Chapter NW1, Problem 5CTQ

Interpretation Introduction

Interpretation: Name of parent chain in below molecules should be given and circled.

  

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, 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 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 parent chain are named in such way that substituents acquire the lowest numbers.

4. If 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 molecule, these are named in alphabetical order.

6. If carbon chains of same length exist in same molecule, chain with the largest number of side chains, followed by lowest number to substituents, chain with the greatest number of carbon atoms in smaller chain and chain with the least branched side chains are preferred over other ones.

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