# IUPAC naming for compounds containing carboxylic acid and anhydride together?

According to IUPAC, the carboxylic acid comes first in priority order for functional groups, while anhydride has no prefix. Then how do you name a compound which contains both a carboxylic acid and an anhydride in it?

The acid is substituted using the usual principles of substitutive nomenclature. The prefix ‘oxo’, denoting $\ce{=O}$, is used to indicate a carbonyl group when the group cannot be cited as suffix. The group $\ce{R-CO-O-{}}$ is indicated by an acyloxy prefix (e.g. ‘acetyloxy’, ‘propanoyloxy’, etc.).
• @user282856 According to current IUPAC recommendations (2013), acyl groups from the carboxylic acids that have retained names are used as preferred prefixes. Since ‘acetic acid’ is the preferred IUPAC name, ‘acetyl’ is the preferred prefix. The corresponding systematic alternatives ‘ethanoic acid’ and ‘ethanoyl’ may be used in general nomenclature. The name ‘acetyloxy’ is the preferred prefix for the group $\ce{CH3-CO-O-{}}$; the contracted name ‘acetoxy’ may be used in general nomenclature. – Loong Sep 22 '16 at 18:02