Question

How would you name the following compounds?
$(i)\,C{H_3} - C{H_2} - Br$
$(ii)H - CHO$

Answer 1

To answer this question, you should recall the concept of IUPAC nomenclature of IUPAC compounds. The IUPAC system rose to the necessity for a systematic approach due to the sheer quantity of discoveries of organic compounds which made the vernacular nomenclature of organic compounds highly inconvenient.

Complete step by step answer:
A set of rules has been formulated by IUPAC for a systematic approach for the nomenclature of organic compounds which has been revised from time to time. Any IUPAC name of the given organic compound consists of three parts of the name which are: parent name, prefix and suffix.
$C{H_3} - C{H_2} - Br\;$: The longest carbon chain consists of two carbon atoms and bromine as substituent is present on the first carbon atom itself. Hence the molecule can be named as bromoethane or ethyl bromide.
In $H - CHO\;$ , the longest carbon chain is of one carbon atom and the functional group is aldehyde. For aldehyde, the secondary suffix for an aldehyde is -al. Hence, the IUPAC name is methanal and the common name is formaldehyde.

Note:
According to the Guidelines set by IUPAC, the nomenclature of compounds must follow these steps:
1.The Longest Chain Rule
2.The Lowest Set of Locants: Numbering of parent chains in which the lowest number is assigned to the carbon atom which carries the substituents.
3.Multiple instances of the same substituent
4.The naming of different substituents
5.Correct naming of different substituents in case they are present at the same positions
6.Naming Complex Substituents