m-Xylene for Isophthalic Acid Production | Aure Chemical
m-Xylene, chemically known as 1,3-dimethylbenzene and identified by CAS number 108-38-3, is an established industrial feedstock for the production of isophthalic acid. Isophthalic acid serves as an important intermediate in unsaturated polyester resins, coating resins, specialty polyesters and selected modified PET or copolyester systems. In commercial practice, m-Xylene normally enters these downstream value chains through isophthalic acid rather than through direct addition to resin or polymer formulations.
Successful sourcing of this single-isomer aromatic depends on more than price. Feedstock specification, isomer purity, impurity profile, batch consistency, packaging, logistics and formal plant qualification can all influence supply suitability. Understanding the relationship among the xylene isomers helps buyers confirm that the material under evaluation is the correct meta isomer rather than mixed xylenes or another dimethylbenzene grade.
Why is m-Xylene used to produce isophthalic acid? m-Xylene contains two methyl groups at the 1,3-positions of the benzene ring. Controlled industrial oxidation converts these side chains into carboxylic-acid groups, producing the aromatic dicarboxylic acid known as isophthalic acid. This structural relationship makes m-Xylene an established feedstock for plants designed around the meta-xylene oxidation route.
What Is m-Xylene?
m-Xylene is the meta isomer of dimethylbenzene. Its molecular formula is C8H10, and its approximate molecular weight is 106.17 g/mol. The two methyl substituents occupy the 1,3-positions on the aromatic ring. This arrangement distinguishes it from o-Xylene, or 1,2-dimethylbenzene, and p-Xylene, or 1,4-dimethylbenzene.
Under normal ambient conditions, m-Xylene is a clear, colorless liquid with a characteristic aromatic odor. Its physical properties, hazard classification and handling requirements should be confirmed against the current safety data sheet for the proposed commercial source.
High-purity m-Xylene differs from mixed xylenes, which may contain variable proportions of o-Xylene, m-Xylene, p-Xylene and ethylbenzene. Accurate CAS identification in every request for quotation helps ensure that the supplier evaluates m-Xylene CAS 108-38-3 against the buyer’s approved specification rather than a general mixed aromatic solvent grade.
Why m-Xylene Is Used as an Isophthalic Acid Feedstock
The two methyl groups of m-Xylene are positioned meta to each other. During industrial oxidation, these methyl substituents are converted into carboxylic-acid groups, producing isophthalic acid. The route has been practiced commercially for decades and is an established process configuration for plants designed to produce isophthalic acid from m-Xylene.
Suitability for continuous industrial use depends on the plant design, catalyst system, reaction medium, purification arrangement and formal feedstock qualification procedure. Not every aromatic-oxidation unit is configured for m-Xylene, and the material is not interchangeable with o-Xylene, p-Xylene or mixed xylenes merely because the products share the molecular formula C8H10.
Feedstock selection remains a plant-specific engineering and commercial decision based on the licensed process, approved raw-material specification and downstream product-quality requirements.
How Isophthalic Acid Is Produced from m-Xylene
Industrial production generally follows a sequence of feedstock control, catalytic oxidation, product recovery and purification. Exact operating conditions are determined by the licensed technology and the individual plant’s design basis. The description below is therefore a general procurement-level overview rather than an operating instruction.
Feedstock receipt and quality confirmation. Incoming m-Xylene is checked against the plant’s approved assay, impurity and documentation requirements before introduction into the process.
Controlled introduction into the oxidation system. The aromatic feed is combined with the reaction medium under conditions managed by the plant’s process-control and safety systems.
Liquid-phase catalytic oxidation. Commercial systems commonly use air or another oxygen-containing gas. Depending on the licensed process, oxidation may take place in an organic-acid medium such as acetic acid and may use cobalt- and manganese-based catalysts with a bromide promoter.
Heat removal and process control. The oxidation reaction is strongly exothermic, so the reactor system incorporates plant-specific heat-management and process-control arrangements.
Formation and recovery of crude isophthalic acid. Isophthalic acid forms during oxidation and is recovered by crystallization, precipitation or another process-specific separation method.
Solid-liquid separation and washing. The crude solid is separated from the liquid phase and washed to reduce residual solvent and soluble impurities.
Purification. The crude material undergoes the purification steps required by the licensed process and intended final grade.
Drying and final quality confirmation. Finished isophthalic acid is dried and analyzed against the applicable specification before storage, packaging or downstream use.
The purification sequence and final quality level depend on whether the plant is producing a technical grade or a higher-purity grade intended for polyester and other demanding downstream applications. Catalyst formulations, impurity-control methods and purification arrangements remain plant-specific.
Feedstock qualification should therefore be based on the buyer’s approved specification rather than on generic process literature or a universal online purity standard.
Why m-Xylene Feedstock Quality Matters
Isophthalic acid producers may review m-Xylene assay, residual o-Xylene and p-Xylene, ethylbenzene, other aromatic impurities, non-aromatic hydrocarbons, water, color, nonvolatile residue, distillation characteristics and catalyst-sensitive trace impurities where relevant. The importance of each parameter depends on the catalyst formulation, oxidation system, purification process and final product requirements.
Analytical methods and acceptance limits should be defined in the purchase specification, quality agreement or plant-qualification documentation. Batch-to-batch consistency is also important. Unexpected changes in impurity profile, analytical results or source characteristics should be communicated and evaluated against the plant’s approved feedstock specification and qualification requirements.
Buyers preparing a technical inquiry may consult the xylene specifications and procurement checklist for the information normally reviewed during raw-material evaluation.
| Quality parameter | Why an isophthalic acid producer may review it | How it should be confirmed |
|---|---|---|
| m-Xylene assay | Determines the proportion of the feed available for the intended oxidation reaction and may affect process performance under plant-specific conditions | Current COA, agreed specification and approved analytical method |
| o-Xylene and p-Xylene content | Forms part of the feedstock impurity profile and may require control under the plant’s approved process specification | Gas-chromatographic analysis and agreed acceptance limits |
| Ethylbenzene | May enter competing oxidation pathways and should remain within the buyer’s approved impurity limits | Current COA, specification and agreed analytical method |
| Other aromatic impurities | May contribute to process-specific oxidation intermediates or final product impurities | Detailed chromatographic profile where required |
| Non-aromatic impurities | May require evaluation for process compatibility, catalyst protection and final product quality | Supplier specification, additional analysis or pre-shipment sample |
| Water | Must remain within the approved feedstock specification because the oxidation process uses a plant-specific solvent and water balance | Karl Fischer or another agreed analytical method |
| Color | Provides a general appearance and incoming quality-control indicator | Visual or instrumental measurement stated on the COA |
| Nonvolatile residue | May indicate the presence of higher-boiling or nonvolatile components requiring evaluation | Agreed test method and specification |
| Sulfur or other catalyst-sensitive trace impurities | May affect catalyst performance depending on the catalyst formulation and plant-specific impurity limits | Plant qualification, quality agreement or additional analysis where required |
Available m-Xylene specifications and supply information can be reviewed on the product page. The applicable specification, source and supporting documents should be confirmed for each proposed supply arrangement and batch.
m-Xylene Compared with Mixed Xylenes
Mixed xylenes may contain o-Xylene, m-Xylene, p-Xylene and ethylbenzene in proportions that vary according to the refining or petrochemical source. A product described only as “xylene” is therefore not chemically equivalent to m-Xylene CAS 108-38-3.
Isophthalic acid producers operating m-Xylene-based units generally require a defined meta-isomer assay and an approved impurity profile. Substitution with mixed xylenes without formal plant review may change feed composition, oxidation behavior, impurity distribution and purification requirements.
Mixed xylenes should not be considered automatically unsuitable for every process, but acceptance depends on the licensed technology, catalyst system and approved feedstock specification. The specific composition and impurity profile are more meaningful than a generalized marketing claim of “high purity.”
m-Xylene Compared with p-Xylene
m-Xylene is associated primarily with isophthalic acid, while p-Xylene is associated primarily with terephthalic acid, purified terephthalic acid and dimethyl terephthalate. The different positions of the methyl groups result in different aromatic dicarboxylic-acid structures after oxidation.
Isophthalic acid and terephthalic acid perform different functions in polyester and resin systems. Neither material should be described as universally better than the other, and m-Xylene and p-Xylene should not be substituted for one another without technical review.
Each pathway requires the correct CAS number, feedstock specification and plant qualification. Buyers evaluating the para-isomer value chain may consult the application guide on p-Xylene for PTA and DMT production.
m-Xylene Compared with o-Xylene
o-Xylene is primarily associated with phthalic anhydride production, while m-Xylene is primarily associated with isophthalic acid. The 1,2- and 1,3-positions of their methyl groups lead to different oxidation products and downstream chemical pathways.
The two feedstocks require separate process qualification, analytical specifications and purchasing documentation. Further information on the ortho-isomer route is available in the application page covering o-Xylene for phthalic anhydride production.
Main Downstream Uses of Isophthalic Acid
m-Xylene is normally supplied to an isophthalic acid producer rather than directly to every downstream resin or polymer manufacturer. The industrial value chain proceeds from m-Xylene to isophthalic acid and then to selected polyester, resin and coating systems.
Established downstream categories include unsaturated polyester resins, coating resins, specialty polyesters, copolyesters and selected PET-modification applications. Isophthalic acid may be used as a comonomer or structural building block, depending on the resin chemistry and polymer architecture.
Final performance depends on the complete downstream formulation, monomer balance, molecular weight, processing conditions and application environment. It should not be attributed directly to m-Xylene purity or to the presence of isophthalic acid alone.
Isophthalic Acid in Unsaturated Polyester Resins and Coatings
Isophthalic acid is used in selected unsaturated polyester and coating-resin systems. Formulators may select IPA-containing resin structures when targeting a particular balance of chemical resistance, durability, mechanical properties, coating performance or service-environment requirements.
The actual result depends on the complete resin formulation, acid and glycol selection, molecular weight, crosslinking chemistry, curing conditions, fillers, reinforcement, additives and intended service environment. Isophthalic acid does not automatically deliver the same performance improvement in every resin system.
The separate application page on m-Xylene in unsaturated polyester resins and coatings examines this downstream pathway in greater detail.
Isophthalic Acid in Specialty Polyesters and PET Modification
Isophthalic acid may be used as a comonomer in selected specialty polyester, copolyester or modified PET systems. Depending on the comonomer level and polymer architecture, it may be selected to modify crystallization behavior, processing characteristics, clarity or other application-specific properties.
The resulting effect must be evaluated within the complete polymer design rather than attributed to the comonomer alone. Polymerization technology, molecular weight, comonomer distribution, processing conditions and final application requirements all influence performance.
Why Consistent m-Xylene Supply Matters
A qualified oxidation plant may review consistency of isomer composition, impurity profile, analytical methods, batch documentation, source continuity, lot traceability, packaging cleanliness and logistics reliability.
Unexpected analytical trends, source changes or changes in impurity distribution should be reviewed under the plant’s supplier-change and feedstock-qualification procedures. A material meeting the written specification should not be assumed to create a process problem, but significant changes in source characteristics may still require communication and formal review.
Clear supplier communication, traceable batch documentation and agreed change-notification procedures help buyers manage raw-material qualification and supply continuity.
Packaging and Transportation Considerations
Industrial quantities of m-Xylene may be evaluated for supply in steel drums where appropriate, road tankers, buyer-provided ISO tanks, supplier-arranged ISO tanks or other bulk arrangements where operationally feasible. Actual availability depends on the approved source, specification, quantity, packaging, loading location, destination, equipment availability, carrier acceptance and dangerous-goods regulations.
In Aure Chemical’s usual operating model, buyer-provided ISO tanks may be considered for certain FCA or FOB arrangements. Where Aure Chemical is requested to arrange the ISO tank and ocean freight, CFR or CIF terms may be evaluated. Incoterms alone do not determine tank ownership or leasing responsibility, and all arrangements remain subject to operational confirmation.
No universal drum size or ISO tank loading quantity should be assumed. Loading depends on equipment design, product density, permitted filling ratio, route requirements and applicable transport rules.
Further practical guidance is available in the article on bulk xylene packaging and ISO tank transportation. The current safety data sheet, carrier requirements and applicable regulations take precedence over general information provided on this page.
Information Required for an m-Xylene RFQ
A clear request for quotation allows the supplier to evaluate technical, commercial and logistical feasibility. Buyers should normally provide:
Product name, stated as m-Xylene or meta-Xylene.
CAS number 108-38-3.
Required assay or complete feedstock specification.
Intended use in isophthalic acid production.
Initial trial quantity, if applicable.
Regular order quantity.
Estimated annual demand.
Preferred packaging.
Whether the buyer can provide an ISO tank.
Destination country.
Destination port or delivery point.
Required Incoterm.
Required documents, such as COA, SDS or certificate of origin.
Target shipment schedule.
Proposed payment method.
Importer and end-user details where compliance review is required.
Plant qualification, sample or approval requirements.
Confidential operating conditions are not normally required during the initial quotation stage. General end-use, specification and qualification information may nevertheless be needed for product-suitability review, compliance assessment, source evaluation, packaging confirmation and logistics planning.
Evaluating m-Xylene Supply with Aure Chemical
Aure Chemical works with qualified Chinese producers and supply partners to evaluate m-Xylene requirements for international industrial buyers. Supply feasibility is reviewed according to the requested specification, quantity, packaging, loading arrangement, destination and current source availability.
Aure Chemical may assist with source evaluation, representative certificate-of-analysis review, safety-data-sheet provision, packaging confirmation, export-document coordination, dangerous-goods logistics evaluation and discussion of FOB, CFR or CIF terms where operationally feasible.
Sample or qualification coordination may also be evaluated according to source capability, required quantity and buyer approval procedures. Availability, timing and documentation must be confirmed for each project rather than assumed in advance.
Industrial buyers may review the available bulk m-Xylene supply information and submit their specification, quantity, packaging, destination and qualification requirements for a formal feasibility evaluation.
Frequently Asked Questions
Why is m-Xylene used to produce isophthalic acid?
The two methyl groups of m-Xylene occupy the 1,3-positions on the benzene ring. Controlled industrial oxidation converts these side chains into carboxylic-acid groups, producing isophthalic acid. This structural relationship makes m-Xylene an established feedstock for plants designed around the meta-xylene oxidation route.
What is the CAS number of m-Xylene?
The Chemical Abstracts Service registry number for m-Xylene is 108-38-3. Using the correct CAS number helps distinguish the meta isomer from mixed xylenes, o-Xylene, p-Xylene and other aromatic solvent or feedstock grades.
Is m-Xylene the same as mixed xylene?
No. Mixed xylenes may contain variable proportions of all three dimethylbenzene isomers together with ethylbenzene. m-Xylene CAS 108-38-3 refers specifically to the meta isomer. Isophthalic acid plants normally require an approved m-Xylene assay and impurity profile that mixed xylenes may not meet without formal qualification.
How is m-Xylene converted into isophthalic acid?
Industrial conversion generally involves liquid-phase catalytic oxidation with air or another oxygen-containing gas. Depending on the licensed process, the system may use an organic-acid medium and cobalt- and manganese-based catalysts with a bromide promoter. The resulting crude isophthalic acid is separated, purified and dried according to plant-specific requirements.
What is the difference between m-Xylene and p-Xylene?
m-Xylene is oxidized primarily to isophthalic acid, while p-Xylene is oxidized primarily to terephthalic acid or purified terephthalic acid and is also associated with DMT production. The different methyl-group positions produce different dicarboxylic-acid structures and downstream polymer roles.
What is the difference between m-Xylene and o-Xylene?
m-Xylene contains methyl groups at the 1,3-positions and is primarily associated with isophthalic acid. o-Xylene contains methyl groups at the 1,2-positions and is primarily associated with phthalic anhydride. Each requires a separate process design, specification and qualification procedure.
Which m-Xylene specification is required for isophthalic acid production?
There is no single universal specification for every plant. Each producer should define an approved feedstock specification covering m-Xylene assay, residual isomers, ethylbenzene, water and other relevant impurities according to its catalyst system, licensed process and final product requirements.
Can m-Xylene be shipped in an ISO tank?
ISO tank shipment may be evaluated where operationally feasible. Arrangements can involve a buyer-provided or supplier-arranged tank, subject to source capability, quantity, loading location, destination, equipment availability, carrier acceptance and dangerous-goods regulations.
What information is needed for an m-Xylene quotation?
Buyers should provide the product name, CAS number, required specification, quantity, estimated annual demand, preferred packaging, destination, Incoterm, required documents, target shipment schedule and any sample or qualification requirements. General end-use information may also be required for compliance and logistics review.
Industrial buyers evaluating m-Xylene for isophthalic acid production may provide Aure Chemical with the required specification, quantity, packaging, destination, Incoterm, shipment schedule and qualification requirements for a supply-feasibility review.