Conformations

s-cis and s-trans

s-cis and s-trans

May 12, 2017

s-cis and s-trans. What does those terms mean? Recall cis and trans. The reason Aldrich Chemical Co. can sell 99% cis-2-butene and 99% trans-2-butene in separate bottles is because of restricted rotation about the …

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Assigning R/S To Newman Projections (And Converting Newman To Line Diagrams)

Assigning R/S To Newman Projections (And Converting Newman To Line Diagrams)

February 1, 2017

This post was co-authored with Matt Pierce of Organic Chemistry Solutions.  Ask Matt about scheduling an online tutoring session here. In two recent posts we discussed how to assign (R/S) to configurations of chir…

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Fused Rings

Fused Rings

August 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…

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Which Cyclohexane Chair Is Of Lower Energy?

Which Cyclohexane Chair Is Of Lower Energy?

July 23, 2014

In the last post, we introduced A values and said they were a useful tool for determining which groups are “bulkiest” on a cyclohexane ring. The greater the A-value (bulk), the more favoured the equatorial…

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Substituted Cyclohexanes:  “A Values”

Substituted Cyclohexanes: “A Values”

July 1, 2014

In the last post we saw that adding a methyl group to cyclohexane results in two chair conformers that are unequal in energy. We saw that the conformer where the methyl group was equatorial is the most stable, sinc…

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Substituted Cyclohexanes – Equatorial vs Axial

Substituted Cyclohexanes – Equatorial vs Axial

June 27, 2014

Just to bring you up to speed, here’s what we mentioned in the last post. At the bottom, I’ll also correct a little fib I made. 1. Cyclohexane, at room temperature, undergoes a conformational interconversion known…

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The Cyclohexane Chair Flip – Energy Diagram

The Cyclohexane Chair Flip – Energy Diagram

June 6, 2014

In the last post,  we showed a video of  a cyclohexane ring flip – turning a cyclohexane chair conformation into a boat and then into the opposite chair. The key observation we made here was that a chair flip …

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The Cyclohexane Chair Flip

The Cyclohexane Chair Flip

May 30, 2014

In our last post, an aerial tour of the cyclohexane chair, we showed that there are two different positions a substituting can occupy on a cyclohexane chair – axial (straight up and down, relative to the ring) a…

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How To Draw A Cyclohexane Chair

How To Draw A Cyclohexane Chair

May 20, 2014

Now that we’ve had an aerial tour of the cyclohexane chair, we’re going to move on to a very important skill: how to properly draw one of these beasties. This takes practice. Your first few attempts in dr…

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An Aerial Tour Of The Cyclohexane Chair

An Aerial Tour Of The Cyclohexane Chair

May 14, 2014

  When I first learned about the cyclohexane chair (as we did in the last post) I was in denial about its importance in organic chemistry. From an aesthetic standpoint, it bothered me that cyclohexane wasn’…

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