Alkyl Halides

Synthesis (3) – Reactions of Alkyl Halides

Synthesis (3) – Reactions of Alkyl Halides

January 10, 2014

In the last post, we began our discussion of synthesis by starting with the reactions of alkanes. Since we’ve learned only one important class of alkane reactions so far (free-radical halogenation), our “reaction map” was very small.  Today we will visit the reactions of a much more synthetically versatile functional group: alkyl halides. Using our […]

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Synthesis (2) – Reactions of Alkanes

Synthesis (2) – Reactions of Alkanes

December 19, 2013

In this post we’re going to begin building our reaction map, starting with the simplest organic compounds of all: alkanes.*We’ve only learned one synthetically important class of alkane reaction: free-radical halogenation. [Combustion is also technically a reaction of alkanes, but producing CO2 and H2O from organic starting materials is not very useful from a synthetic […]

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Guest Post on SN1/SN2/E1/E2 (1): Why Electrons Are Like A Hyperactive Child

Guest Post on SN1/SN2/E1/E2 (1): Why Electrons Are Like A Hyperactive Child

November 4, 2013

Note (from James) When my friend Adam  from The Chemistry Blog offered to write a series of posts on Substitution and Elimination, I immediately said “yes”. This is one of the topics that many students struggle with, particularly at this time of year. Adam has been writing for years on organic chemistry topics [check out […]

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Alkynes Via Elimination Reactions

Alkynes Via Elimination Reactions

June 11, 2013

We’ve gone through elimination reactions before – treatment of alkyl halides with base gives alkenes.  Some time ago we discussed elimination reactions here. Elimination reactions follow the general pattern below, where two adjacent bonds to carbon are broken – usually C-H and C-X, where X is a leaving group – and in place we form […]

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The 2 Most Important Reactions of Alkynes

The 2 Most Important Reactions of Alkynes

May 1, 2013

With the series of posts on alkenes in the can, let’s move on and talk about a closely related functional group that shares many reactions in common with alkenes: acetylenes, or as they are more commonly referred to, “alkynes”. Alkynes, as we shall see, do share many reactions in common with alkenes. However there are […]

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Alkene Addition Pattern #2: The “Three-Membered Ring” Pathway

Alkene Addition Pattern #2: The “Three-Membered Ring” Pathway

March 20, 2013

The “Three-Membered Ring” pathway In the last post we walked through a proposal for how the bromination of alkenes works and showed that it adequately explains many of the experimental observations made for this reaction. Namely, the reaction proceeds with anti addition of substituents across the alkene, and (where relevant) the reaction proceeds with “Markovnikov“ […]

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Bromination of Alkenes: The Mechanism

Bromination of Alkenes: The Mechanism

March 15, 2013

In the last post of this series we showed how the mechanism for bromination of alkenes can’t possibly go through a carbocation intermediate. Why not? We have at least 3 good reasons: The two atoms that form new bonds to carbon add to opposite faces of the alkene (“anti” stereoselectivity) The reaction is stereospecific – (Z)-2-butene […]

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Markovnikov’s Rule (1)

February 8, 2013

Onward with addition reactions! Quiz time: let’s see if you can recognize the patterns in the following 3 reactions. Look carefully. What do each of the major products have in common? Hopefully you can see that in each case, we’re breaking C-C (π) and forming a new C-H and C-Cl bond. But there’s more. The […]

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Deciding SN1/SN2/E1/E2 (2) – The Nucleophile/Base

November 30, 2012

Last time I talked about the process of deciding if a reaction goes through SN1, SN2, E1, or E2 as asking a series of questions. I call it The Quick N’ Dirty Guide To SN1/SN2/E1/E2. This is the second instalment. Once we’ve looked at a reaction and recognized that it has the potential for proceeding through SN1/SN2/E1/E2 – that […]

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Elimination Reactions With Rearrangments

November 9, 2012

One last (weird) reaction to show you with respect to elimination reactions. Can you see what’s weird about it? How did that double bond get over there? Normally when elimination occurs, we remove a hydrogen from the carbon adjacent to the leaving group. But here, something extra has taken place. Let’s look at all the bonds that […]

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