used as a humectant toiletry, propylene glycol is responsible for ensuring that moisture retention within hair occurs for people suffering from excessive dryness;
A healthier alternative to cigarettes with significantly fewer chemicals, electronic (or e-) cigarettes have propylene glycol as their main ingredient, which is able to kill certain strains of bacteria, including pneumococcus and streptococcus, as was famously documented by a TIME article through the workings of Dr. Oswald Hope Robertson many decades back. Due to its antibacterial properties, propylene glycol may be able to provide protection against certain respiratory diseases like pneumonia or influenza when vaporized and inhaled, however further studies must be completed;
Food and Beverage:
propylene glycol is used as a solvent for both food colouring and flavouring;
serves as an emulsifying agent for the alcoholic beverages of Angostura and orange bitters;
labeled as E number E1520 (code representing European Union-acceptable ingredients within food), propylene glycol is also a humectant food additive;
acts as the coolant in liquid cooling systems of fermentation tanks for the production of beer and wine
Pharmaceutical and Cosmetics:
propylene glycol is an active ingredient in medications (adds moisture), cosmetics, mouthwash and toothpaste;
used in saline solutions, hand sanitizers and antibacterial lotions;
deodorant sticks include propylene glycol among their list of ingredients
Propylene glycol is a colourless, viscous, hydroscopic and organic liquid. It contains two hydroxyl groups within its molecular structure and is known to be miscible with many solvents, including water. Propylene glycol has an asymmetrical carbon and as a result has two enantiomers (chemical compounds that are mirror images of one another, but exhibit different characteristics). This has its advantages as commercial production yields a racemic (or 50/50) mixture of the two forms – distinguished as α and β. While α-propylene glycol is the enantiomer most often utilized due to its food processing value, the β form is also industrially-useful as it can produce polymers, be utilized as a solvent in wood paint, and serve as an adhesive and coating, among other things. It is to be assumed, however, that “propylene glycol” specifically implies, “α-propylene glycol”.
With respect to industrial purposes, propylene glycol is made from propylene oxide through either a catalytic or non-catalytic method. Regardless, the reactant is placed under very high temperatures and is treated with minute amounts of either sulphuric acid or alkali. Only one fifth of the final yield, however, is propylene glycol, which leaves room for improvement in regards to percentage yield moving forward.
An alternate method for yielding propylene glycol would be from a series of reactions that include mannitol, an alcohol that looks and tastes like sucrose and produces medicine tablets.