Difference Between O-Xylene and P-Xylene

The key difference between O-xylene and P-xylene is that O-xylene contains two methyl groups attached to the benzene ring at adjacent substituent positions, whereas P-xylene contains two methyl groups attached to the benzene ring at opposite substituent positions.

Xylene is an organic compound. It is one of the three isomers of dimethylbenzene. It contains two methyl groups attached to a benzene ring at different positions. The chemical formula of xylene is (CH₃)₂C₆H₄. The three isomers of dimethylbenzene are ortho-xylene, para-xylene and meta-xylene.

CONTENTS

1. Overview and Key Difference
2. What is O-Xylene
3. What is P-Xylene
4. Similarities Between O-Xylene and P-Xylene 
5. Side by Side Comparison – O-Xylene vs P-Xylene in Tabular Form
6. Summary

What is O-Xylene?

o-Xylene is an isomer of dimethylbenzene in which the two methyl groups are attached to adjacent substituent positions. If there are two substituents attached to two adjacent carbon atoms of benzene, we call this configuration “ortho” configuration. Therefore, the name O-xylene originates from the name “ortho-xylene”. This is a constitutional isomer of para and meta configurations of dimethylbenzene. O-xylene occurs as a liquid at room temperature. It is a colourless liquid which is slightly oily and highly flammable.

We can produce O-xylene via cracking petroleum. That means, O-xylene is a synthetic compound and its source is petroleum oil. And, this liquid material is very useful in the production of phthalic anhydride. Phthalic anhydride is an important precursor for the production of many other substances such as drugs.

What is P-Xylene?

P-Xylene is an isomer of dimethylbenzene in which the two methyl groups are attached to opposite substituent positions. If there are two substituents attached to two opposite carbon atoms of benzene, we call this configuration “para” configuration. Therefore, the name P-xylene derives from the name “para-xylene”. Also, this is a constitutional isomer of ortho and meta configurations of dimethylbenzene. P-xylene occurs as a liquid at room temperature and is colourless and highly flammable.

We can produce P-xylene via catalytic reforming of petroleum naphtha. Then the produced p-xylene is separated through a series of distillation and crystallization processes. Among the other isomers of p-xylene, it has the highest melting point. When considering is applications, p-xylene is important as a chemical feedstock, as a component in the production of polymer materials, etc.

What are the Similarities Between O-Xylene and P-Xylene?

• Xylene is an organic compound having the chemical formula (CH₃)₂C₆H₄.
• Both these are colourless and flammable liquids at room temperature.

What is the Difference Between O-Xylene and P-Xylene?

The key difference between O-xylene and P-xylene is that O-xylene contains two methyl groups attached to the benzene ring at adjacent substituent positions, whereas P-xylene contains two methyl groups attached to the benzene ring at opposite substituent positions.

Moreover, p-xylene has a high melting point compared to o-xylene. It is because the methyl groups in p-xylene are separated in such a way that there is less strain in the molecule. Therefore, p-xylene molecules have comparatively a strong attraction force between them, which makes it difficult to separate the molecules from each other. Thus, this is also a difference between O-xylene and P-xylene. Furthermore, another difference between O-xylene and P-xylene is that the o-xylene has methyl groups at 1 and 2 positions, while the p-xylene has methyl groups at 1 and 4 positions. When considering the production processes, we can produce o-xylene via cracking petroleum while we can produce p-xylene via catalytic reforming of petroleum.

Summary – O-Xylene vs P-Xylene

Xylene is an organic compound having the chemical formula (CH₃)₂C₆H₄. The key difference between O-xylene and P-xylene is that O-xylene contains two methyl groups attached to the benzene ring at adjacent substituent positions, whereas P-xylene contains two methyl groups attached to the benzene ring at opposite substituent positions.

Reference:

1. “Xylene.” Wikipedia, Wikimedia Foundation, 17 Feb. 2020, Available here.

Image Courtesy:

1. “Ortho-Xylol – ortho-xylene 2” By NEUROtiker – Own work (Public Domain) via Commons Wikimedia
2. “Para-Xylol – para-xylene” By NEUROtiker – Own work (Public Domain) via Commons Wikimedia