Chapter NW1, Problem 21CTQ

Interpretation Introduction

Interpretation: The correct name for below cyclic alkanes structures should be given.

  

Concept introduction: Systematic way to name different organic compounds is IUPAC nomenclature. It has three parts: root name, suffix, and prefix.

Rules for nomenclature of alkanes:

1 The longest continuous carbon chain is identified first and named in accordance with number of carbon atoms present in it. For example, a hydrocarbon with one carbon atom has prefix “meth”, that with two carbon atoms has prefix “eth”, that with three carbon atoms has prefix “prop” and so on. Suffix used for alkanes is “ane.”

2. Substituents attached to the parent carbon chain are to be identified. These are named by removal of single hydrogen atom from carbon chain end and named by replacement of suffix “ane” by “yl.” For example, if ${\text{CH}}_{\text{3}}$ is used as substituent, it is named as methyl.

3. Carbons of the parent chain are named in such a way that substituents acquire the lowest numbers.

4. If the same substituent is present more than one time in molecule, it is represented by prefix “di”, “tri” and so on. It depends on number of times substituent occurs in molecule.

5. If two or more substituents are present in the molecule, these are named in alphabetical order.

6. If in a molecule, the carbon chain of same length exists then the parent chain will be the one which contains lowest number of substituents.

7. Prefix “cyclo” is used if cyclic alkane is present in a molecule.