chemistry of high energy materials
TRANSCRIPT
Chemistry of High Energy Materials R.A. Rodriguez Baran GM2012-08-18
High Energy Materials
Explosives Non-explosive materials
High Explosives Low Explosives
1° Explosives 2° Explosives Propellants Pyrotechnics
- Fireworks- Color/flash/sound
[detonate by ignition]- Lead azide- Tetrazene
[need detonator]- TNT- RDX
- Black powder- liquid/solid
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
History of Explosives
What makes an explosion?
Exothermic chemical reaction comprised of an oxidant and fuel, which releasesenergy (gas and heat) in a given time interval.
Whats the difference between explosive, propellants and pyrotechnics?
Rate at which it burns (Flamming gummy bear vs. rocket booster vs. TNT)Speed of reaction will determine subsonic vs. supersonic blast pressure waves
7th century A.D.- "Greek Fire" petroleum distillate used by Byzantines of Constantinopole
13th century - black powder (aka gunpowder) Chinese alchemists
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)
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).
[detonate] [deflagrate-burn rapidly]
Introduction to high energy materials terminologyBrisance: Shattering capabiliy of explosive. Measure of rate an explosivedevelops its maximum pressure.
Relative effectiveness factor (R.E. factor): Measurement of an explosive'spower for military purposese. It is used to compare an explosive'seffectiveness relative to TNT by weight (TNT equivalent/kg or TNTe/kg).
Detonation velocity (VoD): The velocity at which the shock wave front travelsthrough a detonated explosive. Difficult to measure in practice so use gas theory to make prediction.
Specific impulse (Isp): The force with respect to the amount of propellant usedper unit time. Used to calculate propulsion performance.
Oxygen balance (OB%): Expression used to indicate degree to which explosivecan be oxidized. If explosive contains just enough oxygen to form carbondioxide from carbon, water from hydrogen molecules and all metal oxides frommetals with no excess, the explosive is said to have zero oxygen balance.
Chemistry of High Energy Materials R.A. Rodriguez Baran GM2012-08-18
N N
NNO2N
O2N
NO2
NO2
Aliphatic C-nitro compounds
R NO2 R1 NO2
R2
R1 NO2
R3R2
R NO2
NO2
R1 NO2
NO2R2
1° nitroalkane 2° nitroalkane
3° nitroalkane
Terminalgem-dinitroalkane
Internalgem-dinitroalkane
acidic protons(condensation
chemistry)
high explosive withhigh thermal andchemical stability
R1
R2
NO2
NO2NO2
Trinitromethyl ONO2
Me
O2N NO2
NO2
N N
N
NO2
O2N NO2
ONO2
O2NO
TNT
Nitroglycerin (VOD=7750 m/s)
RDX (VOD=8440 m/s)
Chemical types/class of organic explosives
NO2
NO2
O2N NO2
O2NN NNO2
O2NN NNO2
O2NN NNO2
O2N NO2
NF2F2N
N NN N
NN
NO2
NO2
O2N
O2N
O2N NO2
ONO2
ONO2
O2NO
O2NO
NO2
NO2
ONO2
SiONO2
O2NO
O2NO
ONO2
ONO2O2NO
O2NO
Pentaerythritol tetranitrate(PETN) (VOD=8310 m/s)
Aromatic C-nitro compounds
Aliphatic O-nitro compounds
HMX (VOD=9110 m/s)
O2N NO2
NO2
O2N NO2
NO2
HO(NO2)x
x ≥ 4poor chemical
stability
Aliphatic N-nitro compounds
NH
O
NH
NO2
H2N
N
NH2
NO2
N,N'-dinitrourea(DNU) nitroguanadine
1,3,5-trinitrobenzene(TNB)
2,4,6-trinitrophenol(picric acid)
O2NNH
Nitro derivatives of pyrroles, thiopenes, and furans are not practical explosives:1. heat of formation offers no benefits over standard arylene hydrocarbons2. during nitration, these heterocycles are much more prone to oxidation and acid cat. ring opening compared to arenes
S O
heterocycles
NNH
NO2H2N
O2N
4-amino-3,5-dinitropyrazole(LLM-116)
NHN
O2N
NO22,4-dinitroimidazole
(2,4-DNI)
N
NO
furazans/benzofurazansfuroxans/benzofuroxans
O
Hexanitrohexa-azaisowurtzitane(HNIW or CL-20)(VOD=9380 m/s)Si-PETN
novel energetic nitrate eseter
3,3-bis(difluoroamino)octahydro-1,5,7,7-
tetranitro-1,5-diazocine(TNFX)
NN
NH
H2N
NO2N
HN
NH
O2N ONN
N
Ar
N N
O ArAr
1,3,4-oxadiazoles 3-nitro-1,2,4-triazol-5-one(NTO)
O2N
NO2
benzotriazolesN
NN
NH
H2N
N
O2N
H2N
NO2
NH2
NH2 N
NO2N
H2N
NO2
NH2
O O
O
N
N N
N
NH2
NH2
O
O
tetrazoles 1,2,4 triazolespyridine N-oxide tetrazine N-oxidepyrazine N-oxide
H-bondingreduction insensativity
Chemistry of High Energy Materials R.A. Rodriguez Baran GM2012-08-18
Routes to C-Nitro functionality
Nitration chemistry
Borgardt et al. Chem Rev 1964. 64, 19 (polynitro functionality)
The nitro gorup whether attached to aromatic or aliphatic carbon, is probablythe most widely studied of the functional groups and this is in part attributedto its use as an 'explosophore' in many energetic materials.
Direct nitration of aliphatic and alicyclic hydrocarbons possible in the vaporphase using HNO3 or NO2 (toxic redish-brown gas) at elevated temperatures.
Me
NO2H
Me
HNO3
25% Me
NO2
MeNitration with HNO3 is difficult
Me
MeMe
Me
N2O4
N NO
OO
O
+
O2N
NO2H
Me
NO2
Me
O2N
MeMeMe
ONO
Me
O2N
MeMeMe
ONO2
Me
O2N
MeMe
nitro-nitratenitro-nitritedinitro
+
- colorless liquid
Radical methods
Ph1 atm NO
DCE/ rtPh
NO2Ph
NO2
OH
76% 23%
+
Mukaiyama et al. Chem Lett 1995. 505
Al2O3
PhNO2
92%
R
HH
R
R
NO2H
RH
R
NO2H
RH
R
NO2H
R80 - 90%
NaNO3 xs,CAN 2eq
AcOH/CHCl3
Hwu et al. J Chem Soc Chem Commun 1994. 1425Taniguchi et al. JOC 2010. 75, 8126
R
R
R NO2
ClRFe(NO3)3 9H2OFeCl3
MeCN, reflx
N
Cl
N
CO2R
KNO3
H2SO4
TBAN
Ph MeCNNO2BF4
Ph
NHAc
NO2
84%
80 - 90%
S
Br1. nBuLi2. N2O4 -78 °C
S
NO2
TMS AcONO2 NO2
NO2O2N
O2N NO2
1. NaHMDS2. N2O4
NO2O2N
O2N NO2
NO2O2N
O2N NO2
NO2O2N
O2N NO2
NO2
N
Cl
N
CO2R
N
Cl
N
CO2R
NO2
O2N
traditional[NO2
+]
F3C O
O
CF3
OTFAA
F3C O
O
NO2
TBAN * No rxn inpresence ofTEMPO
TMS
O
NO
[2+2]_ OAc
NO2+
NO2
O
NO
_ OAcNO2
ON
O
OAc
Nef
O
ONO2
AcONO2
ONO2
NO2NO2
alkaline nitration
NItration selectivity on arene/heteroarene
76%
44%
77%
Kakiuchi, et al. Synlett 1999. 901
74%
Chemistry of High Energy Materials R.A. Rodriguez Baran GM2012-08-18
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
modified VM (alkali metal nitrites e.g. NaNO2) time and solubility is VIMP
Kornblum et al. JACS 1956. 78, 1497
NO2
R
RO
R
R+
NaNO2 NO2
R
ROH
R
RNO
OH
HO OHphloroglucinol
N O
nitrite ester
1° and 2° nitro compounds
oxidation of isocyanates
O NOH
ONO2H
1.KOtBuamyl nitrate2. H+
1. NBS2. [O]3. [H]
NO2
CF3CO3HN
O OHNO2
O2N NO2S2O8 2-
H+
NO2O2NNO2+
C+H3N
C+H3NNH3+C
NH3+Cl-
NCO
OCN
NO2
O2N
O2N
O2NNO2
NO2
F NO2
NO2NO2
O2N NO2
NO2NO2 (or)
NO2
F NO2
NO2
CO2HR
R
HNO3
20 - 30%
R
R
NO2
NO2MeO2C CO2H
HNO3
60 % MeO2C NO2
NO2
oxidation of amines
Synthesis of an energetic nitrate ester ONO2
ONO2
O2NO
O2NO
NO2
NO2Chavez, D.E. et al. Angew. 2008, 47, 8307
Original Target/Route via modified Kaplan Shechter Rxn
NHO
O
NO2
MeMe
NN
N
NHN
O
OMe
Me
O
O O
OMe
Me NO2
OH
R1 R2
NO2 N
R1 R2
OONaOH 1. NaNO2
2. AgNO3 R1 R2
NO2O2N
N
R1 R2
OO
NO
O Na
R1 R2
NN O
O
O
OAg+
R1 R2
NN O
O
O
OAg
R1 R2
NN O
O
O
O-Ag0
Ag0
Ag+
nitronate
-CH2O
retroaldol
NO O
NHO
O
N
MeMe
NN
N
NH
OO
NHO
O
N
MeMe
NN
N
NH
OO
Fe
activation [O]NH
R
R
N
NN
N
NH
OO
DMDOAcetone/H2O
85%
DMDOAcetone
91%
gem-dinitros from acids
Fluorotrinitromethane
R XN
O
OAg+ ether
R NO2 R ONO+ AgX
O O
O NO
OR
slowXR
R
fast
NaNO2DMSO
NO2
R
RH+
Eaton et al. JOC 1988. 5353
NO2O2N
NO2+
(low yields) KaplanShechter Rxn
via amine thusH2O essential
only usefuloxidant
Chemistry of High Energy Materials R.A. Rodriguez Baran GM2012-08-18
+
Routes to O-Nitro functionalityInitial Results: homocoupled product
HO
HO
NO2
OHH2N
N N
NHN
1.cat. K3[Fe(CN)6] Na2S2O8
1. 2-methoxypropene cat. H+
X
O
O
NO2
MeMe
O
O
NO2
MeMe
O
O
NO2
MeMe
12%NH
NN
N
NH
2. NaOH NO
OMe
Me
O
O
N
O O
MeMe
OON
O O
MeMe
OO
O
O
N
MeMe
OO
NO O
Fe
O
O
N
MeMe
O O
O
O
N
MeMe
OO
O
OMe
Me
activation
O OSO3Na
NaO3S
FeNC
CN
CN
OSO3Na
NC
NC
-NaSO4-
+CN-FeNC
CN
CN
CN
NC
NC
- CN-
O
O
NO2
MeMe
O
O
NO2
MeMe
65% optimized
1.HCl, MeOH
2. Ac2O/HNO3
O2NO
O2NO
NO2
ONO2
ONO2
NO272% (2 steps)
- Use of mixed acids (esterification) and nitrogen oxides described for C-NitraionKey points:1. fuming (anhydrous) HNO3 prep: dry air bubbled through anhydrous HNO3 to remove any oxides of nitrogen present, followed by addition of trace urea to remove any nitrous acid present. AKA "white nitric acid"2. Urea destruction of nitrous acid important to avoid violent fume-off3. O-nitrations with mixed acids of "white nitric acid" above ambient temperatures is dangerous and has increase risk of explosion4. anhydrous HNO3/Ac2O- Acetyl nitrate is generally a weak nitrating agent but in the presence of a strong acid like HNO3, ionization to nitronium ion occurs
NO2
HO
HO
NO2
OH
OHanh HNO3Ac2O
90% HNO3Ac2O
NO2
HO
O2NO
NO2
OH
ONO2
NO2
O2NO
O2NO
NO2
ONO2
ONO2
70%90%
shock sensative
Transfer nitration (neutral conditions - good for acid sensative alcohols)
OH
OH
N
Me
Me MeNO2
ONO2
ONO2N
Me
Me MeH
BF4-
BF4-2 eq
Olah G.A. et al JOC, 1965. 30, 3373
works for 1°, 2°, 3° alcohols
in situ halide displacement with AgNO3
R OHPPh3, I2
R IAgNO3
R ONO2
Low yields for 2°HgNO3 can be used for 2° and3° alkyl halide displacements
decomposition of nitrocarbonates (very mild, rt or reflux MeCN)
RO
O
Cl RO
O
ONO2
AgNO3
PyR ONO2
-AgCl
-CO2
O
O
(or)
ring opening of strained oxygen heterocycles
N2O4
CH2Cl2ONO
ONO2[O]
H2O HOONO2
O2NOONO2
20,164 MPH!!
ONO2
ONO2O2NO
O2NO
comparable stability to PETN
N N
NNO2N
O2N
NO2
NO2
N2O5
CHEETAH calculates as powerful as HMX
m.p. 86 °CDet.Temp
140 °C MeCNquant yield
80%
Chemistry of High Energy Materials R.A. Rodriguez Baran GM2012-08-18
Routes to N-Nitro functionality
nitrodesilylation deamination
R NH2 R ONO2
NO2F
MeCNRO SiR3 RO ONO2
N2O5
CH2Cl2+ O2NO SiR3
- 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
selective O-nitrations
HO
OH
OH
1 eq SOCl(NO3)
2 eq SOCl(NO3)
3 eq SOCl(NO3) O2NO
ONO2
ONO2
O2NO
OH
ONO2
HO
OH
ONO265%
70%
100%
HN NO
O
H+R OH + N2O
- 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
R
2° w/ HNO3/Ac2O
N CNNC
N
MeN
Me
NO2NO2
NO2
93% 22% 6%analines - must contain one or more nitro groups on the aromatic ring
How to get around this problem??- synthesis via condensation chemistry (Mannich, 1,4 addition, etc)
What about if need more direct method??-non-acidic nitrating reagents (nucleophilic nitration)
-chloride ion catalysis
- Nitrolysis of fully substituted nitrogen
R NH2nBuLi-78 °C R NHLi
Et ONO2R N N
OLi
H+R NH
NO2
Ar NH21. Na2. EtONO2
Ar NH2 Ar N NONa
H+Ar NH
NO2
EtONO2Na+-
anhydrous ZnCl2, hydrochloride salt of amine, or dissolved HCl(g) can serveas a source of electropositive chloride under the oxidizing conditions of nitration
2 HCl + 2HNO3 + 3Ac2O 2AcOCl + N2O3 + 4AcOH
AcOCl + R2NH R2NCl + AcOH
R2NCl + HNO3 + Ac2O R2NNO2 + AcOCl + AcOH
Wright et al. Can. J. Res. 1948. 26B, 294
HNO3/Ac2O(w/o chloride)
N CNNC
NO2
93%N
NC CNX
HNO3/Ac2OR = H
NNC CN
HNO3/Ac2OR = Cl- (N+)
R
NO2
70%
Ease of alkyl nitrolysis depends on stability of the resulting cation:benzyl, tertiary (t-Bu), etc...
R NH22 HOCl R NCl2
HNO3/Ac2OR N
NO2
ClR NHNO2
NaHSO3 (aq)
rupture of C−N bond leading to formation on N−NO2
R1 N
O
R2
R2
A
B
Path A
Path B
R1 CO2HNR2
R2
O2N+
R1 N
O
NO2
R2
R2 OH+
Nitramine formation via nitrolysis possible from:
R1N
R1
Ph
R2N NR2R1 N
O
R2
R2
- carbamate- urea- formamide- acetamide- sulfonamide
R1N
R1
Ph
NO2NO2
+
R2N SiR3
R2N NO
O
O
N NOH
OR
Chemistry of High Energy Materials R.A. Rodriguez Baran GM2012-08-18
Synthesis of Hexanitrohexaazaisowurtzitane (HNIW)
- 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.
Syntheses of some nitramine explosives
OH OHO O
NNs NNs
O O
NNs NNs
NOH
O O
NNs NNs
O
N N NsNs
NO2O2N
F2N NF2
NO2O2N
N N NO2O2N
F2N NF2
NO2O2N
TNFX(3,3 bis(difluoroamino)octahydro1,5,7,7 tetranitro 1,5 diazocine)
NH2
HO OH
OH
NH3+Br-
Br Br
Br N
Br
N
NO
CH2BrO2N
N
NO2
CH2BrO2N
N
NO2
NO2O2N
HBr-AcOH160 °C72%
NaOH, 80 °C60 mmHg
1. NaNO2 (aq)2. HCl (aq)
10%
HNO3/TFAA
81%
1. NaHCO3, NaI DMSO, 100 °C
2. NaNO2, NaOHK3Fe(CN)6, K2S2O8
29% (2 steps)TNAZ
NsCl,K2CO3 (aq)
95%
1. CrO3, AcOH2. HOCH2CH2OH TsOH
82% (2 steps)
NH2 NH2 NNs NNs NNs NNs
Br BrK2CO3
76%
1. O3, CH2Cl22. DMS
3. NH2OH/NaOAc86% (3 steps)
1. HNO3/NH4NO3 urea, 33%
2. H2SO492%
F2NSO3H,HNF2, H2SO4,CFCl3
90%
HNO3/SbF6
CF3SO3H
NH2
Ph H
O
O
H+
2 eq.
MeCN/H2Ocat. H+
N
N
N
NN
N
Bn Bn Bn
BnBnBn
N NN N
NN
BnBn
Bn
Bn
Bn Bn
NO2+
messy. Nitration of aromatic rings
XN
Ph[O]
N
PhO Ac2O
N
MeO
N
PhCrO3
N
PhO
H2,[Pd]
decomp.
X
N NN N
NN
BnBn
Bn
Bn
Bn Bn
H2, Pd(OAc)2
Ac2O, PhBr cat.
N NN N
NN
Ac
Ac
Ac
Ac
Bn Bn65%
N NN N
NN
NO2
NO2
O2NO2N
O2N NO2
1. N2O42. HNO3/H2SO4
via nitroso93%
H2,[Pd]
N NN N
NHHN
Ac
Ac
Ac
Ac
DANGER!
1. HCO2H
2. Ph, Δ -H2O
N NN N
NCHOOHCN
Ac
Ac
Ac
Ac
99% HNO3N N
N N
NN
NO2
NO2
O2NO2N
O2N NO2
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
Chemistry of High Energy Materials R.A. Rodriguez Baran GM2012-08-18
N2O5
N2O5O
NN
O
O
O
O[NO2
+][NO3-] - adopts two structures
depending on conditionpolarsublime slightly above rt
non-acidic nitrating reagents (neutral)1° amines/nitramines leads to deamination and formation of nitrate esterby-product but analines are successful.
- 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)
condition: anhyd. HNO3- powerful but acidic and non-selective
condition: chlorinated solvents- clean and selective- non-oxidizing &n non-acidic
N2O5 2 N2O4 + O2rt Stable for 2 weeks at -20 °C
Stable for up to 1 yr at -60 °C
nitronium nitrate salt
No single nitrating agent is as diverse and versatileIt is considered as the future for energetic materials synthesis
Preparation of N2O5 [Deville 1849]AgNO3 + Cl2 (g)
ON
Cl
O+ AgNO3 N2O5
Dehydration of nitric acidHNO3 + P2O5 N2O5 + H3PO4
- 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)
O3N2O4Δ N2O5
Process chemist at Defense and Evaluation Research Agency (DERA) in the UKDevelopment 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 solidcondenser tubes (cooled by dry ice/acetone).
Me
NO2
NO2
N2O5/HNO3
32 °C,quant yield
Me
NO2
NO2
O2N
No explosion hazard
NH
HN
HN
NH
OON
HNN
NH
OO
O2N
NO2
N
NN
NOO
O2N
NO2
NO2
O2N
HNO3
P2O5
HNO3
H2SO4
N-nitrations of ureas
HO
OH
OH
OH
OH
OHN2O5, CCl4
0 °Cquant yield
O2NO
ONO2
ONO2
ONO2
ONO2
ONO2
synthesis of TNT under mild conditions
O-nitrations of polyols
Klapotke T.M. JACS 2007. 129, 6908
O2NO ONO2
O2NO
ONO2PETN- Det. Velocity 8,400 m/s- d= 1.7 g/cm3
- 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
SiO2NO ONO2
O2NO
ONO2
Silicon analogue of PETN
Si(CH2OAc)4 Si(CH2Cl)4
"The crystalline compound exploded on everyoccasion upon contact with Teflon spatula...Solutions in diethyl ether exploded upon the slighestevaporation of the solvent."
Explosives in JACS: Sila explosives
Why does Si-PETN have drastically increased sensativity?
Theoretical: electrostatic potential:1. Surface electrostatic potential, in general, is related to the sensitivity of the bulk2. The more evenly distributed the electrostatic potential is over the surface of a molecule, the more stable it is to impact.
Si ON
O
O2NO
O2NO
O2NO O
VERYlow e- dens
VERY high e- dens