Organic Chemistry Notes - Second Semester

Organic Chemistry Notes - Second Semester
Organic Chemistry Notes - Second Semester
Organic Chemistry Notes - Second Semester
Organic Chemistry Notes - Second Semester
Organic Chemistry Notes - Second Semester
Organic Chemistry Notes - Second Semester
Organic Chemistry Notes - Second Semester
Organic Chemistry Notes - Second Semester
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The Second Semester of Organic Chemistry Notes is 189 pages in length (Section 13 through Section 23) and covers ALL lecture notes and topics discussed in the 2nd semester of your organic chemistry lecture course.

SECTION 13 – CONJUGATED SYSTEMS AND ULTRAVIOLET SPECTROSCOPY

13-1 -- Three Classes of Dienes

· Conjugated Dienes

· Cumulenes (“Allenes”)

· Other, Isolated Double Bonds (d.b.’s)

13-1 -- Relative Stabilities of Dienes

· Heats of Formation (ΔH°f) – Values and Comparisons

13-2 -- Double Bonds of Conjugated Dienes

· Prefer to be Coplanar

· “Cisoid” or S-Cis Conformation

· “Transoid” or S-Trans Conformation

· Resonance Description

13-4 -- Reactions of Dienes – Summary (3 Main Reactions)

13-4 -- Additions of Electrophiles

· Markovnikov Addition

· 1,2-Addition Product vs. 1,4-Addition Product

· Mechanism of the Reaction

· Equilibration via an SN1 Mechanism

· Kinetic Control vs. Thermodynamic Control

13-6 -- Addition of Halogens (X2)

· Also Gives 1,2-Addition Product and 1,4-Addition Product

· Mechanism of the Reaction

· With Br2, Mechanism May Go via a Bromonium Ion Intermediate

13-6 -- The Diels-Alder Reaction (Huge Topic!)

· General Form of the Reaction

· The Diene (4e- Component) and the Dienophile (2e- Component)

· Diene Conformation Must be S-Cis

· Diels-Alder Reaction is Concerted – All Bonding Changes Occur Simultaneously

· Formation of 1 New π-Bond and 2 New σ-Bonds

· Diels-Alder Reaction is Stereospecific

· Formation of Products that are Enantiomers and/or Meso Compounds

· Electronic Requirements of the Diels-Alder Reaction

· The “Endo Effect”

· Endo Substituents vs. Exo Substituents

13-13 -- Ultraviolet-Visible (UV-Vis) Spectroscopy

· Excitation of Electrons (e-‘s)

· Promoting e- from Bonding Molecular Orbital (MO) or Non-Bonding MO

· Bonding Molecular Orbitals (MO’s) and Antibonding MO’s

· Non-Bonding MO’s

· The “Excited State”

· Lowest-Energy Transitions (the HOMO-LUMO gap, and ΔE)

· Conjugated π-Systems

· The Electromagnetic Spectrum and Complimentary Colors

· A Typical UV-Vis Spectrum

· Beer’s Law (A = Є . c . b)

· The Extinction Coefficient (Є) = “Molar Absorptivity”

· λmax Increases with Increasing Conjugation

· Delocalization of π-MO’s

· Systems with Non-Bonding e-‘s and π-Electrons

· π --> π* Transitions vs. n --> π* Transitions

· 3 General Rules for λmax

· What are Chromophores?

SECTION 14 – AROMATIC COMPOUNDS AND AROMATICITY

14-1 -- Definition of Aromaticity

· Cyclic, Planar, Fully Conjugated Array of p-Orbitals

· Huckel’s Rule (“4n + 2”)

14-1 -- Benzene and its Derivatives

· Very Unreactive

· How Stable is Benzene?

· Hydrogenation of Benzene (Addition of H2)

· Benzene Stability Explained by “Model 1” and “Model 2”

· Resonance Energy (or “Aromatic Stabilization Energy”)

· Napthalene and Phenanthrene as Examples

14-3 -- Compounds with Planar, Conjugated, Cyclic Arrays of “4n” π-Electrons

· Antiaromatic Compounds

· Extremely Unstable; Very Reactive

14-4 -- Benzene Derivatives that are Neither Aromatic nor Antiaromatic

14-5 -- More Examples of Aromatic Compounds

· “4n + 2”

· Re-Hybridization of sp3-orbital --> sp2-orbital

14-7 -- More Examples of Antiaromatic Compounds

· “4n”

14-7 -- Spectroscopy of Benzene

· UV-Vis Spectroscopy of Benzene

· IR Spectroscopy of Benzene

· 1H NMR Spectroscopy of Benzene

· Coupling – in 1H NMR

· 1,4-Disubstituted vs. 1,2-Disubstituted vs. 1,3-Disubstituted Benzenes

14-9 -- Nomenclature of Substituted Benzenes

· Monosubstituted Benzenes (Common Names are Used)

· Disubstituted Benzenes – Ortho (o), Meta (m), and Para (p)

· Use of Monosubstituted Benzenes as “Principal Structures” in Nomenclature

· Xylenes = Dimethyl Substituted Benzenes

SECTION 15 – ELECTROPHILIC AROMATIC SUBSTITUTION

15-1 -- The Chemistry of Benzene (C6H6)

15-1 -- General Mechanism of Electrophilic Aromatic Substitution (E.A.S.)

· Delocalization of Charge

· An Addition Reaction is Not Observed

15-2 -- Overview of Electrophilic Aromatic Substitution Reactions

· Nitration (Adding –NO2 to the Benzene Ring)

· Sulfonation (Adding –SO3H to the Benzene Ring)

· Halogenation (Adding “-X” to the Benzene Ring)

· Friedel-Crafts Alkylation (Adding “-R” to the Benzene Ring)

· Friedel-Crafts Acylation (Adding “-COR” to the Benzene Ring)

15-3 -- The Nitration Reaction

· Detailed Mechanism

· Product is Nitrobenzene

15-3 -- The Sulfonation Reaction

· Product is Benzenesulfonic Acid

· Detailed Mechanism

· Use of “Fuming Sulfuric Acid”

· Le Chatelier’s Principle and Possible Desulfonation

· Principle of Microscopic Reversibility

15-5 -- Halogenation of Aromatic Rings

· Product is a Halobenzene

· Use of the Lewis Acid Catalyst, FeCl3

· Detailed Mechanism

· Iodination – Mechanism is a Bit Different (CuCl2 as Catalyst)

15-6 -- Friedel-Crafts Alkylation

· Doesn’t Proceed on Aromatic Rings with Strongly Deactivating Substituents

· Detailed Mechanism – Works Well with R-Cl, R-Br, R-I, or R-F

· Rearrangements of “R” and the Involvement of Free Carbocations

15-8 -- Friedel-Crafts Acylation

· The “Acyl Group”

· Detailed Mechanism

· The “Acylium Ion” – Not Prone to Rearrangement

15-9 -- Use of H+ (D+) as the Electrophile

15-10 -- Directing Effects of Substituents

· Ortho (o), Meta (m), and Para (p) Directors

· Activators vs. Deactivators

· Mechanism of Para Attack by an Electrophile

· Mechanism of Ortho Attack by an Electrophile

· Mechanism of Meta Attack by an Electrophile

15-11 -- More on Activating, o,p-Directoring Groups

· “Electron-Withdrawing” – Induction vs. Resonance

15-13 -- More on Deactivating, m-Directoring Groups

15-13 -- Halogens are o,p-Directors and Weak Activators

15-14 -- Detailed Summary of Substituents’ Directing Effects

· Activating, o,p-Directors (Both Strong and Weak)

· Deactivatinig, m-Directors (Both Strong and Weak)

· Deactivating, o,p-Directors (Weak)

15-14 -- Miscellaneous Notes About E.A.S Reactions

· Important Side Notes on Friedel-Crafts Reactions

· Ortho-Para Product Ratio is Sensitive to Steric Effects

· Important Substituent Transformations (i.e. –NO2 converted to –NH2)

· What if 2 or More Substituents’ Directing Effects Oppose Each Other?

15-17 -- Organic Synthesis of Benzene Derivatives

· The Order of Reactions is Critical

15-18 -- Nucleophilic Aromatic Substitution Reactions (N.A.S.)

· Mechanism #1: Addition-Elimination

· Meisenheimer Complex

· Need a Good Leaving Group (l.g.) and an Electron-Withdrawing Group

· Mechanism #2: Elimination-Addition

· Occurs via “Benzyne” Mechanism

· Need a Very Strong Base

15-21 -- Benzyne Can Act as a Dienophile and React with Dienes

15-22 -- Side-Chain Oxidation Reactions (Use of KMnO4)

15-22 -- Benzylic Bromination Reactions

· Occurs via a Free Radical Chain Mechanism

· NBS = N-Bromosuccinimide

SECTION 16 – REACTIONS AND SYNTHESIS OF ALCOHOLS

16-1 -- Nomenclature of Alcohols

· Principle Group/Chain Contains -OH

· Alkane --> Alkanol, Alkanediol, etc…

· Common Names of Alcohols

16-2 -- Alcohols and Hydrogen Bonding

· Bond Dissociation Energy (BDE) of a Hydrogen Bond ~ 5kcal/mol in Energy

16-2 -- Acidities of Alcohols

· The Alkoxide Anion, RO-

· Factors that Stabilize the Alkoxide Ion

· pKa

16-3 -- Three Factors that Stabilize the Alkoxide Ion, RO-

· Inductive Effects and Electronegative Substituents

· Resonance Effects

· Branching – Steric Hindrance Considerations

16-5 -- Formation of Alkoxide Ions

· Deprotonation of the Alcohol

· Acid-Base Reactions

· Strong Bases Required for Deprotonation

16-6 -- Converting Alkenes --> Alcohols

· 4 Ways

· Various Reagents that Can Be Used (4 Reaction Types)

· Markovnikov vs. non-Markovnikov Regiochemistry

· Diol Formation

16-6 -- Converting Alkyl Halides --> Alcohols

· Occurs via SN2 or SN1 Chemistry

16-7 -- Converting Alcohols --> Alkenes

· Possible Carbocation Rearrangements

· Use of POCl3 to Avoid Rearrangement

16-7 -- Converting Alcohols --> Alkyl Halides

· 4 Ways

· Use of HX, -or- SOCl2, -or- PBr3, -or- Ts-Cl

16-8 -- Reactions of Grignard Reagents with Carbonyl Compounds (C=O)

· R’-MgX + Ketone --> 3° Alcohol

· R’-MgX + Aldehyde --> 2° Alcohol

· R’-MgX + Formaldehyde --> 1° Alcohol

· Alkyllithium Reagents (R-Li) Can Also Be Used

· Esters Add 2 Equivalents of R’-MgX

16-9 -- Grignard Reaction and Carboxylic Acids?

· No Reaction – The Acid “Kills” the Grignard Reagent

16-10 -- Oxidation and Reduction

· “OIL RIG”

· Oxidation Levels and Oxidation Numbers

· Assignment Rules for Oxidation Numbers of Carbon

16-12 -- Hydride (:H-) Reduction Reactions

· Use of Lithium Aluminum Hydride (LiAlH4) or “LAH”

· Use of Sodium Borohydride (NaBH4)

· Solvents Used with LiAlH4 = Diethyl Ether (Et2O) or Tetrahydrofuran (THF)

16-13 -- Types of Hydride Reactions – 2 Types

· Reduction of Ketones and Aldehydes to Form Alcohols

· Reduction of Esters and Carboxylic Acids to Form Alcohols

· Why Can’t NaBH4 Reduce Carboxylic Acids??

16-14 -- Oxidation of Alcohols with Chromium VI Reagents (Cr+6)

· Jones Reagent

· H2Cr2O7 as the Oxidizing Agent

· Use of the Milder Oxidizing Agent Pyridinium Chlorochromate (PCC)

16-16 -- Use of Protecting Groups

· Protecting the Alcohol Functional Group (-OH)

· Use of TBS-Cl

· TBS-Cl vs. TMS-Cl

· Protection / Deprotection Steps

16-18 -- Thiols = “Mercaptans”

16-18 -- Nomenclature of Thiols

16-18 -- Preparation of Thiols – 2 Ways

· Use of Hydrosulfide Anion, HS- in an SN2 Reaction

· Use of Thiourea, (NH2)2C=S

16-19 -- Oxidation of Thiols to Produce Disulfides (R-S-S-R’)

SECTION 17 – ETHERS, EPOXIDES, AND SULFIDES

17-1 -- Nomenclature of Ethers (R-O-R’)

· Common Names of Some Ethers

· Epoxides = Cyclic, 3-Membered Ring Ethers

· “Oxiranes”

· IUPAC Names of Ethers

17-2 -- Preparation of Ethers

· Williamson Ether Synthesis (SN2)

· Possible E2 Side Reactions

17-3 -- Preparation of Epoxides

· 2 Ways to Form a Ring Ether (Epoxide)

· Alkene + Peroxyacid (RCO3H) --> Epoxide + Carboxylic Acid

· Meso Compound Products and Enantiomeric Epoxide Products

· Cyclization of Bromohydrins to Form Epoxides

17-5 -- Ring-Opening Reactions of Epoxides

· The Acid-Catalyzed Epoxide Ring Opening

· The Base-Catalyzed Epoxide Ring Opening

· Stereochemistry Concerns

17-6 -- The Addition of Grignard Reagent to Epoxides

17-6 -- Sulfides (R-S-R’)

· Sulfides = Sulfur Analogs of Ethers

· Preparation of Sulfides

· The Thiolate Ion, RS-

17-7 -- 2 Major Differences Between Sulfides and Ethers

· Sulfides are Good Nucleophiles

· Sulfides are Easily Oxidized (via 1. H2O2; followed by 2. CH3CO3H)

SECTION 18 – ALDEHYDES AND KETONES: NUCLEOPHILIC ADDITION REACTIONS

18-1 -- Nomenclature of Aldehydes and Ketones

· Common Names of Aldehydes and Ketones

· Substituents or “Branches”

· IUPAC Names of Aldehydes and Ketones

18-3 -- Strength of the Carbonyl Bond (C=O)

18-4 -- Spectroscopy of Aldehydes and Ketones

· IR, 1H NMR, and 13C NMR

18-5 -- Nucleophilic Addition Reactions of the Carbonyl Group

· 7 Reactions to be Examined in Detail

· Why are Aldehydes More Reactive than Ketones?

· Effect of Alkyl Groups (Branches)

18-6 -- The Hydration Reaction

· Mechanism of Base-Catalyzed Hydration

· Mechanism of Acid-Catalyzed Hydration

18-8 -- Formation of Acetals (2 Alkoxy Groups, -OR, on a Carbon)

· Acid-Catalyzed Mechanism

· Use of Acetals as Protecting Groups

18-11 -- Cyanohydrin Formation (-CN and -OH on a Carbon)

· Can be Acid-Catalyzed or Base-Catalyzed

· Mechanism of Cyanohydrin Formation

18-11 -- Hydride Reactions

· Use of Lithium Aluminum Hydride, LiAlH4 (or “LAH”)

· Use of Sodium Borohydride, NaBH4

18-12 -- Grignard Additions to the Carbonyl

· Addition of R’-MgX to the Carbonyl (R2C=O)

18-12 -- Reactions of the Carbonyl (C=O) with Amines

· Yields Different Products Depending on the Type of Amine (1° or 2°)

· Mechanisms: Formations of Imines, Carbinolamines, and Enamines

· Tautomerization is Observed

18-14 -- Imine Derivatives

· Hydrazone, Semicarbazone, and Oxime

18-15 -- Reduction of Carbonyls to Methylene Groups (-CH2-)

· Wolff-Kishner Reaction Requires Basic Conditions

· Clemmenson Reduction (Zn/Hg in aqueous HCl)

· Reduction of Thioacetals

18-16 -- The Wittig Reaction

· Phosphonium Ylides (“The Wittig Reagent”)

· Mechanism of Ylide Preparation

· Why is the Reaction not Stereospecific?

18-18 -- Oxidation of Aldehydes

· Oxidation Using Chromium Reagents (PCC, H2CrO4, Jones Reagent, etc…)

· Oxidation Using the Tollens Reagent

18-19 -- Preparation of Aldehydes

· Via Ozonolysis of Alkenes

· Via Hydroboration of Terminal Alkynes (HCΞCR)

· Via Oxidation of Alcohols Using PCC

· Via the Use of Mild Reducting Agents (“:H-“)

18-20 -- Preparation of Ketones

· Via Ozonolysis of Alkenes

· Via Friedel-Crafts Acylation (AlCl3 as Catalyst)

· Via Alkyne Hydration

· Via Oxidation of Alcohols Using PCC or H2CrO4

· Via Addition of “:R-“ to Acid Chlorides

18-21 -- Conjugate Additions of Nucleophiles to α,β-Unsaturated Carbonyls

· “Michael Addition”

· Resonance-Stabilized Enolate Ion

· Protonation and Tautomerization

18-22 -- Some Nucleophiles Add Directly to the Carbonyl Carbon

· Less Basic Nucleophiles vs. Strongly Basic Nucleophiles

· Kinetic vs. Thermodynamic Control

· Resonance-Stabilization of the Negative (-1) Charge

SECTION 19 – CARBOXYLIC ACIDS

19-1 -- Nomenclature of Carboxylic Acids

· Common Names of Carboxylic Acids

· Diacids

· Systematic Names of Carboxylic Acids (IUPAC)

· Dioic Acids

19-3 -- Spectroscopy of Carboxylic Acids

· IR and 1H NMR

· D2O Exchange

19-3 -- Polarity of Carboxylic Acids

· Why are Smaller Carboxylic Acids Water-Soluble?

· Hydrogen Bonding

· Carboxylate Salts and Water Solubility

19-4 -- Acidity of Carboxylic Acids

· The Acid Dissociation Reaction

· Effect of Electronegative Substituents on Acidity

19-5 -- Preparation of Carboxylic Acids

· Via Oxidation of Aromatic Compounds Containing Benzylic Hydrogens

· Via Oxidation of Alcohols or Aldehydes

· Via Grignard Reagent (R-MgX) + CO2

· Via Nitrile (R-CΞN:) Hydrolysis

19-6 -- Reactions of Carboxylic Acids

· Reduction with Lithium Aluminum Hydride (LiAlH4)

· The Hunsdieker Reaction and its Detailed Mechanism (Involves Radicals)

SECTION 20 – CARBOXYLIC ACID DERIVATIVES and NUCLEOPHILIC ACYL SUBSTITUTION REACTIONS

20-1 -- General Classes and Nomenclature of Carboxylic Acid Derivatives

· Acid Halides (“Alkanoyl Halides”)

· Acid Anhydrides

· Esters: Straight-Chained Esters and Cyclic Esters (“Lactones”)

· Amides (“Alkanamides”; 1°, 2°, and 3°)

· Cyclic Amides (“Lactams”)

· Imides – 2 Fused Amides

· Nitriles, R-CΞN: (“Alkanenitriles”)

20-5 -- Priority Order of Principle Groups in Carboxylic Acid Derivatives

· Main Chain vs. Substituents (“Branches”)

· Some Common Substituents

20-5 -- Structures, Properties, & Spectrosopy of Carboxylic Acid Derivatives

· Esters Prefer to be Planar (Z-conformation vs. E-conformation)

· IR Spectroscopy of Esters

· IR Spectroscopy of Acid Anhydrides (asymmetric stretch & symmetric stretch)

· Amides Prefer to be Planar

· IR and 1H NMR for Amides

20-8 -- Reactions of Carboxylic Acid Derivatives (BIG TOPIC) – thru p.20-26

· The Mechanism of Acyl Substitution Reactions Under Basic Conditions

· The Mechanism of Acyl Substitution Reactions Under Acidic Conditions

· Tetrahedral Intermediates, Reaction Rates, and Relative Stabilities

· Relative Reactivities of Carboxylic Acid Derivatives

20-9 -- Hydrolysis Reactions (Addition of H2O)

· Acid Halides + H2O --> ?

· Acid Anhydrides + H2O --> ?

· Esters (and Lactones) + H2O --> ? (acid-catalyzed vs. base-catalyzed)

· Amides (and Lactams) + H2O --> ? (acid-catalyzed vs. base-catalyzed)

· Nitriles + H2O --> ?

20-12 -- Reactions with Nucleophiles Other than Water

· Acid Chlorides --> Esters (via use of Pyridine)

· Acid Chlorides --> Amides

· Acid Chlorides --> Anhydrides (involves use of a Carboxylate Salt)

· Mixed Anhydrides

· Dehydration of 2 Carboxylic Acids Produces an Anhydride

· Anhydrides --> Esters

· Cyclic Anhydrides --> One Half-Ester + One Half-Acid

· Transesterification: Converting One Ester to Another Ester

· Transesterification can be Acid-Catalyzed or Base-Catalyzed

· Esters--> Amides

· Acids --> Acid Chlorides

· Use of SOCl2 (Thionyl Chloride) and PCl3 or PBr3

· Acids --> Anhydrides (via use of P2O5)

· Acids --> Esters (via acid-catalyzed mechanism only)

20-19 -- Summary of Carbonyl Substitution Reactions

20-19 -- Reactions of –COOH Derivatives with Carbanionic Nucleophiles, “:R-“

· R-MgX (Grignard Reagent), R-Li (Alkyllithium Reagent), and R2CuLi Reagent

· Acid Chlorides + Carbanionic Nucleophiles --> ?

· Esters + Carbanionic Nucleophiles --> ?

· Carboxylic Acids + Carbanionic Nucleophiles --> ?

20-21 -- Reactions with Hydride Equivalents (“:H-“) as Nucleophiles

· “Reductions”

· LiAlH4 (Lithium Aluminum Hydride) and NaBH4 (Sodium Borohydride)

· Acid Chlorides --> Alcohols or Aldehydes

· Use of LiAlH(OtBu)3 – Bulkier Version of LiAlH4

· Anhydrides --> 2 Alcohols

· Esters --> Alcohols or Aldehydes

· Use of DIBAH (Diisobutylaluminum hydride)

· Acids --> Alcohols (via LiAlH4 or borane, BH3)

· Amides --> Amines (using LiAlH4)

20-26 – The Chemistry of Nitriles, R-CΞN:

· Preparation of Nitriles (via SN2, or P2O5, or SOCl2, or POCl3)

20-26 – Reactions of Nitriles

· Reduction with LiAlH4 or DIBAH

· Reduction with Grignard Reagent (R’-MgX)

SECTION 21 – CARBONYL ALPHA-SUBSTITUTION REACTIONS

21-1 -- The Enolization Reaction

· Keto-Enol Tautomerization

· Enols of β-Dicarbonyls

· Percent Enolization (%) of Various Compounds at Equilibrium

21-2 -- Acid-Catalyzed Enolization Reaction

21-2 -- Base-Catalyzed Enolization Reaction

· Resonance Stabilization

· Alpha-Hydrogens (α-Hydrogens) are Relatively Acidic

21-4 -- Relative Acidities of the α-Hydrogen

21-5 -- Five Reactions of Enols and Enolates: pp. 21-5 through 21-14

· D2O-Exchange

· Halogenation Reaction

· Haloform Reaction

· Alkylation Reaction

· Preparation of α-Alkylated Carbonyl Compounds

21-5 -- D2O-Exchange

· Usually Base-Catalyzed

21-5 -- Halogenation Reaction

· Under Acidic Conditions

· Under Basic Conditions

21-7 -- Haloform Reaction

· Occurs with Methyl Ketones (RCOCH3)

· Iodoform Test for Methyl Ketones

21-8 -- Alkylation Reactions – Occur via the Enolate Ion

· Strong Base Required to Deprotonate the Carbonyl Compound

· Strong Non-Nucleophilic Bases: NaH, iPr2N-, Lithium Diisopropyl Amide (LDA)

· Enolates Can Be Alkylated at Either the Carbon (C) or the Oxygen (O)

· Formation of Different Enolates – Kinetic Control vs. Thermodynamic Control

· Using Triethylamine, Et3N, and/or Trimethylsilyl Chloride, Me3SiCl, or “TMS-Cl”

21-12 -- Preparation of α-Alkylated Carbonyl Compounds

21-12 -- Preparation of α-Alkylated Esters and Carboxylic Acids

· Direct Preparation vs. Malonic Ester Synthesis

· Diethyl Malonate = “Malonic Ester”

· Saponification Step and Decarboxylation (-CO2) Step in the Mechanism

21-13 -- Preparation of α-Alkylated Ketones

· Direct Preparation vs. Acetoacetic Ester Synthesis

· Ethyl Acetoacetate = “Acetoacetic Ester”

21-15 -- Retrosynthetic Analysis

· Definition of Retrosynthetic Analysis and the Art of “Working Backwards”

21-16 -- The Selenation Reaction

· Useful in Making α,β-Unsaturated Carbonyl Compounds

· Phenylselenyl Bromide, PhSeBr

· The Oxidation Step [ox] Can Occur via H2O2 or O3

· Selenides and Selenoxides

SECTION 22 – CARBONYL CONDENSATION REACTIONS

22-1 -- Overview of Carbonyl Condensation Reactions

· Aldol Condensation Reaction

· Claisen Condensation Reaction

22-1 -- Aldol Condensation Reactions

22-1 -- Base-Catalyzed Aldol Condensation Reactions

· Reaction is Reversible

· Dehydration of the Alcohol Product Effects Equilibrium

22-3 -- Aldol Reactions Can Also Be Acid-Catalyzed

· Reaction is Reversible

· Dehydration of the Alcohol Product Effects Equilibrium

22-4 -- "Crossed” or “Mixed” Aldol Condensations

· Involve the Reaction of 2 Different Carbonyl Compounds

22-5 -- Intramolecular Aldol Condensation Reactions

· Favorable When 5- or 6-Membered Rings are Formed

22-5 -- Claisen Condensation Reactions

· Use of an Appropriate Alkoxide Ion

· Avoiding Transesterification

· Use of a Strong, Non-Nucleophilic Base

22-6 -- Intramolecular Claisen Condensations

· The Diechman Condensation

22-7 -- ”Crossed” or “Mixed” Claisen Condensations

· With 2 Different Esters as the Reactants

· With 1 Ketone and 1 Ester as the Reactants

22-8 -- More Diechman Condensations

22-9 -- Retrosynthetic Analysis Involving Aldol or Claisen Condensations

· The “To Do” List -- How to Approach Retrosynthetic Analysis Problems

· Identifying the Newly Formed C-C Bond

· Determining if an Aldol or Claisen Condensation Will Actually Work

22-12 -- The Michael Reaction

· Also Referred to as the “Michael Addition Reaction”

· α,β-Unsaturated Carbonyl Compounds

· Major vs. Minor Products

22-13 -- The Robinson Annulation Reaction

· A Special Type of Michael Reaction

· Building of a “New Ring” Onto the Molecule

22-14 -- The Stork Enamine Reaction

· Makes a 1,5-Dicarbonyl Product

· Mechanism Involves a 3-Step Process

· Enamines Also Do Michael Additions

· Use of Pyrrolidine in the Stork Enamine Reaction

22-15 -- Retrosynthetic Analysis with the Stork Enamine Reaction in Mind

SECTION 23 – AMINES

23-1 -- Primary (1°), Secondary (2°), and Tertiary (3°) Amines

23-1 -- Nomenclature of Amines

· Common Names – “Alkyl Amines”

· IUPAC Names – “Alkanamines”

· Naming Amines With –NH2 as a Substituent (Branch)

· Use of “N-“ as a Locator

· Ammonium and Iminium Ions

23-3 -- Structures of Amines

· Simple Amines are Pyramidal

· Complicated Amines (i.e. Aniline) Can “Flatten Out”

23-4 -- Spectroscopy of Amines

· IR Spectroscopy of Amines

· 1H NMR Spectroscopy of Amines

23-5 -- Basicity of Amines

· Amine Basicity Relative to H2O and OH-

· Alkylamines and Their Conjugate Acids (pKa ~ 10-11)

· Resonance Effects and Electron-Withdrawing Substituents

23-7 -- Acidity of Amines

· Alkyl Amines (pKa ~ 35-38) Have Very Strong Conj. Bases - Amide Ions, R2N-

23-8 -- Reactions of Amines – pp.23-8 through pp.23-19 – BIG TOPIC

23-8 -- Alkylation of Amines

· Direct Alkylation of Amines (SN2 with Amines as Nucleophiles)

· Exhaustive Alkylation of Amines

· Reductive Alkylation of Amines (Use of NaBH4 or H2/catalyst)

23-10 -- Gabriel Synthesis of 1° Amines

· Use of Pthalimide in an SN2 Reaction

· Gabriel Synthesis Adds –NH2 to the R-group of R-Br

23-12 -- Preparation of Amines via Reduction Reactions

· Reduction of Azides (R-N3)

· Reduction of Nitriles (R-CΞN:)

· Reduction of Amides Using Lithium Aluminum Hydride (LiAlH4, or “LAH”)

23-13 -- The Hofmann Elimination

· Step 1 - Overalkylation of the Amino Group

· Step 2 – “Switching” I- with OH-

· Step 3 - E2 Elimination (via Heat, Δ) to Form Less-Substituted Alkene

· “Hofmann Regiochemistry” is Observed

23-14 -- The Hofmann Rearrangement

· Involves Transformation of 1° Amide in Basic Solution to an Amine

23-15 -- The Curtius Rearrangement

· Converts an Acyl Azide to an Amine

· Mechanism Involves an Isocyanate Intermediate (O=C=N-R)

· Curtius Rearrangements Performed in H2O vs. in Alcohol (R’OH)

23-16 -- Diazonium Ion Chemistry

· [ R-NΞN <--> R-N=N ]+1 , an Alkyl Diazonium Ion (Add lone pairs on N’s!!)

· N2 is an Excellent Leaving Group (l.g.)

· Diazonium Ions are Very Unstable

· Aryl Diazonium Ions (Ar-NΞN:)+1 are More Stable

· Aryl Diazonium Ions in Electrophilic Aromatic Substitution (E.A.S) Reactions

· Azobenzenes and UV-VIS Spectroscopy

23-18 -- Rearrangement of Alkyl Azides

· Analogous to Curtius Rearrangement

· Rearrangement Occurs Thermally (via Heat), or Photochemically (via UV light)

Total Pages
189 pages
Answer Key
N/A
Teaching Duration
1 Semester
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