due to difficulty to detonate (insensative).
1866 - Mixing of NG with silica (PBX) to make malleable paste (dynamite)
late 19th century - nitration chemistry on common materials (resins,cotton, etc.)
1910 - military use of TNT for artillery shells and armour-piercing shells
1939-1945 - World War II - Research on explosives intesified (nitration chemistry)
Developlment of cyclotrimethylenetrinitramine (RDX) and
cyclotetramethylenetetranitramine (HMX).
Introduction to high energy materials terminology
Brisance: Shattering capabiliy of explosive. Measure of rate an explosive
develops its maximum pressure.
Relative effectiveness factor (R.E. factor): Measurement of an explosive's
power for military purposese. It is used to compare an explosive's
effectiveness relative to TNT by weight (TNT equivalent/kg or TNTe/kg).
Exothermic chemical reaction comprised of an oxidant and fuel, which releases
energy (gas and heat) in a given time interval.
Detonation velocity (VoD): The velocity at which the shock wave front travels
through a detonated explosive. Difficult to measure in practice so use
gas theory to make prediction.
Whats the difference between explosive, propellants and pyrotechnics?
Specific impulse (Isp): The force with respect to the amount of propellant used
per unit time. Used to calculate propulsion performance.
Rate at which it burns (Flamming gummy bear vs. rocket booster vs. TNT)
Speed of reaction will determine subsonic vs. supersonic blast pressure waves
Oxygen balance (OB%): Expression used to indicate degree to which explosive
can be oxidized. If explosive contains just enough oxygen to form carbon
dioxide from carbon, water from hydrogen molecules and all metal oxides from
metals with no excess, the explosive is said to have zero oxygen balance.
Chemistry of High Energy Materials
R.A. Rodriguez
Chemical types/class of organic explosives
Aromatic C-nitro compounds
Aliphatic C-nitro compounds
NO2
R1
1° nitroalkane
R2
2° nitroalkane
NO2
high explosive with
high thermal and
chemical stability
NO2
Internal
gem-dinitroalkane
Trinitromethyl
N
H
O2NN
NO2
O2N
S
O2N
O2N
N
H
N
4-amino-3,5-dinitropyrazole
(LLM-116)
O2NN
NO2
NNO2
H2N
NO2
N
NH2
O
pyridine N-oxide
O2N
H 2N
N
N
O
NH2
NO2
NH2
N
N
N
O
O2N
NO2
N
NH2
pyrazine N-oxide tetrazine N-oxide
NO2
Ar
F2 N
benzotriazoles
tetrazoles
N
H2N
N
H
N
NO2
1,2,4 triazoles
NH2
nitroguanadine
O2N
NNO2
O2N
NF2
3,3-bis(difluoroamino)
octahydro-1,5,7,7tetranitro-1,5-diazocine
(TNFX)
N
Ar
N
O
NO2
NO2
O2NN
ONO2
N
N
NO2
O2N
H2N
N
H
N
N
ONO2
ONO2
O2NO
N
N
NO2
O2N
NO2
N
H
O2N
Si
H2N
NO2
N,N'-dinitrourea
(DNU)
Si-PETN
N
N
H
ONO2
NO2
O2NO
N
N
O
O2N
novel energetic nitrate eseter
furazans/benzofurazans
furoxans/benzofuroxans
N
N
O
ONO2
O2NO
N
N
N
RDX (VOD=8440 m/s) HMX (VOD=9110 m/s)
O
NO2
O2N
Pentaerythritol tetranitrate
(PETN) (VOD=8310 m/s)
O2NO
O2N
NO2
ONO2
NNO2
N
NH
2,4-dinitroimidazole
(2,4-DNI)
Aliphatic N-nitro compounds
Nitroglycerin (VOD=7750 m/s)
O
O
NH2
x≥4
poor chemical
stability
N
O2NO
O2N
N
NO2
O2N
ONO2
O2NO
NO2
(NO2)x
1,3,5-trinitrobenzene 2,4,6-trinitrophenol
(TNB)
(picric acid)
O2NO
O
H2N
O2N
TNT
NO2
O2N
NO2
Aliphatic O-nitro compounds
Nitro derivatives of pyrroles, thiopenes, and furans are not practical explosives:
1. heat of formation offers no benefits over standard arylene hydrocarbons
2. during nitration, these heterocycles are much more prone to oxidation and
acid cat. ring opening compared to arenes
H-bonding
reduction in
sensativity
HO
Me
ONO2
NO2
heterocycles
NO2
NO2
R1
NO2
NO2
3° nitroalkane
NO2
R2
NO2
R1
acidic protons
(condensation
chemistry)
Terminal
gem-dinitroalkane
R2
R3
R1
R
NO2
NO2
NO2
NO2
R2
R
Baran GM
2012-08-18
1,3,4-oxadiazoles
N
N
NO2
NO2
N
N
NO2
Hexanitrohexaazaisowurtzitane
(HNIW or CL-20)
(VOD=9380 m/s)
H
N
O2N
Ar
N
N
N
O
NH
3-nitro-1,2,4-triazol-5-one
(NTO)
Chemistry of High Energy Materials
R.A. Rodriguez
Nitration chemistry
TMS
_ OAc
TMS
Routes to C-Nitro functionality
NO2
Me
HNO3
25%
Me
Me
N2O4
Me
O
Me
Me
NO2
H
Me
NO2
Me
O2N
O
N
O
O2N
N
Me
Me
Me
Me
O
O2N
ONO
Me
Me
Me
Me
dinitro
O2N
+
ONO2
nitro-nitrite
1. NaHMDS
2. N2O4
O2N
NO2
Ph
OH
DCE/ rt
Ph
+
NO2
Ph
76%
74%
O2N
NO2
2. N2O4 -78 °C
77%
NItration selectivity on arene/heteroarene
Kakiuchi, et al. Synlett 1999. 901
H
H
NaNO3 xs,
CAN 2eq
R
R
AcOH/CHCl3
80 - 90%
H
R
NO2
R
H
H
R
H
R
NO2
R
R
R
R
Hwu et al. J Chem Soc Chem Commun 1994. 1425
Taniguchi et al. JOC 2010. 75, 8126
Ph
NO2BF4
MeCN
84%
TBAN
CO2R
O
NO2
NO2
NO2
O2N
NO2
Cl
N
N
CO2R
Cl
NO2
R
O2N
N
NHAc
Ph
O2N
Cl
80 - 90%
NO2
H
MeCN, reflx
NO2
H2SO4
traditional
[NO2+]
44%
N
Fe(NO3)3 9H2O R
FeCl3
O2N
KNO3
Cl
NO2
92%
NO2
S
23%
Ph
OAc
NO2
Al2O3
Mukaiyama et al. Chem Lett 1995. 505
O
O2N
1. nBuLi
S
NO2
O
N
NO2
O2N
Br
- colorless liquid
1 atm NO
NO2
O
N
NO2
nitro-nitrate
Radical methods
Nef
AcONO2
OAc
O
Me
Me
Me
Me
NO2
NO2+
ONO2
alkaline nitration
O2N
+
_
O
Nitration with HNO3 is difficult
NO2
O
N
Direct nitration of aliphatic and alicyclic hydrocarbons possible in the vapor
phase using HNO3 or NO2 (toxic redish-brown gas) at elevated temperatures.
H
O
ONO2
[2+2]
Borgardt et al. Chem Rev 1964. 64, 19 (polynitro functionality)
NO2
NO2
NO2
AcONO2
The nitro gorup whether attached to aromatic or aliphatic carbon, is probably
the most widely studied of the functional groups and this is in part attributed
to its use as an 'explosophore' in many energetic materials.
Baran GM
2012-08-18
F3 C
O
O
O
TBAN
CF3
F3C
O
NO2
TFAA
76%
N
NO2
N
CO2R
* No rxn in
presence of
TEMPO
Chemistry of High Energy Materials
R.A. Rodriguez
1° and 2° nitro compounds
Victor Meyer rxn
- alkyl chlorides too slow
- only good for 1° (2° alkyl halide gives nitrate ester)
- nitrate ester arises from desproportionation of silver nitrate acc. by heat/light
R
+
X
N
O
NOH
O
ether
R
OAg
NO2
+
AgX
R
O
NO
1.KOtBu
amyl nitrate
2. H+
1. NBS
2. [O]
3. [H]
O
NaNO2
DMSO
fast
X
R
R
R
N
NO2 +
O
R nitrite ester
R
H+
OH
NO2
HO
OH
phloroglucinol
O
O
N
NO
R
CO2H
R
HNO3
F
20 - 30%
R
NO2
CO2H
O
NO2
MeO2C
NH3+Cl-
O
Ag+
N
R2
O
O
Acetone
91%
NH3+C
C+H3N
NH
DMDO
Acetone/H2O
85%
O2N
Eaton et al. JOC 1988. 5353
Ag0
Ag+
Ag
O O
N
O
O O
-Ag0
N O
R1
R2
O
R2
O
N
N O
R1
retro
aldol
O
N
O
NH
O
Me
via amine thus
H2O essential
R2
ONO2
R2
-CH2O
O
Me
O
NO2
Me
O
OH
N
Fe
NO2
NO2
R1
Me
N
O2N
NCO
2. AgNO3
NO2
ONO2
NO2
NO2
Me
N
O2N
NO2
O2N
N O
NO2
O
NO2
Original Target/Route via modified Kaplan Shechter Rxn
O
oxidation of isocyanates
OCN
R1
O Na
DMDO
C+H3N
N
O2N
NO2+
O2N
Kaplan
Shechter Rxn
1. NaNO2
O O
Me
NO2
O
R2
R1
nitronate
N
Me
N
R2
NO2
oxidation of amines
O
NaOH
NO2
NO2
HNO3
60 %
N
O2NO
R1
MeO2C
H+
O
Chavez, D.E. et al. Angew. 2008, 47, 8307
NO2
NO2
O
O2NO
R1
NO2
R
NO2
S2O8 2-
Synthesis of an energetic nitrate ester
Kornblum et al. JACS 1956. 78, 1497
gem-dinitros from acids
R
only useful
oxidant
OH
R
OR
NO2
NO2
NO2 (or)
NO2
O2N
NO2
F
NO2
N
(low yields)
O
Fluorotrinitromethane
NO2
OH
R
NO2
slow
O
R
R
R
O NaNO
2
O
NO2+
O2N
NO2
NO2H
modified VM (alkali metal nitrites e.g. NaNO2) time and solubility is VIMP
R
CF3CO3H
Baran GM
2012-08-18
O
Me
N
O
activation
NH
O
Me
O
Me
O
NH
N
N
N
N
O
[O]
O
R
N
O
NH
NH
O
NH
N
N
N
R
NH
N
N
N
Chemistry of High Energy Materials
R.A. Rodriguez
Initial Results: homocoupled product
HO
1. 2-methoxypropene
Me
cat. H+
NO2
HO
OH
Me
2. NaOH
Me
O
N
O
Me
O
O
N
O
O
O
Me
Me
O
O
Me
O
N
O
NC
CN
+CN-
CN
CN
O2NO
m.p. 86 °C
Det.Temp
140 °C
O2NO
- Use of mixed acids (esterification) and nitrogen oxides described for C-Nitraion
Key points:
H
N
1. fuming (anhydrous) HNO3 prep: dry air bubbled through anhydrous HNO3 to
O
O
N
X
H2N
remove any oxides of nitrogen present, followed by addition of trace urea
N
N
NO2
to
remove any nitrous acid present. AKA "white nitric acid"
N
O
N
N
2. Urea destruction of nitrous acid important to avoid violent fume-off
Me
NO2
NH 3. O-nitrations with mixed acids of "white nitric acid" above ambient temperatures
Me O
O Me
is dangerous and has increase risk of explosion
NO2
NH
Me
4. anhydrous HNO3/Ac2O- Acetyl nitrate is generally a weak nitrating agent but
12%
O
in the presence of a strong acid like HNO3, ionization to nitronium ion occurs
O
O
Me
O
-NaSO4NO2
N
NC
CN
NC Fe
NC
O
O2NO
O
NaO3S
O
OSO3Na
O
ONO2
1.HCl, MeOH
ONO2
2. Ac2O/HNO3
N
O Me
72% (2 steps)
O2NO
O
HO
OH
O
NO2
OH
O Me
65% optimized
ONO2
OH
NO2
OH
NO2
O2NO
ONO2
comparable
stability to PETN
N
N
N
N
NO2
Me
Me
N
Me
2 eq NO2
Olah G.A. et al JOC, 1965. 30, 3373
ONO2
+
MeCN
quant yield
ONO2
Me
N
H
BF4Me
in situ halide displacement with AgNO3
R
O2N
O2NO
Me
Me
O2N
70%
ONO2
Transfer nitration (neutral conditions - good for acid sensative alcohols)
NO2
O
HO
Ac2O
shock sensative
Fe
O2NO
20,164 MPH!!
90%
ONO2
OH 90% HNO3
BF4Me
NO2
anh HNO3 HO
Ac2O
NO2
O
Me
NO2
ONO2
SO3Na
CN
NO2
O
Me
O
O Me
O
N
O
Me
Me
O
NC Fe
O
N
Me
CNNC
Routes to O-Nitro functionality
1.cat. K3[Fe(CN)6]
Na2S2O8
NO2
Me
activation
-
O
Me
O
O
Baran GM
2012-08-18
OH
PPh3, I2
R
I
AgNO3
R
CHEETAH calculates
as powerful as HMX
Low yields for 2°
HgNO3 can be used for 2° and
3° alkyl halide displacements
ONO2
decomposition of nitrocarbonates (very mild, rt or reflux MeCN)
O
RO
O
AgNO3
Py
Cl
RO
-AgCl
ONO2
-CO2
ring opening of strained oxygen heterocycles
NO2
works for 1°, 2°, 3° alcohols
N2O4
O (or)
CH2Cl2
O
ONO
ONO2
R
ONO2
80%
H2O
[O]
N2O5
HO
O2NO
ONO2
ONO2
Chemistry of High Energy Materials
R.A. Rodriguez
selective O-nitrations
1 eq SOCl(NO3)
65%
ONO2
OH
nitrodesilylation
anhydrous ZnCl2, hydrochloride salt of amine, or dissolved HCl(g) can serve
as a source of electropositive chloride under the oxidizing conditions of nitration
ONO2
OH
3 eq SOCl(NO3) O2NO
100%
RO SiR3
-chloride ion catalysis
OH
2 eq SOCl(NO3) O2NO
70%
OH
HO
HO
2 HCl
ONO2
RO
CH2Cl2
ONO2 + O2NO SiR3
R NH2
R2NCl
NO2F
R
MeCN
HN
N
R
N
O
N
R
NC
N
O
CN
Me
93%
22%
How to get around this problem??
- synthesis via condensation chemistry (Mannich, 1,4 addition, etc)
N
R NH2
R NH2
Ar NH2
nBuLi
-78 °C
R NHLi
1. Na
2. EtONO2
Et
ONO2
R N
N
-
O
Ar N
N
ONa
HNO3
Ac2O
R2NNO2
+
+
+
+
4AcOH
AcOH
+
AcOCl
+
AcOH
N
HNO3/Ac2O
R = Cl- (N+)
CN
R
N
NC
HNO3/Ac2O
R=H
CN
NO2
N
NC
70%
CN
Me
2 HOCl
R NCl2
HNO3/Ac2O
R N
NO2 NaHSO (aq)
3
R NHNO2
Cl
6%
A
Path A
O2N
O
R1
N
R2
N
+
R1 CO2H
R2
R2
O
Path B
R2
B
R1
NO2
N
+
R2 OH
R2
Nitramine formation via nitrolysis possible from:
NO2
R NH
R1
OLi
Ar NH2
Na+
EtONO2
R2NCl
N2O3
- Nitrolysis of fully substituted nitrogen
rupture of C−N bond leading to formation on N−NO2
What about if need more direct method??
-non-acidic nitrating reagents (nucleophilic nitration)
H+
R2NH
+
X
analines - must contain one or more nitro groups on the aromatic ring
O
2AcOCl
AcOCl +
93%
HNO3/Ac2O
(w/o chloride)
NO2
N
NO2
R OH + N2O
3Ac2O
NO2
NC
- Direct nitration of a 1° amine to a nitramine using HNO3/mixed acids is not
possible due to instability of the tautomeric isonitramine in strongly acidic
conditions. 2° amines are more stable and can undergo electrophilic nitration
using HNO3/Ac2O
NO2
2° w/ HNO3/Ac2O
H+
+
Wright et al. Can. J. Res. 1948. 26B, 294
- Compounds resulting from nitration of nitrogen are of far less use for
mainstream organic synthesis. However the N-NO2 group is an important
'explosophore' and is present in many enrgetic materials
OH
2HNO3
ONO2
Routes to N-Nitro functionality
O
+
ONO2
deamination
N2O5
Baran GM
2012-08-18
H+
NO2
Ar NH
R1
N
R1
NO2+
R1
Ph
N
NO2
Ph
O
R2N
NR2
R2N SiR3
R2N NO
R1
- carbamate
- urea
R2 - formamide
N
- acetamide
R2
- sulfonamide
Ease of alkyl nitrolysis depends on stability of the resulting cation:
benzyl, tertiary (t-Bu), etc...
Chemistry of High Energy Materials
R.A. Rodriguez
Synthesis of Hexanitrohexaazaisowurtzitane (HNIW)
Syntheses of some nitramine explosives
- Many nitramines are more powerful than aromatic C-nitro compounds and have
high brisance and high chemical stability and low sensativity to impact and
friction compared to nitrate ester explosives. This is why they are of interest to
military applications.
O
NH2
+
Ph
cat. H+
N
O
Ph
[O]
N
Bn
Ph
O
N
CrO3
O
Bn
N
N
N
N
O
Me
Ac2O
N
Bn
Bn
Bn
Bn
Bn
N
Ph
Bn
N
MeCN/H2O
H
H
2 eq.
Bn
Bn
N
N
N
N
O2N
O2N
N
N
N
Bn
N
N NO2
N
NO2
NNs
NsCl,
K2CO3 (aq)
95%
OH
Bn
1. CrO3, AcOH
2. HOCH2CH2OH
TsOH
NNs
82% (2 steps)
OH
Br
Bn
X NO2+
O2N
1. HNO3/NH4NO3
urea, 33%
NNs
2. H2SO4
92%
NNs
1. O3, CH2Cl2
2. DMS
NNs
O
O
NNs
NNs
O
O
76%
Br
K2CO3
NOH
NO2
NNs
decomp. messy. Nitration
of aromatic rings
NNs
3. NH2OH/NaOAc
86% (3 steps)
O
NNs
O
O
Ph
Ac
O2N
1. N2O4
N
O
Bn
Bn H , Pd(OAc)
Ac
Ac 2. HNO3/H2SO4 2N
N
2
2
N
N
via nitroso
Ac2O, PhBr cat.
N
N
N
N
N
93%
65%
Bn
O2N
Bn
Bn
Bn DANGER!
H2,
99% HNO3
NO2
[Pd]
O2N
N
NH2
N
N
H2,
[Pd] X
NH2
Bn
N
N
N
Baran GM
2012-08-18
Ac
Ac
Ac
HN
N
N
N
Ac
N
N
N
N
Ac
NH
1. HCO2H
2. Ph, Δ
-H2O
Ac
Ac
OHCN
HNIW aka CL-20
- explosive/propellant (low smoke-emission)
- most powerful to date (better oxidizer-to-fuel than RDX/HMX)
- first prep by Nielsen 1987 Naval Air Warefare
- pilot plant in 1990 for 200 kg in China Lake facility
- unmatched performance in specific impulse,
burn rate, detonation velocity (9.38 km/s = 21,000 MPH!!)
- highest density than any other explosive (d = 2.044 g/cm3)
- thermally stable (250 -260 °C) but sensative to mechanical stress
still greater stability than nitrocellulose, PETN and others.
- 4 different polymprphs with different densities/properties
NO2
N
N NO2
F2NSO3H,
90% HNF2, H2SO4,
CFCl3
Ns
N
NO2
O2N
NO2
N
N
F2 N
O2N
HNO3/SbF6
Ns
CF3SO3H
N
N
N
NO2
NF2
TNFX
(3,3 bis(difluoroamino)octahydro
1,5,7,7 tetranitro 1,5 diazocine)
Ac
NCHO
N
F2N
NF2
Ac
N
N
O2N
NO2
NH2
OH HBr-AcOH Br
HO
160 °C
72%
OH
O2N
NO2
N
NO2
TNAZ
NH3+BrBr
Br
NaOH, 80 °C
60 mmHg
Br
1. NaHCO3, NaI
DMSO, 100 °C
N
O2N
2. NaNO2, NaOH
K3Fe(CN)6, K2S2O8
29% (2 steps)
CH2Br
1. NaNO2 (aq)
2. HCl (aq)
10%
O2N
CH2Br
HNO3/TFAA
N
NO2
81%
N
NO
Chemistry of High Energy Materials
R.A. Rodriguez
N2O5
No single nitrating agent is as diverse and versatile
It is considered as the future for energetic materials synthesis
Preparation of N2O5 [Deville 1849] O
AgNO3
non-acidic nitrating reagents (neutral)
1° amines/nitramines leads to deamination and formation of nitrate ester
by-product but analines are successful.
N2O5
O
O
O nitronium nitrate salt
N
N
O
[NO2+][NO3-]
O
condition: chlorinated solvents
- clean and selective
- non-oxidizing &n non-acidic
HNO3
- adopts two structures
depending on condition
condition: anhyd. HNO3
- powerful but acidic and non-selective
- 1st prepared over 150 years ago but due to difficult prep and low thermal
stability (require -60 °C long term storage) received little attention.
- Environmental restrictions and push for green chemistry sparked interest
Advantage: Rxns are very clean
- faster and less exothermic (due to absence of oxidation byproducts)
- high yields
- simple isolation
- non-acidic conditions possible with this reagent (compared to mixed acids)
rt
Stable for 2 weeks at -20 °C
N2O5
2 N2O4 + O2
Stable for up to 1 yr at -60 °C
synthesis of TNT under mild conditions
Me
N2O5/HNO3
O2N
NO2
H
N
O
O
N
H
O2N
HNO3
H2SO4
N
O
O-nitrations of polyols
OH
OH
OH
HO
OH
OH
O2N
H
N
N
NO2
P2O5
N
N
N
N
O
O
O2N
NO2
ONO2 ONO2
N2O5, CCl4
0 °C
quant yield
HNO3
NO2
ONO2 ONO2
AgNO3
N2O5
H3PO4
N2O4
O3
N2O5
Process chemist at Defense and Evaluation Research Agency (DERA) in the UK
Development of a flow process: Using commercial ozonizer to generate 5 - 10%
mix of ozone in oxygen and mixed in flow with N2O4. N2O5 is trapped in solid
condenser tubes (cooled by dry ice/acetone).
Explosives in JACS: Sila explosives
O2NO
O2NO
ONO2
PETN
- Det. Velocity 8,400 m/s
- d= 1.7 g/cm3
VERY high edens
Si
Klapotke T.M. JACS 2007. 129, 6908
- Used in WW I
- One of most high energy explosives known
- more shock sensative than TNT. used as booster mix
- Europe marketed as lentonitrat (vasodilator) like NG
ONO2
ONO2
ONO2
"The crystalline compound exploded on every
occasion upon contact with Teflon spatula...
Solutions in diethyl ether exploded upon the slighest
evaporation of the solvent."
Si(CH2OAc)4
Si(CH2Cl)4
Why does Si-PETN have drastically increased sensativity?
Theoretical: electrostatic potential:
1. Surface electrostatic potential, in general, is related to the sensitivity of the bulk
2. The more evenly distributed the electrostatic potential is over the surface of a
molecule, the more stable it is to impact.
O2NO
O2NO
ONO2
O2NO
+
+
- isolation by sublimation and collection trap at -78 °C
- stream of ozone needed to avoid collection on N2O4
- if don't care about acidity, can use HNO3/P2O5 mixture directly (no ozone stream)
VERY
low e- dens
O
N
H
N2O5
Cl
Δ
O2NO
NO2
N
O
P2O5
O2NO
No explosion hazard
N-nitrations of ureas
Cl2 (g)
Silicon analogue of PETN
32 °C,
quant yield
NO2
N
H
+
Me
NO2
H
N
+
Dehydration of nitric acid
polar
sublime slightly above rt
Baran GM
2012-08-18
O2NO
O
Si
N
O
O