chapter 15 carboxylic acids, esters, and derivatives
TRANSCRIPT
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)