Practice Problems on SN1, SN2, E1 E2 - Answers 1 Describe the

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Practice Problems on SN1 SN2 E1 & E2

Practice Problems on S N1 S N2 E1 & E2 - Answers 1 Describe the following chemical reactions as S N1 S N2 E1 & E 2 Draw a curved arrow mechanism for each reaction NaI 3 3 Cl KCN DMSO CN Br NaOH H2O heat BrH 2O OH I CH3CH2O-Na+ ethanol HI NaSH DMSO HSH Br HO KOH DMSO OTs NaNH2 NH3 TsO NH3 H2N O O CH CH3 TsO acetone O O CH CH3 I SN2 E2

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Practice Problems on SN1 SN2 E1 & E2

Practice Problems on SN1 SN2 E1 & E2 Describe the following chemical reactions as SN1 SN2 E1 & E2 Draw a curved arrow mechanism for each reaction KCN For each of the chemical substitution reactions below identify the major products and whether the reaction is likely an SN1 or SN2 Br NaCN

How do I know if sn1/sn2/e1/e2 is primary or tertiary?
So for our purposes, in order for SN1/SN2/E1/E2 to take place, we generally need to see an alkyl halide ( or alkyl sulfonates, such as tosylates and mesylates – See post: Tosylates and Mesylates ). Once you’ve identified an alkyl halide, the next step is to determine whether it is primary, secondary, or tertiary.
How to choose between E2 and S N 2?
To choose between E2 and S N 2, you need to remember that the more substituted the substrate the more it prefers the E2 mechanism (3 o > 2 o > 1 o) and vice versa, less substituted substrates prefer the S N 2 route (1 o > 2 o > 3 o ).
What is a good substrate for S N 1/s N 2/e1/e2 reactions?
Primary, secondary, tertiary (and methyl) carbons attached to good leaving groups (such as alkyl halides and sulfonates) are good substrates for S N 1/S N 2/E1/E2 reactions. If this is not clear, review here
What is SN1 SN2 E2?
This will also be covered in another subsequent article ( See article – Deciding SN1/SN2/E1.E2 – The Role of Temperature ), but the short answer is, “ heat “. If heat is applied, then expect the reaction to be E1.

First Off: Determine If The Substrate Is Primary, Secondary Or Tertiary

What’s the very first step in deciding whether a reaction goes through SN1, SN2, E1 or E2? 1. The very first thing is to identify a good leaving group such as Cl, Br, I, or OTs/OMs (For a refresher, see this previous post – How To Tell Where Substitution and Elimination Reactions Will Happen) 2. The other key thing to note is that with very few ex

Looking at Some Reactions

Once you can classify alkyl halides as primary, secondary, tertiary (or methyl) the next step is to do it in the context of several reactions, where it’s not uncommon to see things drawn up a little unconventionally. Before asking any other questions, look at the reactions below and see if you can identify potential substrates for SN1/SN2/E1/E2 re

So The Alkyl Halide Is Primary – Now What?

All right. Let’s say we’ve identified our alkyl halide as primary. Now what do we do? We can make a confident prediction. When the substrate is primary (or methyl), expect SN2 These reactions will almost certainly not be SN1 or E1. [Note 1] That’s because the first step of SN1/E1 is loss of a leaving group to form a carbocation, and primary carboca

So The Alkyl Halide Is Tertiary – What then?

Secondary alkyl halides are a bit thorny, so let’s skip them for a moment and move straight to tertiary. If the substrate is tertiary, you can rule out SN2. Why? SN2 reactions generally don’t happen on tertiary alkyl halides because the SN2 proceeds through a backside attack (to the C-LG sigma* orbital) , and the backside of tertiary alkyl halides

It’S Secondary – Now What?

Finally we get to the “fun” part: secondary alkyl halides. (Note – your definition of “fun” may vary) The short news is that for secondary alkyl halides, we cant rule anything out. Depending on conditions, each of the four reaction patterns could potentially be observed. I’m not going to be able to summarize the whole range of possibilities in one

A Look Ahead

Although this is intended to be just one article in a sequence that walk through the process of deciding SN1/SN2/E1/E2, I appreciate that not everyone will go through this sequentially. This is an outline of the thought process: 1. The role of the substrate (this article) 2. The role of the nucleophile/base (next ) 3. The role of the solvent (SN2

Some Examples with Alcohols

We’ve been talking about reactions of alkyl halides, but these reactions can happen with alcoholsas well. In their neutral form alcohols are poor nucleophiles and are also poor substrates for SN1/SN2/E1/E2 reactions since the hydroxide group (HO–) is a poor leaving group. However, adding an acid or a basecan change the alcohol’s personality dramati

Summary

Identifying the type of substrate (primary, secondary, tertiary or methyl halide) is the first step towards identifying a reaction as SN1/SN2/E1/E2.I personally find it more helpful to look at it from the perspective of ruling things out rather than the inverse.If the alkyl halide is primary, you can rule out SN1 and E1, and rule out E2 unless the nucleophile is a very bulky base.If the alkyl halide is tertiary, you can rule out SN2. masterorganicchemistry.com

Notes

Note 1. It is also possible for the SN1 pathway to operate with primary allylichalides that are capable of forming extremely stable carbocations, particularly in very polar solvents such as mixtures of water and ethanol or formic acid. One classic example is gamma, gamma dimethylallyl chloride, where the SN1 pathway is dominant. Note 2. Note that I

References and Further Reading

One key reference for understanding the interplay between SN1/SN2/E1 and E2 reactions is an older, but very valuable review by Prof. Andrew Streitweiser (Berkeley) in “Solvolytic Displacement Reactions” (McGraw-Hill, 1962, New York) which summarizes hundreds of publications on the subject prior to 1960. Most of the book is a republication of an ear

Practice SN1 SN2 E1 or E2 Mechanism Given Reactant and Product

PDF	Practice Tests Answer Keys Organic Chemistry I 1. JASPERSE CHEM 350 TEST 1. VERSION 1 Organic Chemistry I - Jasperse Of the SN1/SN2/E1/E2 reactions rearrangements are likely to occur in:.

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PDF	Practice Set Answer Keys Organic Chemistry I Table of Contents Practice Set Answer Keys Organic Chemistry I Test 2 PS#1: PS1: Radical Bromination Practice Set ... E2. OH. Br. SN1. E1. NaI. I. +. NaBr. +. SN2.

PDF	Objectives Organic Chemistry 350.pdf organic reactions such as SN2 SN1

PDF	Practice Questions 1. What is true about the reaction between ( R)-2 f) Answers b and d. 2. The following reaction goes through an SN2 mechanism. CH3CH2CH2Br + -OH ? CH3CH2CH2OH + Br-.