Structural Isomers

<< Introduction to Organic Chemistry

 

List structural isomers for an organic compound of given molecular formula

 

Prerequisite knowledge

• Structural isomerism (chain/position/functional group)

 

Approach

1. Draw the structure with the longest possible chain

2. If a functional group is present, shift the position of the group to get all the different positional isomers

3. After all positional isomers have been identified, draw the structure of the next longest chain (minus 1 C)

4. Shift the position of the functional group and/ or substituent to get all the different isomers

5. Repeat steps 3 & 4 until no more variations

 

Example

 

There are 4 structural isomers for C₄H₁₀Cl.

 

Practice

 

Draw the structural isomers for the following compounds.

• C₅H₁₀

• C₇H₁₆

• C₅H₁₁Br

• C₄H₁₀O