2-Methyl-1,3-propanediol (MPD / MPO)

Branched Asymmetric Diol Polyol Monomer · Purity ≥99.5% · No CMR Classification · MPD Supplier from China · Global Shipping

✓ Regulatory Advantage - No CMR · Not HAP-Listed · No REACH Annex XIV/XVII Restriction · Combustible Liquid (Flash Point ~113°C)

MPD (CAS 2163-42-0) has a clean regulatory profile: not classified as a reproductive toxicant (Repr. 1B), carcinogen, mutagen, or other CMR substance under EU CLP Regulation 1272/2008. Not listed on REACH Annex XIV, not subject to REACH Annex XVII restrictions, and not a US EPA Hazardous Air Pollutant (HAP). Flash point ~113°C - Combustible Liquid (Class III-B), requiring standard combustible liquid storage without the explosion-proof infrastructure mandated for flammable liquids. MPD is EU REACH registered and TSCA-listed. This straightforward regulatory profile allows use across EU, US, and global markets without the complex authorization, restriction, or HAP reporting obligations that affect DMF, DCM, and other regulated solvents. Sinolook provides EU CLP-compliant SDS and TSCA/REACH confirmation with every shipment.

ℹ MPD Structural Advantage - Branched Asymmetric Diol

MPD's key structural feature is its methyl-branched, asymmetric 1,3-diol: HOCH₂–CH(CH₃)–CH₂OH. This gives three polymer-design advantages over linear diols (1,3-PDO, 1,4-BDO): (1) No crystallinity - the methyl branch prevents chain-packing crystallisation, producing permanently flexible, amorphous polymer segments with lower Tg; (2) Asymmetric OH reactivity - one faster primary OH and one slightly hindered primary OH, enabling controlled branching density in polyester and PU synthesis; (3) Superior solubility & compatibility - branched structure reduces inter-chain hydrogen bonding, improving compatibility with aromatic acids and diverse isocyanates. Compared to NPG (symmetric gem-dimethyl diol), MPD's asymmetric structure produces softer, more flexible polymers better suited to coating and elastomer applications.

ℹ Hydroxyl Value Specification - Important Note for Buyers

The theoretical hydroxyl value of pure MPD (MW 90.12 g/mol, 2 OH groups) is ~1,245 mg KOH/g (calculated as: 2 × 56,100 / 90.12). The value of 530–550 mg KOH/g sometimes cited in the market corresponds to polyols of approximately MW 210 g/mol (such as neopentyl glycol-based short-chain polyesters) and is not the correct value for pure MPD monomer. For polyester or polyurethane formulation calculations using MPD, always use OHV ~1,245 mg KOH/g or request the analytically determined OHV from the batch COA.

Why is the hydroxyl value of MPD ~1,245 mg KOH/g - much higher than most polyols?

The OHV measures total OH group content per gram: OHV = (number of OH groups × 56,100) / molecular weight. For MPD: 2 × 56,100 / 90.12 = 1,245 mg KOH/g. This is high compared to polymeric polyols (OHV 30–300 mg KOH/g) due to their much higher molecular weights (500–4,000 g/mol), but entirely consistent with other low-MW diol chain extenders - BDO (MW 90.12) also has OHV ~1,245 mg KOH/g. In PU formulation using MPD as a chain extender, the MDI:MPD weight ratio is calculated from the isocyanate index and OHV. Using the correct OHV (1,245, not the sometimes-cited 530–550) is essential for accurate formulation.

How does MPD compare to propylene glycol (PG) in personal care applications?

MPD (1,3-diol; INCI: Methylpropanediol) and propylene glycol (1,2-propanediol; INCI: Propylene Glycol) are evaluated on three dimensions: (1) Skin feel - MPD's 1,3-diol geometry is reported to provide a lighter, less greasy feel than PG at equivalent concentrations; (2) Antimicrobial activity - PG has documented activity against Gram-positive bacteria and fungi above ~15%; MPD has different and generally lower antimicrobial potency, so formulations relying on PG for preservation contribution need to adjust their preservation system when substituting; (3) Regulatory positioning - MPD enables 'propylene glycol-free' label claims for consumers seeking to avoid PG. Contact our technical team for MPD-for-PG substitution guidance in specific formulation types.

Can MPD be used in unsaturated polyester resin (UPR) for FRP composites?

MPD can be used as a co-diol in UPR synthesis - the hydroxyl groups react with maleic anhydride and phthalic anhydride in the standard condensation polymerisation to produce the polyester backbone. MPD's contributions vs standard diols (propylene glycol, ethylene glycol): (1) reduced crystallinity of the polyester; (2) improved flexibility and impact toughness of the cured composite. However, MPD's higher cost than propylene glycol limits its use to specialty applications where the flexibility contribution justifies the premium - for example, flexible vinyl ester FRP liners for chemical tanks, or gel coat formulations requiring improved chip and crack resistance.

What is the difference between MPD (2-methyl-1,3-propanediol) and MPG (monopropylene glycol / 1,2-propanediol)?

These are completely different compounds despite similar abbreviations. MPG (monopropylene glycol, 1,2-propanediol, CAS 57-55-6) is a 1,2-diol widely used as a solvent, humectant, and antifreeze. MPD (2-methyl-1,3-propanediol, CAS 2163-42-0) is a 1,3-diol with a methyl branch on the central carbon - a polyol monomer for polymer synthesis. They have different molecular weights (76.09 vs 90.12 g/mol), different reactivities in polymerisation (1,2-diol vs 1,3-diol spacing affects polyester ring-forming tendency), and different applications (MPG: solvent/humectant; MPD: polymer monomer). Always use the full name or CAS number to avoid confusion when ordering.

Contact Sinolook - Your Trusted MPD / MPO Supplier

Whether you are a polyurethane elastomer producer incorporating MPD as a chain extender for superior low-temperature flexibility in automotive TPU skins, footwear components, or industrial rollers; a powder coating polyester manufacturer using MPD to reduce crystallinity and improve flow in TGIC-cured systems; a waterborne PU dispersion formulator leveraging MPD's liquid state for PUD synthesis; a polymeric plasticiser producer synthesising low-migration MPD-based polyester plasticisers; or a personal care formulator seeking a skin-feel-differentiated propylene glycol alternative - Sinolook Chemical delivers purity ≥99.5%, permanent liquid-state handling convenience, correct analytical hydroxyl value, and clean regulatory documentation. Our team responds within 24 hours.