Introduction to Itaconic Acid
Itaconic acid (CAS 97-65-4), also called methylenesuccinic acid, is an unsaturated dicarboxylic acid that has become one of the most important bio-based platform chemicals. It is produced at commercial scale by fermentation of sugars using the mould Aspergillus terreus, and it is prized as a bio-based alternative to petroleum-derived monomers such as acrylic and methacrylic acid.
Its two carboxylic acid groups and its exocyclic carbon–carbon double bond make it a versatile monomer: it can be polymerised, esterified, added across (Michael addition) and converted into a family of derivatives, including dimethyl itaconate and itaconic anhydride. Those products feed into coatings, adhesives, paper and textile sizes, superabsorbent polymers, plastics and resins.
This article covers the chemistry and properties of itaconic acid, its industrial production by fermentation and by older thermal routes, its derivatives, specifications, applications and sourcing. PolyBlueChem can supply itaconic acid (CAS 97-65-4) as a bulk raw material; see the itaconic acid product page for the current specification.
Chemical Identity and Structure
Itaconic acid is a five-carbon, unsaturated 1,4-dicarboxylic acid. Structurally it is a methylene-substituted succinic acid: a succinic acid backbone (two –CH2COOH arms) bearing an exocyclic methylene group (=CH2) at the alpha position. That unsaturation is the key to its reactivity.
| Property | Value |
|---|---|
| Common name | Itaconic acid (IA) |
| IUPAC name | 2-Methylidenebutanedioic acid (methylenesuccinic acid) |
| CAS number | 97-65-4 |
| Molecular formula | C5H6O4 |
| Molecular weight | 130.10 g/mol |
| SMILES | C=C(CC(=O)O)C(=O)O |
| Appearance | White to off-white crystalline powder |
| Class | Unsaturated dicarboxylic acid (bio-based platform chemical) |
Isomers. Itaconic acid has two geometric isomers with the same formula, citraconic acid (cis-methylmaleic acid) and mesaconic acid (trans-, also called methylfumaric acid). Heating itaconic acid can isomerise it to citraconic acid, a point that matters in high-temperature processing.
Physical and Chemical Properties
| Property | Typical value / behaviour |
|---|---|
| Appearance | White to off-white crystalline solid |
| Melting point | Approx. 165–168 °C (with decomposition on strong heating) |
| Solubility in water | Readily soluble |
| Solubility in organics | Soluble in ethanol and acetone; less soluble in non-polar solvents |
| Acidity (pKa) | pKa1 approx. 3.8, pKa2 approx. 5.4 (dibasic acid) |
| Reactive site | Exocyclic methylene (C=C) plus two carboxylic acids |
| Decomposition | Decarboxylates and isomerises on strong heating |
| Polymerisation | Readily homo- and co-polymerises through the double bond |
Itaconic acid is a stronger acid than simple monocarboxylic acids, reflecting its two carboxyl groups, and it is fully miscible with water at practical concentrations. These properties — good water solubility, dibasic character and a polymerisable double bond — are what make it useful as a bio-based monomer and intermediate.
Reactivity of the Unsaturated Dicarboxylic Acid
Itaconic acid’s chemistry is dominated by two functional features. Their reactions define both its derivatives and its applications.
- Radical polymerisation. The exocyclic double bond undergoes free-radical homo- and copolymerisation, which is the basis of its use in latexes, coatings, adhesives and superabsorbents.
- Esterification. Both carboxyl groups can be esterified, giving mono- and di-esters such as dimethyl itaconate.
- Michael addition. The activated double bond adds nucleophiles, useful in crosslinking and functionalisation.
- Anhydride formation. On heating, itaconic acid can lose water to form itaconic anhydride.
- Decarboxylation and isomerisation. Strong heating causes loss of CO2 and isomerisation to citraconic or mesaconic acid, which must be managed in high-temperature processes.
- Salt formation. The dibasic acid forms mono- and di-salts, relevant to water treatment and to aqueous formulations.
Industrial Production: The Thermal Route
Before fermentation became dominant, itaconic acid was produced by the dry distillation (pyrolysis) of citric acid, which loses water and carbon dioxide to give itaconic acid and related products. This route established the material historically but is inefficient and has largely been superseded by fermentation for commercial supply.
Industrial Production: Fermentation
Today, essentially all commercial itaconic acid is produced by aerobic fermentation of a carbohydrate feedstock using Aspergillus terreus (and closely related strains that produce it as a secondary metabolite). The process is a well-established, bio-based manufacturing route.
| Stage | Purpose | Notes |
|---|---|---|
| 1. Feedstock preparation | Provide a fermentable sugar | Glucose, sucrose, starch hydrolysate or molasses; sterilised medium |
| 2. Inoculation | Introduce the production organism | Spores or preculture of Aspergillus terreus |
| 3. Aerobic fermentation | Produce itaconic acid | Stirred, aerated bioreactor; controlled temperature and pH; several days |
| 4. Biomass separation | Remove fungal biomass | Filtration or centrifugation |
| 5. Recovery and purification | Isolate itaconic acid | Crystallisation, or an ion-exchange/evaporation route |
| 6. Drying and finishing | Deliver the specification | Drying to a white crystalline powder; milling and screening |
Because the product is an acid, the fermentation broth is usually kept near its pKa range and the acid is recovered by crystallisation or by adsorption onto ion-exchange resin followed by elution and concentration. Modern process development focuses on raising the titre and yield, reducing the cost of recovery and using cheaper or waste-derived feedstocks.
Derivatives and Related Products
Much of itaconic acid’s commercial value lies in its derivatives, which are made by esterification, dehydration or polymerisation.
| Derivative | Made by | Typical use |
|---|---|---|
| Dimethyl itaconate | Esterification with methanol | Monomer and chemical intermediate |
| Mono-esters | Partial esterification | Surfactants, functional monomers |
| Itaconic anhydride | Dehydration on heating | Crosslinking and functionalisation |
| Citraconic / mesaconic acid | Isomerisation | Specialty intermediates |
| Itaconate polymers and copolymers | Free-radical (co)polymerisation | Latexes, coatings, adhesives, superabsorbents |
Specifications and Grades
Itaconic acid is supplied against a technical specification, with assay, moisture, colour and the level of related organic acids being the key parameters.
| Parameter | Typical specification |
|---|---|
| Appearance | White crystalline powder |
| Assay (purity) | Typically 99% or higher, by titration or HPLC |
| Moisture | Low (loss on drying), grade-dependent |
| Related organic acids | Within set limits |
| Colour | White to off-white; colour controlled for clear or light-coloured products |
| Heavy metals / ash | Within applicable limits |
| Particle size | Agreed where flow or dissolution matters |
Applications: Polymers and Resins
The largest use of itaconic acid is as a bio-based monomer for polymers and resins. The table below summarises the main polymer applications.
| Application | How itaconic acid is used |
|---|---|
| Coatings and paints | Co-monomer that improves adhesion, hardness and water resistance in acrylic and styrene-acrylic latexes |
| Adhesives | Functional monomer in emulsion polymers for adhesion and stability |
| Paper and textile sizes | Co-monomer in binders and sizes |
| Superabsorbent polymers | Bio-based co-monomer in crosslinked polyacrylic absorbents |
| SBR latex and rubber | Co-monomer with styrene and butadiene to modify latex properties |
| Plastics and resins | Building block for unsaturated polyester and specialty resins |
As a bio-based, difunctional, water-soluble monomer, itaconic acid is attractive where formulators want to reduce reliance on petroleum-derived acrylic and methacrylic monomers, and the carboxylic acid groups in the finished polymer also improve adhesion and pigment dispersion.
Other Applications
- Water treatment and drilling fluids: itaconic-acid copolymers act as scale inhibitors and dispersants.
- Agricultural and functional chemicals: derivatives are used in a range of specialty formulations.
- Chemical intermediate: a precursor to esters, anhydrides and other unsaturated acids.
- Pharmaceutical and research use: a building block in synthesis and a reference material.
Comparison with Related Monomers
Itaconic acid competes with several unsaturated acids as a monomer. The table compares the most relevant ones.
| Monomer | Origin | Functional groups | Notes |
|---|---|---|---|
| Itaconic acid | Bio-based (fermentation) | Two –COOH, one C=C | Difunctional, water-soluble, bio-based |
| Acrylic acid | Petrochemical | One –COOH, one C=C | Dominant commodity monomer; highly reactive |
| Methacrylic acid | Petrochemical | One –COOH, one substituted C=C | Used where harder polymers are wanted |
| Maleic anhydride | Petrochemical | Cyclic anhydride, C=C | Used for polyesters and copolymers |
Itaconic acid’s advantages are its bio-based origin, its two carboxylic acid groups and its water solubility; its main challenge is that it polymerises more slowly than acrylic monomers, so it is generally used as a co-monomer rather than the sole monomer.
Quality Control and Analytical Methods
- Assay and purity by acid-base titration and/or HPLC.
- Identity by melting point, IR and, where required, NMR.
- Moisture by loss on drying or Karl Fischer titration.
- Related organic acids (for example citraconic and mesaconic acid) by HPLC.
- Colour and heavy metals / ash per specification.
Regulatory, Safety and Handling
Itaconic acid is a dibasic organic acid and is handled as an ordinary industrial chemical. It is bio-based, non-volatile and readily biodegradable, which is part of its appeal. Points for buyers:
- Handling. As a powder, it can generate dust; use appropriate ventilation and protective equipment and follow the safety data sheet.
- Storage. Store dry and sealed; the solid is hygroscopic and should be protected from moisture to prevent caking.
- Regulatory. Itaconic acid and its principal esters are established industrial chemicals; some grades and derivatives are used in food-contact or other regulated applications, so the specific grade and its documentation must be confirmed for the intended use.
- Documentation. COA and SDS are supplied; request food-contact or other statements where relevant.
Market and Supply Overview
- Bio-based positioning. Itaconic acid is one of the best-known bio-based platform chemicals, produced by fermentation rather than from petroleum, which drives growing interest as a drop-in or partial replacement for acrylic monomers.
- Production base. Manufactured by fermentation at facilities that operate the Aspergillus terreus process.
- Price drivers. Feedstock (sugar) cost, fermentation yield and titre, energy for recovery, and grade and documentation.
- Quality differentiators. Assay, colour, related-acid profile and consistency.
- Packaging. Typically 25 kg bags or fibre drums with moisture-tight liners.
Procurement and Sourcing Guide
- Assay and related acids. Confirm the assay and the citraconic/mesaconic and other related-acid limits.
- Colour. Specify colour if the end product is clear or light-coloured.
- Grade and documentation. Match the grade to your use and request the COA and any regulatory statements you need.
- Particle size and moisture. Specify for your feeding and dissolution process.
- Consistency. Ask for recent batch history if assay or colour is critical.
PolyBlueChem can supply itaconic acid (CAS 97-65-4) as a bulk raw material. To request current specifications, a COA or a quotation, contact the PolyBlueChem team.
Itaconic Acid as a Bio-based Platform Chemical
Itaconic acid belongs to a small group of chemicals that governments and industry bodies have identified as high-potential bio-based platform molecules — building blocks that can be converted into many downstream products and that can be made from renewable feedstocks rather than petroleum. Its inclusion in such lists reflects three practical features:
- It is genuinely bio-based today. Commercial production is by fermentation, not by a petrochemical route, so it is a real bio-based feedstock rather than a demonstration concept.
- It is difunctional and functionalisable. Two carboxylic acid groups plus a reactive double bond give chemists many handles for making derivatives and polymers.
- It can substitute for petrochemical monomers. In many polymer systems itaconic acid can replace or partly replace acrylic and methacrylic acid, allowing formulators to reduce the petrochemical content of a product.
The main technical reason it has not replaced acrylic monomers outright is the reactivity of its double bond: the exocyclic methylene polymerises more slowly and can be sterically hindered, so itaconic acid is typically used as a co-monomer at a modest level rather than as the principal monomer. That is enough to deliver the benefits — bio-based content plus improved adhesion — without disrupting the polymerisation kinetics of a coating or adhesive.
Itaconic Acid in Coatings, Adhesives and Latexes
The largest single outlet for itaconic acid is as a co-monomer in emulsion polymers: acrylic, styrene-acrylic and styrene-butadiene latexes used in coatings, adhesives, paper coatings and binders. The table below summarises how it behaves in each system.
| System | Role of itaconic acid | Benefit |
|---|---|---|
| Acrylic and styrene-acrylic latexes | Carboxyl-functional co-monomer | Improved adhesion, pigment dispersion and colloidal stability |
| Architectural and industrial coatings | Co-monomer | Hardness, water resistance and adhesion to difficult substrates |
| Pressure-sensitive and laminating adhesives | Functional co-monomer | Adhesion and latex stability without solvent |
| Paper and board coatings | Co-monomer in binder latexes | Binder strength and coating performance |
| Styrene-butadiene rubber latex | Co-monomer | Modified latex properties for paper and textile uses |
Two effects explain its value in these systems. First, the carboxylic acid groups introduced into the polymer raise the surface polarity, which improves adhesion and the wetting and dispersion of pigments. Second, because the acid groups can be neutralised, they give the latex colloidal stability, reducing the need for other stabilisers. These benefits are obtained at low co-monomer levels, which keeps the impact on polymerisation rate small.
Superabsorbent Polymers and Functional Uses
Beyond coatings and adhesives, itaconic acid is used where its difunctionality and water solubility add value:
- Superabsorbent polymers. Itaconic acid is a bio-based co-monomer in crosslinked absorbent polymers for hygiene and agricultural applications, where it can partially substitute for petrochemical acrylic acid.
- Water treatment and scale control. Itaconate copolymers act as dispersants and scale inhibitors in cooling water, boilers and oilfield systems, exploiting the carboxylic acid groups’ affinity for mineral surfaces and metal ions.
- Drilling fluids. Copolymers contribute to fluid control in some water-based formulations.
- Detergents and dispersants. As a water-soluble, carboxyl-rich monomer it contributes to the performance of detergent builders and dispersants.
- Specialty resins. Itaconic acid and its esters build carboxyl functionality into unsaturated polyester and other specialty resins.
Handling, Packaging and Storage
- Form and packaging. Supplied as a crystalline powder or granulate, typically in 25 kg bags or fibre drums with moisture-tight inner liners.
- Moisture. Itaconic acid is hygroscopic; keep packaging sealed and store in a dry area to prevent caking and weight gain.
- Temperature. Store at ambient temperature; avoid excessive heat, which can cause isomerisation and decarboxylation over time.
- Dust. Minimise dust generation and use appropriate ventilation and protective equipment, following the safety data sheet.
- Shelf life. The solid is stable for a defined shelf life when stored correctly; confirm the recommended shelf life and retest policy with the supplier.
Why Itaconic Acid: A Practical Summary
In practice, formulators choose itaconic acid for a combination of reasons rather than a single one:
- Bio-based content. It is produced by fermentation and raises the renewable content of a formulation.
- Adhesion and stability. Its carboxyl groups improve adhesion, pigment dispersion and latex stability.
- Water solubility. It polymerises readily in aqueous systems, fitting emulsion processes.
- Versatility. It converts into esters, anhydrides and isomers for a wide range of downstream products.
The usual design pattern is to use it as a low-level co-monomer that provides these benefits without dominating the polymerisation kinetics — a role in which it offers a practical, bio-based improvement over an all-petrochemical monomer set.
Frequently Asked Questions
What is itaconic acid and what is its CAS number?
Itaconic acid (methylenesuccinic acid) is an unsaturated dicarboxylic acid and a bio-based platform chemical; its CAS number is 97-65-4. See the itaconic acid product page for specifications.
What is the molecular formula and weight of itaconic acid?
C5H6O4 and 130.10 g/mol.
How is itaconic acid produced?
Commercially by aerobic fermentation of sugars with Aspergillus terreus. Historically it was made by pyrolysis of citric acid, but that route is largely obsolete. More detail is in the related reading below.
Is itaconic acid bio-based?
Yes. It is produced by fermentation and is regarded as one of the key bio-based platform chemicals, used as a bio-based alternative or co-monomer to petroleum-derived acrylic monomers.
What is itaconic acid used for?
Mainly as a monomer and co-monomer in polymers and resins — coatings, adhesives, paper and textile binders, superabsorbents and latexes — and as an intermediate for esters and anhydrides.
What are the main derivatives of itaconic acid?
Dimethyl itaconate, mono-esters, itaconic anhydride and the isomers citraconic and mesaconic acid, together with a wide range of itaconate polymers and copolymers.
Is itaconic acid soluble in water?
Yes, it is readily water-soluble, which is an advantage in aqueous polymerisation and in water-based formulations.
How should itaconic acid be stored?
Store dry and sealed in moisture-tight packaging; it is hygroscopic and can cake if exposed to humid air.
What are the two isomers of itaconic acid?
Citraconic acid (the cis form) and mesaconic acid (the trans form), both with the same formula C5H6O4. Heating itaconic acid can isomerise it to citraconic acid.
Can itaconic acid replace acrylic acid completely?
Usually not in practice, because its double bond polymerises more slowly. It is normally used as a low-level co-monomer that adds bio-based content, adhesion and latex stability.
What is the melting point of itaconic acid?
Approximately 165–168 °C, with decomposition on strong heating.
Is itaconic acid biodegradable?
It is a readily biodegradable bio-based organic acid, which is part of its environmental appeal compared with petrochemical monomers.
Why is itaconic acid called a platform chemical?
Because it is a bio-based building block that can be converted into many downstream products, including esters, anhydrides and a wide range of polymers and copolymers.
Does itaconic acid improve latex stability?
Yes. Its carboxylic acid groups, once partly neutralised, help stabilise latex particles, which is one reason it is used as a co-monomer in emulsion polymers.
Is itaconic acid a solid or a liquid?
At room temperature it is a white to off-white crystalline solid with a melting point near 165–168 °C; it is supplied as a powder or granulate.
References and Disclaimer
References. Published chemistry and properties of itaconic acid and its isomers; literature on the Aspergillus terreus fermentation route and on itaconic acid as a bio-based platform chemical; manufacturer technical data for industrial grades. Specifications quoted are representative and should be confirmed against the current certificate of analysis.
Disclaimer. This article is provided for general technical and commercial information only and does not constitute a specification or a warranty of fitness for any particular use. Users are responsible for confirming regulatory status, safe handling and suitability of the material for their own application.