Ch. 8 - Elimination ReactionsSee all chapters
All Chapters
Ch. 1 - A Review of General Chemistry
Ch. 2 - Molecular Representations
Ch. 3 - Acids and Bases
Ch. 4 - Alkanes and Cycloalkanes
Ch. 5 - Chirality
Ch. 6 - Thermodynamics and Kinetics
Ch. 7 - Substitution Reactions
Ch. 8 - Elimination Reactions
Ch. 9 - Alkenes and Alkynes
Ch. 10 - Addition Reactions
Ch. 11 - Radical Reactions
Ch. 12 - Alcohols, Ethers, Epoxides and Thiols
Ch. 13 - Alcohols and Carbonyl Compounds
Ch. 14 - Synthetic Techniques
Ch. 15 - Analytical Techniques: IR, NMR, Mass Spect
Ch. 16 - Conjugated Systems
Ch. 17 - Aromaticity
Ch. 18 - Reactions of Aromatics: EAS and Beyond
Ch. 19 - Aldehydes and Ketones: Nucleophilic Addition
Ch. 20 - Carboxylic Acid Derivatives: NAS
Ch. 21 - Enolate Chemistry: Reactions at the Alpha-Carbon
Ch. 22 - Condensation Chemistry
Ch. 23 - Amines
Ch. 24 - Carbohydrates
Ch. 25 - Phenols
Ch. 26 - Amino Acids, Peptides, and Proteins

The E1 mechanism is similar to E2 in that you get an elimination product, but the path to get there is completely different. It’s important that we understand how it’s different from E2. 

Concept #1: Drawing the E1 Mechanism.

Summary: A neutral nucleophile reacts with an inaccessible leaving group to produce elimination in two-steps.

Concept #2: Understanding the properties of E1. 

Properties of E1 reactions:

  • Nucleophile =  Weak
  • Leaving Group =  Highly Substituted
  • Reaction coordinate = Intermediate
  • Reaction = Two-Step
  • Rate =  Unimolecular
  • Rate =  k[RX]
  • Stereochemistry = Non-stereospecific

Practice: Predict the product

Practice: Predict the product

Additional Problems
Which of the following shows the first step for an E1 reaction?
Which equation corresponds to the overall reaction for which steps 1 and 2 describe the mechanism? 
What best describes the species at the rate-determining transition state? 
Which of the following shows part of the mechanism for an E1 elimination?
Provide the mechanism for the following reaction. Be sure to include all intermediates, formal charges and arrows depicting electron movement.
Predict the product and draw the full arrow-pushing mechanism of this reaction. 
How many atoms and electrons are directly involved in the bond-making and bond-breaking of the first step in an E1 reaction? (A) three atoms, four electrons (B) two atoms, four electrons  (C) three atoms, two electrons  (D) two atoms, two electrons (E) four atoms, four electrons  (F) four atoms, two electrons
Which of the following is  least likely to be found in the product mixture which results when 2,2-dimethyl-3-pentanol is heated in phosphoric acid? A) 2, 3-dimethyl-2-pentene B) (Z)-4, 4-dimethyl-2-pentene C) 4, 4-dimethyl-1-pentene D) 2, 3-dimethyl-1-pentene E) (E)-4, 4-dimethyl-2-pentene
Create the full arrow pushing mechanism which shows all intermediates and all products that result from these reactions. If alkenes are produced, indicate which is major and minor.
Provide the major product for the following compound.
Answer each of the following questions dealing with the given alkyl halides. Which compound cannot under an E1 reaction? 
Answer each of the following questions dealing with the given alkyl halides. Which compound will undergo an E1 reaction to form a tetrasubstituted alkene, but undergoes an E2 reaction to form a trisubstituted alkene?   
For the transition state structure below, choose an organic reaction in which it is involved and give a chemical equation for your selected organic reaction that includes the following: (i) structural formula(s) for the organic reactant(s); be sure to show stereochemistry appropriately when necessary (ii) the experimental conditions (Give structural formulas for organic compounds. Give a chemical formula or inorganic reactants or catalysts . If heat and/or light is needed, be sure to indicate it appropriately.) (iii) structural formula(s) for the major organic product(s); be sure to show stereochemistry appropriately when necessary. As we do for most organic reaction equations, the chemical equations that you give do not need to be balanced.
Draw the final product for the following E1 reactions. 
Draw the final product for the following E1 reactions. 
Based on the E1 mechanism for the acid-catalyzed dehydration of a tertiary alcohol as summarized in arrows 1 and 4, which arrow(s) represent(s) more than one elementary step?a. Arrow 1b. Arrow 4c. Both 1 and 4d. Neither 1 nor 4
Based on the E1 mechanism for the conversion of a tertiary alkyl chloride to an alkene as summarized in arrows 3 and 4, which arrow(s) represent(s) more than one elementary step? a. Arrow 3b. Arrow 4c. Both 3 and 4d. Neither 3 nor 4 
Based on the E1 mechanism for the conversion of a tertiary alkyl chloride to an alkene as summarized in arrows 3 and 4, which arrow(s) correspond(s) to exothermic processes? a. Arrow 3b. Arrow 4c. Both 3 and 4d. Neither 3 nor 4
Which of the following alkyl halides undergoes E1 reactions with the fastest rate?
Consider the following pair of reactions. Predict the type of elimination mechanism, predict which reaction of the pair will occur at the fastest rate, and draw the correct organic product.  
Draw the structure of an alkyl halide that could be used in an E1 reaction to give the following alkene as the only alkene product:
Consider the following pair of reactions. Predict the type of elimination mechanism, predict which reaction of the pair will occur at the fastest rate, and draw the correct organic product. Assume the same solvent is used in both reactions. 
Give the mechanism of the reaction shown below.