Isopropylideneglycerol

1,2-Isopropylideneglycerol (IPG) is a relatively high-boiling solvent and reagent that also goes by the names 2,2-dimethyl-1,3-dioxolane-4-methanol, acetone glycerol, and the trade name Solketal. It is miscible with water and organic solvents that range in polarity from alcohols to hydrocarbons. The molecule has a stereogenic center, but the article of commerce is normally the racemic mixture.

IPG was first synthesized in 1895 by legendary German organic chemist Emil Fischer¹ during his research on the reactions of sugars with aldehydes and ketones. He and his colleagues treated anhydrous glycerol with acetone and a catalytic amount of hydrogen chloride. Researchers have continued to refine the synthesis; today, IPG is produced continuously using heterogeneous catalysis.

IPG is used as a starting material for producing glycerides by esterification of its hydroxyl group and transesterification of the isopropylidine moiety. It is also widely used as a solvent for chemical reactions and as a component of various types of cleaning solutions.

The wide availability of byproduct glycerol from biodiesel manufacture allows IPG producers to claim that it is a “green” solvent. As an example, the chemical giant Solvay makes it in Brazil under the trade name Augeo Clean Multi. In addition to the solvent’s sustainability, Solvay claims benefits such as low vapor pressure, slight odor, high flash point, and low human and environmental toxicity.

1. Fischer was the 1902 recipient of the Nobel Prize in Chemistry.