Q34E - Organic Chemistry (Mcmurry)

Question

Draw and name all monochloro derivatives of 2,5-dimethyl hexane ${\mathbf{C}}_8{\mathbf{H}}_{17}\mathbf{Cl}$ .

Step-by-Step Solution

Answer

There are 3 monochloro derivatives of 2,5-dimethyl hexane, namely; 2-chloro-2,5-dimethyl hexane, 1-chloro-2,5-dimethyl pentane and 3-chloro-2,5-dimethyl hexane.

Step 1: Isomerism

Chemical compounds which have identical chemical formula but have different chemical structures, different properties, are known to be exhibiting isomerism. Therefore, the compounds which exhibit isomerism are called isomers.

It is of two types- structural and stereoisomerism. Here we will be talking about structural isomerism. In structural isomerism the constituent atoms are linked in different ways in each isomer. For example- Alkane with formula ${\text{C}}_{\text{5}}{\text{H}}_{\text{12}}$  can have three isomers, showing chain isomerism ( type of isomerism where the molecular formula of isomers is same but they have different length of C chains).

Monobromo pentane can have 8 isomers showing position isomerism (type of structural isomerism where the molecular formula of isomers is same but they have different positions of functional groups attached).

Step 2: Monochloro derivatives of 2,5-dimethyl hexane

There is no direct formula to find out the structures possible but you can always go like replacing one hydrogen at a time with chlorine, from the carbon skeleton and then naming it ( IUPAC nomenclature). By following IUPAC nomenclature, you can ensure that you have not made a duplicate structure.

If monochlorination of 2,5-dimethyl hexane is carried out, we can get three position isomers as can be seen from the equation given below.

Monochloro derivatives of 2,5-dimethyl hexane