Amide Formation

[thechenster]

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When you attack a carbonyl (Carboxylic acid, COOH for example) with any given amine (NR3), why will an amide not form if u add in base or acid.

So basically, carbonyl + amine==>amid except when there's acid or base present. Can anyone explain why acid/bases intereferes with this formation?

 

[Flamen04]

First of all, an amide will not form if it just attacks ANY carbonyl. The carbonyl group it is attacking must have a leaving group so that the NR3 group can take its place. Therefore, the most common ways to form an amide is to react an amine with a carboxylic acid, ester, acid anhydride, or acid chloride.

Now this reaction cannot happen in the presence of acids or bases. Why? Because in the presence of acids or bases, an acid base reaction occurs when you want a nucleophilic substitution reaction to happen instead. The base reacts with the carboxylic acid, for example, creating a carboxylate group with a terrible O- leaving group. Likewise, the acid protonates the amine, decreasing its ability to act as a nucleophile and kick the leaving group outta there.

 

[thechenster]

Ahh I see, thanks a lot

 

[loveoforganic]

FYI, you need an additional reaction to activate the carbonyl group when reacting with carboxylic acids.