What is the Difference Between Ortho Nitrophenol and Para Nitrophenol

The key difference between ortho nitrophenol and para nitrophenol is that ortho nitrophenol consists of a -OH group and a -NO2 group at 1^st and 2^nd positions of the ring structure, whereas para nitrophenol consists of a -OH group and a -NO2 group attached to the 1^st and 4^th positions of the ring structure.

Ortho and para nitrophenol are aromatic organic compounds containing -OH and -NO2 groups as substitutes in a benzene ring. Nitrophenol can be defined as an organic compound having a benzene ring attached to a -OH group and -NO2 group at two positions of the benzene ring. Hence, this compound has the chemical formula HOC6H5-x(NO2)x. Nitrophenol is the conjugate base of nitrophenolate. Typically, nitrophenol compounds are more acidic than phenols. Furthermore, there are two types of nitrophenol known as mono-nitrophenols and di-nitrophenols. Mono-nitrophenols contain one -NO2 group per molecule, while there are two -NO2 groups in a di-nitrophenol molecule. We can name them ortho, para, or meta nitrophenols according to the position of the -OH group and -NO2 group in this molecule.

CONTENTS

1. Overview and Key Difference
2. What is Ortho Nitrophenol 
3. What is Para Nitrophenol 
4. Similarities Between Ortho Nitrophenol and Para Nitrophenol
5. Ortho Nitrophenol vs Para Nitrophenol in Tabular Form
6. Summary – Ortho Nitrophenol vs Para Nitrophenol 

What is Ortho Nitrophenol?

Ortho nitrophenol is an organic compound having a benzene ring attached to a -OH group and a -NO2 group at the 1^st and 2^nd positions of the benzene ring. In other words, this compound has its substituted groups attached to the adjacent/neighbouring carbon atoms. Ortho nitrophenol occurs as a yellow crystalline solid.

This compound has comparatively fewer intermolecular hydrogen bonds present in its solution. The volatility of this compound is low due to the same reason.

What is Para Nitrophenol?

Para nitrophenol is an organic compound having a benzene ring attached to a -OH group and a -NO2 group at the 1^st and 4^th positions of the benzene ring. Therefore, the substituted groups are not attached to the adjacent carbon atoms.

This compound has comparatively more intermolecular hydrogen bonds present in its solution. The volatility of this compound is also high because of this property.

Similarities Between Ortho Nitrophenol and Para Nitrophenol

1. Ortho nitrophenol and para nitrophenol are isomers of nitrophenol.
2. Both contain intermolecular hydrogen bonds.
3. They are more acidic than phenol.

Difference Between Ortho Nitrophenol and Para Nitrophenol

Ortho and para nitrophenol are aromatic organic compounds containing -OH and -NO2 groups as substitutes in a benzene ring. The key difference between ortho nitrophenol and para nitrophenol is that ortho nitrophenol consists of a -OH group and a -NO2 group at 1^st and 2^nd positions of the ring structure, whereas para nitrophenol consists of a -OH group and a -NO2 group attached to the 1^st and 4^th positions of the ring structure. Moreover, para nitrophenol has higher volatility and melting point than ortho nitrophenol.

The below infographic lists the differences between ortho nitrophenol and para nitrophenol in tabular form for side by side comparison.

Summary – Ortho Nitrophenol vs Para Nitrophenol

Nitrophenol can be defined as an organic compound having a benzene ring attached to a -OH group and -NO2 group at two positions of the benzene ring. Hence, this compound has the chemical formula HOC6H5-x(NO2)x. There are three forms of nitrophenol as ortho, para and metal form. The key difference between ortho nitrophenol and para nitrophenol is that ortho nitrophenol consists of a -OH group and a -NO2 group at 1^st and 2^nd positions of the ring structure, whereas para nitrophenol consists of a -OH group and a -NO2 group attached to the 1^st and 4^th positions of the ring structure.

Reference:

1. “4-Nitrophenol.” National Center for Biotechnology Information. PubChem Compound Database, U.S. National Library of Medicine.

Image Courtesy:

1. “O-Nitrophenol” By NEUROtiker – Own work (Public Domain) via Commons Wikimedia
2. “4-Nitrophenol acsv” By Calvero – Own work (Public Domain) via Commons Wikimedia