26. Amines

Rank each set of compounds in order of increasing basicity.

(b) aniline, p-methylaniline, p-nitroaniline

Predict the products of the following reactions:

(a) excess NH₃ + Ph–CH₂CH₂CH₂Br →

Propose a mechanism to show the individual alkylations that form this quaternary ammonium salt.

What is the major product of the following reactions?

c.

Draw the product formed when pyridine reacts with ethyl bromide

Explain why the reaction of an alkyl halide with ammonia gives a low yield of primary amine.

Show how you would convert alanine to the following derivatives. Show the structure of the product in each case.

(c) N-benzyloxycarbonyl alanine

(d) tert-butyloxycarbonyl alanine

Within each structure, rank the indicated nitrogens by increasing basicity.

(d)

(e)

In each pair of compounds, select the stronger base, and explain your choice.

(c)

(d)

Guanidine (shown) is about as strong a base as hydroxide ion. Explain why guanidine is a much stronger base than most other amines.

Explain why N,N,2,6-tetramethylaniline (shown) is a much stronger base than N,N-dimethylaniline.

Addition of one equivalent of ammonia to 1-bromoheptane gives a mixture of heptan-1-amine, some dialkylamine, some trialkylamine, and even some tetraalkylammonium bromide.

(a) Give a mechanism to show how this reaction takes place, as far as the dialkylamine. 

(b) How would you modify the procedure to get an acceptable yield of heptan-1-amine?

Rank the amines in each set in order of increasing basicity.

(a)

Rank the amines in each set in order of increasing basicity.

(e)

Which of the amines listed next is resolved into enantiomers? In each case, explain why interconversion of the enantiomers does or does not take place.

(a) cis-2-methylcyclohexanamine 

(b) N-ethyl-N-methylcyclohexanamine 

(c) N-methylaziridine 

(d) ethylmethylanilinium iodide

(e) methylethylpropylisopropylammoniumiodide