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Alkyne Addition Reactions – The “Concerted” Pathway

Alkyne Addition Reactions – The “Concerted” Pathway

June 4, 2013

How does the chemistry of alkynes compare to alkenes? As we’ve seen in some previous posts, there are some significant differences, but a lot of the chemistry “rhymes”, if you will. In the series on …

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Hydroboration of Alkenes

Hydroboration of Alkenes

March 22, 2013

So far in this series on alkenes, we’ve gone through two families of mechanism pathways. In the carbocation pathway, we saw reactions that proceed with “Markovnikov” regioselectivity, a mixture of &#…

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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 fo…

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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 …

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Bromination of Alkenes – How Does It Work?

Bromination of Alkenes – How Does It Work?

March 6, 2013

In a previous post we went through the key reactions of the carbocation pathway. It’s a family of reactions which proceed through 1) attack of an alkene upon an acid, forming a free carbocation, and 2) attack of…

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Addition Reactions: Stereochemistry

Addition Reactions: Stereochemistry

January 30, 2013

In the last post on alkene addition reactions, we discussed one of the two key themes to look for in addition reactions: regiochemistry (in other words – what “region” of the alkene do different ato…

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Addition Reactions: Regioselectivity

Addition Reactions: Regioselectivity

January 28, 2013

In the previous post on addition, we talked about the key pattern of addition reactions [break C-C π, form two new bonds to adjacent carbons] and how this is the exact opposite pattern of elimination reactions we we…

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The E2 Reaction and Cyclohexane Rings

The E2 Reaction and Cyclohexane Rings

October 18, 2012

Last time we compared the E1 and E2 reactions and mentioned one of the key differences was the stereochemistry of the E2 reaction. Remember that in the E2, the leaving group is always “anti” to the hydroge…

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Comparing the E1 and E2 Reactions

Comparing the E1 and E2 Reactions

October 10, 2012

Now that we’ve gone through the mechanisms of the E1 and E2 reactions, let’s take a moment to look at them side by side and compare them. Here’s how each of them work: Here’s what each of these…

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The E2 Mechanism

The E2 Mechanism

September 27, 2012

Having gone through the E1 mechanism for elimination reactions, we’ve accounted for one way in which elimination reactions can occur. However, there’s still another set of data that describes some eliminat…

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