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Identifying Where Substitution and Elimination Reactions Happen
Last updated: May 22nd, 2023 |
Identifying Carbons Where Substitution and Elimination Reactions Can Take Place
- Substitution and elimination reactions need a leaving group in order for them to occur.
- Look for a good leaving group on the substrate undergoing the substitution or elimination reaction.
- If there is no good leaving group, then there won’t be a substitution or elimination reaction. It’s that simple.
- What makes a good leaving group? Review here (See Article: What Makes a Good Leaving Group), but the bottom line is look for halogens and other species that are weak bases.
- Hydroxyl groups (HO) are poor leaving groups unless acid is present.
- Furthermore, SN1/SN2 and E1/E2 generally only happen on sp3-hybridized carbons.
- sp2-hybridized carbons such as alkenyl, aryl and alkynyl halides will not undergo SN1/SN2/E1/E2
Table of Contents
- Look For A Good Leaving Group On The Substrate
- The Leaving Group Must Be On An sp3 Hybridized Carbon
- Identify The Type of Carbon As Primary, Secondary, or Tertiary
- Acid Makes Alcohols (and Ethers) Into Better Leaving Groups
- Multiple Functional Groups
- Quiz Yourself!
- (Advanced) References and Further Reading
This article presumes you are familiar with the SN1, SN2, E1, and E2 reactions. If you need a review on any of these reactions, please follow these links and then come back.
In nucleophilic substitution reactions, the substrate or electrophile (an electron-pair acceptor, e.g. an alkyl halide) undergoes attack by a nucleophile (the electron-pair donor). A new carbon-nucleophile bond forms, and a carbon-leaving group bond breaks off from the substrate.
In elimination reactions, a base breaks a C-H bond on the substrate, and a new C-C pi bond forms, with the breaking of a carbon-leaving group bond from the substrate.
Both of these reactions require the loss of a leaving group from the substrate (i.e. the molecule which is accepting a lone pair from the nucleophile, or is being deprotonated by a base).
If there’s no good leaving group on the substrate… then no substitution or elimination reaction can happen! It’s that simple.
Common examples of good leaving groups are species that can be weak bases once they accept a lone pair of electrons:
- Halogens (Cl, Br, I, but not F, as the C-F bond is very strong)
- Sulfonates [OTs or OMs]
- Acyloxy groups (O-C(O)R)
- Positively charged groups containing oxygen [OH2 (+), OH(R)(+)], nitrogen [NR3(+)], or even sulfur [SR2(+)]
(There is an excellent correlation between low pKa and leaving group ability of the conjugate base. For more on this, see article: What Makes A Good Leaving Group?)
Examples of poor leaving groups include strong bases such as hydroxide (HO–), alkoxides, amides (NH2–)hydride (H–) and carbanions (R–). The fluoride ion (F–) also tends to be a poor leaving group in substitution and elimination reactions since it forms extremely strong bonds to carbon. [Note 1] The cyano group (CN) is a weak base but does not tend to act as a leaving group in substitution or elimination reactions. [Note 2]
So the first order of business in determining the product of any of these reactions is to identify the site(s) on the substrate where there is a good leaving group.
In other words, look for groups that will be weak bases when they accept a lone pair of electrons.
Not all molecules are capable of substitution or elimination!
For example, hydrocarbons do not act as substrates in SN1/SN2 or elimination reactions because the leaving groups would have to be the extremely strong bases H(-) or alkyl anions (e.g. CH3(-) ).
Some hydrocarbons can act as nucleophiles in substitution and elimination reactions, but that’s different than being the substrate. (See post: Acetylides from Alkynes And Their Use In Substitution Reactions)
These exercises give you the challenge of identifying sites on a molecule where substitution or elimination can occur.
If you identify the leaving group, then you are identifying at least one of the bonds that will break. You are halfway there!
Here’s another set of examples.
As these quizzes should hopefully have driven home, you want to look for halogens, sulfonates, or other species that will be weak bases once they depart from the substrate.
Some groups that are poor leaving groups can be made into better leaving groups through the addition of acids. More on that below.
In substitution and elimination reactions, the transition state generally involves the formation of partial positive charge at the carbon bearing the leaving group.
Carbocations are most stable when they are formed through the loss of a leaving group on an sp3-hybridized carbon. Removing a leaving group from an sp2 or sp-hybridized carbon is very difficult, since the greater s-character means the electrons are held closer to the nucleus. [See article: Carbocation Stability] [Note 3]
So another key to identifying where a nucleophilic substitution or elimination reaction will occur is to examine the carbon attached to the good leaving group.
- If the leaving group is attached to an sp3 hybridized carbon, then this is a good candidate for the site of the reaction.
- If it is attached to an sp2 or sp hybridized carbon, then it is unlikely to undergo nucleophilic substitution or elimination.
In this exercise, identify the carbon atoms which are capable of undergoing substitution or elimination.
Here is another set of examples.
It’s important to know the few exceptions. [Note 4] Elimination to give alkynes occurs on sp2 hybridized carbon using the extremely strong base NaNH2. [See article: Alkynes via Elimination Reactions]. Another exception, more common in advanced courses, is a reaction related to the SN2 called the SN2-prime (SN2′) where formation of C-Nu and breakage of C-LG is accompanied by the shifting over of a C-C pi bond. [Note 5]
Once a plausible site for substitution or elimination has been found, the next step is to be able to classify that carbon as primary, secondary or tertiary.
Why is this important? Because it will greatly help in determining whether a reaction proceeds via SN1, SN2, E1 or E2 pathway.
I have more to say on this in the subsequent article (See article: SN1/SN2/E1/E2 – The Substrate)
Here is another quiz:
If you have made it this far, and have not covered alcohols or epoxides, then you are probably ready to proceed to the next article.
If you are covering the substitution and elimination reactions of alcohols and ethers, however, you’ll need to know another important twist.
Hydroxyl groups (OH) are poor leaving groups in substitution and elimination reactions. Unless strong acid is present, in which case they can be protonated to give their conjugate acids. (See article: The Conjugate Acid Is A Better Leaving Group)
How do you know if the alcohol or ether might be protonated? Look for strong acids such as HCl, HBr, HI, H2SO4 or TsOH.
The restriction that substitution and elimination reactions only happen on sp3 hybridized carbons still applies, however.
See if you can identify the carbons in each case which can undergo substitution or elimination reactions.
As a side note, positively-charged sulfur, nitrogen and even phosphorus can also be good leaving groups. The leaving group in these cases are neutral amines (NR3) sulfides (SR2) or phosphines (PR3).
There are times where you will be presented with cases where multiple good leaving groups are present, and your challenge will be to find the one site on the molecule where substitution or elimination is most likely to occur.
As we saw before, look for a good leaving group attached to an sp3 hybridized carbon.
You might see other groups like OH, NH2, or SH in addition to the good leaving group. Those are likely nucleophiles that will react with the substrate via an intramolecular substitution reaction. (See article: Intramolecular SN2 Reactions)
Epoxides are a special case of ethers that will undergo substitution reactions without the addition of acid. That is due to the considerable ring strain of the three-membered ring (See article: Epoxide Ring-Opening With Base).
In summary, the process for identifying where SN1/SN2/E1/E2 reactions happen looks like this.
- Identify good leaving groups (such as halides, but also OTs and OMs, among others)
- … that are attached to sp3 (alkyl) hybridized carbons.
- Additionally, alcohols and ethers can undergo SN1/SN2/E1/E2 if strong acid is present.
The next step is to identify the carbon bearing the leaving group as primary, secondary, or tertiary. That will help to narrow down whether the reaction will participate in an SN1, SN2, E1 or E2 reaction. More on that in the next post.
Next Post: Deciding SN1/SN2/E1/E2 – The Substrate
Note 2 – Despite being a weak base (the pKa of HCN is 9.2) the cyanide ion does not act as a good leaving group in SN2 reactions for reasons similar to that for fluoride ion; the C–CN bond is just too strong. (One estimate is that the reaction is unfavorable by about 15 kcal/mol, which makes displacement of CN(-) very unlikely)
In fact, methyl cyanide, more commonly known as acetonitrile, is a commonly used polar aprotic solvent for SN2 reactions.
Here’s one way to look at it.
Remember how s-orbitals are held closer to the nucleus, which is why acetylide ions are more stable than alkyl anions? You can think of alkenyl and alkynl carbons as having a great effective electronegativity than alkyl carbons, which makes them “hold on” to electrons more tightly and making it more difficult for an electron pair to leave.
So in other words, alkenyl and alkynyl carbons form stronger bonds.
Another, related explanation has to do with the relative abilities of carbon to stabilize positive charge as the amount of s-character increases.
The E1 and SN1 reactions go through carbocations, whereas the SN2 reaction requires a partially-positive charged carbon in the transition state.
So each of these reactions involves a transition state where the central carbon bears a partial positive charge.
If you recall that the ability to stabilize a lone pair of electrons increases as s-character increases (sp3 < sp2 < sp ) then think of the trend in the opposite direction; the ability of a carbon to stabilize a positive charge decreases as s-character increases, as the empty orbital is held closer to the positively charged nucleus.
For more on the stability of carbocations, see this post on Carbocation Stability.
Note 4 -One exception to the “no SN1/SN2/E1/E2 on sp2 hybridized carbons” is formation of alkynes from alkenyl halides via use of the extremely strong base NaNH2. See article – Synthesis of Alkynes via Elimination of Alkenyl Halides
Note 5. Another exception to the “no SN1/SN2/E1/E2 on sp2 hybridized carbons” is found in a reaction known as the SN2-prime (SN2′) reaction. It’s similar to the SN2 in that it is concerted and bimolecular, but slightly different in that the attack does not occur directly on the sp2-hybridized alkyl halide.
It’s not a reaction that comes up too much in introductory organic, but a good exam question.
In Streitweiser’s Solvolytic Displacement Reactions, page 31, :
[According to calculations] the reaction of methyl bromide with hydroxide ion is exothermic by 16 kcal/mol. The equivalent increase in the activation energy of the reverse reaction corresponds to a factor of 10-12 in rate; i.e. the rate is far too slow to be observed. Since the reactions of alkyl halides with ethoxide, phenoxide, acetate, hydrosulfide, cyanide, thiosulfate and sulfite ions are all exothermic by 10-20 kcal, the reverse reactions will be slower by factors of 10-7 to 10-14 and will, therefore, not be observed except under the most exceptional conditions.”
- Mechanism of ionic reactions. The heat of ionic substitution reactions
R. A. Ogg
Trans. Faraday Soc., 1935,31, 1385-1392
Measurement of the heats of reaction for some simple nucleophilic substitution reactions of alkyl halides with various nucleophiles.
00 General Chemistry Review
01 Bonding, Structure, and Resonance
- How Do We Know Methane (CH4) Is Tetrahedral?
- Hybrid Orbitals and Hybridization
- How To Determine Hybridization: A Shortcut
- Orbital Hybridization And Bond Strengths
- Sigma bonds come in six varieties: Pi bonds come in one
- A Key Skill: How to Calculate Formal Charge
- Partial Charges Give Clues About Electron Flow
- The Four Intermolecular Forces and How They Affect Boiling Points
- 3 Trends That Affect Boiling Points
- How To Use Electronegativity To Determine Electron Density (and why NOT to trust formal charge)
- Introduction to Resonance
- How To Use Curved Arrows To Interchange Resonance Forms
- Evaluating Resonance Forms (1) - The Rule of Least Charges
- How To Find The Best Resonance Structure By Applying Electronegativity
- Evaluating Resonance Structures With Negative Charges
- Evaluating Resonance Structures With Positive Charge
- Exploring Resonance: Pi-Donation
- Exploring Resonance: Pi-acceptors
- In Summary: Evaluating Resonance Structures
- Drawing Resonance Structures: 3 Common Mistakes To Avoid
- How to apply electronegativity and resonance to understand reactivity
- Bond Hybridization Practice
- Structure and Bonding Practice Quizzes
- Resonance Structures Practice
02 Acid Base Reactions
- Introduction to Acid-Base Reactions
- Acid Base Reactions In Organic Chemistry
- The Stronger The Acid, The Weaker The Conjugate Base
- Walkthrough of Acid-Base Reactions (3) - Acidity Trends
- Five Key Factors That Influence Acidity
- Acid-Base Reactions: Introducing Ka and pKa
- How to Use a pKa Table
- The pKa Table Is Your Friend
- A Handy Rule of Thumb for Acid-Base Reactions
- Acid Base Reactions Are Fast
- pKa Values Span 60 Orders Of Magnitude
- How Protonation and Deprotonation Affect Reactivity
- Acid Base Practice Problems
03 Alkanes and Nomenclature
- Meet the (Most Important) Functional Groups
- Condensed Formulas: Deciphering What the Brackets Mean
- Hidden Hydrogens, Hidden Lone Pairs, Hidden Counterions
- Don't Be Futyl, Learn The Butyls
- Primary, Secondary, Tertiary, Quaternary In Organic Chemistry
- Branching, and Its Affect On Melting and Boiling Points
- The Many, Many Ways of Drawing Butane
- Wedge And Dash Convention For Tetrahedral Carbon
- Common Mistakes in Organic Chemistry: Pentavalent Carbon
- Table of Functional Group Priorities for Nomenclature
- Summary Sheet - Alkane Nomenclature
- Organic Chemistry IUPAC Nomenclature Demystified With A Simple Puzzle Piece Approach
- Boiling Point Quizzes
- Organic Chemistry Nomenclature Quizzes
04 Conformations and Cycloalkanes
- Staggered vs Eclipsed Conformations of Ethane
- Conformational Isomers of Propane
- Newman Projection of Butane (and Gauche Conformation)
- Introduction to Cycloalkanes (1)
- Geometric Isomers In Small Rings: Cis And Trans Cycloalkanes
- Calculation of Ring Strain In Cycloalkanes
- Cycloalkanes - Ring Strain In Cyclopropane And Cyclobutane
- Cyclohexane Conformations
- Cyclohexane Chair Conformation: An Aerial Tour
- How To Draw The Cyclohexane Chair Conformation
- The Cyclohexane Chair Flip
- The Cyclohexane Chair Flip - Energy Diagram
- Substituted Cyclohexanes - Axial vs Equatorial
- Ranking The Bulkiness Of Substituents On Cyclohexanes: "A-Values"
- The Ups and Downs of Cyclohexanes
- Cyclohexane Chair Conformation Stability: Which One Is Lower Energy?
- Fused Rings - Cis-Decalin and Trans-Decalin
- Naming Bicyclic Compounds - Fused, Bridged, and Spiro
- Bredt's Rule (And Summary of Cycloalkanes)
- Newman Projection Practice
- Cycloalkanes Practice Problems
05 A Primer On Organic Reactions
- The Most Important Question To Ask When Learning a New Reaction
- The 4 Major Classes of Reactions in Org 1
- Learning New Reactions: How Do The Electrons Move?
- How (and why) electrons flow
- The Third Most Important Question to Ask When Learning A New Reaction
- 7 Factors that stabilize negative charge in organic chemistry
- 7 Factors That Stabilize Positive Charge in Organic Chemistry
- Common Mistakes: Formal Charges Can Mislead
- Nucleophiles and Electrophiles
- Curved Arrows (for reactions)
- Curved Arrows (2): Initial Tails and Final Heads
- Nucleophilicity vs. Basicity
- The Three Classes of Nucleophiles
- What Makes A Good Nucleophile?
- What makes a good leaving group?
- 3 Factors That Stabilize Carbocations
- Equilibrium and Energy Relationships
- What's a Transition State?
- Hammond's Postulate
- Grossman's Rule
- Draw The Ugly Version First
- Learning Organic Chemistry Reactions: A Checklist (PDF)
- Introduction to Addition Reactions
- Introduction to Elimination Reactions
- Introduction to Free Radical Substitution Reactions
- Introduction to Oxidative Cleavage Reactions
06 Free Radical Reactions
- Bond Dissociation Energies = Homolytic Cleavage
- Free Radical Reactions
- 3 Factors That Stabilize Free Radicals
- What Factors Destabilize Free Radicals?
- Bond Strengths And Radical Stability
- Free Radical Initiation: Why Is "Light" Or "Heat" Required?
- Initiation, Propagation, Termination
- Monochlorination Products Of Propane, Pentane, And Other Alkanes
- Selectivity In Free Radical Reactions
- Selectivity in Free Radical Reactions: Bromination vs. Chlorination
- Halogenation At Tiffany's
- Allylic Bromination
- Bonus Topic: Allylic Rearrangements
- In Summary: Free Radicals
- Synthesis (2) - Reactions of Alkanes
- Free Radicals Practice Quizzes
07 Stereochemistry and Chirality
- Types of Isomers: Constitutional Isomers, Stereoisomers, Enantiomers, and Diastereomers
- How To Draw The Enantiomer Of A Chiral Molecule
- Introduction to Assigning (R) and (S): The Cahn-Ingold-Prelog Rules
- Assigning Cahn-Ingold-Prelog (CIP) Priorities (2) - The Method of Dots
- Enantiomers vs Diastereomers vs The Same? Two Methods For Solving Problems
- Assigning R/S To Newman Projections (And Converting Newman To Line Diagrams)
- How To Determine R and S Configurations On A Fischer Projection
- The Meso Trap
- Optical Rotation, Optical Activity, and Specific Rotation
- Optical Purity and Enantiomeric Excess
- What's a Racemic Mixture?
- Chiral Allenes And Chiral Axes
- On Cats, Part 4: Enantiocats
- On Cats, Part 6: Stereocenters
- Stereochemistry Practice Problems and Quizzes
08 Substitution Reactions
- Introduction to Nucleophilic Substitution Reactions
- Walkthrough of Substitution Reactions (1) - Introduction
- Two Types of Nucleophilic Substitution Reactions
- The SN2 Mechanism
- Why the SN2 Reaction Is Powerful
- The SN1 Mechanism
- The Conjugate Acid Is A Better Leaving Group
- Comparing the SN1 and SN2 Reactions
- Polar Protic? Polar Aprotic? Nonpolar? All About Solvents
- Steric Hindrance is Like a Fat Goalie
- Common Blind Spot: Intramolecular Reactions
- The Conjugate Base is Always a Stronger Nucleophile
- Substitution Practice - SN1
- Substitution Practice - SN2
09 Elimination Reactions
- Elimination Reactions (1): Introduction And The Key Pattern
- Elimination Reactions (2): The Zaitsev Rule
- Elimination Reactions Are Favored By Heat
- Two Elimination Reaction Patterns
- The E1 Reaction
- The E2 Mechanism
- E1 vs E2: Comparing the E1 and E2 Reactions
- Antiperiplanar Relationships: The E2 Reaction and Cyclohexane Rings
- Bulky Bases in Elimination Reactions
- Comparing the E1 vs SN1 Reactions
- Elimination (E1) Reactions With Rearrangements
- E1cB - Elimination (Unimolecular) Conjugate Base
- Elimination (E1) Practice Problems And Solutions
- Elimination (E2) Practice Problems and Solutions
11 SN1/SN2/E1/E2 Decision
- Identifying Where Substitution and Elimination Reactions Happen
- Deciding SN1/SN2/E1/E2 (1) - The Substrate
- Deciding SN1/SN2/E1/E2 (2) - The Nucleophile/Base
- Deciding SN1/SN2/E1/E2 (3) - The Solvent
- Deciding SN1/SN2/E1/E2 (4) - The Temperature
- Wrapup: The Quick N' Dirty Guide To SN1/SN2/E1/E2
- Alkyl Halide Reaction Map And Summary
- SN1 SN2 E1 E2 Practice Problems
12 Alkene Reactions
- E and Z Notation For Alkenes (+ Cis/Trans)
- Alkene Stability
- Addition Reactions: Elimination's Opposite
- Selective vs. Specific
- Regioselectivity In Alkene Addition Reactions
- Stereoselectivity In Alkene Addition Reactions: Syn vs Anti Addition
- Hydrohalogenation of Alkenes and Markovnikov's Rule
- Hydration of Alkenes With Aqueous Acid
- Rearrangements in Alkene Addition Reactions
- Addition Pattern #1: The "Carbocation Pathway"
- Halogenation of Alkenes and Halohydrin Formation
- Oxymercuration Demercuration of Alkenes
- Alkene Addition Pattern #2: The "Three-Membered Ring" Pathway
- Hydroboration Oxidation of Alkenes
- m-CPBA (meta-chloroperoxybenzoic acid)
- OsO4 (Osmium Tetroxide) for Dihydroxylation of Alkenes
- Palladium on Carbon (Pd/C) for Catalytic Hydrogenation
- Alkene Addition Pattern #3: The "Concerted" Pathway
- A Fourth Alkene Addition Pattern - Free Radical Addition
- Alkene Reactions: Ozonolysis
- Summary: Three Key Families Of Alkene Reaction Mechanisms
- Synthesis (4) - Alkene Reaction Map, Including Alkyl Halide Reactions
- Alkene Reactions Practice Problems
13 Alkyne Reactions
- Acetylides from Alkynes, And Substitution Reactions of Acetylides
- Partial Reduction of Alkynes With Lindlar's Catalyst or Na/NH3 To Obtain Cis or Trans Alkenes
- Hydroboration and Oxymercuration of Alkynes
- Alkyne Reaction Patterns - Hydrohalogenation - Carbocation Pathway
- Alkyne Halogenation: Bromination, Chlorination, and Iodination of Alkynes
- Alkyne Reactions - The "Concerted" Pathway
- Alkenes To Alkynes Via Halogenation And Elimination Reactions
- Alkynes Are A Blank Canvas
- Synthesis (5) - Reactions of Alkynes
- Alkyne Reactions Practice Problems With Answers
14 Alcohols, Epoxides and Ethers
- Alcohols - Nomenclature and Properties
- Alcohols Can Act As Acids Or Bases (And Why It Matters)
- Alcohols - Acidity and Basicity
- The Williamson Ether Synthesis
- Ethers From Alkenes, Tertiary Alkyl Halides and Alkoxymercuration
- Alcohols To Ethers via Acid Catalysis
- Cleavage Of Ethers With Acid
- Epoxides - The Outlier Of The Ether Family
- Opening of Epoxides With Acid
- Epoxide Ring Opening With Base
- Making Alkyl Halides From Alcohols
- Tosylates And Mesylates
- PBr3 and SOCl2
- Elimination Reactions of Alcohols
- Elimination of Alcohols To Alkenes With POCl3
- Alcohol Oxidation: "Strong" and "Weak" Oxidants
- Demystifying The Mechanisms of Alcohol Oxidations
- Protecting Groups For Alcohols
- Thiols And Thioethers
- Calculating the oxidation state of a carbon
- Oxidation and Reduction in Organic Chemistry
- Oxidation Ladders
- SOCl2 Mechanism For Alcohols To Alkyl Halides: SN2 versus SNi
- Alcohol Reactions Roadmap (PDF)
- Alcohol Reaction Practice Problems
- Epoxide Reaction Quizzes
- Oxidation and Reduction Practice Quizzes
- What's An Organometallic?
- Formation of Grignard and Organolithium Reagents
- Organometallics Are Strong Bases
- Reactions of Grignard Reagents
- Protecting Groups In Grignard Reactions
- Synthesis Problems Involving Grignard Reagents
- Grignard Reactions And Synthesis (2)
- Organocuprates (Gilman Reagents): How They're Made
- Gilman Reagents (Organocuprates): What They're Used For
- The Heck, Suzuki, and Olefin Metathesis Reactions (And Why They Don't Belong In Most Introductory Organic Chemistry Courses)
- Reaction Map: Reactions of Organometallics
- Grignard Practice Problems
- Degrees of Unsaturation (or IHD, Index of Hydrogen Deficiency)
- Conjugation And Color (+ How Bleach Works)
- Introduction To UV-Vis Spectroscopy
- UV-Vis Spectroscopy: Absorbance of Carbonyls
- UV-Vis Spectroscopy: Practice Questions
- Bond Vibrations, Infrared Spectroscopy, and the "Ball and Spring" Model
- Infrared Spectroscopy: A Quick Primer On Interpreting Spectra
- IR Spectroscopy: 4 Practice Problems
- 1H NMR: How Many Signals?
- Homotopic, Enantiotopic, Diastereotopic
- Diastereotopic Protons in 1H NMR Spectroscopy: Examples
- C13 NMR - How Many Signals
- Liquid Gold: Pheromones In Doe Urine
- Natural Product Isolation (1) - Extraction
- Natural Product Isolation (2) - Purification Techniques, An Overview
- Structure Determination Case Study: Deer Tarsal Gland Pheromone
17 Dienes and MO Theory
- What To Expect In Organic Chemistry 2
- Are these molecules conjugated?
- Conjugation And Resonance In Organic Chemistry
- Bonding And Antibonding Pi Orbitals
- Molecular Orbitals of The Allyl Cation, Allyl Radical, and Allyl Anion
- Pi Molecular Orbitals of Butadiene
- Reactions of Dienes: 1,2 and 1,4 Addition
- Thermodynamic and Kinetic Products
- More On 1,2 and 1,4 Additions To Dienes
- s-cis and s-trans
- The Diels-Alder Reaction
- Cyclic Dienes and Dienophiles in the Diels-Alder Reaction
- Stereochemistry of the Diels-Alder Reaction
- Exo vs Endo Products In The Diels Alder: How To Tell Them Apart
- HOMO and LUMO In the Diels Alder Reaction
- Why Are Endo vs Exo Products Favored in the Diels-Alder Reaction?
- Diels-Alder Reaction: Kinetic and Thermodynamic Control
- The Retro Diels-Alder Reaction
- The Intramolecular Diels Alder Reaction
- Regiochemistry In The Diels-Alder Reaction
- The Cope and Claisen Rearrangements
- Electrocyclic Reactions
- Electrocyclic Ring Opening And Closure (2) - Six (or Eight) Pi Electrons
- Diels Alder Practice Problems
- Molecular Orbital Theory Practice
- Introduction To Aromaticity
- Rules For Aromaticity
- Huckel's Rule: What Does 4n+2 Mean?
- Aromatic, Non-Aromatic, or Antiaromatic? Some Practice Problems
- Antiaromatic Compounds and Antiaromaticity
- The Pi Molecular Orbitals of Benzene
- The Pi Molecular Orbitals of Cyclobutadiene
- Frost Circles
- Aromaticity Practice Quizzes
19 Reactions of Aromatic Molecules
- Electrophilic Aromatic Substitution: Introduction
- Activating and Deactivating Groups In Electrophilic Aromatic Substitution
- Electrophilic Aromatic Substitution - The Mechanism
- Ortho-, Para- and Meta- Directors in Electrophilic Aromatic Substitution
- Understanding Ortho, Para, and Meta Directors
- Why are halogens ortho- para- directors?
- Disubstituted Benzenes: The Strongest Electron-Donor "Wins"
- Electrophilic Aromatic Substitutions (1) - Halogenation of Benzene
- Electrophilic Aromatic Substitutions (2) - Nitration and Sulfonation
- EAS Reactions (3) - Friedel-Crafts Acylation and Friedel-Crafts Alkylation
- Intramolecular Friedel-Crafts Reactions
- Nucleophilic Aromatic Substitution (NAS)
- Nucleophilic Aromatic Substitution (2) - The Benzyne Mechanism
- Reactions on the "Benzylic" Carbon: Bromination And Oxidation
- The Wolff-Kishner, Clemmensen, And Other Carbonyl Reductions
- More Reactions on the Aromatic Sidechain: Reduction of Nitro Groups and the Baeyer Villiger
- Aromatic Synthesis (1) - "Order Of Operations"
- Synthesis of Benzene Derivatives (2) - Polarity Reversal
- Aromatic Synthesis (3) - Sulfonyl Blocking Groups
- Birch Reduction
- Synthesis (7): Reaction Map of Benzene and Related Aromatic Compounds
- Aromatic Reactions and Synthesis Practice
- Electrophilic Aromatic Substitution Practice Problems
20 Aldehydes and Ketones
- What's The Alpha Carbon In Carbonyl Compounds?
- Nucleophilic Addition To Carbonyls
- Aldehydes and Ketones: 14 Reactions With The Same Mechanism
- Sodium Borohydride (NaBH4) Reduction of Aldehydes and Ketones
- Grignard Reagents For Addition To Aldehydes and Ketones
- Wittig Reaction
- Hydrates, Hemiacetals, and Acetals
- Imines - Properties, Formation, Reactions, and Mechanisms
- All About Enamines
- Breaking Down Carbonyl Reaction Mechanisms: Reactions of Anionic Nucleophiles (Part 2)
- Aldehydes Ketones Reaction Practice
21 Carboxylic Acid Derivatives
- Nucleophilic Acyl Substitution (With Negatively Charged Nucleophiles)
- Addition-Elimination Mechanisms With Neutral Nucleophiles (Including Acid Catalysis)
- Basic Hydrolysis of Esters - Saponification
- Proton Transfer
- Fischer Esterification - Carboxylic Acid to Ester Under Acidic Conditions
- Lithium Aluminum Hydride (LiAlH4) For Reduction of Carboxylic Acid Derivatives
- LiAlH[Ot-Bu]3 For The Reduction of Acid Halides To Aldehydes
- Di-isobutyl Aluminum Hydride (DIBAL) For The Partial Reduction of Esters and Nitriles
- Amide Hydrolysis
- Thionyl Chloride (SOCl2)
- Diazomethane (CH2N2)
- Carbonyl Chemistry: Learn Six Mechanisms For the Price Of One
- Making Music With Mechanisms (PADPED)
- Carboxylic Acid Derivatives Practice Questions
22 Enols and Enolates
- Keto-Enol Tautomerism
- Enolates - Formation, Stability, and Simple Reactions
- Kinetic Versus Thermodynamic Enolates
- Aldol Addition and Condensation Reactions
- Reactions of Enols - Acid-Catalyzed Aldol, Halogenation, and Mannich Reactions
- Claisen Condensation and Dieckmann Condensation
- The Malonic Ester and Acetoacetic Ester Synthesis
- The Michael Addition Reaction and Conjugate Addition
- The Robinson Annulation
- Haloform Reaction
- The Hell–Volhard–Zelinsky Reaction
- Enols and Enolates Practice Quizzes
- The Amide Functional Group: Properties, Synthesis, and Nomenclature
- Basicity of Amines And pKaH
- 5 Key Basicity Trends of Amines
- The Mesomeric Effect And Aromatic Amines
- Nucleophilicity of Amines
- Alkylation of Amines (Sucks!)
- Reductive Amination
- The Gabriel Synthesis
- Some Reactions of Azides
- The Hofmann Elimination
- The Hofmann and Curtius Rearrangements
- The Cope Elimination
- Protecting Groups for Amines - Carbamates
- The Strecker Synthesis of Amino Acids
- Introduction to Peptide Synthesis
- Reactions of Diazonium Salts: Sandmeyer and Related Reactions
- Amine Practice Questions
- D and L Notation For Sugars
- Pyranoses and Furanoses: Ring-Chain Tautomerism In Sugars
- What is Mutarotation?
- Reducing Sugars
- The Big Damn Post Of Carbohydrate-Related Chemistry Definitions
- The Haworth Projection
- Converting a Fischer Projection To A Haworth (And Vice Versa)
- Reactions of Sugars: Glycosylation and Protection
- The Ruff Degradation and Kiliani-Fischer Synthesis
- Isoelectric Points of Amino Acids (and How To Calculate Them)
- Carbohydrates Practice
- Amino Acid Quizzes
25 Fun and Miscellaneous
- Organic Chemistry GIFS - Resonance Forms
- Organic Chemistry and the New MCAT
- A Gallery of Some Interesting Molecules From Nature
- The Organic Chemistry Behind "The Pill"
- Maybe they should call them, "Formal Wins" ?
- Intramolecular Reactions of Alcohols and Ethers
- Planning Organic Synthesis With "Reaction Maps"
- Organic Chemistry Is Shit
- The 8 Types of Arrows In Organic Chemistry, Explained
- The Most Annoying Exceptions in Org 1 (Part 1)
- The Most Annoying Exceptions in Org 1 (Part 2)
- Reproducibility In Organic Chemistry
- Screw Organic Chemistry, I'm Just Going To Write About Cats
- On Cats, Part 1: Conformations and Configurations
- On Cats, Part 2: Cat Line Diagrams
- The Marriage May Be Bad, But the Divorce Still Costs Money
- Why Do Organic Chemists Use Kilocalories?
- What Holds The Nucleus Together?
- 9 Nomenclature Conventions To Know
- How Reactions Are Like Music