Acetals, Ketals, Hemiacetals, and Hemiketals

Combustible.

Acetals, ketals, hemiacetals, and hemiketals react similarly to ethers, although members of this group would be less likely to form explosively unstable peroxides when exposed to oxygen. Members of this group may react violently with strong oxidizing agents. In other reactions, which typically involve the breaking of the carbon-oxygen bond, acetals are relatively inert.

Most are non-toxic.

Acetal compounds are formed by addition of alcohol molecules to aldehyde molecules. If one molecule of aldehyde (RCHO) reacts with one molecule of alcohol (R1OH) a hemiacetal is formed (RCH(OH)OR1). Further reaction with a second alcohol molecule produces a full acetal (RCH(OR1)2). Aldehyde groups are often converted into acetal groups to protect them before performing other reactions on different parts of the molecule. Most glycosidic bonds in carbohydrates and other polysaccharides are acetal linkages. Acetaldehyde diethyl acetal is an important flavouring compound in distilled beverages. The plastic known as acetal is a polyacetal of formaldehyde.

1,3-Dioxane, dioxolane, mezerein, ninhydrin, piperonal, acetal, glucose.