Chapter 12, Problem 12.148EP

Interpretation Introduction

Interpretation:

The IUPAC name for the nine isomeric halogenated hydrocarbons that have molecular formula of ${\text{C}}_{\text{4}}{\text{H}}_{\text{8}}{\text{Cl}}_{\text{2}}$ has to be given.

Concept Introduction:

The derivative of alkane with halogen instead of one or more hydrogen atoms is known as halogenated alkane.  If the same is present in cycloalkane, then it is known as halogenated cycloalkane.  They are product of reaction between alkane/cycloalkane with halogens.

IUPAC nomenclature for halogenated alkanes/cycloalkanes:

Similar to the alkyl groups, the halogen is also treated as substituents present on the carbon chain.  They are called as fluoro-, chloro-, bromo-, and iodo-.

If the carbon chain contains both alkyl and halogen, they both are considered of equal ranks.  The numbering is done in a way so that the substituents get the least number, whether it is an alkyl or a halo group.

In IUPAC names, the groups that are present on the carbon chain are written in alphabetical order.

Common names:

Halogenated alkanes are also named as alkyl halides.  These are not IUPAC names.  They are common names.  In a common name, two parts are present.  First part is the name of the hydrocarbon (alkyl group).  Second part gives the halogen present in the compound.  The halogen is considered as though it is present as an ion even though no ions are present.

Isomers:

Isomers are compounds which have same molecular formula but different structural formula.  They have different chemical and physical property.