Ortho-Xylene
The highest-boiling xylene isomer, separated by straight distillation and oxidised almost entirely to phthalic anhydride.
Molecular Structure
What is Ortho-Xylene?
Ortho-xylene is the 1,2-disubstituted xylene isomer — a benzene ring with methyl groups on adjacent carbons. It is a clear liquid boiling at 144.5 °C, the highest of the three isomers.
That boiling point is what makes o-xylene commercially convenient. It sits about 5 °C above meta- and para-xylene, a wide enough gap to separate it from the mixed xylene stream by conventional fractional distillation, without the adsorption or crystallisation steps the other two isomers require.
Its two adjacent methyl groups are ideally placed for oxidation to a cyclic anhydride, and that single reaction accounts for the overwhelming majority of o-xylene demand: vapour-phase oxidation over vanadium pentoxide to phthalic anhydride.
Chelora supplies ortho-xylene fractionated from mixed xylenes to ≥99.0 wt%, with m+p-xylene and non-aromatics controlled for phthalic anhydride oxidation service. Available in ISO tanks, road tankers and drums.
Quick Reference
Key Physical & Chemical Properties
Structure & Bonding
Ortho substitution puts the two methyl groups on adjacent ring carbons — the geometry that lets oxidation close a five-membered anhydride ring, and the reason o-xylene and phthalic anhydride are effectively one market.
Skeletal structure — methyls at C-1 and C-2 (ortho)
Structural Identity
- IUPAC Name1,2-Dimethylbenzene
- Molecular FormulaC₈H₁₀
- Molecular Weight106.17 g/mol
- Hybridisationsp² ring, sp³ methyl carbons
- Substitution pattern1,2-disubstituted (ortho)
- Bond lengths1.39 Å ring C–C; 1.50 Å C–CH₃
- GeometryPlanar ring, C₂ᵥ symmetry
- Isomer separationFractional distillation (≈5 °C bp gap)
- CAS Number95-47-6
- InChI KeyCTQNGGLPUBDAKN-UHFFFAOYSA-N
Product Specifications
Chelora supplies Ortho-Xylene in standard and custom grades. Contact us for specification sheets tailored to your process.
| Chemical name | Ortho-Xylene (o-xylene) |
|---|---|
| CAS Number | 95-47-6 |
| Molecular formula | C₈H₁₀ |
| Molecular weight | 106.17 g/mol |
| Purity (standard grade) | ≥ 99.00 wt% |
| Purity (commercial grade) | ≥ 98.00 wt% |
| m- + p-Xylene (max) | ≤ 0.70 wt% |
| Ethylbenzene (max) | ≤ 0.20 wt% |
| Non-aromatics (max) | ≤ 0.30 wt% |
| Total sulfur (max) | ≤ 1.0 ppm wt |
| Water (max) | ≤ 200 ppm wt |
| Colour | ≤ 20 Pt-Co (Hazen) |
| Distillation range | 143.5 – 145.5 °C |
| Density | 0.876 – 0.882 g/cm³ at 20 °C |
| Flash point | 32 °C (closed cup) |
| Autoignition temperature | 463 °C |
| Flammable limits | 0.9 – 6.7% v/v in air |
| UN Number | UN 1307 |
| IMDG / ADR Class | Class 3 (Flammable Liquid), PG III |
Downstream Applications & Derivatives
Key derivative chains and industrial uses of Ortho-Xylene.
Phthalic Anhydride
Vapour-phase oxidation over a vanadium pentoxide catalyst converts o-xylene to phthalic anhydride. This is the dominant outlet and takes the large majority of global o-xylene supply.
Plasticisers
Phthalic anhydride esterified with 2-ethylhexanol or isononanol gives DOP and DINP for flexible PVC — cable, flooring, film and synthetic leather.
Unsaturated Polyester & Alkyd Resins
PA is a core diacid unit in unsaturated polyester resins for FRP, marine and construction composites, and in alkyd resins for decorative and industrial coatings.
Pigments & Dye Intermediates
Phthalic anhydride routes give phthalimide, phthalonitrile and copper phthalocyanine — the blue and green pigment family used in inks, coatings and plastics.
High-Boiling Solvent
A 144 °C boiling point makes o-xylene useful where a slower evaporation rate is wanted — baking enamels, resin thinning, industrial degreasing and reaction media.
Agrochemical & Fine Chemicals
Nitration and amination routes give 3,4-dimethylaniline and related intermediates for herbicides and pharmaceuticals, alongside o-tolualdehyde derivatives.
Why source Ortho-Xylene through Chelora Petrochem?
Verified Origin
Full origin certification and asset-backed supply chain documentation — no grey-market supply.
Grade Flexibility
Standard and commercial grades available. Isomer purity, ethylbenzene and non-aromatic content can be tightened for phthalic anhydride oxidation duty.
Full Documentation
CoA, SDS, UN transport docs, REACH compliance, and destination-market certificates with every shipment.
Logistics Support
Experienced in bulk aromatic liquid logistics — ISO tanks, road tankers, and drums with nitrogen blanketing where required, for Indian and international delivery.
Storage & Handling Guidelines
Always refer to the full SDS before handling. The following is a summary of key requirements.
- Store in a bunded, well-ventilated, dedicated area away from ignition sources, heat and direct sunlight.
- All electrical equipment in storage and transfer areas must be ATEX/IECEx rated for the applicable zone.
- Bond and earth tanks, tankers, drums and hoses before every transfer — aromatic liquids accumulate static readily.
- Keep away from strong oxidisers, acids and halogens; use PTFE or Viton seals, as many elastomers swell in aromatics.
- Maintain a nitrogen blanket on bulk storage where the tank headspace can sit inside the flammable range.
- Fit fixed flammable-vapour detection with audible and visual alarms set below the LEL in enclosed storage and pump areas.
- Provide local exhaust ventilation at sampling, drumming and loading points, and monitor personal exposure against the OEL.
- Keep foam, dry chemical or CO₂ media available for firefighting — water jets spread the burning liquid.
Hazard Summary
Classification: Flam. Liq. 3 (H226) · Acute Tox. 4 dermal/inhalation (H312, H332) · Skin Irrit. 2 (H315) · Eye Irrit. 2 (H319) · STOT SE 3 (H335) · STOT RE 2 (H373) · Asp. Tox. 1 (H304).
Health: Causes central nervous system depression at elevated vapour concentrations, and defatting dermatitis on repeated skin contact. Aspiration into the lungs can cause chemical pneumonitis — never induce vomiting.
Exposure limits: ACGIH TLV 100 ppm 8-h TWA with a 150 ppm STEL; EU IOELV 50 ppm TWA / 100 ppm STEL with a skin notation; OSHA PEL 100 ppm TWA. Confirm the limit in force in your jurisdiction.
Flammability: Flash point 32 °C — a Class 3 PG III liquid, but ambient temperatures in warm climates can approach the flash point, so treat storage areas as potentially flammable atmospheres.
PPE minimum: Chemical splash goggles, nitrile or Viton gloves, flame-retardant antistatic clothing, and organic-vapour respiratory protection where ventilation cannot hold exposure below the limit.
Consult the full SDS for exposure limits, spill containment, emergency response, and disposal before any use.
Frequently Asked Questions
Technical and commercial questions about Ortho-Xylene sourcing and specifications.
What is ortho-xylene used for?
The overwhelming majority of o-xylene is oxidised to phthalic anhydride, which then goes into DOP and DINP plasticisers for flexible PVC, unsaturated polyester and alkyd resins, and phthalocyanine pigments. Smaller volumes are used as a high-boiling solvent and as a route to 3,4-dimethylaniline and related agrochemical intermediates.
Why is o-xylene separated by distillation when the other isomers are not?
Ortho-xylene boils at 144.5 °C, roughly 5 °C above meta-xylene (139.1 °C) and para-xylene (138.4 °C). That gap is large enough for conventional fractional distillation, although it needs a tall column with a high reflux ratio. Meta- and para-xylene boil within 1 °C of each other, so they have to be separated by adsorption, crystallisation or complexation instead.
How does o-xylene become phthalic anhydride?
Air oxidation in the vapour phase over a supported vanadium pentoxide/titanium dioxide catalyst at around 350–400 °C. Both methyl groups are oxidised and the resulting diacid dehydrates to the cyclic anhydride. The adjacent (ortho) placement of the methyl groups is what makes the five-membered anhydride ring possible — the meta and para isomers give isophthalic and terephthalic acid instead.
What is the difference between mixed xylenes and o-xylene?
Mixed xylenes is the raw C₈ aromatics cut from a reformer or cracker, typically containing all three xylene isomers plus ethylbenzene, and is sold mostly as a solvent or as feed to an aromatics separation complex. Isomer-grade o-xylene has been fractionated out of that stream to ≥98–99 wt% and is bought specifically for phthalic anhydride production.
What impurities matter in o-xylene?
For oxidation service the key limits are residual m- and p-xylene, ethylbenzene, non-aromatics and sulfur. Ethylbenzene and non-aromatics burn to CO₂ without giving useful product, hurting yield; sulfur shortens catalyst life. Colour and water are controlled as general quality indicators.
What documentation does Chelora provide?
Every shipment includes a Certificate of Analysis covering purity, isomer distribution, ethylbenzene, non-aromatics, sulfur, water, colour and distillation range; a Safety Data Sheet (GHS/REACH); UN 1307 Class 3 PG III transport documentation; an origin certificate; and any destination-market certificates required.
Request a quote or specification sheet
Talk to Chelora's sourcing team about Ortho-Xylene grade, volume, logistics, documentation, and lead times. We respond within one business day.
