Carboxylic acids & esters

1 Chapter 16 Carboxylic Acids and Esters 16.1 Carboxylic Acids Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings 2 A carboxylic acid  Contains a carboxyl group, which is a carbonyl group (C=O) attached to a hydroxyl group (—OH).  Has the carboxyl group on carbon 1. carbonyl group O || CH3 — C—OH hydroxyl group or CH3COOH carboxyl group Carboxylic Acids 3 Models of Carboxylic Acids  The three-dimensional models show the geometry of atoms in carboxylic acid molecules. Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings 4 The IUPAC names of carboxylic acids  Replace the -e in the alkane name with -oic acid. CH4 methane HCOOH methanoic acid CH3—CH3 ethane CH3—COOH ethanoic acid  Number substituents from the carboxyl carbon 1. CH3 O | ║ CH3—CH—CH2—C—OH 4 3 2 1 3-methylbutanoic acid IUPAC Names 5 The common names of simple carboxylic acids  Are formic acid (1C), acetic acid (2C), propionic acid (3C), and butyric acid (4C). HCOOH formic acid CH3—COOH acetic acid  Locate substituents using α, β, γ for the carbon atoms adjacent to the carboxyl carbon. CH3 γ β| α CH3—CH—CH2—COOH 3-methylbutanoic acid (β-methylbutryic acid) Common Names 6 Alpha Hydroxy Acids Alpha hydroxy acids (AHAs)  Occur naturally in fruit, milk, and sugarcane.  Are used in skin care products. Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings 7 Names and Sources of Some Carboxylic Acids TABLE 16.1 Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings 8 Common Carboxylic Acids Methanoic acid (formic acid) O ║ H─C─OH ethanoic acid (acetic acid) O ║ CH3─C─OH Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings 9 Aromatic Carboxylic Acids Benzoic acid  Is the aromatic carboxylic acid.  Locates substituents by assigning 1 to the carbon attached to the carboxyl group.  Has common names that assign prefixes ortho, meta, and para for 2 substituents. ortho 1, 2 location meta 1, 3 location para 1, 4 location 10 Aromatic Carboxylic Acids OHC O OHC O OHC O Cl NH 2 benzoic acid 3-chlorobenzoic acid 4-aminobenzoic acid m-chlorobenzoic acid p-aminobenzoic acid [...]... acid 17 Chapter 16 Carboxylic Acids and Esters 16.2 Properties of Carboxylic Acids Copyright © 2007 by Pearson Education, Inc Publishing as Benjamin Cummings 18 Polarity of Carboxylic Acids Carboxylic acids   Are strongly polar Have two polar groups: hydroxyl (−OH) and carbonyl (C=O) δ O ║δ + δ - + δ CH3CO H 19 Boiling Points of Carboxylic Acids The boiling points of carboxylic acids   Are higher... in Water Carboxylic acids   Water molecules Form hydrogen bonds with many water molecules With 1-4 carbon atoms are very soluble in water Copyright © 2007 by Pearson Education, Inc Publishing as Benjamin Cummings 22 Boiling Points and Solubility TABLE 16.2 Copyright © 2007 by Pearson Education, Inc Publishing as Benjamin Cummings 23 Acidity of Carboxylic Acids Carboxylic acids   Are weak acids Ionize... Cummings 24 Acid Dissociation Constants Carboxylic acids   TABLE 16.3 Have small Ka values Exist mostly as molecules and a few ions in aqueous solutions 25 Neutralization of Carboxylic Acids Carboxylic acid salts  Are a product of the neutralization of a carboxylic acid with a strong base – + CH3—COOH + NaOH CH3—COO Na + H2O acetic acid  sodium acetate (carboxylic acid salt) Are used as preservatives... Chapter 16 Carboxylic Acids and Esters 16.3 Esters 16.4 Naming Esters Copyright © 2007 by Pearson Education, Inc Publishing as Benjamin Cummings 29 Esters In an ester,  The H in the carboxyl group is replaced with an alkyl group O || CH3 — C—O—CH3 ester group Copyright © 2007 by Pearson Education, Inc Publishing as Benjamin Cummings 30 Esterification Esterification is  The reaction of a carboxylic. .. CH3─CH2─COOH propanoic acid (propionic acid) CH3 | B CH3─CH─CH2─COOH 3-methylbutanoic acid (β-methylbutyric acid) O C 3-bromobenzoic acid C OH (m-bromobenzoic acid) Br 14 Preparation of Carboxylic Acids   Carboxylic acids can be prepared by oxidizing primary alcohols or aldehydes The oxidation of ethanol produces ethanoic acid (acetic acid) OH | [O] CH3—CH2 O || [O] CH3—C—H ethanol ethanal (ethyl alcohol)... reduce inflammation C OH O Is an ester of salicylic acid and acetic acid Oil of wintergreen   O O C CH3 Is used to soothe sore muscles Is an ester of salicylic acid and methanol O C O CH3 OH 35 Esters in Plants Esters give flowers and TABLE 16.4 fruits their pleasant fragrances and flavors 36 Copyright © 2007 by Pearson Education, Inc Publishing as Benjamin Cummings ... Solution Write the equation for the reaction of propanoic acid and methanol in the presence of an acid catalyst O || CH3—CH2—C—OH + H—O—CH3 propanoic acid O H + methanol || CH3—CH2—C—O—CH3 + H2O 33 Naming Esters The name of an ester contains the names of   The alkyl group from the alcohol The carbon chain from the acid with –ate ending from alcohol from acid O methyl || CH3— O—C —CH3 ethanoate (acetate) . 1 Chapter 16 Carboxylic Acids and Esters 16.1 Carboxylic Acids Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings 2 A carboxylic. of Carboxylic Acids Chapter 16 Carboxylic Acids and Esters Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings 19 Polarity of Carboxylic