Lecture 10

Question 1

Why do we need new explosive materials?

Answer 1

• Many current explosives aren’t very ‘clean’
• Explosives with a higher nitrogen content generally reduce the production of CO/C
• Increased tunability is preferable

Question 2

What properties are desired to be tunable?

Answer 2

• Crystal packing
• Stability
• Detonation products
• Tagging

Question 3

What is the current issue with the current widely used explosives?

Answer 3

• They don’t give us environmentally friendly products
• CO and CO2 not nice to generate large quantities into the atmosphere
• They can also generate NOX gases like NO2

Question 4

What can we incorporate to reduce the production of C and CO

Answer 4

We can try to incorporate more nitrogen into explosives as this reduces the production of CO/C and gives more nitrogen gas which is what the air is made of up anyways

Question 5

What PPE is required for < 500 mg of explosives?

Answer 5

• Helmet
• Face Shield
• Leather Coat
• Kevlar Gloves
• Kevlar Suit
• Blast Shield

Question 6

Azidotetrazoles

Answer 6

• These compounds exhibit multiple spontaneous explosions
• They’re quite sensitive so possibly interested as primary explosives
• A large number of N atoms in a small molecule 🡪 entropically favourable detonation
• They create a lot of gas per molecule even though its relatively small
• They contain a lot of nitrogen

Question 7

How do you form azidotetrazoles?

Answer 7

IDK
-This gives us tunability of components as we can use different salts (changing the M ion) which subtly change the properties

Question 8

How is nitroiminotetrazoles formed?

Answer 8

Aminotriazole is nitrated

Question 9

Nitration

Answer 9

Nitric acid is added in the presence of a strong acid

Question 10

Nitroiminotetrazoles

Answer 10

-These compounds temper the properties of azidotetrazoles
- Comparable properties to RDX 🡪 amazingly a secondary explosive
- Explosive salts can be produced when paired with guanidiniums
- It is sensitive even though it has two energetic groups next to each other
- This is partly due to the stabilisation from the aromaticity

Question 11

How can you monitor the products of a new explosive material?

Answer 11

• We could detonate the new explosive and capture the gases created
• The gases could be analysed using gas phase FTIR
• We can look at small molecules which can be differentiated by the different vibrational modes

Question 12

Whats the problem with GC for the analysis of products in an explosion?

Answer 12

GC is good for volatile compounds however the detonation products we form aren’t always volatile compounds which is what GC looks at

Question 13

What factors are important for determining explosive stability?

Answer 13

• Oxygen balance
• Crystal packing
• Impact sensitivity

Question 14

Crystal packing trend

Answer 14

There is a trend between crystal packing and density of how much we can pack and the impact sensitivity

Question 15

How can you model crystal packing?

Answer 15

Determining the density

Question 16

What can control crystal packing?

Answer 16

• The use of explosive salts can control the crystal packing but this can be hard to predict.
• Eg changing a salt could decrease the crystal packing
• Packing silver into the crystal can increase the density
• The crystal packing can effect the impact sensitivity

Question 17

Stability of nitrogen-containing compounds

Answer 17

• There is a limit to the stability achievable with nitrogen-based explosives
• Want to maximise the number of N=N and N≡N bonds but synthetically challenging
• Actual trends are complex 🡪 combination of kinetic and thermodynamic stability

Question 18

What N bonds are entropically favoured?

Answer 18

We want to maximise N double bonds and triple bonds as they are entropically favoured

Question 19

Other than N bonds, what can contribute to the stability of an explosive?

Answer 19

Phenol aromatic groups introduce an element of stability

Question 20

Hexanitrohexaazowurzitane

Answer 20

• Another secondary explosive
• Developed by US military and national labs
• Stabilised as a 1:1 cocrystal with TNT!
• Not stabilised by cocrystallisation with 98% H2O2
• Has a lot of ring strain so there is a lot of chemical energy

Question 21

How does stereochemistry affect the properties?

Answer 21

Changing the stereochemistry changes the properties

Question 22

What effect would steric hindrance have?

Answer 22

It could increase the sensitivity

Question 23

What are regiomers?

Answer 23

This is when both functional groups are attached to the same carbon.