"How Are We Related, Again?" A few weeks ago, at a family reunion in Ontario, I introduced my relatives to the joy of liquid nitrogen ice cream. My cousins were there, as were many of their children. So were a few of my dads' cousins. Being a family reunion, they invited their (grown) children, … [Read more...]
Stereochemistry of the Diels-Alder Reaction
Here's what we've learned about the Diels Alder reaction so far: [previous post in this series] 3 pi bonds are always broken 2 sigma bonds and a pi bond are always formed, resulting in a new six-membered ring electron withdrawing groups on the dienophile increase the reaction … [Read more...]
Optical Purity and Enantiomeric Excess
In our last post on optical rotation, we saw that when Louis Pasteur crystallized a salt of a compound then known as "racemic acid" he discovered that it formed two different types of crystals. When redissolved in water, one set of crystals rotated plane-polarized light clockwise (dextrorotatory, … [Read more...]
Optical Rotation, Optical Activity, and Specific Rotation
As the title suggests, today's post is all about optical rotation, optical activity, and specific rotation. This post was co-authored with Matt Pierce of Organic Chemistry Solutions. Ask Matt about scheduling an online tutoring session here. Here's a quick summary of what we'll cover … [Read more...]
Assigning R/S To Newman Projections (And Converting Newman To Line Diagrams)
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 chiral carbons in a variety of situations, both simple and more complex. So far, all … [Read more...]
Determining R/S (2) – The Method of Dots
This post was co-authored with Matt Pierce of Organic Chemistry Solutions. Ask Matt about scheduling an online tutoring session here. In our first post on the Cahn-Ingold-Prelog (CIP) Rules, we gave a broad overview of how to assign R or S to chiral centers in a molecule. We followed this up … [Read more...]
Introduction to Assigning (R) and (S): The Cahn-Ingold-Prelog Rules
This post was co-authored by Matt Pierce of Organic Chemistry Solutions. Ask Matt about scheduling an online tutoring session here. Previously on MOC we've described enantiomers: molecules that are non-superimposable mirror images of each other. Perhaps the most memorable example is these … [Read more...]
Chiral Allenes And Chiral Axes
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 contain both sigma [ σ] bonding formed through "head-on" orbital overlap [i.e. "single bonds"] and also pi [ … [Read more...]
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