Question

The IUPAC name of $C{H_3}C{H_2}CH{(CH)_3}CH(CHO)C{H_2}C{H_3}$ is:
A.2 – sec – butylbutanal
B.2,3 – diethylbutanal
C.2 – ethyl – 3 – methyl – pentanal
D.3 – methyl – 2 – ethyl – pentanal

Answer 1

For the aldehydes we add the suffix "al" and there is an ethyl group present at carbon – 2 position and a methyl group are present at carbon - 3 position.

Complete step by step answer:
Given,
$C{H_3}C{H_2}CH{(CH)_3}CH(CHO)C{H_2}C{H_3}$
Number of Carbon atoms (C) are 8
Number of Hydrogen atoms (H) are 16
And number of Oxygen atom (O) is 1
The molecular formula is ${C_8}{H_{16}}O$
There are two substitutes i.e. ethyl and methyl.
First of all, according to IUPAC rules, the numbering of the carbon chain should be from the left side, so that the carbon atom attached to the ethyl group gets the least number.
Longest carbon chain has to be chosen such that the functional group has the lowest number.
So, we start numbering from the carbon of the aldehyde group $\left( { - CHO} \right)$ . Thus, there are 5 carbons is the longest chain.
At carbon – 2 position, an ethyl group is present and at carbon - 3 position, a methyl group is present. For the aldehydes we add the suffix "al".

The IUPAC name of $C{H_3}C{H_2}CH{(CH)_3}CH(CHO)C{H_2}C{H_3}$ is 2–ethyl–3–methyl–pentanal.

Therefore, the correct answer is option (C).

Note: We should find and the name the longest continuous carbon chain and we should identify and name groups attached to the chain, then we should number the chain consecutively, starting at the end nearest a substituent group and at last we should designate the position of each substituent group by an appropriate number and name. Also, the name of the compound should be written out with the substituents in the alphabetical order which is followed by the base name.