PM - Propylene Glycol Monomethyl Ether

About This Product

Propylene glycol monomethyl ether, known as PM, PGME or 1-methoxy-2-propanol, has the formula C4H10O2 and CAS number 107-98-2. It is a clear colourless liquid, fully miscible with water and with most organic solvents, and it is the highest-volume glycol ether in the propylene series. Its commercial dominance rests on a point of isomer chemistry that is worth understanding. Reacting propylene oxide with methanol can attach the methyl group at either end of the propylene unit, giving the alpha isomer, in which the hydroxyl sits on a secondary carbon, or the beta isomer, in which it sits on a primary carbon. Only the beta isomer is metabolised to a methoxypropionic acid analogous to the harmful metabolites of the ethylene series; the alpha isomer is metabolised harmlessly by a different route. Commercial PM is therefore manufactured and specified to contain over 99.5 percent alpha isomer, and it is that purity, not the class of chemistry, that gives P-series ethers their favourable toxicological profile relative to EM and EE. Isomer ratio is accordingly a specification point, not a technicality. It is used in coatings and inks, electronics and semiconductor cleaning, industrial and household cleaners, agrochemical formulation and as a coupling solvent. Bio Green Chem supplies PM to specification on assay, alpha isomer content, water, acidity, colour and residue.