Question

IUPAC name of the compound:
${C_2}{H_5} - CH(C{H_3}) - C{H_2} - CH{(C{H_3})_2}$
1. 2, 4 dimethylhexane.
2. 1, 3 dimethylhexane.
3. 2, 2 dimethylhexane.
4. 3, 5 dimethylhexane.

Answer 1

Hint: A systematic name of an organic compound is generally derived by identifying the parent hydrocarbon and the functional group(s) attached to it. By further using prefixes and suffixes, the parent name can be modified to t obtain the actual name.

Complete Step by step answer: There is a systematic procedure to write the IUPAC name. Rules for naming the compound are as following:
-First of all, the longest carbon chain in the molecule is identified.
-Then after this the carbon atoms of the parent chain are numbered to identify the parent alkane and to locate the positions of the carbon atoms at which branching takes place due to the substitution of alkyl group in place of hydrogen atoms. The numbering is done in such a way that the branched carbon atoms get the lowest possible numbers.
-The names of alkyl groups attached as a branch are then prefixed to the name of the parent alkane and position of the substituents is indicated by the appropriate numbers. If different alkyl groups are present, they are listed in alphabetical order.
-If two or more identical substituent groups are present then the numbers are separated by commas. The names of identical substituents are not repeated, instead prefixes such as di (for 2), tri (for 3), and so on.
-If two substituents are found in equivalent positions, the lower number is given to the one coming first in the alphabetical listing.
So according to this the longest chain is having 6 carbons. That parent chain will have six carbons so we will use hex for this. Now as it is unsaturated it does not have a double or triple bond so it will have –ane as a suffix. And since two methyl groups are attached on the parent chain at the positions 2 and 4. So the correct IUPAC name of the compound ${C_2}{H_5} - CH(C{H_3}) - C{H_2} - CH{(C{H_3})_2}$ as per rules is 2, 4 dimethylhexane.

That is the 1st option is correct.

Note: Always keep in mind that the numbering is done in such a way that the branched carbon atoms get the lowest possible numbers. And the parent chain will have the maximum number of carbon possible in the compound.