Question

IUPAC name of $C_6{H}_5-C{H}_2-C{H}_2-N{H}_2$
(A) $$2-phenylethanamide$$
(B) $$2-phenylethanamine$$
(C) $$2-phenylethylamine$$
(D) $$3-phenylethanamine$$

Answer 1

Hint:To solve this question, we must first understand the rules and procedure of IUPAC nomenclature. Then we need to learn the names of all the basic functional groups and then use the names to write the IUPAC name of the given compound according to the predefined rules and then only we can conclude the correct answer.

Complete step-by-step answer:Before we move forward with the solution of this given question, let us first understand some basic concepts:IUPAC nomenclature of organic compounds refers to the systematic approach taken for the nomenclature of organic compounds as per the recommendation of the International Union of Pure and Applied Chemistry (often abbreviated to IUPAC).
Rules for Nomenclature:
*Longest Chain Rule: The parent hydrocarbon must be identified and subsequently named. The parent chain belonging to the compound in question is generally the longest chain of carbon atoms, be it in the form of a straight chain or a chain of any other shape.
*Lowest Set of Locants: The carbon atoms belonging to the parent hydrocarbon chain must be numbered using natural numbers and beginning from the end in which the lowest number is assigned to the carbon atom which carries the substituents.
*Multiple instances of the same substituent: Prefixes which indicate the total number of the same substituent in the given organic compounds are given, such as di, tri, etc.
*Naming of different substituents: In the organic compounds containing multiple substituents, the corresponding substituents are arranged in alphabetical order of names in the IUPAC nomenclature of organic compounds in question.
*Naming of different substituents present at the same positions: In the scenario wherein two differing substituent groups are present at the same position of the organic compound, the substituents are named in ascending alphabetical order.
*Naming Complex Substituents: Complex substituents of organic compounds having branched structures must be named as substituted alkyl groups whereas the carbon which is attached to the substituent group is numbered as one. These branched and complex substituents must be written in brackets in the IUPAC nomenclature of the corresponding compounds.
Step 1: In the given compound: $C_6{H}_5-C{H}_2-C{H}_2-N{H}_2$ , we can clearly see that there is:Parent hydrocarbon chain is ethane, an amine and a phenyl group which is at the second carbon atom according to the above rules of numbering the longest chain.
Step 2: So, by considering all the aspects of the step 1 we can conclude that the IUPAC name of the given compound is: $$2-phenylethanamine$$

So, clearly we can conclude that the correct answer is Option (B).

Note:The aim of the nomenclature IUPAC program is to create an international standard for designating compounds to promote communication. The purpose of the system is to give a unique and unambiguous name to each structure, and to compare each name with a unique and unambiguous structure.