[a confused chiral girl]

hey all 

I made a big mistake on this question as I thought it would be a nucleophilic substitution. However, it should be CH3COO- and CH3CH2CH2NH3+ because of acid base reaction. IS it always acid/base rxn when there is N (amide, amine etc)? or else... how can I tell if it is NAS or acid/base....? 

[maakii]

With carboxylic acids and amines (which are acids and bases!) they will react to form salts easily, only under special conditions, such as enzyme action (in the formation of peptides) will they from an amide bond.

Amides are not good bases even if they have an N, for the lone pair is delocalised, I will leave it up to you to draw the resonance structures.

Alcohols are generally not very good bases, and can you imagine getting CH3COO- and CH3CH2CH2OH3+ in your mixture? 

[organoman]

Maakii is absolutely right. amines and carboxylic acids react to form salt pretty much the same way as amine and HCl form.
second reaction looks acid catalysed esterification.May be H+ concentration  is more alcohol can undergo dehydration too. But not sure how would the excess of alcohol contribute in this case.Had it been dicarboxylic acid and excess of alcohol product would be polyester. Can anybody comment further.

[Dolphinsiu]

      NH2- + H2O  < = >   NH3+ + OH-
Weak base + Weak acid  < = > Strong acid + Strong base

The above equilibrium shift from right to left.

Therefore, OH- is a strong base than NH2-
then OH- is poor leaving group, nucleophilic substituation is impossible!

Only when carbonyl compound is protonated, H2O is better leaving group and substitution will occur in higher possiblility theoretically!