Home / Wrapup: The Quick N’ Dirty Guide To SN1/SN2/E1/E2
SN1/SN2/E1/E2 Decision
Wrapup: The Quick N’ Dirty Guide To SN1/SN2/E1/E2
Last updated: November 29th, 2022 |
The Quick N’ Dirty Guide To SN1/SN2/E1/E2 : Putting It All Together
The previous several posts dealt with an approach to solving substitution and elimination problems that can only be described as a Quick N’ Dirty Guide to SN1/SN2/E1/E2. The basic premise is this: given 15-20 minutes to describe the basic principles by which one could figure out if a given reaction goes down one of these pathways, these are, in my opinion, the key factors to consider.
Quick N’ Dirty rules, by their nature, do not cover exceptions. To learn about some of the exceptions, I advise you to go back and read the individual posts
Even further back, I urge you to understand the key concepts behind each reaction, such as
And of course the mechanism of each of these reactions
Finally, I will preface this by saying that the best way to learn and understand how these reactions work is to do a lot of practice problems and pay particular attention to situations where you get the wrong answer – they are instructive.
Here goes:
Question 1: Is the carbon containing the leaving group methyl (only one carbon), primary, secondary, or tertiary?
- Quick N’ Dirty Rule #1: If primary, the reaction will almost certainly be SN2 [prominent, commonly encountered exceptions: 1) a bulky base such as tBuOK will tend to give elimination products [E2]; 2) primary carbons that can form relatively stable carbocations (i.e. allylic/benzylic) may proceed through the SN1/E1 pathway.] Also – methyl carbons always proceed through SN2.
- Quick N’ Dirty Rule #2: If tertiary, the reaction cannot be SN2. [Because tertiary alkyl halides are too hindered for the SN2. Depending on the type of nucleophile/base, it will either proceed with concerted elimination [E2] or through carbocation formation [SN1/E1]
Question 2: Does the nucleophile/base bear a negative charge?
- Quick N’ Dirty Rule #3: Charged nucleophiles/bases will favor SN2/E2 pathways [i.e. rule out SN1/E1]. [So, for example, if SN2 has already been ruled out [e.g. for a tertiary carbon, according to Question 1] then the reaction will therefore be E2. This is the case for tertiary alkyl halides in the presence of strong bases such as NaOEt, etc. The strength of the [charged] nucleophile/base can be important! An important special case is to be aware of charged species that are weak bases [such as Cl, N3, –CN, etc.] these will favor SN2 reactions over E2 reactions].
- Quick N’ Dirty Rule #4: If a charged species is not present, the reaction is likely to be SN1/E1. [so if the only reagent is, say, H2O or CH3OH you are likely looking at carbocation formation resulting in an SN1/E1 reaction.]
Question 3: Is the solvent polar protic or polar aprotic?
- Quick N’ Dirty Rule #5: All else being equal, polar aprotic solvents favor substitution [SN2] over elimination [E2]. Polar protic solvents favor elimination [E2] over substitution [SN2]. [Note that this rule is generally only important in the case of trying to distinguish SN2 and E2 with a secondary alkyl halide and a charged nucleophile/base. This is not meant to distinguish SN1/E1 since these reactions tend to occur in polar protic solvents, which stabilize the resulting carbocation better than polar aprotic solvents.]
Question 4: Is heat being applied to the reaction?
- Quick N’ Dirty Rule #6: Heat favors elimination reactions. [This only becomes an important rule to apply when carbocation formation is indicated and we are trying to decide whether SN1 or E1 will dominate. At low temperatures SN1 products tend to dominate over E1 products; at higher temperatures, E1 products become more prominent.]
Writing this post makes me feel like a nun giving out condoms. I realize there will be many who are reading this an hour before their exam and are completely clueless on this subject. All I have to say is, God help you. And do more fricking practice problems so you don’t put yourself in this situation next time.
Notes
Related Articles
- Alkyl Halide Reaction Map And Summary
- SN1 SN2 E1 E2 Practice Problems (MOC Membership)
- The SN1 Mechanism
- The SN2 Mechanism
- The E1 Reaction
- The E2 Mechanism
- 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
Struggling with SN1/SN2/E1/E2? Our Org 1 Summary Sheets (PDF) contain a full-page flowchart on deciding SN1/SN2/E1/E2, as well as two more pages summarizing substitution and elimination reactions, in addition to many other Org 1 topics.
Check them out now!
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
- How To Draw A Bond Rotation
- 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
10 Rearrangements
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
- SN1 vs E1 and SN2 vs E2 : The Temperature
- Deciding SN1/SN2/E1/E2 - The Solvent
- 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
- Cyclopropanation of Alkenes
- 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
15 Organometallics
- 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
16 Spectroscopy
- 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
18 Aromaticity
- 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
- Transesterification
- 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
- Decarboxylation
- 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
23 Amines
- 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
24 Carbohydrates
- 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
I wish I had found you ages ago, none of this has made sufficient sense. My exam tmrw will not be pretty, but hoping for the best regardless.
A day before the exam really you’re a life saver thank you and may god always bless and protect you i will pray for you man really thank you from the bottom of my heart ❤️
thanks man you saved my ass, i forgot the basics.
opening organic chemistry book after 2 months
I do not approve. But if the post was helpful, I am at least glad.
Each and every thing is wrong.
Specific examples?
You should mention that except CH3Cl all primary carbons undergo E1 mechanism because elimination requires at least 2 carbons(Though this may be taken under common sense
It does seem like common sense. However….. :- )
Yo James I just want to say how much i appreciate this quick and dirty guide! It really nicely summarizes the process in how to pick which pathway that is needed to take! Ive used a bunch of flow charts but nothing has helped me more than this guide!
Loved the post. its about 30 minutes before my exam and i was boned, but due to this page i will do great on my exam. if you don’t practice/read forums/ study you’ll get an A anyways.
Well, I hope you’re right Nick.
Question. If I have a primary substrate. No beta branching. And I have o-ch3 and CH3OH as the solvent. What would I be getting. I feel like I might have a mix of SN2 and E2 and I can’t really tell. CH3OH is a polar protic solvent which favors E2, but since it is a primary carbon and O-CH3 is a good nucleophile and a good base it might favor SN2.
Sounds like a Williamson Ether synthesis. SN2.
Hey James.You haven’t mentioned about 2° alkyl halide.Please generalize that too.And one more doubt. Will there substitution take when we use strong base but weak nucleophile for tertiary alkyl halide?
Haha! It’s not quite an hour before the test- about 23 hours. But yeah. I’m going to need loads of help and prayers. Thanks for your site by the way- it’s already helped me make sense out of things that have confused me for weeks. I’ve still got a ways to go, a long ways- but, thank you for helping me as I try to go that distance.
After all this time, I finally got all my questions right. James when I open an university, I’ll make you the Head of Chemistry department!!!
I am really thankful for this. I’m that type of student who is really clueless about OrgChem and my professor got mad today and she said that there will be quizzes every meeting and those would be in essay type of questions. I’m dying and now when I see this, I see a beam of light huhuhu thank you very much! :) God bless you, a nun giving out condoms.
Wow, thank you! This is really helpful!
That last paragraph rofl
Awesome! Actually reading this about 30 hours before the final lol. Really helpful though, I’ve done surprisingly well this semester but the final is the ACS exam. The prof told us there’s a ton of sn1 and sn2 on it so hopefully this info will help:)
My professor was amazing, but I can’t find my notebook from first semester so I’m glad I found this lol
How will you avoid or minimize the elimination product in a tertiary substrate undergoing substitution reaction?
By substitution reaction, I take it that you mean favor the SN1 vs E1, since a SN2 reaction will not occur on a tertiary substrate.
Some elimination products will always accompany an SN1 product (assuming that there are beta hydrogens adjacent to the leaving group.
Elimination reactions are favoured by heat. So one can favor the SN1 pathway to a greater extent by keeping the temperature down.
A flowchart would be great.
Its an excellent job in field of organic chemistry,priceless for us students.The author deserves a lot.If tomorrow i turn to be a millionaire,i would contribute a hefty sum of money to take this work ahead!
Whoever decided this guy shouldn’t be a professor should be fired.
Hah. My favourite comment ever
Having you explain this seriously puts my professor to shame.
That last paragraph helped relieve some stress before my OChem test in an hour.
Thanks so much for these guides! They are so helpful. Also the last paragraph definitely made me chuckle
Thank you so much for your postings!
This website has helped me fighting with organic chem a lots.
A week before my exam. This is a nice quick review on stuff i havent seen in ages. Now if only I could find some practice problems. :-)
Thank you for your cruel honesty. Many of us needs
To hear that. Keep it up!
I have a question about E1 and E1cb. Can you explain to me how to different them?
Here’s a post I wrote on the C1cb:
https://www.masterorganicchemistry.com/2020/02/11/e1cb-elimination-unimolecular-conjugate-base/
Your guide is much clear than my professor! It is really nice !!
Literally reading this an hour before my exam D; God help me!
Great Guide thanks a lot, but any idea of catchup or addition about E1cb reactions, got this all but am clueless about it…
This world needs more nuns handing out condoms. Great review, and thanks for pointing out the exceptions to the “quick and dirty” rules.
What an excellent resource, thank you for this insightful website.
@ Chemistry Student,
I believe you’re full of crap, and though you are right about the simplification, the information is not wrong. I’ve read my textbook before visiting this site and it serves as a great review!
“Writing this post makes me feel like a nun giving out condoms. I realize there will be many who are reading this an hour before their exam and are completely clueless on this subject. All I have to say is, God help you.” – hahahah… you got me!
Dont use this guide. It horribly over simplifies everything and a lot of it is just plain wrong. Just go study and learn the material in class or from the textbook.
It *does* over simplify things, you are right. Do you think you could be more specific about the criticisms? What would make this better? Thank you.
Chemistry Student you are not correct about the information to be wrong! It does simplify things, if you think you could do better at making a short guide to help out people why don’t you? I do agree that is simplifies everything and I do agree that one needs to study the materials from ones class. I do disagree with you saying not to use the guide to help one study. I have an extremely hard professor that teaches very little in class so I have to use every resource available to help learn the information. This site helps a ton and is a great SUPPLEMENTAL tool for learning the material. The class average on the 2nd test we took in class was a 40% if that tells you anything about our professor. The class is filled with extremely smart people that are going to be going to; medical school, PA or Pharm D. There is no need to be rude to the person that created it just because you do not like it. The person put in a lot of work and time to create it and should be thanked instead.
I do agree that the reactions are being over-simplified here, but isn’t that the point of a “Quick N’ Dirty Guide”? To be just that?
No one is implying that this should be a student’s sole resource when learning reactions and mechanisms. I’m pretty sure that the author intended this to be a supplement, nothing more. A textbook or simple rote learning through tons of problems is the more ideal way to go, yes. It is AMAZING how well a person can pick up these trends just by forcing themselves to work through more difficult reactions ad nauseum. But the whole point of this guide seems to be… exactly as the title describes it: a quick, easy little step-by-step guide to refresh the memory before a test. If a student were to only use this guide to learn the reactions, then, no, I wouldn’t be surprised if that student failed. But it also isn’t meant to be the one and only resource, either.
Moreover, the information isn’t “just plain wrong”. It is simplified, but it is not incorrect. Heck, the author even acknowledged that there are exceptions (as there are for everything in organic chemistry) and stated that this isn’t a substitute for learning the material through a class or textbook. It’s just a quick overall review of many of the trends. I really don’t understand your accusation, is all I’m sayin’, I suppose.
Guess She only had 20 minutes before her exam.
Listen here. If you don’t like this guide, then leave. This guide is freaking fantastic when your confused on a topic or want clarification on a top or just a refresher. Don’t assume that ALL learn from only this website. Sure some people do but 8/10 most people learn from a variety of sources– lecture, textbook, videos, professors. etc.
I love all the people defending the site! Hilarious :) I like the site too btw…
Ha! I have been studying thoroughly, I do get flustered easily though and this website really helps so much with putting concepts in different groups so I don’t get totally overwhelmed and pass out from the huge amount of information I have just been assaulted with.
“Writing this post makes me feel like a nun giving out condoms.” LMAO! This is why I love your writing, and can tolerate reading your blog about organic chemistry, James.
lol at last phrase. 4 hours before exam actually. but what the heck with this guide and a little bit of luck I will succeed!
there is no such thing as luck in organic chemistry
true!
Very true! Whenever I have guessed the product in any of my tests, I have never ever been correct!
YOU are amazing. This helps tons