17-1 Naming the Aldehydes and Ketones cedence over the ketone aroup CHAPTER 17 时 Aldehydes and Ketones: The Carbonyl Group 二 s paCnaagewrpCahAnaertomofnea eaagaeaasc 9格 岩品 o9990 BGmogaetCR2mgethempestkeone,pm iou-dnio 2ssa2 me hyunctio 1 1 CHAPTER 17 Aldehydes and Ketones: The Carbonyl Group 17-1 Naming the Aldehydes and Ketones The aldehyde function takes precedence over the ketone group in nomenclature. Simpler aldehydes often retain their common names. These are constructed by dropping the –ic or –oic acid ending and replacing it with –aldehyde: Many ketones also have common names consisting of the substituent names followed by the word ketone. Dimethyl ketone is best known as acetone. Phenyl ketones have common names ending in –phenone. IUPAC nomenclature treats aldehydes as derivatives of alkanes. The ending –e is replaced by –al. An alkane becomes an alkanal. Chem Abstracts retains the common names of the first two aldehydes: The names parallel those of the 1-alkanols except that the aldehyde carbon is assumed to be C1 and does not have to be specified. When an aldehyde is attached to a ring it is called a carbaldehyde. The carbon atom bearing the aldehyde is C1. The simplest aromatic aldehyde, benzenecarbaldehyde, is referred to using its common name, benzaldehyde, by Chem Abstracts. Ketones are called alkanones, the ending –e of the alkane is replaced with –one. IUPAC provides an exception for the simplest ketone, propanone, the common name of which is acetone. The carbonyl carbon of a ketone is assigned the smallest possible number, regardless of the presence of other substituents or the – OH, C=C or C≡C functional groups. Aromatic ketones are named as aryl-substituted alkanones. Ketones are called cycloalkanones when part of a ring. The carbonyl carbon is assigned C1 in this case. The systematic name of the fragment is “alkanoy.” The older term “acyl” is widely used. Both IUPAC and Chemical Abstracts retain the older names “formyl” and “acetyl” for the groups and . The term “oxo” denotes the location of a ketone carbonyl group when present with an aldehyde function