Stereochemistry

Chiral Allenes And Chiral Axes

Chiral Allenes And Chiral AxesJanuary 13, 2015

We’ve met alkenes before – right? Just in case you haven’t, let’s review the basics, because today’s post is going to depend on understanding a few of the most important concepts. Alkenes…

Bridged Bicyclic Rings (And How To Name Them)

Bridged Bicyclic Rings (And How To Name Them)August 14, 2014

In the last post we started our discussion of structures with more than one ring, using decalin as our key example. We saw how much the stereochemistry at the ring junction can affect the overall shape of the molecul…

Fused Rings

Fused RingsAugust 5, 2014

At the beginning of this series I said that the fact that carbon can form rings leads to all kinds of interesting consequences. We’re going to see many examples of that in our post today! So far, we’ve on…

Cycloalkanes – Dashes And Wedges

Cycloalkanes – Dashes And WedgesMarch 20, 2014

In the last post, we mentioned that one of the consequences of the fact that carbon can form rings is that small rings (less than 8 carbons) are so rigid that they can’t be turned inside out [video]. One of the …

Partial Reduction of Alkynes

Partial Reduction of AlkynesMay 8, 2013

Alkynes bear many similarities to alkenes, but as we have already seen, their chemistry can differ in subtle and interesting ways. Today’s post is another case in point. The reduction of alkenes by hydrogen in …

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…

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…

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 …

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…

Markovnikov’s Rule (2) – Why It Works

Markovnikov’s Rule (2) – Why It WorksFebruary 11, 2013

Understanding Why Markovnikov’s Rule Works Let’s assemble all the facts we know about the reactions of alkenes with an acid like HCl so far. Regiochemistry: as we saw in the last post, reactions of alkenes…