Question

36 The IUPAC name of 3 CH3 - 2 CH - CHO - CH2CH3 a) 2 methyl butanal
b) butane - 2 - aldehyde. c) 2-ethylpropanal, d) 3-methyl isobutraldehyde
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Answer 1

C. 2-ethylpropanal

Longest carbon chain has to be chosen such that the functional group has the lowest number.

So, we start numbering from the carbon of aldehydic group (−CHO). Thus, there are 5 carbons in the longest chain.

At C-2, ethyl group and at C-3, methyl group is present. The suffix used for aldehydes is "al".