2.  In chemistry, a carbene is a molecule
containing a neutral carbon atom with a
valence of two and two unshared valence
electrons.
 The general formula is RR'C:, but the
carbon can instead be double-bonded to
one group.
 The term "carbene" may also merely refer
to the compound H2C:

4. R C CHN2
O
α-diazoketone
R
C CH N N
** +
O -N2
R R
C C C CH
**
H
O O

5. - Synthesis of analogues of
carboxylic acids
- Synthesis of amides from
carboxylic acids
- Synthesis of esters from
carboxylic acids

6. SOCl2
R C OH R C Cl
O O CH2N2
R
C CH N N
** +
O -N2
R R
C C C CH
**
H
O O
CH OH
NH
H2O
3
3
O
O
O R-CH2-C-NH2
R-CH2-C-OH
R-CH2-C-O CH3