Week 4 - Carboxylic acid derivatives

Question 1

Relative reactivates of carboxylic acid derivatives in water, and why?

Answer 1

Acyl halides are most reactive, then anhydrides, then esters, then amides. The more stable the compound is, the less it wants to react. The stability of the compound depends on the extent to which the minor resonance form helps to stabilize. Thus, there is most resonance contribution when the heteroatom on the acid is NH2, since NH2 is the least electronegative and is ok with having a positive charge on it (draw it!). Cl is the worst, because it has a long, weak bond with the carbon in resonance (because its p orbitals are so much bigger than those of the carbon)

Question 2

Acyl halide naming

Answer 2

Acyl halides are named alkanoyl halides after the alkanoic acid from which they were derived. Halides of cycloalkanecarboxylic acids are named cycloalkane carbonyl halides.

Question 3

Water + acyl chlorides

Answer 3

Goes to carboxylic acids

Question 4

Amines + acyl chlorides

Answer 4

Goes to amides

Question 5

Organometalics + acyl chlorides

Answer 5

Goes to a ketone

Question 6

Selective reduction of acyl halides to form aldehydes

Answer 6

Let the LiAlH4 react with 3 molecules of tert-butyl alcohol, to make it so three of its hydrogens can’t react. This way it won’t over reduce the acyl halide into an alcohol, but will stop at the aldehyde.

Question 7

Ester naming

Answer 7

Esters are named as alkyl alkanoates. As a substituent, the ester grouping is called an alkoxycarbonyl. Cyclic esters are called lactones (common name)