The methyl branch at C2 disrupts the regular packing of polymer chains derived from MPD, reducing crystallinity and increasing chain flexibility. Polyesters and polyurethanes built with MPD as a diol monomer have lower glass transition temperatures (Tg) and better low-temperature flexibility than those built with linear diols of similar chain length. This makes MPD particularly valuable for flexible coating and PU elastomer applications.

Both hydroxyl groups in MPD are primary - attached to terminal carbon atoms, not the branched C2 position. This means they are less sterically hindered than the secondary OH in, for example, 1,2-propanediol, and react readily with acids, isocyanates, and other electrophiles. The primary OH character gives MPD predictable and complete condensation reactivity in polyester synthesis and good chain-extension kinetics in polyurethane systems.

The asymmetric structure created by the off-centre methyl group disrupts the hydrogen-bond network between MPD molecules more effectively than a symmetric diol would. The result is a lower liquid viscosity (~75–90 mPa·s at 25 °C) than would be expected for a diol of this molecular weight and functionality. Lower viscosity translates directly to easier handling, lower pump energy, and better wetting of solid reactants in polymerisation.

Polyesters derived from MPD show improved hydrolytic stability compared to those from unhindered linear diols, because the methyl branch creates steric protection around the ester linkage, slowing acid- or base-catalysed hydrolysis. This translates to better weathering and moisture resistance in exterior coatings - a key reason MPD is used in high-durability alkyd and polyester coatings for demanding applications.

MPD is used as a diol monomer in polyester polyol and alkyd resin synthesis for architectural and industrial coatings. The β-methyl branch reduces crystallinity, improves flexibility, and lowers Tg compared to equivalent NPG or 1,4-BDO-based resins. MPD-containing polyesters show improved low-temperature impact resistance and better adhesion to substrates where rigid coatings would crack. Used in coil coatings, can coatings, and flexible packaging lacquers.

In polyurethane formulations, MPD acts as a short-chain diol chain extender or soft-segment diol modifier. Its two primary hydroxyl groups react efficiently with MDI, TDI, or HDI isocyanates. MPD-extended PU elastomers and coatings show good flexibility, low-temperature performance, and resistance to hydrolysis. Used in flexible PU coatings for textiles and leather, waterborne PU dispersions, and PU sealants requiring cold-crack resistance.

MPD is approved as a cosmetic ingredient (INCI name: 2-Methyl-1,3-propanediol) functioning as a humectant, solvent, and viscosity-modifying agent in leave-on and rinse-off formulations. Its moderate molecular weight and full water miscibility make it effective at holding moisture in skin without the greasiness of higher-MW glycols. Used in moisturisers, serums, hair conditioners, and cleansers as a glycerol or 1,3-propanediol partial substitute.

MPD reacts with phthalic anhydride, adipic acid, or other plasticiser acids to produce specialty plasticisers with lower volatility and better low-temperature performance than conventional phthalates. The methyl branch introduces the non-symmetry that suppresses crystallisation in plasticised PVC, improving low-temperature flexibility. MPD-based dibenzoate plasticisers serve as phthalate-alternative options for applications requiring regulatory compliance.

MPD serves as a synthetic intermediate for cyclic carbonates (via CO₂ reaction), specialty glycols, and niche pharmaceutical intermediates. Its two primary hydroxyls can be selectively protected or modified, making it a useful C4 building block in fine chemical synthesis. Applications include synthesis of 2-methyl-2-propyl-1,3-propanediol (MPPD, used in agrochemicals) and various specialty esters.

MPD production is concentrated among a small number of producers. LyondellBasell is the principal Western producer, manufacturing MPD via the hydroformylation of allyl alcohol. Chinese producers have expanded capacity significantly in the 2010s–2020s and now supply a substantial share of Asian demand. Chinese-origin MPD is competitively priced and available in technical grade for coatings and PU applications.

• 200 L steel drums: ~190–200 kg net; suitable for small to medium volumes; MOQ typically 1 pallet (4–5 drums)
• IBC (1,000 L): ~1,000 kg net; economical for medium volumes (>1 MT/order)
• ISO tank: ~18–22 MT; lowest per-unit cost; for high-volume buyers (>15 MT/order)

MPD is classified as a combustible liquid with flash point 107 °C. This places it outside IMDG Class 3 (flammable liquids, <60 °C flash point) for most transport purposes - it is not classified as a dangerous good under IMDG for sea freight at standard concentrations. Road transport under ADR: not subject to ADR requirements unless temperature exceeds 60 °C. Standard B/L cargo; no DGD required for most shipments.

• Certificate of Analysis (COA) - per batch, with all QC parameters
• Safety Data Sheet (SDS) - GHS-compliant, 16 sections, in destination language
• Certificate of Origin - for import duty purposes
• For cosmetic use: INCI declaration + heavy metals data
• For EU buyers: REACH registration confirmation (Sinolook holds EU OR registration)

Q1: What is the difference between MPD and MPO?

MPD and MPO refer to the same compound - 2-methyl-1,3-propanediol (CAS 2163-42-0). "MPD" stands for methylpropanediol, while "MPO" is an alternative abbreviation used in some supplier catalogues, particularly by Asian manufacturers. Both designations appear in trade documentation, SDS, and technical data sheets. When sourcing or specifying this compound, always confirm the CAS number (2163-42-0) to avoid confusion with structurally similar diols such as 2-methyl-1,3-propylene glycol or other C4 diols.

Q2: Can MPD be used to replace neopentyl glycol (NPG) in polyester resins?

Partial substitution is feasible; full substitution changes resin properties significantly. NPG (2,2-dimethyl-1,3-propanediol) has two gem-methyl groups providing maximum steric protection and a high Tg in derived polyesters, making it the benchmark for exterior weathering-resistant coatings. MPD has one methyl group and therefore gives lower Tg, better flexibility, and lower cost at the expense of some weathering resistance. In formulations where flexibility is more important than maximum UV durability - flexible coatings, PU systems, plasticiser intermediates - MPD can replace NPG fully or substantially. For premium outdoor powder coatings and coil coatings where weathering resistance is paramount, NPG remains the preferred diol. A dedicated comparison is available: MPD vs Neopentyl Glycol vs 1,3-Propanediol.

Q3: Is MPD approved for use in cosmetics in the EU and US?

Yes - MPD is listed in the EU CosIng database under the INCI name "2-Methyl-1,3-Propanediol" and is permitted as a cosmetic ingredient (solvent/humectant) in the EU under the Cosmetics Regulation (EC) No 1223/2009, subject to general safety assessment requirements (CPSR). In the US, MPD is used in personal care products regulated under FDA's OTC monograph system and the PCPC Cosmetic Ingredient Review (CIR) framework; it does not appear on the FDA's prohibited/restricted lists for cosmetics as of 2025. Cosmetic formulators should use a purity-grade product with APHA ≤ 10 and heavy metals ≤ 5 ppm and include MPD in the product's safety assessment.

Q4: What is the hydroxyl value of MPD and how is it used in polyester formulation?

MPD has a hydroxyl value of approximately 1,220 mg KOH/g, corresponding to an equivalent weight of ~45 g/eq (MW 90.12 ÷ 2 OH groups). In polyester formulation, the equivalent weight is used in stoichiometric calculations to balance the molar ratio of diol to diacid. For example, to prepare a polyester from MPD and adipic acid with an acid/diol molar ratio of 1:1, you would use 45 g of MPD per 73 g of adipic acid (equivalent weight). The high hydroxyl value (high OH functionality per unit mass) means that relatively small amounts of MPD contribute significant reactive sites per kg of formulation.

Q5: Does MPD require dangerous goods (DG) documentation for sea freight?

No - MPD's flash point of 107 °C places it above the IMDG Class 3 dangerous goods threshold (60 °C). For standard sea freight at ambient temperatures, MPD is not classified as a dangerous good under the IMDG Code and does not require a Dangerous Goods Declaration. It is shipped as a normal cargo chemical on a standard bill of lading. The SDS should accompany the shipment as good practice and some ports of entry require it, but the DG declaration and DG surcharges associated with hazardous chemicals like solvents do not apply. This is a significant practical advantage over DCM (UN 1593, Class 6.1) and flammable solvents - lower freight costs, no DG booking complications, and acceptance by a wider range of shipping lines.

Q6: Where is MPD produced and who are the main global suppliers?

LyondellBasell (Netherlands/USA) has historically been the primary Western producer, manufacturing MPD via hydroformylation of allyl alcohol. Chinese chemical manufacturers have significantly expanded MPD production capacity since 2015 and now supply the majority of Asian demand at competitive pricing. Sinolook Chemical Co., Ltd. exports MPD from China to customers in Southeast Asia, South Asia, the Middle East, Africa, and Europe, with full COA documentation, REACH OR support for EU buyers, and reliable DG-compliant shipping. Contact us via WhatsApp (0086 18150362095), WeChat/Tel (0086 13400715622), or email (sales@sinolookchem.com) for a quotation.