AlkeneCC

Summary: Alkene Reaction Pathways

Summary: Alkene Reaction PathwaysApril 25, 2013

In this post we’ll do a final review of alkene addition reactions and sum up the three major pathways (and two minor classes of reactions worth paying attention to). Reaction Pathway #1 – The Carbocation P…

Alkene Reactions: Ozonolysis

Alkene Reactions: OzonolysisApril 23, 2013

Today’s post represents not so much a pattern in alkene reactions, so much as it does a very common reaction that bears mentioning along with the rest. What makes this reaction special is that it does not simpl…

A Fourth Alkene Addition Pattern – Free Radical Addition

A Fourth Alkene Addition Pattern – Free Radical AdditionApril 12, 2013

I’ve written that there are three major alkene reactivity patterns [carbocation, three membered ring, and concerted], but there are two minor pathways as well. This post discusses one of them. As discussed previ…

An Arrow-Pushing Dilemma In Concerted Reactions

An Arrow-Pushing Dilemma In Concerted ReactionsApril 5, 2013

Up to now, drawing out reaction mechanisms using the curved arrow formalism has been fairly straightforward. Yes, sometimes there is some ambiguity with respect to which carbon of a C-C π bond is forming a new bond …

Alkene Addition Pattern #3: The “Concerted” Pathway

Alkene Addition Pattern #3: The “Concerted” PathwayApril 2, 2013

In contrast to alkene addition reactions in the Carbocation Pathway and the 3-Membered Ring Pathway, we saw in the last two posts that hydroboration of alkenes is anomalous. The regioselectivity of the reaction is …

Hydroboration of Alkenes: The Mechanism

Hydroboration of Alkenes: The MechanismMarch 28, 2013

In the last post we saw that the results of hydroboration of alkenes are not in accord with any of the two families of mechanisms we’ve previously seen (carbocation pathway, 3-membered ring pathway). With hydrob…

Hydroboration of Alkenes

Hydroboration of AlkenesMarch 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 &#…

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

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

Bromination of Alkenes: The Mechanism

Bromination of Alkenes: The MechanismMarch 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 …

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…