CHAPTER 3 ACIDS AND BASES IN ORGANIC CHEMISTRY 3.1 INRODUCTION The important of acid-base reaction 1. is a simple, fundamental reaction 2. enable you to see the mechanism of the reaction 3. illustrate the process of bond breaking and bond making examine important ideas about the relationship between the structure of molecules and their reactivity 5. illustrate the important role solvents play in chemical reactions 6. find something familiar in General chemistry
CHAPTER 3 ACIDS AND BASES IN ORGANIC CHEMISTRY 3.1 INRODUCTION The important of acid-base reaction: 1. is a simple, fundamental reaction. 2. enable you to see the mechanism of the reaction 3. illustrate the process of bond breaking and bond making 4. examine important ideas about the relationship between the structure of molecules and their reactivity. 5. illustrate the important role solvents play in chemical reactions 6. find something familiar in General chemistry
3.1A THE BRNSTED-LOWRY DEFINATION OF ACIDS AND BASES According to the brnsted-Lowry theory, an acid is a substance that can donate a proton, and a base is a substance that can accept a proton. For example H-0:+H H-O-H + CI H Base Acid Conjugate Conjugate (proton (proton acid of base of acceptor) sonor) HCI bydrogen chloride, a very strong acid, transfers its proton to water Water acts as a base and accepts the proton
3.1A THE BRNSTED-LOWRY DEFINATION OF ACIDS AND BASES According to the brnsted-Lowry theory, an acid is a substance that can donate a proton, and a base is a substance that can accept a proton. For example: H O H H Cl H O + H H Cl - + + Base (proton acceptor) Acid (proton sonor) Conjugate acid of H2 O Conjugate base of HCl Hydrogen chloride, a very strong acid, transfers its proton to water. Water acts as a base and accepts the proton
The molecule or ion forms when an acid loses its proton is called the conjugate base of that acid Such as the chloride ion The molecule or ion that forms when a base accepts a proton is called the conjugate acid of that base. Such as the hydronium ion Other strong acids that completely transfer a proton when dissolved in water are hydrogen iodide hydrogen bromide and sulfuric acid HI ho H3O +I HBr+H2O→H3O+Br H2SO4+H2O—-H3O+HSO HSO+H2O之一H2O++SO4 The proton transfer is stepwise in sulfuric acid, the first proton Transfer completely, the second only to the extent of 10%
The molecule or ion forms when an acid loses its proton is called the conjugate base of that acid. Such as the chloride ion. The molecule or ion that forms when a base accepts a proton is called the conjugate acid of that base. Such as the hydronium ion. Other strong acids that completely transfer a proton when dissolved in water are hydrogen iodide, hydrogen bromide, and sulfuric acid. HI + H2 O HBr + H2 O H2 SO4 + H2 O HSO4 - + H2 O H3O + + I - H3O + +Br - H3 O + +HSO4 - H3 O + + SO4 2- The proton transfer is stepwise in sulfuric acid, the first proton Transfer completely, the second only to the extent of ～10%
When an aqueous solution of sodium hydroxide is mixed with an aqueous solution of hydrogen chloride, the reaction that occurs is between hydronium and hydroxide ions Total lonic reaction: H-0+-H+:cr:+Na++H-0:--2H-0+Nat+:Cr H Spectator ions Net reaction. H-OH+H-o H H The net reaction is simply HO OH 2 HbO
When an aqueous solution of sodium hydroxide is mixed with an aqueous solution of hydrogen chloride, the reaction that occurs is between hydronium and hydroxide ions. H O - H O+ H H Cl - + + Na + + H O H + Na + + Cl - 2 Spectator ions Total Ionic Reaction: Net Reaction: H O + H H + H O - H O H 2 The net reaction is simply: H3 O + + OH - 2 H2 O
3.1B THE LEWS DEFINITION OF ACIDS AND BASES Lewis proposed that acids be defined as electron-pair acceptors and bases be defined as electro-pair donors For example H NH H-NH Lewis acid Lewis base (electron-pair(electron-pair acceptor) donor) Cl-Al+: NH- CI-Al-NH3 C Lewis acid ewis base (electron-pair(electron-pair acceptor) donor
3.1B THE LEWS DEFINITION OF ACIDS AND BASES Lewis proposed that acids be defined as electron-pair acceptors and bases be defined as electro-pair donors. For example: H + + NH3 NH3 + H Lewis acid (electron-pair acceptor) Lewis base (electron-pair donor) + NH3 Lewis acid (electron-pair acceptor) Lewis base (electron-pair donor) Cl Al Cl Cl Cl Al - Cl Cl NH3 +