Chapter 15: Carboxylic Acids and Esters

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Chapter 15Carboxylic Acids and Esters
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• CARBOXYLIC ACIDS
• The functional group of carboxylic acids is the
  carboxyl group.
• Many carboxylic acids have common names.

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• CARBOXYLIC ACIDS IUPAC NOMENCLATURE
• Find the longest carbon chain that contains the
  COOH group.
• Drop the e from the end of the hydrocarbon name
  and substitute oic acid.
• Number the longest chain. Carbon number 1 is the
  carboxyl carbon.
• Name and number other substituents.
• Examples

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• Aromatic acid names are derived from the parent
  compound, benzoic acid.
• Example

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• PHYSICAL PROPERTIES OF CARBOXYLIC ACIDS
• Low molecular weight carboxylic acids are liquids
  at room temperature and have characteristically
  sharp or unpleasant odors.
• The COOH group is very polar. Hydrogen bonding
  between COOH groups creates dimers (two
  identical molecules bonded together).
• This gives carboxylic acids high boiling points
  (greater than alcohols).

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• PHYSICAL PROPERTIES, cont.
• COOH groups can hydrogen bond with water. If
  the hydrophobic R group is not too large,
  carboxylic acids are very water soluble.

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• ACIDITY OF CARBOXYLIC ACIDS
• Carboxylic acids behave as weak acids (low
  dissociation), forming carboxylate ions in water.
• Example

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• SALTS OF CARBOXYLIC ACIDS
• Carboxylic acids react readily with strong bases
  (NaOH, KOH) to form salts.

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• Examples

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• SALTS, cont.
• To name a carboxylic acid salt, name the metal
  ion first and change the ic ending of the acid
  name to ate.
• Example

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• USEFUL CARBOXYLIC ACID SALTS
• Na and K salts of long-chain acids are used as
  soaps (sodium stearate).
• Calcium and sodium propanoate are used as
  preservatives in bakery products.
• Sodium benzoate is a food preservative used in
  ketchup and soda pop.
• Zinc 10-undecylenate is used to treat athletes
  foot.

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• CARBOXYLIC ESTERS
• The ester functional group with the ester linkage
  between the carbonyl carbon and the oxygen atom

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• ESTERS, cont.
• Esterification is the process of forming an ester
  linkage between a carboxylic acid and an alcohol.

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• Examples

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• ESTERS, cont.
• Because of the reversible nature of the
  esterification reaction, carboxylic acid
  chlorides and carboxylic acid anhydrides are used
  instead of the carboxylic acid to obtain higher
  product (ester) yields.

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• ESTERS, cont.
• Examples

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• ESTERS, cont.
• Specific Examples

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• NAMING ESTERS
• The first word of the name of an ester is the
  name of the alkyl or aromatic group (R')
  contributed by the alcohol.
• The second word is the carboxylic acid name, with
  the ic acid ending changed to ate.

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• NAMING ESTERS, cont.
• Examples

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• ESTER REACTIONS
• Ester hydrolysis the reverse of esterification

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• Specific Examples

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• ESTER REACTIONS, cont.
• Saponification similar to hydrolysis, but
  carried out with a strong base to produce a
  carboxylic acid salt

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• Examples

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• Esters of Inorganic Acids
• Esters can be formed by reacting alcohols with
  inorganic acids such as sulfuric, nitric, or
  phosphoric acids

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• INORGANIC ACID ESTERS, cont.
• Because phosphoric acid has three OH groups, it
  can form mono-, di-, and triesters.
• Mono- and diesters are very important
  biologically.

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• PHOSPHORIC ANHYDRIDES
• Phosphate esters that have two or three phosphate
  groups linked together

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• Adenosine diphosphate (ADP) and adenosine
  triphosphate (ATP) are two phosphoric anhydrides
  of great biological importance. In each case,
  the R group is adenosine.