Quick answer: Ortho-xylene - usually shortened to o-xylene - is itself the common name. The formal IUPAC name is 1,2-dimethylbenzene, which shows up in strict chemical nomenclature, while "ortho-xylene" and "o-xylene" are what appear on purchase orders, Safety Data Sheets, and supplier catalogs. Both refer to the same substance, CAS 95-47-6.
Where "Ortho" Comes From
Ortho/meta/para is a standard chemistry naming system describing how close two substituents sit on a benzene ring: ortho means adjacent carbons, meta means one carbon apart, para means directly across the ring. Xylene has three isomers built on this pattern - ortho-, meta-, and para-xylene - each with different industrial uses, so the prefix isn't just terminology; it identifies which specific compound is being referenced.
Other Names You'll See for the Same Compound
- Ortho-xylene / o-xylene (the standard common name)
- 1,2-Dimethylbenzene (the IUPAC name)
- 1,2-Xylene
- o-Xylol
- o-Methyltoluene
- 2-Methyltoluene
- o-Dimethylbenzene
All of these resolve to CAS 95-47-6, along with a fixed PubChem CID and ECHA EC number (202-422-2). Checking the CAS number is the quickest way to confirm a match regardless of which name a supplier or database uses.
O-Xylene vs. Its Sister Isomers by Name
| Common Name | IUPAC Name | CAS Number |
|---|---|---|
| Ortho-xylene (o-xylene) | 1,2-Dimethylbenzene | 95-47-6 |
| Meta-xylene (m-xylene) | 1,3-Dimethylbenzene | 108-38-3 |
| Para-xylene (p-xylene) | 1,4-Dimethylbenzene | 106-42-3 |
Frequently Asked Questions
Is O-xylene the same thing as ortho-xylene?
Yes - "o-xylene" is the standard abbreviation of "ortho-xylene," both referring to CAS 95-47-6.
Why do some suppliers list it as "1,2-Xylene" instead of "ortho-xylene"?
Both describe the same substitution pattern; "1,2-xylene" just states the position numerically instead of using the word "ortho."
How can I confirm I'm ordering the right compound if a supplier uses an unfamiliar name?
Cross-check the CAS number - 95-47-6 is unique to ortho-xylene regardless of which synonym appears on the label.
