Lactones: What are They? How Are They Made?

The simplest lactones are unsubstituted cyclic esters that can conceivably be prepared from single linear molecules that contain both the alcohol and carboxylic acid functionalities. Notice the featured image of this article. It pictures four of the simplest lactones. The single molecule preparations from linear structures should be: HO-CH₂-COOH → α-acetolactone + H₂O HO-CH₂-CH₂-COOH → β-propiolactone + H₂O HO-CH₂-CH₂-CH₂-COOH → γ-butyrolactone + H₂O HO-CH₂-CH₂-CH₂-CH₂-COOH → δ-valerolactone + H₂O α-acetolactone Known more simply as acetolactone, this molecule is unstable and hence transient. The synthetic reaction for acetolactone written above, would produce close to 100 percent of the desired product, if it were stable. β-propiolactone [caption id="attachment_10179" align="alignright" width="308"] Preparation from carbon monoxide and ethylene oxide.[/caption] Sometimes called simply propiolactone, this molecule is stable, but is being phased out for many applications,…
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