1 Draw all of the acyclic amines that have the chemical formula C4H9N. Ignore stereochemistry, if any.Amine vs. Imine What does IUPAC say? The International Union of Pure and Applied Chemistry General Methodology: (1) amines are compounds formally derived from ammonia by replacing one, two, or three of its hydrogen atoms by hydrocarbyl groups, and having the general tructures R-NH2 (primary amines), R2NH (secondary amines), R3N (tertiary amines). (2) imines are compounds having the structure R-N=CR2 (R = H, hydrocarbyl), corresponding either to ketimines, RR′C=NR″ or to aldimines, RCH=NR′ Full credit for testbank question 138 (3 points) 2Chapter 3 An Introduction to Organic Reactions: Acids and Bases 3In This Chapter : 1. Rules that show how to classify reactive groups within molecules from the standpoints of acids and bases as well as from electron-rich and electron-poor domains 2. The step-by-step processes of a chemical reaction and how to codify these processes into a few specific, easy-to-understand types 4Reactions and Their Mechanisms There are four general types of organic reactions: 1- Substitutions 2- Additions 54- Rearrangements 3- Eliminations 6Cleavage of Covalent Bonds • Homolysis • Heterolysis 7In Class Problem: Designate the following reactions as (1) a substitution, (2) an elimination, (3) an addition, (4) a rearrangement, (5) some combination of the former 8Designate the following reactions as (1) a substitution, (2) an elimination, (3) an addition, (4) a rearrangement, (5) some combination of the former In Class Problem: 9Designate the following reactions as (1) a substitution, (2) an elimination, (3) an addition, (4) a rearrangement, (5) some combination of the former In Class Problem: 10Heterolytic reactions almost always occur at polar bonds. The reaction is often assisted by formation of a new bond to another molecule. The following two examples illustrate two types of heterolytic cleavage reactions: (1) An example of a unimolecular reaction process: 11(2) An example of a bimolecular reaction process: 12Introduction to Acid-Base Chemistry • Many of the reactions that occur in organic chemistry are either acid–base reactions themselves or they involve an acid–base reaction at some stage • Acid–base reactions are simple fundamental reactions that will enable you to see how chemists use curved arrows to represent mechanisms of reactions and how they depict the processes of bond breaking and bond making that occur as molecules react Brønsted-Lowry Definition of Acids and Bases Brønsted–Lowry acid–base reactions involve the transfer of protons Brønsted–Lowry acid: a substance that can donate (lose) a proton Brønsted–Lowry base: a substance that can accept (remove) a proton 13+H OHH ClO HHHCl+Base (H+ acceptor) Acid (H+ donor) Conjugate Acid of H2O Conjugate Base of HCl Hydronium ion (H3O+) is the strongest acid that can exist in water to any significant extent: Any stronger acid will simply transfer its proton to a water molecule to form hydronium ions Hydroxide ion (HO-) is the strongest base that can exist in water to any significant extent: Any base stronger than hydroxide will remove a proton from water to form hydroxide ions Example: Hydrogen chloride is a very strong acid. When dissolved in water essentially all hydrogen chloride molecules transfer their proton to water. 14Total ionic reaction: Hydrochloric acid (HCl) + Sodium hydroxide (NaOH) 2 H OHO HHHCl+NaHO++ +Na ClSpectator ions Net reaction 2 H OHO HHH+HO15In Class practice: Reaction of acetic acid with hydroxide. Which example show the correct movement of electrons? 1) 2) 16Lewis Acids: electron pair acceptors Lewis Bases: electron pair donors Opposite Charges Attract and React BF3 and NH3 react based on their relative electron densities. BF3 has substantial positive charge on the boron. NH3 has substantial negative charge localized at the lone pair on nitrogen. Lewis Definition of Acids and Bases 17In Class Problem: Write an equation that shows the Lewis acid and Lewis base in the reaction of (a) boron trifluoride (BF3) with tert-butyl alcohol ((CH3)3COH) (b) molecular chlorine (Cl2) with aluminum chloride (AlCl3). 18Lewis Acid (empty p orbital of Aluminum allows AlCl3 acts as e⊖ pair acceptor) Lewis Base (e⊖ pair donor) +Cl AlNH3ClClAl NH3ClClClIn Lewis acid–base theory, the attraction of oppositely charged species is fundamental to reactivity 19Heterolysis of Bonds to Carbons: Carbanions and Carbocations Reaction can occur to give a carbocation or carbanion depending on the nature of Z. 20Heterolysis of Bonds to Carbons: Carbanions and Carbocations • Carbocations (Lewis acids) have only 6 valence electrons and a positive charge. • Carbanions (Lewis bases) have 8 valence electrons and a negative charge. 21Terminology for Lewis Acids and Bases Electrophiles (“electron-loving” reagents ): seek electrons to obtain a stable valence shell of electrons. They are electron-deficient species e.g. carbocations. All Lewis acids are electrophiles. Nucleophiles (“nucleus-loving” reagents): seek a proton or some other positively charged center. They are electron-rich species e.g. carbanions. 22 +BC BCanion(a Lewis base)carbocation(a Lewis acidand electrophile)+H OHH ClO HHHCl+Base (H+ acceptor) Acid (H+ donor) Conjugate Acid of H2O Conjugate Base of HCl Hydronium ion (H3O+) is the strongest acid that can exist in water to any significant extent: Any stronger acid will simply transfer its proton to a water molecule to form hydronium ions Hydroxide ion (HO-) is the strongest base that can exist in water to any significant extent: Any base stronger than hydroxide will remove a proton from water to form hydroxide ions Example: Hydrogen chloride is a very strong acid. When dissolved in water essentially all hydrogen chloride molecules transfer their proton to water. 23Strengths of Acids and Bases Ka and pKa Acetic acid is a relatively weak acid and a 0.1M solution is only able to protonate water to the extent of about 1%. The equilibrium equation for this reaction is: Dilute acids have a constant concentration of water (about 55.5 M) and so the concentration of water can be factored out to obtain the acidity constant (Ka). Ka for acetic acid is 1.76 X 10-5 Any weak acid (HA) dissolved in water fits the general Ka expression. The