Mono Propylene Glycol (MPG)
The glycol you are allowed to eat. One extra methyl group over MEG changes the metabolism completely, which is why MPG goes into food, medicines and cosmetics.
Molecular Structure
What is Mono Propylene Glycol (MPG)?
Mono propylene glycol is a three-carbon chain with hydroxyls on the first two carbons — one primary, one secondary — and a methyl group at the end. Structurally it is MEG with an extra carbon, and it is made by hydrating propylene oxide much as MEG is made from ethylene oxide.
That extra methyl group changes the toxicology entirely. MEG is oxidised to oxalic acid, which crystallises in the kidneys; MPG's secondary alcohol is oxidised instead to lactic acid, which the body already handles as a normal metabolite. The result is a glycol with GRAS status in food, a pharmacopoeial monograph, and wide use in cosmetics.
The two hydroxyls have different reactivity — primary and secondary — which is useful in resin chemistry, and the methyl group disrupts crystal packing enough that MPG-based polyesters are more soluble and less brittle. Unsaturated polyester resins are the largest single industrial outlet.
Chelora supplies MPG in industrial and USP/EP grades. Pharmacopoeial grade is certified for ethylene glycol and diethylene glycol content, which is the specification that matters most after repeated global incidents of contaminated glycol reaching oral medicines.
Quick Reference
Key Physical & Chemical Properties
Structure & Bonding
One primary hydroxyl, one secondary hydroxyl, and a methyl group. The methyl is what makes MPG metabolise to lactic acid rather than oxalic acid — the single structural difference that separates a food additive from a poison.
Skeletal structure — primary and secondary hydroxyls on a C₃ chain
Structural Identity
- IUPAC NamePropane-1,2-diol
- Common namesMPG, propylene glycol, PG, E1520
- Molecular FormulaC₃H₈O₂
- Molecular Weight76.09 g/mol
- Functional groupsOne primary, one secondary hydroxyl
- StereochemistryChiral — commercial grade is racemic
- Metabolised toLactic acid — a normal metabolite
- Made fromHydration of propylene oxide
- Food statusGRAS; EU food additive E1520
- CAS Number57-55-6
- InChI KeyDNIAPMSPPWPWGF-UHFFFAOYSA-N
Product Specifications
Chelora supplies Mono Propylene Glycol (MPG) in standard and custom grades. Contact us for specification sheets tailored to your process.
| Chemical name | Mono propylene glycol |
|---|---|
| CAS Number | 57-55-6 |
| Molecular formula | C₃H₈O₂ |
| Molecular weight | 76.09 g/mol |
| Purity — industrial grade (min) | ≥ 99.50 wt% |
| Purity — USP/EP grade (min) | ≥ 99.50 wt% |
| Ethylene glycol (USP/EP, max) | ≤ 0.10 wt% |
| Diethylene glycol (USP/EP, max) | ≤ 0.10 wt% |
| Dipropylene glycol (max) | ≤ 0.30 wt% |
| Water (max) | ≤ 0.20 wt% (Karl Fischer) |
| Acidity as acetic acid (max) | ≤ 0.005 wt% |
| Residue on ignition (max) | ≤ 0.007 wt% |
| Chloride (max) | ≤ 1.0 ppm wt |
| Iron (max) | ≤ 0.10 ppm wt |
| Colour | ≤ 10 Pt-Co (Hazen) |
| Specific gravity | 1.0360 – 1.0380 at 20/20 °C |
| Distillation range | 185 – 189 °C |
| Flash point | 99 °C (closed cup) |
| Autoignition temperature | 371 °C |
| Transport classification | Not regulated as dangerous goods |
Downstream Applications & Derivatives
Key derivative chains and industrial uses of Mono Propylene Glycol (MPG).
Unsaturated Polyester Resins
The largest industrial outlet. MPG's methyl group disrupts crystallinity, giving resins better solubility in styrene and tougher, less brittle laminates for FRP, marine and construction composites.
Food, Flavour & Beverage
GRAS-listed and approved as E1520, used as a humectant, flavour carrier and solvent in bakery, confectionery, flavourings and beverage concentrates.
Pharmaceutical & Personal Care
A USP/EP-monographed solvent and carrier in oral and topical medicines, and a humectant and viscosity modifier across creams, lotions and cosmetic formulations.
Aircraft & Runway De-icing
The basis of Type I and Type IV aircraft de-icing and anti-icing fluids, preferred over ethylene glycol formulations on toxicity and environmental grounds.
Heat Transfer & Antifreeze
Inhibited MPG is the standard secondary-loop coolant wherever an accidental leak could reach food, drinking water or people — breweries, dairies, ice rinks and HVAC.
Liquid Detergents & Technical
A coupling agent and stabiliser in liquid detergents and cleaners, a plasticiser in cellophane and adhesives, and a humectant in tobacco and pet food.
Why source Mono Propylene Glycol (MPG) through Chelora Petrochem?
Verified Origin
Full origin certification and asset-backed supply chain documentation — no grey-market supply.
Grade Flexibility
Industrial and USP/EP grades supplied. Pharmacopoeial grade is certified for ethylene glycol and diethylene glycol content on every lot, with full pharmacopoeial testing documentation.
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 stainless steel, aluminium or lined tanks under a nitrogen pad — glycols are hygroscopic and pick up water from humid air, which is a specification failure rather than a safety issue.
- Keep carbon steel out of the wetted path where colour and iron specifications matter; iron pickup shows up directly as colour on the certificate.
- Protect from prolonged heat and air. Extended exposure to both causes oxidation to aldehydes and organic acids, which raises acidity and destroys UV transmittance.
- Segregate grades rigorously. Fibre-grade, industrial and pharmacopoeial materials must not share hoses, pumps or lines, and dedicated equipment is the norm.
- Verify identity on receipt, not just on paper. Glycols look alike, mix freely and are commonly mis-shipped or adulterated — confirm by test before the material enters your process.
- Bund all storage and prevent any release to drains, surface water or groundwater.
- Provide eyewash and washing facilities at transfer points, and control mist or aerosol generation at spray and heated-handling points.
- Label every container clearly and never decant into unmarked or food-type containers.
- For USP/EP and food applications, verify ethylene glycol and diethylene glycol content on every incoming lot by test — a supplier certificate alone is not adequate assurance and has repeatedly proved worthless in real incidents.
Hazard Summary
Classification: MPG has no harmonised CLP classification and is generally not classified as hazardous. It has very low acute toxicity, is GRAS-listed for food use in the United States and approved as food additive E1520 in the EU.
The real risk is identity, not toxicity: MPG's hazard profile is benign, but it is one of the substances most often targeted by adulteration. Diethylene glycol has repeatedly been substituted for propylene glycol and glycerine in oral medicines, causing mass fatalities — most recently in cough syrup incidents in the 2020s. Pharmacopoeial monographs require testing for EG and DEG for exactly this reason.
Verify, do not assume: Any buyer using MPG in a food, pharmaceutical or oral-care application should test every incoming lot for ethylene glycol and diethylene glycol rather than relying on a certificate of analysis. In the documented incidents, the paperwork was in order and the material was not.
Grade segregation: Industrial and pharmacopoeial grades must not share storage, hoses or pumps. Cross-contamination from previous product residues is a routine cause of USP-grade failures.
Occupational hazards: Minimal. Mild eye irritation on direct contact, and prolonged skin contact may cause mild irritation in some individuals. No widely established occupational exposure limit; control mist generation with general good practice.
Fire: A combustible liquid with a flash point of 99 °C. Not a flammable liquid at ambient, but heated handling should be assessed.
PPE minimum: Safety glasses and gloves for routine handling; more only where hot material or mist generation is involved.
Consult the full SDS for exposure limits, spill containment, emergency response, and disposal before any use.
Frequently Asked Questions
Technical and commercial questions about Mono Propylene Glycol (MPG) sourcing and specifications.
What is MPG used for?
Unsaturated polyester resins are the largest single outlet, where MPG gives tougher, more styrene-soluble resins for composites. Beyond that it goes into food as E1520, into pharmaceuticals and cosmetics under USP and EP monographs, into aircraft and runway de-icing fluids, into food-safe heat transfer fluids for breweries, dairies and ice rinks, and into liquid detergents as a coupling agent.
Why is MPG safe for food when MEG is toxic?
It comes down to what each one is metabolised into. Both are oxidised by alcohol dehydrogenase, but MEG's primary alcohols lead through to oxalic acid, which forms calcium oxalate crystals that damage the kidneys. MPG has a secondary alcohol at the second carbon, and it is oxidised instead to lactic acid — a compound the body produces and clears routinely. That single structural difference is why MPG is GRAS-listed and MEG is a poison.
What is the difference between industrial and USP grade MPG?
The assay is often the same, at 99.5% minimum. The difference is the impurity testing. USP and EP grades are tested against the pharmacopoeial monograph, which includes specific limits on ethylene glycol and diethylene glycol, plus residue on ignition, acidity, water and identification tests. The material must also be produced, stored and transported under conditions that prevent cross-contamination, which normally means dedicated equipment throughout.
Why does MPG need testing for diethylene glycol?
Because DEG is cheap, looks identical, mixes freely and has repeatedly been substituted for propylene glycol and glycerine in oral medicines — causing mass poisonings from the 1937 Elixir Sulfanilamide disaster through to cough syrup fatalities in several countries in the 2020s. In those incidents the certificates of analysis looked correct. Pharmacopoeial monographs therefore require the receiving manufacturer to test for EG and DEG on every lot rather than relying on supplier documentation.
Why is MPG preferred over MEG for de-icing and heat transfer?
Toxicity and exposure. Aircraft de-icing fluid runs off onto the ground and into surface water in large volumes, and secondary coolant loops in breweries, dairies and ice rinks can leak into product or public spaces. MPG's low toxicity makes an accidental release a manageable problem rather than a serious one. MEG performs slightly better thermally at equivalent concentration, so it stays in sealed automotive systems where leakage exposure is limited.
What documentation does Chelora provide?
Every shipment includes a Certificate of Analysis covering purity, dipropylene glycol, water, acidity, residue on ignition, chloride, iron, colour, specific gravity and distillation range; for USP/EP grade, certified ethylene glycol and diethylene glycol content with full pharmacopoeial test documentation; a Safety Data Sheet (GHS/REACH); confirmation that the material is not regulated as dangerous goods; an origin certificate; and any food-contact or destination-market certificates required.
Request a quote or specification sheet
Talk to Chelora's sourcing team about Mono Propylene Glycol (MPG) grade, volume, logistics, documentation, and lead times. We respond within one business day.
