4-Methylsulfonylphenylacetic-acid
| Name of Product | 4-Methylsulfonylphenylacetic-acid |
|---|---|
| CAS No | 90536-66-6 |
| API Name | Etodolac |
| Therapeutic use:- | NSAID |
| Form:- | API Powder |
| Status | Commercial |
Product Overview
4-(Methylsulfonyl)phenylacetic acid, also written 4-mesylphenylacetic acid or 4-methanesulfonylphenylacetic acid, is a white to off-white crystalline solid supplied under CAS 90536-66-6.
Structurally it is phenylacetic acid carrying a methylsulfone group at the para position a small molecule with two handles: a carboxylic acid for coupling, and a methylsulfone that is already in its final oxidation state.
The 4-methylsulfonylphenyl group is the structural signature of the methylsulfone class of selective COX-2 inhibitors.
It is the fragment that gives these molecules their selectivity for cyclooxygenase-2 over cyclooxygenase-1, and it appears unchanged in the finished drug. This intermediate supplies it ready-made.
Its principal commercial destination is etoricoxib.
The acid is converted to its lithium or alkali metal salt, condensed with a 6-methylnicotinate derivative to give the ketosulphone 1-(6-methylpyridin-3-yl)-2-[4-(methylsulfonyl)phenyl]ethanone and that ketone is then cyclised with a suitable three-carbon reagent to build the bipyridine of etoricoxib.
Grades and specifications are available on request.
Actiza has over 12 years of B2B pharmaceutical export experience, 500+ global clients and a supply footprint across 40+ countries, backed by WHO-GMP and ISO-certified group manufacturing infrastructure in Gujarat, India.
Key Highlights
Supplied pre-oxidised removes a hydrogen peroxide oxidation step from the downstream route.
Certificate of Analysis and GHS-format Safety Data Sheet with every batch.
12+ years of export experience across 40+ countries.
Application in Synthesis
This intermediate feeds one dominant commercial route, and the way it fits into that route is the reason to buy it.
The Etoricoxib Route
| Step | Transformation |
|---|---|
| 1 | Conversion to the alkali metal salt |
| 2 | Condensation with a 6-methylnicotinate derivative |
| 3 | Cyclisation of the ketosulphone with a three-carbon reagent |
Two Routes, One Decision
There are two established industrial approaches to the ketosulphone, and they differ in where the sulfide is oxidised to the sulfone:
| Route A oxidise late | Route B buy it pre-oxidised | |
|---|---|---|
| Starting material | 4-(Methylthio)phenylacetic acid | 4-(Methylsulfonyl)phenylacetic acid (this product) |
| Sequence | Condense first, then oxidise the ketosulfide | Condense directly no oxidation step |
| Oxidation conditions | Metal-catalysed hydrogen peroxide oxidation | Not required |
| Process safety | A peroxide oxidation on a late-stage, high-value intermediate | No peroxide handling |
| Impurity risk | Under-oxidation leaves sulfoxide; over-oxidation and peroxide residues create their own species | Sulfur oxidation state is fixed and verified before the material ships |
| Where the burden sits | In the customer’s plant | With the supplier |
For a manufacturer, Route B removes a peroxide oxidation from a late stage of the route.
That is one fewer unit operation, one fewer set of process safety controls, one fewer catalyst to source and remove, and one fewer place for the batch to go wrong on a molecule that has already accumulated cost.
Applications at a Glance
| Application | Role | Notes |
|---|---|---|
| Etoricoxib manufacture | Key starting material for the ketosulphone intermediate | The dominant commercial application; etoricoxib has been marketed since 2002 |
| Methylsulfone COX-2 inhibitor chemistry generally | Supplies the 4-methylsulfonylphenyl pharmacophore | The structural feature shared across this inhibitor class |
| Heterocyclic diaryl building block | Coupling partner via the carboxylic acid | Research and development-scale use |
Industry Segments Served
Etoricoxib and COX-2 inhibitor API manufacturers
CDMOs and contract synthesis organisations executing client-owned routes
Sulfide and Sulfoxide the Impurities That Define This Product
The methylsulfone group is made by oxidising a methylthio group, and oxidation of a sulfide passes through the sulfoxide on the way to the sulfone.
That single fact determines the impurity profile of this intermediate.
The Two Named Impurities
4-(Methylthio)phenylacetic acid unoxidised sulfide, present if the oxidation did not go to completion
4-(Methylsulfinyl)phenylacetic acid the sulfoxide, the intermediate oxidation state
Both are structurally almost identical to the product and both will follow it through the condensation step into the customer’s ketosulphone, and onward into their crude etoricoxib, as their own related substances.
Why This Matters More Here Than Usual
Consider the customer’s position. The reason they bought the pre-oxidised acid is precisely to avoid running an oxidation.
Which means they have no oxidation step in which sulfide or sulfoxide carried in with the raw material could be converted through to the sulfone. Whatever arrives, stays.
A manufacturer running Route A has an oxidation late in the sequence that cleans up incomplete oxidation. A manufacturer running Route B does not.
The control has to happen at the supplier, and that is exactly why the buyer is paying for a pre-oxidised material rather than making it themselves.
A certificate that reports only total impurities does not answer the question they are actually asking.
Technical Specifications
The parameters below represent our standard commercial specification.
Customer-specific specifications can be agreed at enquiry stage.
| Parameter | Specification |
|---|---|
| Chemical Name (IUPAC) | 2-[4-(Methylsulfonyl)phenyl]acetic acid |
| Common Synonyms | 4-Methylsulfonylphenylacetic acid; 4-Mesylphenylacetic acid; 4-(Methanesulfonyl)phenylacetic acid; 4-MSPAA |
| CAS Number | 90536-66-6 |
| MDL Number | MFCD00216495 |
| EC / EINECS Number | Available on request |
| Molecular Formula | C₉H₁₀O₄S |
| Molecular Weight | 214.24 g/mol |
| Appearance | White to off-white crystalline powder |
| Assay / Purity | Available on request |
| Identification | IR and ¹H-NMR conform to reference standard |
| Melting Range | Available on request |
| Stage of Synthesis | Key starting material |
| Downstream API | Etoricoxib, via the ketosulphone intermediate (CAS 221615-75-4) |
| 4-(Methylthio)phenylacetic Acid | Available on request |
| 4-(Methylsulfinyl)phenylacetic Acid | Available on request |
| Other Related Substances | Individual and total limits as per in-house standard; reported on COA |
| Water Content (Karl Fischer) | Available on request |
| Loss on Drying | Available on request |
| Sulphated Ash / Residue on Ignition | Available on request |
| Residual Solvents | As per ICH Q3C |
| Elemental Impurities | Controlled; ICH Q3D statement supplied on request |
| Solubility | Soluble in methanol, ethanol, DMSO and aqueous alkali; sparingly soluble in water |
| Storage Condition | Store cool, ideally refrigerated, in tightly closed original packing, protected from moisture |
| Shelf Life | As stated on the batch COA, in unopened original packing under recommended storage |
| GHS Classification | Available on request |
| Transport Classification | Available on request |
Handling & Storage Guidance
This is a stable crystalline carboxylic acid with no significant reactivity hazard. Handling requirements are routine, and the storage points that matter are about preserving specification rather than managing risk.
Store cool, ideally refrigerated, in tightly closed containers protected from moisture
Allow refrigerated containers to reach room temperature before opening to prevent condensation on the solid
Minimise open-container time and re-seal the inner liner after dispensing; keep desiccant in place
Note that water content matters downstream the salt formation and drying step operates at low moisture, so moisture picked up in the customer’s store becomes their problem later
Standard chemical-resistant gloves, eye protection and dust control during weighing
Keep away from strong oxidising agents and strong bases
Consult the Safety Data Sheet supplied with the batch before handling
Regulatory & Documentation Support
This is a starting material, so a DMF or CEP does not apply to it as a standalone item.
What buyers need is a well-characterised material with documentation supporting both their manufacturing filing and their impurity control strategy.
Packaging, MOQ & Logistics
| Parameter | Details |
|---|---|
| Standard Packing | Sealed HDPE containers with double LDPE inner liner, desiccant-protected, in outer fibre or HDPE drums |
| Pack Sizes | Available on request |
| Minimum Order Quantity | Available on request |
| Production Lead Time | Available on request |
| Monthly Capacity | Available on request |
| Sampling | Samples available against request |
| Shipping Terms | FOB / CIF / CFR / EXW, as agreed |
| Mode of Transport | Sea freight; air freight availability available on request, subject to DG classification |
| Transit Protection | Desiccant-protected palletised loading; temperature-managed where destination and season require |
| Port of Loading | Available on request |
| Export Documentation | Standard commercial documentation |
Why Choose Us as Your Supplier
We Take the Oxidation Off Your Plant
Supplying the acid already at the sulfone oxidation state removes a hydrogen peroxide oxidation, its catalyst, its process safety controls and its rework risk from your sequence.
That is the value of this product, and it is why the specification below matters.
Batch-to-Batch Consistency
Every batch released against the same analytical protocol with retained samples held for the declared shelf-life.
Where a customer qualifies our material into a validated route, we notify any change that could affect the impurity profile before it reaches their site.
Export & Client Support
With 12+ years of B2B pharmaceutical export experience, 500+ global clients and shipments across Asia, Africa, Latin America, the CIS region and the Middle East, our commercial and documentation teams work across time zones.
Frequently Asked Questions
Why buy the pre-oxidised acid instead of the methylthio version?
Because it removes an oxidation step from your plant.
The alternative route condenses the methylthio acid first and then oxidises the resulting ketosulfide, a step that is run in the customer’s plant.
Starting from the sulfone means no peroxide handling, no catalyst to source and remove, no process safety controls around a peroxide oxidation on a late-stage intermediate, and no sulfoxide rework when that oxidation under-runs.
Which API is this used to make?
Etoricoxib. The acid is converted to its alkali metal salt, condensed with a 6-methylnicotinate derivative to give the ketosulphone intermediate, and that ketone is cyclised to build the chloro-bipyridine core of the drug.
The 4-methylsulfonylphenyl group it supplies is the structural signature of the methylsulfone class of selective COX-2 inhibitors.
What assay do you supply?
Assay figures are available on request, together with the analytical method.
Confirm the assay figure and the method rather than relying on the product name alone.
What is the Minimum Order Quantity?
Minimum order quantities are available on request, stated separately for bulk manufacturing and for gram-scale quantities.
Are samples available?
Yes. Samples are available against a formal request.
If you are evaluating a switch from the methylthio route, we would encourage a qualification quantity large enough to run a full ketosulphone batch rather than a laboratory trial.
Request a Quote
Tell us the grade, quantity and destination, and our team will respond with pricing, lead time and the documentation set for 4-(Methylsulfonyl)phenylacetic Acid (CAS 90536-66-6).