Difference Between Iso and Neo Structures

The key difference between iso and neo structures is that the prefix iso refers to an organic compound containing all carbon atoms except one forming a continuous chain whereas the prefix neo refers to an organic compound containing all carbon atoms except two forming a continuous chain.

We use prefixes in organic chemistry in order to distinguish one organic molecule from another.  We use these prefixes along with the name of the compound. Since these prefixes are specific for different functional groups in organic molecules, we can easily identify organic molecules even they have closely related chemical structures.

CONTENTS

1. Overview and Key Difference
2. What is Iso Structures
3. What is Neo Structures
4. Side by Side Comparison – Iso vs Neo Structures in Tabular Form
5. Summary

What is Iso Structures?

Iso is a prefix that we use to name an organic compound containing all carbon atoms except one forming a continuous chain. Therefore, we use this term when there is a single branch in the molecule. This branch occurs at the end of the carbon chain.

We call this branch “terminal isopropyl group”. For example, when there is a methyl group attached to the second carbon of the carbon chain, we use the prefix iso to name this molecule. Ex: isopropyl alcohol. We can use this prefix to name compounds having a minimum of 4 carbon atoms.

What is Neo Structures?

Neo is a prefix that we use to name an organic compound containing all carbon atoms except two forming a continuous chain. This means these compounds have two branches which arise from the main carbon chain. These branches occur at the end of the molecule. We name this functional group as “terminal tert-butylgroup”.

Therefore, if we name a compound with the prefix neo, it means this compound we are naming has two methyl groups attached to the same carbon atom at the terminal of the carbon chain. We can use this prefix when there is a minimum of 5 carbon atoms in the carbon chain.

What is the Difference Between Iso and Neo Structures?

Iso is a prefix that we use to name an organic compound containing all carbon atoms except one forming a continuous chain. We can use this prefix to name compounds having a minimum of 4 carbon atoms. Moreover, we use the prefix “iso” to name compounds having “terminal isopropyl group”. Neo is a prefix that we use to name an organic compound containing all carbon atoms except two forming a continuous chain. We can use this prefix when there is a minimum of 5 carbon atoms in the carbon chain. In addition, we use the prefix “neo” to name compounds having “terminal tert-butyl group”.

Summary – Iso vs Neo Structures

We use different prefixes in organic chemistry to name different chemical compounds. “iso”, and “neo” are such two prefixes. The difference between iso and neo structures is that the prefix iso refers to an organic compound containing all carbon atoms except one forming a continuous chain whereas the prefix neo refers to an organic compound containing all carbon atoms except two forming a continuous chain.

Reference:

1. “Illustrated Glossary of Organic Chemistry – Common Names (n, Neo, Iso, Sec, Tert).” How to Use a Rotary Evaporator.Available here 
2. Mariya. “Mariya.” Askiitians.com, 1 Dec. 2017. Available here  

Image Courtesy:

1.’Isopropyl group’By Su-no-G – Own work. Made with CorelDRAW, not with ChemDraw., (Public Domain) via Commons Wikimedia 
2.’Tert-butyl group’By Su-no-G – self work with ChemDraw, (Public Domain) via Commons Wikimedia