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Carboxylic acids

Carboxylic acids. Lec.11. Introduction . The functional group of a carboxylic acid is the carboxyl group so named because it is made up of a carb onyl group and a hydr oxyl group. The general formula for an aliphatic carboxylic acid is RCOOH. Nomenclature. IUPAC System

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Carboxylic acids

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  1. Carboxylic acids Lec.11

  2. Introduction • The functional group of a carboxylic acid is the carboxyl group so named because it is made up of a carbonyl group and a hydroxyl group • The general formula for an aliphatic carboxylic acid is RCOOH

  3. Nomenclature • IUPAC System • carboxylic acid is derived from that of the longest carbon chain that contains the carboxyl group by dropping the final -e from the name of the parent alkane and adding the suffix -oicfollowed by the word acid . • The chain is numbered beginning with the carbon of the carboxyl group. • Because the carboxyl carbon is understood to be carbon 1, there is no need to give it a number. Formic acid Acetic acid

  4. If the carboxylic acid contains a carbon-carbon double or triple bond, change the infix from -an- to -en- or -yn • Dicarboxylic acids are named by adding the suffix -dioic acid to the name of the carbon chain that contains both carboxyl groups

  5. Examples: 2- B. Common Names When common names are used, the Greek letters α, β,Ƴ …are often added as a prefix to locate substituents. The α-position in a carboxylic acid is next to the carboxyl group; an α -substituent in a common name is equivalent to a 2-substituent in an IUPAC name.

  6. Examples: 2- • The carboxyl group has priority over alcohol, aldehyde, or ketone functionality in naming. In the latter cases, the prefix oxo-is used to locate the carbonyl group of the aldehyde or ketone, as in these examples:

  7. Physical Properties • Carboxylic acids have significantly higher boiling points than other types of organic compounds of comparable molecular weight, such as alcohols, aldehydes, and ketones. • Carboxylic acids are polarso Carboxylic acids interact with water molecules by hydrogen bonding through both the carbonyl and hydroxyl groups. Because of greater hydrogen bonding interactions, carboxylic acids are more soluble in water than are alcohols,, aldehydes, and ketones of comparable molecular weight

  8. Preparation of Carboxylic Acids • Oxidation of Primary Alcohols and Aldehydes B. Reaction of Grignard Reagents with Carbon Dioxide +MgX acid C. Oxidation of alkynes

  9. REACTIONS: 1-Esterification(Fischer esterification) • Esters can be prepared by treating a carboxylic acid with an alcohol in the presence of an acid catalyst, most commonly H2SO4, or gaseous HCl. • Acid-catalyzed esterification is reversible • (Esterification Hydrolysis)

  10. 2- Decarboxylation Decarboxylation is the loss of CO2 from the carboxyl group of a molecule. Almost any carboxylic acid, heated to a very high temperature, undergoes thermal decarboxylation 3-Reduction Lithium aluminum hydride (LiAlH4) reduces a carboxylic acid to a primary alcohol, although heating is required.

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