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

Here is the best flowchart you’ll ever learn in your life. Seriously.

 

Professors rarely tell you which mechanisms to use. Instead, they’ll give you a set of reagents and ask you to figure it out yourself. This flowchart basically explains that entire process. Let’s go! 

Determining Mechanisms

When do you use this flowchart? Whenever you have a nucleophile and a GOOD leaving group. 

Concept #1: Overview of the flowchart. 

In general, the left side of the flowchart predicts SN2 /E2 mechanisms, and the right side predicts SN1/E1 mechanisms, but there are exceptions.

Concept #2: How to predict SN2 and E2 mechanisms. 

Here is a list of some more bulky bases that some professors like to use. Be aware that this is not a comprehensive list! 

You may also see NaNHand NaH (small, non-nucleophilic bases) react via an E2 for primary leaving groups, so keep that in mind! 

Concept #3: How to predict SN1 and E1 mechanisms. 

Additional Problems
True/False. Identify the statements as either True or False.    Reduction of an alkyne to an alkene with sodium metal in liquid ammonia is a partial radical mechanism. In polar protic solvents a selenide anion (Se-2) is a stronger nucleophile as compared to a sulfide anion (S-2). The leaving group and the departing hydrogen in an E2 elimination reaction has to be on the same side. Halogens have lower priority as compared to alkenes in IUPAC naming system. The rate of a SN1 reaction increases with increasing carbocation stability. Sodium hydroxide is a strong base and can be used to deprotonate terminal alkynes in a 100% yield. Carbocations form tight ion-pairs with halide anion. In SN2 reactions the rate-determining step involves two molecules. Iodine is a better leaving group than fluorine because iodine is more polarizable than fluorine.  Vinylic carbocations can undergo carbocation rearrangement.
Identify the mechanistic pathways, respectively, for the products in the reaction below. a) E1, SN1 b) E1, SN2 c) E2, SN1 d) E2, SN2
The major product(s) of this reaction would be a) only (R) b) only (S) c) (R) and (S) d) achiral
Consider the compounds below and answer the following questions. a) Which of the compounds below will most readily react via SN1?      b) Which of the compounds below will not significantly undergo SN2 reaction?      c) True/False: Reacting compound I with CH 3CH2ONa will favor SN2 reaction.      d) Which of the compounds below will react with KCN to form a product with R-configuration?      e) Which of the compounds below will react via SN2 most readily?      
Identify whether the following substrate favors SN2, SN1, both or neither: 
Identify whether the following substrate favor SN2, SN1, both or neither: 
Identify whether the following substrate favor SN2, SN1, both or neither: 
Supply a structural formula for the major organic product(s) when the product(s) is(are) not given; if no reaction occurs, write N.R. If the major product is a mixture of stereoisomers (such as a pair of enantiomers or a pair of diastereomers), give a structural formula for each of the stereoisomers in the mixture. 
Identify whether the following substrate favor SN2, SN1, both or neither: 
Supply a structural formula for the major organic product(s) when the product(s) is(are) not given; if no reaction occurs, write N.R. If the major product is a mixture of stereoisomers (such as a pair of enantiomers or a pair of diastereomers), give a structural formula for each of the stereoisomers in the mixture. 
Identify whether the following substrate favor SN2, SN1, both or neither: 
Identify whether the following substrate favor SN2, SN1, both or neither: 
Although useful in agriculture as a soil fumigant, methyl bromide is an ozone-depleting chemical, and its production is being phased out. The industrial preparation of methyl bromide is from methanol, by reaction with hydrogen bromide. Write a mechanism for this reaction and classify it as SN1 or SN2. 
Determine the major product formed for the following reactions. 
Pick the true statement regarding the mechanism of the reaction shown below (alkyl sulfonate esters and alkyl halides behave similarly). A) It is an E1 reaction. B) It is an E2 reaction.  C) It is an SN2 reaction.  D) It is an SN1 reaction.  E) It is either an E1 or SN1 reaction.
The following transformation takes place with what kind of mechanism? a. E2 b. SN2 c. SN1only d. SN1+ E1 e. Bridged ion intermediate
 Supply a structural formula for the major organic product(s) when the product(s) is(are) not given; if no reaction occurs, write N.R. IMPORTANT: If the major product is a mixture of stereoisomers, give a structural formula for each of the stereoisomers in the mixture.
Provide a mechanistic rationalization for the observed stereochemical outcome of this reaction. What kind of a reaction is this (E1, SN1, E2, SN2)?
Provide likely product or starting material and circle the correct answers to the questions that follow each problem.
Provide likely product or starting material and circle the correct answers to the questions that follow each problem.
Provide likely product or starting material and circle the correct answers to the questions that follow each problem.
Which product (or products) would you expect to obtain from each of the following reactions? In each part give the mechanism (SN1, SN2, E1, or E2) by which each product is formed and predict the relative amount of each product (i.e., would the product be the only product, the major product, a minor product, etc.?).  
Which product (or products) would you expect to obtain from each of the following reactions? In each part give the mechanism (SN1, SN2, E1, or E2) by which each product is formed and predict the relative amount of each product (i.e., would the product be the only product, the major product, a minor product, etc.?).  
Which product (or products) would you expect to obtain from each of the following reactions? In each part give the mechanism (SN1, SN2, E1, or E2) by which each product is formed and predict the relative amount of each product (i.e., would the product be the only product, the major product, a minor product, etc.?).  
Which product (or products) would you expect to obtain from each of the following reactions? In each part give the mechanism (SN1, SN2, E1, or E2) by which each product is formed and predict the relative amount of each product (i.e., would the product be the only product, the major product, a minor product, etc.?).  
Which product (or products) would you expect to obtain from each of the following reactions? In each part give the mechanism (SN1, SN2, E1, or E2) by which each product is formed and predict the relative amount of each product (i.e., would the product be the only product, the major product, a minor product, etc.?).  
Which product (or products) would you expect to obtain from each of the following reactions? In each part give the mechanism (SN1, SN2, E1, or E2) by which each product is formed and predict the relative amount of each product (i.e., would the product be the only product, the major product, a minor product, etc.?).  
Which product (or products) would you expect to obtain from each of the following reactions? In each part give the mechanism (SN1, SN2, E1, or E2) by which each product is formed and predict the relative amount of each product (i.e., would the product be the only product, the major product, a minor product, etc.?).  
Which product (or products) would you expect to obtain from each of the following reactions? In each part give the mechanism (SN1, SN2, E1, or E2) by which each product is formed and predict the relative amount of each product (i.e., would the product be the only product, the major product, a minor product, etc.?).  
Which product (or products) would you expect to obtain from each of the following reactions? In each part give the mechanism (SN1, SN2, E1, or E2) by which each product is formed and predict the relative amount of each product (i.e., would the product be the only product, the major product, a minor product, etc.?).  
Which product (or products) would you expect to obtain from each of the following reactions? In each part give the mechanism (SN1, SN2, E1, or E2) by which each product is formed and predict the relative amount of each product (i.e., would the product be the only product, the major product, a minor product, etc.?).  
Although ethyl bromide and isobutyl bromide are both primary halides, ethyl bromide undergoes SN2 reactions more than 10 times faster than isobutyl bromide does. When each compound is treated with a strong base/nucleophile (EtO-), isobutyl bromide gives a greater yield of elimination products than substitution products, whereas with ethyl bromide this behavior is reversed. What factor accounts for these results?  
Predict the product(s).  
Write mechanisms that account for the products of the following reactions:  
Write mechanisms that account for the products of the following reactions:  
For each reaction, mark all of the statements below that correctly describe the reaction. 
Answer each of the following questions dealing with the given alkyl halides a) Which compound will undergo E1 most readily?        b) Which compound will undergo E2 most readily?       c) Which compounds would form a trisubstituted alkene as the major E1 and E2 product?       d) Which compound(s) cannot undergo elmination at all?      
Answer each of the following questions dealing with the given alkyl halides a) Which compound cannot undergo an E1 reaction?   b) Which compound will undergo an E1 reaction to form a tetrasubstituted alkene, but undergoes an E2 reaction to form a trisubstituted alkene?       c) Which compounds cannot undergo an SN2 substitution?     d) Which compound will form a nitrile, R–CN, with S configuration on treatment with KI followed by NaCN (both in polar aprotic solvent)?     e) Which compound will form a nitrile with S configuration on treatment with NaCN in polar aprotic solvent?     
The rate of the reaction (CH3)3 CCl + NaSCH2CH3 → (CH3)2C=CH2 + CH3CH2SH + NaCl is first-order in (CH3)3CCl and first-order in NaSCH2CH3 . Give the symbol (E1 or E2) for the most reasonable mechanism, and use curved arrows to show the flow  of electrons.    
The following reaction below is probably   A) an SN1-type reaction involving the protonated alcohol as the substrate. B) an SN2 -type reaction involving the protonated alcohol as the substrate. C) an E1 -type reaction involving the protonated alcohol as the substrate. D) an E2 -type reaction involving the protonated alcohol as the substrate. E) an epoxidation reaction.
The mechanism of the following reaction is a) SN1 b) SN2 c) E1 d) E2
Predict the product(s) for the following reaction.
Consider the reactions shown and answer the associated questions. 
For the reaction shown below, draw the structure of the major product(s). Where appropriate, write "No Reaction". Assume all chiral starting materials are optically pure. Show stereochemistry where appropriate. Indicate whether the product exists as a single enantiomer or a racemic mixture.
For the reaction shown below, draw the structure of the major product(s). Where appropriate, write "No Reaction". Assume all chiral starting materials are optically pure. Show stereochemistry where appropriate. Indicate whether the product exists as a single enantiomer or a racemic mixture.
Which compound will be the organic product after the following two steps:
Provide the final reaction product or "no reaction" if you believe it is the case. Please provide the R/S stereochemistry for each chiral center in the product provided (if any), also indicate if the compound is not optical active.
Predict the organic product of the following reaction. When appropriate, be sure to indicate stereochemistry. If more than one product is formed be sure to indicate the major product. Draw your answer in skeletal form. You will be graded on the product your draw from the reaction no other information is needed for this question.
Predict the major organic product of each of the following reactions. In spite of the structural complexity of some of the starting materials, the functional group transformations are all of the type described in this chapter.  
Predict the organic product(s) for the following reaction. Be sure to indicate stereochemistry when appropriate. If stereoisomers are produced draw one and label the relationship between the stereoisomers. (enantiomers, diastereomers, etc.).
Predict the major organic product of each of the following reactions. In spite of the structural complexity of some of the starting materials, the functional group transformations are all of the type described in this chapter.  
Predict the product(s).
Predict the product(s).
Predict the major organic product of each of the following reactions. In spite of the structural complexity of some of the starting materials, the functional group transformations are all of the type described in this chapter.  
Predict the product(s).
Predict the product(s).
Predict the product(s).
Predict the product(s).
Predict the product(s).
Predict the major organic product of each of the following reactions. In spite of the structural complexity of some of the starting materials, the functional group transformations are all of the type described in this chapter.
Predict the major organic product of each of the following reactions. In spite of the structural complexity of some of the starting materials, the functional group transformations are all of the type described in this chapter.
Predict the major organic product of each of the following reactions. In spite of the structural complexity of some of the starting materials, the functional group transformations are all of the type described in this chapter.
Predict the major organic product of each of the following reactions. In spite of the structural complexity of some of the starting materials, the functional group transformations are all of the type described in this chapter.
The reaction between compound 1 and NaOCHMe2 in Me2CHOH as a solvent produces a mixture of two different products 2 and 3, containing a double bond, with a relative yield of 50% and 50% respectively. What are the structures of compounds 2 and 3?b.  Which one of products 2 or 3 will be obtained as the major product if we do this reaction with MeO- +Na as the base in MeOH as solvent? Explain your answer with 1-2 sentencesc. Which one of products 2 or 3 will be obtained as the major product if we do this reaction with (CH3)3CO- +Na as the base in (CH3)3COH as solvent? Explain your answer with 1-2 sentencesd. Based on the data above, what products and in what relative ratios would we obtain by treating compound 4 with NaOCHMe2 in Me2CHOH as the solvent under the same conditions as above? Explain your answer with 1-2 sentences.
Predict the product(s) for the following reaction.
Predict the product(s) for the following reaction.
Predict the product(s).
Predict the product(s) for the following reaction.
Predict the product(s).
Predict the product(s).
Predict the product(s).
Be sure to answer all parts.Draw the products in the following reaction. Part 1 Identify which mechanism(s) the reaction will undergo. Part 2 The number of SN1 product(s): The number of E1 product(s):
Draw the major organic product(s) of the following reaction. 
What product would you expect from the following reaction? 
Predict the major substitution products of the following reaction. Use the wedge/hash bond tools to indicate stereochemistry. If there is more than one major product possible, draw all of them
Provide the major organic product of the reaction shown below.  
Draw the neutral organic products
Draw the major organic product(s) of the following reaction.  
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.  
What is (are) the most likely product(s) for the following reaction?  
What organic produce(s) is/are formed in the following reaction ?a. I and IVb. IIIc. I, II and IIId. IVe. I and II  
Draw the major organic product(s) of the following reaction.
What organic product (s) is/are formed in the following reaction?
Draw the major organic product (other than ethanol) formed in the following reaction.
Predict the product of the following reaction.
Draw the major organic product for the same substrate with two different conditions.
For the following reaction, choose the most likely reaction pathway and draw the major product. Only draw the resulting organic species, omit counterions. 
Draw the major organic product(s) of the following reaction.  
Give the major organic product(s) for the following reaction.  
When 3-iodo-3-ethylpentane is heated in methanol, the major organic product is an _____ that is generated through an _____ mechanism. a. ether, SN2b. ether, SN1c. alkene, E2d. ether, E1e. alcohol, E1 
Complete the reaction below.
Draw the major organic product for the following reaction:  
Provide the major organic product of the following.
Draw a structural formula for the substitution product of the reaction shown below.  
For the following reaction, choose the most likely reaction pathway and draw the major product. Only draw the resulting organic species, omit counterions. 
Consider the reaction below Compound C is the: a. E2 Productb. SN1 productc. E 1 productd. SN2 product 
By what mechanism(s) is the following reaction likely to occur? 
Draw a structural formula for the substitution product of the reaction shown below. 
Part A Draw the product formed when the structure shown below undergoes solvolysis in CH3CH2OH with heat.