dead (thing)

DEAD- diethylazodicarboxylate

     O      O
    ||     ||
/\  /\     /\  /\
   O   N=N   O

Orange liquid of density 1.106 gcm^-3 and a boiling point of 106^oC at 13mm Hg.

Another molecule with a silly name, DEAD happens to be rather appropriately acronymed given the associated risks:

Stability- Stable, but...

• May explode if heated under confinement.
• May be shock sensitive.
• Decomposes vigorously if heated above 100 C.
• Incompatible with strong acids, strong bases, strong oxidizing agents, strong reducing agents.
• Light sensitive.

Toxicology- Toxic.

• May act as a carcinogen or mutagen.
• May cause irreversible effects.
• Eye, skin and respiratory irritant.

Beyond having an entertaining name, DEAD (C₆H₁₀ N₂O₄ , synonyms Diazenedicarboxylic acid, diethyl ester; diethyl azodicarboxylate) is of note for its role in the Mitsunobu Reaction. This mild reaction is used for the activation of alcohols to nucleophilic attack, meaning the hydroxyl group can be replaced by a range of nucleophiles; an example of nucleophilic substitution. Triphenylphosphine is also required to obtain the following activation:

Ph₃P + ROH + EtO₂CN=NCO₂Et --> Ph₃PO⁺R + EtO₂CN^--N(H)CO₂Et

The Intermediate obtained has a region of positive charge which is then vulnerable to nucleophilic attack:

 
R-CH-R                          R-CH-R
  |     + Nu-     -->             |        + Ph3P=O
 +OPPh3                           Nu

With secondary alcohols, this causes inversion of the oxygen substituted centre stereochemically, creating a different optical isomer. This is a result of the PPh₃ group attached to the intermediate being very large stereochemically, so the incoming nucleophile attacks from the opposite side.

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Also, my nickname at school, but this was more to do with corpse-like appearance than dubious stability and useful action upon alcohols...
Journal Ref: M.J.Arco, M.H.Trammel and J.D.White, Journal of Organic Chemistry Vol 41 Page 2075 (1976)