carbon-oxygen by drawing the electrons in the direction of the positive oxygen.)
- Step 3 is a Lewis acid-base reaction.
3.14 ACIDS AND BASES IN NONAQUEOUS SOLUTIONS
- The amide ion (NH 2 – ) of sodium amide (NaNH 2 ) is a very powerful base:
H O H + NH 2 − H O− + NH 3
Stronger acid
pKa = 15. 74
Stronger base Weaker base Weaker acid
pKa = 3 8
liquid
NH 3
1) Leveling effect: the strongest base that can exist in aqueous solution in
significant amounts is the hydroxide ion.
- In solvents other than water such as hexane, diethyl ether, or liquid ammonia
(b.p. –33 °C), bases stronger than hydroxide ion can be used. All of these
solvents are very weak acids.
C C H + NH 2 − + NH 3
Stronger acid
pKa = 2 5
Stronger base
(from NaNH 2 )
Weaker base Weaker acid
pKa = 3 8
HCliquidNH H C −
3
1) Terminal alkynes:
C C H + NH 2 − + NH 3
Stronger acid
pKa ~ 2 5
Stronger base Weaker base Weaker acid
pKa = 3 8
RCR C −
liquid
NH 3
=
- Alkoxide ions (RO–) are the conjugate bases when alcohols are utilized as
solvents.
