Guaiacol
Guaiacol is the molecule that most of the world's vanilla flavour is built from. One methoxy group next to one hydroxyl, and from there the route runs to vanillin, to guaifenesin and to a long list of flavour and fragrance materials. It also melts at room temperature, which makes it unusually interesting to handle.
Chelora Chemicals supplies guaiacol to flavour, pharmaceutical and fine-chemical producers worldwide, with a batch COA and GHS safety data sheet on every consignment.
Product identity
- CAS Number
- 90-05-1
- IUPAC name
- 2-Methoxyphenol
- Molecular formula
- C₇H₈O₂
- Molecular weight
- 124.14 g/mol
- EC / EINECS
- 201-964-7
- Transport status
- Generally non-DG*
- SMILES
- COc1ccccc1O
- HS Code
- 2909 50*
* Confirm the exact HS heading and the transport classification with your customs broker and freight forwarder — ether-phenols can be read differently by mode and by destination tariff schedule.
What Guaiacol is used for
Guaiacol is a colourless to pale yellow crystalline solid or oily liquid, depending entirely on the ambient temperature, with a characteristic smoky, medicinal odour. Structurally it is catechol with one of the two hydroxyls methylated — and that single methyl group is what converts a reactive dihydroxy benzene into a stable, useful intermediate.
Its largest outlet by a wide margin is synthetic vanillin, produced by condensing guaiacol with a two-carbon reagent and oxidising the result. Its second major outlet is guaifenesin, the expectorant formed by reacting guaiacol with a glycerol-derived epoxide. It also serves eugenol and isoeugenol chemistry, and is used directly as a flavour and fragrance material.
Where it sits in the chain
- Guaiacol (this product) catechol monomethyl ether; the pivot point between a cheap commodity diol and the flavour chain.
- Catechol the upstream dihydroxy benzene, and the residual impurity to watch for here.
- Vanillin the dominant downstream, and the reason the market moves as it does.
- Guaifenesin the pharmaceutical downstream, made by etherifying the free hydroxyl.
Where the methylation route is used, the methylating agent is typically dimethyl sulfate, which we also supply — see the full intermediate range.
Appearance and handling character
The material is slightly soluble in water, freely soluble in ethanol, ether and chloroform, and it sits right on the solid–liquid boundary at normal warehouse temperature. It darkens on exposure to air and light as the phenol oxidises, and it has a high flash point, so it is not a flammable liquid for transport purposes. The classification is driven by eye damage and oral toxicity rather than by fire risk.
| Parameter | Typical value |
|---|---|
| Appearance | Colourless to pale yellow crystals or oily liquid |
| Assay (GC) | 99.0% min |
| Melting range | 26 – 29 °C |
| Catechol | 0.1% max |
| Phenol | 0.1% max |
| Water (KF) | 0.3% max |
| Colour (APHA) | 50 max |
| Refractive index @ 20 °C | ≈ 1.542 |
Important: the figures above are indicative of commercial-grade material and are offered for planning only. The batch certificate of analysis is the governing document. Catechol content and colour are the figures that carry furthest downstream — tell us your target and we will quote against it.
| Property | Value |
|---|---|
| Physical state | Solid or liquid, depending on ambient |
| Melting point | 26 – 29 °C |
| Boiling point | 204 – 206 °C |
| Density | ≈ 1.11 g/cm³ @ 25 °C |
| Flash point | ≈ 82 °C (closed cup) |
| Water solubility | Slightly soluble; soluble in alcohol and ether |
Physical constants compiled from public reference data for CAS 90-05-1 and rounded for readability. Treat them as orientation, not as a specification.
Where our customers put this intermediate to work
One very large flavour application, one solid pharmaceutical one, and a long tail of fragrance chemistry.
Synthetic vanillin
The dominant downstream — condensation and oxidation convert guaiacol into the world's most-used flavour compound.
- Low catechol and colour essential
- Food-chain traceability available
- Technical desk review of your route
Guaifenesin manufacture
Etherification of the free hydroxyl with a glycerol-derived epoxide gives the expectorant used across cough and cold products.
- API intermediate route
- End-use declaration required
- Full impurity profile on request
Eugenol & isoeugenol chemistry
A building block for the clove-note aroma chemicals and for downstream fragrance materials built on the same ring.
- Fragrance intermediate routes
- Colour-critical grades available
- Bulk quantities available
Flavour & fragrance use
Used directly at trace levels for smoky, phenolic and medicinal notes in flavour compounds and smoke flavourings.
- Food-grade specification available
- Tight colour and odour profile
- Small packs available
Pharmaceutical derivatives
Guaiacol carbonate, guaiacolsulfonate salts and related expectorant derivatives are built directly from this material.
- Compendial-grade specification
- Heavy metals and residuals reported
- Custom quantities available
Research & analytical use
A standard substrate in peroxidase assays and a reference material in lignin and smoke-chemistry analysis.
- Packs from 500 g
- Reference-grade material on request
- Full analytical documentation
How we supply Guaiacol
Chelora Chemicals is a supplier and sourcing partner, not a manufacturer. On an intermediate that feeds both a food chain and a pharmaceutical one, owning no plant means we are never selling you a technical lot because it is what the unit made — we route your order to the producer whose colour and residual profile suits your end use.
We place your order with whichever qualified producer best matches your assay, your residual limits, your price point and your delivery window.
We keep a second qualified source on this line. Guaiacol production is tied to catechol supply and, increasingly, to lignin-based routes, and the two do not move together.
- Catechol and phenol residues reported every batch. They are the route markers, and on a vanillin or guaifenesin route they carry straight through.
- Colour stated on the COA. On a flavour application colour is a quality specification, not a cosmetic one, and we treat it that way.
- We ask whether it is food or pharma chain. The documentation and the traceability expectations are different, and the time to settle that is at enquiry.
- Packing and transit temperature planned together. A material that melts at 27 °C needs the route thought about, not just the drum specified.
- Batch COA shared before dispatch. You approve assay, residuals and colour against your own spec while the material is still in our warehouse.
- Export machinery handled in-house. Classification, packing, labelling, freight booking and customs paperwork are ours to manage.
Packed the way your plant receives it
This material can arrive solid or liquid depending on the season and the route, so the pack has to work either way. Tell us the destination and we will plan for it.
Lined steel / HDPE drums
The standard commercial format, with a wide opening so solidified material can be melted out or dug out cleanly.
Nitrogen-blanketed drums
Available where colour is critical, particularly for flavour-chain material on a long or warm route.
Small drums & jerricans
Smaller formats for flavour houses and pharmaceutical users consuming modest quantities per campaign.
Trial / sample quantities
Small sealed packs dispatched so your R&D team can qualify the grade before committing to larger volumes.
Incoterms to suit you
Quoted on the Incoterm your purchasing team works to, with export documentation filed before the booking is made.
Campaign despatch
We hold contracted tonnage and release it against your production calendar instead of landing it all at once.
Eye damage is the controlling hazard
Guaiacol is not a flammable liquid and is not acutely toxic at the levels commonly published, but it causes serious eye damage and is harmful if swallowed. On a material that is often warm and liquid during transfer, that combination deserves proper attention. The summary below is orientation only — the safety data sheet supplied with your consignment is the authoritative document.
Classified hazards
H318Causes serious eye damage.H302Harmful if swallowed.H315Causes skin irritation.H335May cause respiratory irritation.
Hazard statements reflect classifications commonly published for CAS 90-05-1. Suppliers do differ on this product, and some SDS classify the eye hazard as irritation rather than damage. Always read the SDS issued with your specific batch rather than assuming the classification above applies to the material in your drum.
Spill & handling orientation
Plan your response before the pallet arrives. Sections 4, 5 and 6 of the SDS are the authoritative instructions and should be posted at the point of use.
- Sealed goggles, not safety glasses. H318 means serious eye damage, and a splash during a warm liquid transfer is the realistic exposure scenario.
- Warm drums gently and evenly. Use a drum heater or warm room, not a direct flame or an immersion element; local overheating darkens the product.
- Expect a persistent smell. The odour threshold is extremely low, so a trace spill will be noticeable across a whole building long after it is cleaned.
- Absorb spills with inert material. Collect and dispose of as chemical waste; do not wash to drain.
- Keep away from oxidising agents and strong bases. Standard practice for a phenol.
Storage
- Cool, dark and tightly closed. Air and light drive the oxidation that darkens the material and shows up as an off-specification colour result.
- Expect phase change in store. The drum will solidify below about 26 °C and melt above it; repeated cycling is not harmful but does promote colour drift if the drum is not sealed.
- Do not store near a heat source. Warmth plus air contact is the combination that turns pale yellow into brown.
- Segregate from oxidising agents, strong bases and acids. Standard practice for a phenolic ether.
- Shelf life typically 24 months. In sealed original packing. Re-check assay and colour before use after extended storage.
Handling & PPE
- Eye protection is the primary control. Sealed goggles or a face shield at every transfer, sampling and melting operation.
- Chemical-resistant gloves and apron. Particularly where warm liquid is being pumped or decanted.
- Ventilate transfer areas. The vapour is irritating and the odour is persistent even at trace levels.
- Use closed transfer where possible. It keeps air off the product and the product off the operator at the same time.
- Dispose of as chemical waste. Do not discharge washings to an uncontrolled drain.
Transport
Guaiacol is commonly shipped as non-regulated general cargo, with a flash point well above the flammable-liquid threshold. Classification is nevertheless mode and destination specific, so we confirm it per consignment and issue the declaration where one is required — ask us for the current shipping paperwork when you plan the shipment.
What travels with every consignment
A chemical shipment is only as good as the file that travels with it. Verifying what the source plant sends is precisely the work you are buying from a supplier.
Certificate of Analysis
Batch-specific assay by GC, melting range, residual catechol and phenol, water content and colour — checked against your specification before release.
GHS Safety Data Sheet
Full 16-section SDS in GHS format covering hazards, exposure controls, handling, storage, spill response, toxicology and disposal, in the language your destination requires.
GC method & chromatogram
Analytical method and batch chromatogram on request, so your QC can reproduce the residual profile rather than take it on trust.
Food-chain documentation
Where the material feeds a flavour application, food-grade specification, allergen and GMO statements are supplied with the consignment.
Certificate of Origin
Chamber-attested where required, plus preferential-origin forms where a trade agreement gives your import duty relief.
Retained & pre-shipment samples
Pre-shipment samples carry the same COA as the commercial lot, so what your laboratory qualifies is exactly what arrives.
One hydroxyl methylated, one left free
Guaiacol exists commercially because capping one of catechol's two hydroxyls leaves a molecule that is stable enough to handle and still reactive enough to build on. The routes below are the general industrial pattern, not a process disclosure.
Start from catechol
Catechol, itself made from phenol, is the usual petrochemical starting point; lignin-derived routes are also now in commercial use.
Methylate one hydroxyl
Selective monomethylation caps one of the two hydroxyls, typically with a methylating agent such as dimethyl sulfate or with methanol.
Distil and purify
Fractional distillation separates guaiacol from unreacted catechol and over-methylated by-product, and sets the colour.
Build downstream
In use, the free hydroxyl is etherified to guaifenesin, or the ring is functionalised and oxidised to give vanillin.
Why catechol content and colour matter downstream
On this intermediate, the residuals do not stay behind:
- Catechol is unmethylated starting material. It reacts in the next step too, giving by-products that are difficult and expensive to separate from vanillin.
- Colour signals oxidation. Dark material has already lost some guaiacol to oxidation products, and those products are coloured in the finished flavour compound as well.
- Water affects the next step. On an etherification route, moisture competes with the reagent and costs yield directly.
- Odour carries at trace levels. Guaiacol is detectable at parts per billion, so a residual impurity with its own odour profile is a flavour problem at concentrations that barely register analytically.
That is why we quote against your written residual and colour limits rather than a generic "technical grade", and why the batch COA is shared for approval before dispatch rather than sent with the invoice.
| Material | Position in the route |
|---|---|
| Guaiacol CAS 90-05-1 — this product | Catechol monomethyl ether |
| Catechol CAS 120-80-9 | Upstream feedstock & key residue |
| Vanillin CAS 121-33-5 | The dominant downstream |
| Dimethyl sulfate CAS 77-78-1 | Methylating agent on one route |
We supply across this intermediate family, including dimethyl sulfate — see the full intermediate range. Send the CAS number and we will confirm the correct material before quoting.
What actually moves the price of this product
Knowing what drives the quote helps you time a purchase and read whether an offer is realistic.
Catechol supply
Catechol is produced in a handful of plants worldwide and is itself downstream of phenol, so the chain is narrow at two points.
- A concentrated upstream supply base
- Phenol cycles feed through catechol
- We flag feedstock-driven moves in the quote
Vanillin demand
This is effectively a single-downstream market. Vanillin demand and vanillin pricing drive guaiacol more than anything else does.
- Ask us what the vanillin chain is doing
- Contracted call-off smooths the exposure
- We hold a second qualified source
Food versus technical grade
Flavour-chain material carries tighter colour, odour and traceability requirements and prices accordingly.
- Never cross-shop grades on price alone
- Food chain carries the documentation
- We will say when technical grade will do
Route temperature and packing
A warm container darkens the material and a cold one solidifies it; neither is fatal, but both affect what arrives usable.
- Specify the route as well as the Incoterm
- Inert blanketing available where it matters
- We quote FOB, CIF, CFR or DDP as you prefer
Bio-based route competition
Lignin-derived guaiacol and vanillin are growing, and where a customer wants a natural or bio-based claim the economics change entirely.
- Ask us about bio-based availability
- Claims documentation differs
- We track both routes on your behalf
Source availability
A plant turnaround or a catechol disruption can take capacity offline at short notice on a chain this narrow.
- We hold a second qualified source on this line
- Qualify the alternate before you need it
- Ask us about dual-source contracts
| If your end use is… | Specify |
|---|---|
| Vanillin manufacture | Low catechol, low colour, food chain |
| Guaifenesin / API route | Full impurity profile, low water |
| Flavour & fragrance direct use | Food-grade, tight odour and colour |
| Fragrance intermediate synthesis | Standard 99% commercial grade |
| Laboratory / analytical use | Small pack, full COA and chromatogram |
Not sure which row you are in? Describe what you make from it and our technical desk will recommend the grade — including telling you when a cheaper specification would do the job just as well.
Support that goes beyond shipping the drum
What our technical desk will do
- Establish food chain or pharma chain first. The traceability and documentation expectations differ enough that it changes which source we approach.
- Confirm catechol and colour limits. Both are route residues that carry downstream, and we settle them before pricing.
- Plan the transit temperature with you. On a material that melts at 27 °C this is a real conversation, not a formality.
- Flag the methylating-agent connection. If you are considering making guaiacol rather than buying it, we supply dimethyl sulfate and will be straight about what that reagent involves.
Regulatory & compliance notes
- Flavour use is separately regulated. Guaiacol is a permitted flavouring substance in several jurisdictions with its own identity and purity requirements; confirm your position before you order.
- Natural versus synthetic claims are strictly controlled. A bio-based route does not automatically support a natural claim; the documentation requirements are specific.
- Import controls vary by destination. We check destination rules before quoting, not after you have raised the PO.
- Chemical inventory listings differ between regions. We will supply the identity data you need for that filing.
None of the above is legal advice — your own regulatory affairs team owns the final compliance position for your import and your workplace. What we commit to is accurate product identity data, an honest statement of the hazard classification and complete documentation to work from.
From enquiry to delivered pallet
Send the specification
Product name or CAS 90-05-1, your assay, catechol and colour limits, quantity, pack preference and destination port.
Receive a firm quote
Pricing, lead time, packing and Incoterm confirmed in writing within 24 hours — our sourcing desk is staffed around the clock.
Qualify and approve
Sample dispatched if you are qualifying a new source. Batch COA shared for your approval before the material is released.
Ship and track
Freight booked, export documents issued, and the consignment tracked through transit and clearance to your plant.
What buyers ask us about Guaiacol
What is guaiacol used for?
Why does it arrive as a liquid sometimes and a solid other times?
What purity do you normally supply?
Why are catechol and phenol limited on the specification?
Why does the material darken in storage?
Is it a dangerous good for transport?
What is the minimum order quantity?
How should we store it?
Do you manufacture this yourself?
Request pricing on Guaiacol
Send your required assay, catechol and colour limits, quantity, pack format and destination port. Our sourcing desk is available 24 hours a day, 7 days a week, and comes back with pricing, lead time and packing options.