21. Aldehydes and Ketones: Nucleophilic Addition

Propose mechanisms for the three imine-forming reactions just shown.

Predict the major products of the following reactions.

(e)

Rank the following carbonyl compounds in order of increasing equilibrium constant for hydration:

CH₃COCH₂Cl ClCH₂CHO CH₂O CH₃COCH₃ CH₃CHO

Show how you would synthesize octanal from each compound. You may use any necessary reagents.

(g) ethyl octanoate

Draw structures of the following derivatives.

(d) the ethylene acetal of hexan-3-one

Identify A through O:

Show how Wittig reactions might be used to synthesize the following compounds. In each case, start with an alkyl halide and a ketone or an aldehyde.

(a) Ph–CH=C(CH₃)₂

(b) Ph–C(CH₃)=CH₂

Using cyclohexanone as the starting material, describe how each of the following compounds can be synthesized:

f.

Draw the product of each of the following reactions:

d.

Explain why acetals do not react with nucleophiles.

LOOKING AHEAD CHAPTERS 8, 17 In Chapters 8 and 17 we learn two reaction for the synthesis of the alcohol shown. (a) Show a mechanism for each of the reactions. (b) If you were designing a synthetic route, which would be considered more sustainable? Consider all factors. [Assume the starting organic molecules are equally green.]

Give the structures of the carbonyl compound and the amine used to form the following imines.

(d)

(e)

(f)

Draw structures of the following derivatives.

(g) the (E) isomer of the ethyl imine of propiophenone

Acetals can serve as protecting groups for 1,2-diols, as well as for aldehydes and ketones. When the acetal is formed from acetone plus the diol, the acetal is called an acetonide. Show the acetonides formed from these diols with acetone under acid catalysis.

Predict the products of the following reactions.

(a)

(b)