Isobutyr

Isobutyr is not a single chemical compound, but a common stem used in organic chemistry to refer to substituents derived from the isobutyl and isobutyryl groups, or to compounds rooted in isobutyric acid. In practice, the term appears in the names of several related groups and their derivatives and does not designate a standalone substance.

The isobutyl group is a four-carbon alkyl substituent with the formula -CH2-CH(CH3)2. It is attached to the rest of a molecule through the terminal CH2 group. Isobutyl occurs in many natural and synthetic compounds, including alcohols and esters. A well-known example is isobutyl alcohol (isobutanol), 2-methyl-1-propanol, and the ester isobutyl acetate, where the isobutyl group is linked to acetate.

The isobutyryl group is the acyl substituent derived from isobutyric acid (2-methylpropanoic acid), with the structure -CO-CH(CH3)2 when attached to another moiety via the carbonyl carbon. Isobutyryl is found in derivatives such as isobutyryl chloride and various isobutyrate esters or amides. These compounds are used as intermediates in organic synthesis and in the preparation of fragrances, flavors, and pharmaceuticals.

Isobutyric acid itself, also called isobutyranic acid or 2-methylpropanoic acid, is a volatile carboxylic acid with a sharp odor. It occurs in small quantities in foods and in some fermentation processes and serves as a chemical intermediate in industrial applications. Related safety and handling considerations apply due to its irritant properties.

Overall, isobutyr serves as a nomenclatural root rather than a specific substance, linking a family of isobutyl- and isobutyryl-derived compounds frequently encountered in chemistry and industry.

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