Organic Chemistry Study Tips
By James Ashenhurst
Trapped in SN1/SN2/E1/E2 Hell? Start Here
Last updated: October 25th, 2016
It’s that time of year when everyone starts making jokes about the backside attack. Here’s a few resources to check out:
- An SN1/SN2/E1/E2 summary sheet from FreelanceTeach: PDF
- Practice problems (and solutions) from Prof. Bill Reusch: link (go to right hand side under “Functional Group Reactions”, start at #16)
- SUNY Stony Brook Random Exam Generator – go to Chem 321 Exam #2 (this focuses on SN1/Sn2/E1/E2 as well as on some conformational analysis).
- Video series on SN1/SN2/E1/E2 from FreelanceTeach on Youtube
- In a hurry? My Org 1 Summary Sheets package includes both a flowchart of the SN1/SN2/E1/E2 and also a summary sheet that covers all the most important concepts in each of these reactions. Plus you get 18 other awesome summary sheets. It’s like having an instant set of study notes for your course!
Good luck!
Related Posts:
00 General Chemistry Review
- Gen Chem and Organic Chem: How are they different?
- How Gen Chem Relates to Organic Chem, Pt. 1 - The Atom
- From Gen Chem to Organic Chem, Pt. 2 - Electrons and Orbitals
- From Gen Chem to Organic Chem, Pt. 3 - Effective Nuclear Charge
- From Gen Chem to Organic Chem, Pt. 4 - Chemical Bonding
- From Gen Chem to Organic Chem, Pt. 5 - Understanding Periodic Trends
- From Gen Chem to Org Chem, Pt. 6 - Lewis Structures, A Parable
- From Gen Chem to Org Chem, Pt. 7 - Lewis Structures
- From Gen Chem to Org Chem, Pt. 8 - Ionic and Covalent Bonding
- From Gen Chem to Org Chem, Pt. 9 - Acids and Bases
- From Gen Chem to Organic Chem, Pt. 10 - Hess' Law
- From Gen Chem to Organic Chem, Pt. 11 - The Second Law
- From Gen Chem to Org Chem Pt. 12 - Kinetics
- From Gen Chem to Organic Chem, Pt. 13 - Equilibria
- From Gen Chem to Organic Chem, Part 14: Wrapup
01 Bonding, Structure, and Resonance
- How Concepts Build Up In Org 1 ("The Pyramid")
- Review of Atomic Orbitals for Organic Chemistry
- How Do We Know Methane Is Tetrahedral?
- Hybrid Orbitals
- A Hybridization Shortcut
- 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
- Evaluating Resonance Forms (2): Applying Electronegativity
- Evaluating Resonance Forms: Factors That Stabilize Negative Charges
- Evaluating Resonance Forms (4): Positive Charges
- Exploring Resonance: Pi-Donation
- Exploring Resonance: Pi-acceptors
- In Summary: Resonance
- Drawing Resonance Structures: 3 Common Mistakes To Avoid
- How to apply electronegativity and resonance to understand reactivity
02 Acid Base Reactions
- Introduction to Acid-Base Reactions
- Walkthrough of Acid Base Reactions (1)
- Walkthrough of Acid Base Reactions (2): Basicity
- Walkthrough of Acid-Base Reactions (3) - Acidity Trends
- Five Key Factors That Influence Acidity
- Walkthrough of Acid-Base reactions (4) - 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
- Putting Acidity In Perspective
- Acid Base Reactions: What's the Point?
03 Alkanes and Nomenclature
- Summary Sheet - Alkane 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
- Common Mistakes: Drawing Tetrahedral Carbons
- Common Mistakes in Organic Chemistry: Pentavalent Carbon
- Table of Functional Group Priorities for Nomenclature
- Organic Chemistry IUPAC Nomenclature Demystified With A Simple Puzzle Piece Approach
04 Conformations and Cycloalkanes
- Conformations
- Newman Projections
- Putting the Newman into ACTION
- Introduction to Cycloalkanes (1)
- Cis And Trans Cycloalkanes
- Cycloalkanes - How To Calculate Ring Strain
- Cycloalkanes - Ring Strain In Cyclopropane And Cyclobutane
- Ring Strain in Cyclopentane and Cyclohexane
- An Aerial Tour Of The Cyclohexane Chair
- How To Draw A Cyclohexane Chair
- The Cyclohexane Chair Flip
- The Cyclohexane Chair Flip - Energy Diagram
- Substituted Cyclohexanes - Equatorial vs Axial
- Substituted Cyclohexanes: "A Values"
- The Ups and Downs of Cyclohexanes
- Which Cyclohexane Chair Is Of Lower Energy?
- Fused Rings
- Bridged Bicyclic Rings (And How To Name Them)
- Bredt's Rule (And Summary of Cycloalkanes)
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?
- Leaving Groups Are Nucleophiles Acting In Reverse
- What makes a good leaving group?
- 3 Factors That Stabilize Carbocations
- Three Factors that Destabilize Carbocations
- What's a Transition State?
- Hammond's Postulate
- Grossman's Rule
- Draw The Ugly Version First
- Learning 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
- Isomers From Free Radical Reactions
- Selectivity In Free Radical Reactions
- Selectivity in Free Radical Reactions: Bromine vs. Chlorine
- Halogenation At Tiffany's
- Allylic Bromination
- Bonus Topic: Allylic Rearrangements
- In Summary: Free Radicals
- Synthesis (2) - Reactions of Alkanes
07 Stereochemistry and Chirality
- On Cats, Part 4: Enantiocats
- On Cats, Part 6: Stereocenters
- The Single Swap Rule
- Introduction to Assigning (R) and (S): The Cahn-Ingold-Prelog Rules
- Determining R/S (2) - The Method of Dots
- Types of Isomers: Constitutional Isomers, Stereoisomers, Enantiomers, and Diastereomers
- Enantiomers vs Diastereomers vs The Same? Two Methods For Solving Problems
- Assigning R/S To Newman Projections (And Converting Newman To Line Diagrams)
- 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
08 Substitution Reactions
- Introduction to Nucleophilic Substitution Reactions
- Walkthrough of Substitution Reactions (1) - Introduction
- Two Types of 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
09 Elimination Reactions
- Walkthrough of Elimination Reactions (1)
- Elimination Reactions (2): Zaitsev's Rule
- Elimination Reactions Are Favored By Heat
- Two Types of Elimination Reactions
- The E1 Reaction
- The E2 Mechanism
- Comparing the E1 and E2 Reactions
- The E2 Reaction and Cyclohexane Rings
- Bulky Bases in Elimination Reactions
- Comparing the E1 and SN1 Reactions
- Elimination (E1) Reactions With Rearrangements
10 Rearrangements
11 SN1/SN2/E1/E2 Decision
12 Alkene Reactions
- Alkene Nomenclature: Cis and Trans and E and Z
- Addition Reactions: Elimination's Opposite
- Selective vs. Specific
- Addition Reactions: Regioselectivity
- Addition Reactions: Stereochemistry
- Markovnikov's Rule (1)
- Markovnikov's Rule (2) - Why It Works
- Curved Arrows and Addition Reactions
- Addition Pattern #1: The "Carbocation Pathway"
- Rearrangements in Alkene Addition Reactions
- Bromination of Alkenes - How Does It Work?
- Bromination of Alkenes: The Mechanism
- Alkene Addition Pattern #2: The "Three-Membered Ring" Pathway
- Hydroboration of Alkenes
- Hydroboration of Alkenes: The Mechanism
- Alkene Addition Pattern #3: The "Concerted" Pathway
- An Arrow-Pushing Dilemma In Concerted Reactions
- A Fourth Alkene Addition Pattern - Free Radical Addition
- Alkene Reactions: Ozonolysis
- Summary: Alkene Reaction Pathways
- Synthesis (4) - Reactions of Alkenes
13 Alkyne Reactions
- The 2 Most Important Reactions of Alkynes
- Partial Reduction of Alkynes To Obtain Cis or Trans Alkenes
- Hydroboration and Oxymercuration of Alkynes
- Alkyne Reaction Patterns - The Carbocation Pathway
- Alkyne Addition Reactions: The 3-Membered Ring Pathway
- Alkyne Addition Reactions - The "Concerted" Pathway
- Alkynes Via Elimination Reactions
- Alkynes Are A Blank Canvas
- Synthesis (5) - Reactions of Alkynes
14 Alcohols, Epoxides and Ethers
- Alcohols (1) - Nomenclature and Properties
- How To Make Alcohols More Reactive
- Alcohols (3) - Acidity and Basicity
- The Williamson Ether Synthesis
- Williamson Ether Synthesis: Planning
- Synthesis of Ethers (2) - Back To The Future
- Ether Synthesis Via Alcohols And Acid
- Cleavage Of Ethers With Acid
- Epoxides - The Outlier Of The Ether Family
- Opening Of Epoxide With Base
- Opening of Epoxides With Acid
- 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 Alcohol Oxidations
- Intramolecular Reactions of Alcohols and Ethers
- Protecting Groups For Alcohols
- Thiols And Thioethers
- Calculating the oxidation state of a carbon
- Oxidation and Reduction in Organic Chemistry
- Oxidation Ladders
- SOCl2 and the SNi Mechanism
- Synthesis (6) - Reactions of Alcohols
15 Organometallics
- What's An Organometallic?
- Synthesis of Grignard and Organolithium Reagents
- Organometallics Are Strong Bases
- Reactions of Grignard Reagents
- Protecting Groups In Grignard Reactions
- Synthesis Using Grignard Reagents (1)
- Grignard Reactions And Synthesis (2)
- Gilman Reagents (Organocuprates): How They're Made
- Gilman Reagents (Organocuprates): What They're Used For
- Common Mistakes with Carbonyls: Carboxylic Acids... Are Acids!
- The Heck, Suzuki, and Olefin Metathesis Reactions (And Why They Don't Belong In Most Introductory Organic Chemistry Courses)
- Reaction Map: Reactions of Organometallics
16 Spectroscopy
- Degrees of Unsaturation (Index of Hydrogen Deficiency)
- How Bleach Works: Understanding Colors From Nature
- Introduction To UV-Vis Spectroscopy
- UV-Vis Spectroscopy: Absorbance of Carbonyls
- UV-Vis Spectroscopy: Some Practice Questions
- Bond Vibrations, IR Spectroscopy, and the "Ball and Spring" Model
- Infrared Spectroscopy: A Quick Primer On Interpreting Spectra
- IR Spectroscopy: Some Simple Practice Problems
- Homotopic, Enantiotopic, Diastereotopic
- Liquid Gold: Pheromones In Doe Urine
- Natural Product Isolation (1) - Extraction
- Natural Product Isolation (2) - Purification of Crude Mixtures Overview
- Structure Determination Case Study: Deer Tarsal Gland Pheromone
17 Dienes and MO Theory
- What To Expect In Organic Chemistry 2
- How Concepts Build Up In Org 2
- Are these molecules conjugated?
- Conjugation and Resonance
- Molecular Orbital Diagram For A Simple Pi Bond - Bonding And Antibonding
- 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 Control
- 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
- Molecular Orbitals 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
- Regiochemistry In The Diels-Alder Reaction
18 Aromaticity
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
- 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 of Diazonium Salts: Sandmeyer and Related Reactions
- 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"
- Aromatic Synthesis (2) - Polarity Reversal
- Aromatic Synthesis (3) - Sulfonyl Blocking Groups
- Synthesis (7): Reaction Map of Benzene and Related Aromatic Compounds
20 Aldehydes and Ketones
- Weird Nomenclature In Carbonyl Chemistry
- The Simple Two-Step Pattern For Seven Key Reactions of Aldehydes and Ketones
- Wittig Reaction
- Imines and Enamines
- Acid Catalysis Of Carbonyl Addition Reactions: Too Much Of A Good Thing?
- On Acetals and Hemiacetals
- Carbonyl Chemistry: 10 Key Concepts (Part 1)
- Carbonyls: 10 key concepts (Part 2)
- Breaking Down Carbonyl Reaction Mechanisms: Anionic Nucleophiles (Part 1)
- Breaking Down Carbonyl Reaction Mechanisms: Reactions of Anionic Nucleophiles (Part 2)
21 Carboxylic Acid Derivatives
- Simplifying the reactions of carboxylic acid derivatives (part 1)
- Carbonyl Mechanisms: Neutral Nucleophiles, Part 1
- Carbonyl chemistry: Anionic versus Neutral Nucleophiles
- Proton Transfers Can Be Tricky
- Let's Talk About the [1,2] Elimination
- Carbonyl Chemistry: Learn Six Mechanisms For the Price Of One
- Summary Sheet #5 - 9 Key Mechanisms in Carbonyl Chemistry
- Summary Sheet #7 - 21 Carbonyl Mechanisms on 1 page
- How Reactions Are Like Music
- Making Music With Mechanisms
- The Magic Wand of Proton Transfer
- The Power of Acid Catalysis
22 Enols and Enolates
23 Amines
- Amides: Properties, Synthesis, and Nomenclature
- Basicity of Amines And pKaH
- 5 Factors That Affect Basicity 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
- Introduction to Peptide Synthesis
- The Strecker Synthesis of Amino Acids
24 Carbohydrates
- D and L Sugars
- What is Mutarotation?
- Reducing Sugars
- Pyranoses and Furanoses: Ring-Chain Tautomerism In Sugars
- The Big Damn Post Of Sugar Nomenclature
- 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
25 Fun and Miscellaneous
- 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" ?
- Introduction To Synthesis
- 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)
- Org 1 Review Quizzes
- 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
I teach it to my class like we’re prosecutors in court trying to build a case for either SN1, SN2, E1, or E2. How do we build the case? We examine the evidence.
What evidence do we get from the nucleophile? It’s a good nucleophile, like I-? That’s evidence for SN2. It’s a poor base, like I-? That’s evidence against E2.
What evidence do we get from the elctrophile? It’s a primary halide? That’s evidence for SN2/E2 and evidence against SN1/E1 (because the resulting carbocation in the SN1/E1 mechanism would be a primary carbocation and we won’t form primary, unstable carbocations).
What evidence do we get from the solvent? It’s a polar aprotic solvent? That increases the nucleophilicity of the already strong nucleophile. That’s evidence for SN2
Then put it all together – look at all the evidence as a whole. I’ve got lots of evidence against an SN1/E1, a couple of pieces of evidence pointing toward SN2, and some evidence against E2.
Sounds like we’re doing an SN2 reaction!
Problem is, sometimes the evidence points in a couple of different directions – so how do we sort out the conflicting evidence and put together a case for one reaction pathway over another? That’s why this unit is so difficult. Sometimes deciding what the evidence means is really really hard.
I actually think trying to flow chart this problem is a bad way to approach it. It makes students think this is all ‘rules based,’ when really its so much more nuanced than that. To say we can flow chart this unit makes students think they can apply a set of rules and if I do things the same way every time, I’ll get a nice, neat, one single right answer every time. It’s way more complicated and nuanced than that.
Just curious, im taking ochem right now…
Is this site still active/maintained?
hell yeah!
do you do short private tutoring sessions? say if i had a few questions on a certain homework problems, and need verfication, would you be available within a certain timeframe to be able to provide aid and guidance?
right now given my current schedule that is just not possible. I realize there’s a demand for this kind of service however.
Good point re the “evidence-based” approach versus a “rules-based approach”.
In light of the fact that ochem is a premed requirement, another way to look at it might be as a “diagnosis”. What can we rule out, based on the evidence? What’s consistent? What’s inconsistent?
This thought process is pervasive in medicine. My dad’s a retired GP and he had to use this kind of thinking all the time.
I realize this is a really old comment but I just have to say that I love this idea. I’m going to try to think about it that way and maybe make a study sheet to help me see it like that. I’m pre-med and love chemistry so it’s perfect :)
HI James!!! Thanks for checking in and seeing that things are better with me and organic chemistry I am enjoying it a lot more than the first time around. I like th exam generator. That’s pretty cool! I’ve realized that it’s a looot of practice and critical thinking skills. It’s not something that you can memorize instead really thing about what is the next next. Over all I like it more than I thought I would in organic chemistry II. Thank you!!! i will use some of the info that you have on your blog for midterm II. Thank you!
You’re welcome! Glad I could be of help.
Thank you thank you thank you! I love the flow chart. My Org 1 Final exam is in two days, wish me luck! :) Thanks for the great resources.
ps I’m a McGillian too!
Thanks for the comments, very helpful and easy to understand!
I just came across this blog and it has been very helpful. I am taking Org 1 and 2 this summer… quite a challenge. Very fast paced so it is crucial to stay on top of the material and practice as much as possible. This past week we began learning mechanisms and they are giving me a hard time. I understand them individually but do not know how to determine which one needs to be used in different situations.
This is an extremely common problem – for instance, understanding when something like OH(-) acts as a base and when it acts as a nucleophile can be tricky at first. The more problems/reactions you see, the more you’ll get the hang of it.
THANKS !
thanq very much it is very useful to teach students
Thanks mate.. Really helpful info
This is an absolute lifesaver. Thank you. I was having a really hard time understanding how to choose one over the other. The flow chart was especially useful.
Awesome, mak!
James,
Thank you so much. I was so confused with substitution and elimination reactions. I understand them more clearly now all thank to you. Again, thank you. I truly appreciate the time and effort that you put in to make the tutorials available for free. Please keep up your good work.
Best.
The whole overview for SN1, SN2, E1 and E2 is very clear. The only think I miss, which would make this picture even more complete to my opinion, is the E1cB mechanism. In which in which first a deprotonation of a β-hydrogen occurs followed by the loss of a leaving group from the α-carbon.
Thanks so much for making this website. Big help!
Glad to hear you find it useful!
What happens when 2-Bromo,2-Chlorobutane is treated with NaI/acetone in Sn2 Condition? And i love ur work