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Unformatted text preview: Chapter 16 – Carbonyl Compounds I Carbonyl group: a carbon double bonded to oxygen; the most important functional group Carbonyl compounds: compounds containing carbonyl groups, very abundant in nature Acyl group: consists of a carbonyl group attached to an alkyl group or and aryl group Class I carbonyl compounds are those in which the acyl group is attached to a group (or atom) that can be replaced by another group • Carboxylic acids • Acyl halides • Acid anhydrides • Esters • Amides Carboxylic acid derivatives: differ from a carboxylic acid only in the nature of the group or atom that has replaced the OH group of the carboxylic acid (class I compounds) Class II carbonyl compounds are those in which the acyl group is attached to a group that cannot be readily replaced by another group • Aldehydes • Ketones Remember! The lower the pK a , the stronger the acid and the weaker its conjugate base. 16.1 Nomenclature of Carboxylic Acids and Carboxylic Acid Derivatives In systematic (IUPAC) nomenclature, a carboxylic acid is named by replacing the terminal “e” of the alkane name with “oic acid.” For example, the one-carbon alkane is methan e , so the one-carbon carboxylic acid is methan oic acid. Number of Carbons Systematic Name Common Name 1 Methanoic acid Formic acid 2 Ethanoic acid Acetic acid 3 Propanoic acid Propionic acid 4 Butanoic acid Butyric acid 5 Pentanoic acid Valeric acid 6 Hexanoic acid Caproic acid α-carbon: the carbon adjacent to the carbonyl carbon β-carbon: the carbon adjacent to the α-carbon, and so on Acyl halides have a Cl or Br in place of the OH group of a carboxylic acid. Acyl halides are named by using the acid name and replacing “ic acid” with “yl chloride” (or “yl bromide”). For acids ending with “carboxylic acid,” “carboxylic acid” is replaced with “carbonyl chloride” (or “bromide”). Loss of water from two molecules of a carboxylic acid results in an acid anhydride . “Anhydride” means “without water.” Symmetrical anhydrides are named by taking the acid name and replacing “acid” with “anhydride.” Mixed anhydrides are named by stating the names of both acids in alphabetical order, followed by “anhydride.” An ester has an OR’ group in place of the OH group of a carboxylic acid. In naming an ester, the name of the group (R’) attached to the carboxyl oxygen is stated first, followed by the name of the acid, with “ic acid” replaced by “ate.” Salts of carboxylic acids are named in the same way. The cation is named first, followed by the name of Salts of carboxylic acids are named in the same way....
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This note was uploaded on 04/18/2008 for the course CHEM 328 taught by Professor Boyles during the Spring '08 term at SDSMT.
- Spring '08
- Organic chemistry