Question

How can I draw the structures of 4 isomers of amides for the formula `C_5H_11NO` ?

Answer 1

There are at many isomeric amides with formula C₅H₁₁NO. Here's how to draw the unsubstituted amides.

If the amide is unsubstituted, it must contain a CONH₂ group. The rest of the molecule must be C₄H₉.

So you draw all possible chains containing 4 carbon atoms. Then you add the CONH₂ group to every possible location on these chains.

4 C in a Row

You can put the amide group on C-1 or C-2. This gives pentanamide

and 2-methylbutanamide.

3 C in a Row

This gives us a 2-methylpropane chain. You can put the amide group on C-1 or C-2.

This gives 3-methylbutanamide

and 2,2-dimethylpropanamide.