Question

IUPAC Name of ${(C{H_3})_3}C - CH = C{H_2}$
A. 2,2-methylbut-3-ene
B. 2,2-dimethylpent-4-ene
C. 3,3-dimethylbut-1-ene
D. hex-1-ene

Answer 1

According to the rules of nomenclature, the longest parent chain is determined in the structure of the organic compound. Next, the priority is given to the functional groups. After that, the priority is given to the multiple bonds present in the compound. At last, the substituents are determined and the nomenclature is done by assigning the numbers to the additional groups present on the parent carbon chain in order to mark the location of the multiple bonds, substituents and the functional groups.

Complete step by step answer: In naming of the chemical compounds, the IUPAC nomenclature plays an important role. The IUPAC nomenclature of organic chemistry is a method of providing a name to the organic chemical compounds as suggested by the International Union of Pure and Applied Chemistry (IUPAC). It is published in the book named as Nomenclature of Organic Chemistry (also known as the Blue Book). Generally, each possible organic compound should have a name from which a clear structural formula can be derived. We also have an IUPAC nomenclature of inorganic chemistry.
To avoid long and difficult names in normal communication, the official IUPAC naming suggestions are not always followed in practice, except when it is necessary to give an absolute definition to a compound. The IUPAC names can sometimes be easier and simpler than older names, such as in the case of methanol, instead of methyl alcohol. For comparatively simpler molecules, they can be more easily understood than the non-systematic names, which are needed to continuously look over.
According to the rules of the nomenclature, the compound ${(C{H_3})_3}C - CH = C{H_2}$ is named as
2,2-dimethyl pent-4-ene. This is so because the longest parent carbon chain contains five carbon atoms and the double bond gets the lowest numbering as there is no functional group present on the parent carbon chain.
Hence, the answer is 2,2-dimethylpent-4-ene.
So, the correct option is “Option B”.

Note: The common or trivial name is generally shorter and clearer. This is why the trivial names are preferred. These non-systematic names are usually derived from the source of origin of the compound. In addition to this, very long names may create ambiguity and are usually less clear than the structural formula.