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Learn about the structures, properties, and synthesis methods of carboxylic acids, esters, acid anhydrides, amides, and more in Chapter 15. Explore their roles in flavor, chemistry, and biology. Understand naming conventions and properties compared to alkanes and alcohols.
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Chapter 15 Carboxylic Acids, Esters, and derivatives
Where found • Tartness in fruits • Rancid butter • Animal fats and plant oil • Clothing
Structure of Carboxylic Acids • Presence of the carbonyl group: C=O • Additional presence of • Formic acid • Acetic acid
Structure of Esters • A carboxylic acid derivative • Presence • Methyl propionate
Structure of Acid Anhydrides • Presence of two carbonyl carbons connected by an oxygen
Structure of Amides • Presence of • More in chapter 16
Structure of Acid Halide • Presence of
Synthesis of Carboxylic Acids • Selective oxidation • Benzoic acid • From
Naming Carboxylic Acids • Longest chain with carboxyl group. The carboxyl carbon is C1 • Ending of –e is changed to –oic acid • Substituents are used as prefixes with numbers to show location • Two carboxyl groups are an alkanedioic acid with separate numbers to show location
Items of Interest • Table 15.2 page 437 • Box 15.1 page 441
Properties of Carboxylic Acids • How do the m.p. and b.p. compare to: • Alkanes? • Alcohols? • How does solubility compare to: • Alkanes? • Alcohols
Acidity of Carboxylic Acids • Weak acids • Only about 1 to 2% ionization to H+ • HCl is 100% ionized • Acidic enough to turn blue litmus red
Carboxylate Salts • More soluble in higher pH environment (i.e. blood) • Important in biological functions
Properties of Carboxylate Salts • Ionic molecules • Injections of medicine with a carboxyl groups are given with the salt • The salts are basic – red to blue litmus
Naming Carboxylate Salts • Positive ion named first • Change the acid from –ic acid to –ate • Name: • CH3COO-Na+ • CH3CH2CH2CH2COO-K+
Soaps • Salts of long chain carboxylic acids (fatty acids – derived from animals and plants) • Conversion process is called • Sodium stearate CH3(CH2)16COO-Na+ • Need a long chain and ionic head (Fig 15.1)
Esters • An ester, RCOOR’ is formed • Process is called esterification • Thioesters – involve Sulfur (Thiol) p. 446
Naming Esters • Two parts • Alkoxy – alcohol (aryloxy for phenol) • Acyl – acid • The group is named first • The part is named second and change from –ic acid to –ate • Name: CH3OOC(CH2)3CH3
Polyesters • Esterification becomes polymerization if there are two functional groups per molecule • Dicarboxylic acids • Diols • See page 449 • Condensation reaction if water is a by-product • Addition polymerization if no by-products (alkenes)