Question

Give the IUPAC name of $C{{H}_{2}}=C(C{{H}_{3}})-C{{H}_{2}}-Br$.

Answer 1

Hint: For naming a compound starts with the carbon at the end closest to the functional group. The branched groups need to be looked for, and the nomenclature of them shall be done by counting the number of carbon atoms present of the branched group. Then note the position of the group on the main carbon chain.

Complete step by step solution:
We have been provided with a compound: $C{{H}_{2}}=C(C{{H}_{3}})-C{{H}_{2}}-Br$,
For writing the IUPAC name of a compound, we need to follow certain rules:
(1) Identify the longest carbon chain. This chain is called the parent chain.
(2) Identification of all of the substituents (groups emerging from the parent chain).
(3) Numbering the carbons of the parent chain should be done by giving the end as a priority that gives the substituents the lowest numbers. When comparing a series of numbers, the series that is the "lowest" is the one which contains the lowest number at the occasion of the first difference. We assign the lowest number to the one which will come first in the name if two or more side chains are in equivalent positions,
(4)If the same substituent occurs repeatedly, then the location of the points on which the substituent occurs is given. We assign prefixes like di, tri, tetra in such cases.
(5)In the case of two or more different substituents, listing in alphabetical order is done using the base name. The only prefix which is used when we put the substituents in alphabetical order is iso as in isobutyl or isopropyl.
(6)If chains of equal length need to be chosen as the parent chain, then the choice goes in series to:
a) the chain containing/including the greatest number of side chains.
b) the chain whose substituents are given the lowest numbers.
c) the smaller side chain having the most number of carbon atoms.
d)the chain having the least branched side chains.
So, in the compound: $C{{H}_{2}}=C(C{{H}_{3}})-C{{H}_{2}}-Br$,
The parent chain has 3 carbons. The parent chain is numbered in such a way that the double bond gets the lowest number. The substitutions are methyl group at 2nd carbon and bromo at 3rd carbon. Priority functional group is alkene so we assign the suffix as −ene. The IUPAC name of the compound is 3−Bromo−2−methylprop−1−ene.

So, the IUPAC name of the compound $C{{H}_{2}}=C(C{{H}_{3}})-C{{H}_{2}}-Br$: 3−Bromo−2−methylprop−1−ene.

Note: Drawbacks of the Trivial Nomenclature System, For one specific compound, several trivial names can exist.