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The IUPAC name of the compound
$CH_3-CH_2-CH(CH_3)-CH(CH_3)-COCl$
is :-
$CH_3-CH_2-CH(CH_3)-CH(CH_3)-COCl$
is :-
A
3,4-dimethylpentanoyl chloride
B
1-chloro-1-oxo-2,3-dimethylpentane
C
2-ethyl-3-methylbutanoyl chloride
D
2,3-dimethylpentanoyl chloride
Detailed Solution
The functional group is the acid chloride group, $-COCl$, so the suffix is '-oyl chloride'.
Select the longest carbon chain that includes the carbon of the $-COCl$ group. It has five carbon atoms, so the parent name is pentanoyl chloride.
Number the chain starting from the carbon of the $-COCl$ group, which is always C-1.
$\overset{5}{C}H_3-\overset{4}{C}H_2-\overset{3}{C}H(CH_3)-\overset{2}{C}H(CH_3)-\overset{1}{C}OCl$
There are methyl substituents on C-2 and C-3.
So the IUPAC name is 2,3-dimethylpentanoyl chloride.
Choosing a four-carbon chain (2-ethyl-3-methylbutanoyl chloride) is wrong because it is not the longest chain, and 3,4-dimethyl numbering starts from the wrong end.
Select the longest carbon chain that includes the carbon of the $-COCl$ group. It has five carbon atoms, so the parent name is pentanoyl chloride.
Number the chain starting from the carbon of the $-COCl$ group, which is always C-1.
$\overset{5}{C}H_3-\overset{4}{C}H_2-\overset{3}{C}H(CH_3)-\overset{2}{C}H(CH_3)-\overset{1}{C}OCl$
There are methyl substituents on C-2 and C-3.
So the IUPAC name is 2,3-dimethylpentanoyl chloride.
Choosing a four-carbon chain (2-ethyl-3-methylbutanoyl chloride) is wrong because it is not the longest chain, and 3,4-dimethyl numbering starts from the wrong end.