enantiomers

Optical Rotation, Optical Activity, and Specific Rotation

February 7, 2017

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…

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What’s a Racemic Mixture?

What’s a Racemic Mixture?

May 23, 2012

What do you notice about these three pictures? Count the number of left gloves and right gloves.  6 left and 6 right gloves, correct? What about this one: I count 8 right gloves, 4 left gloves. So there’s a sli…

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The Single Swap Rule

The Single Swap Rule

January 24, 2011

I don’t think there are that many “tricks” to doing well in organic chemistry, but there are a few. I was kind of surprised last month when I talked to a number of students who hadn’t ever come…

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The Meso Trap

The Meso Trap

January 12, 2011

Question: Are these molecules enantiomers, diastereomers, or the same? If you immediately recognized this as a molecule with an internal plane of symmetry (and thus an achiral molecule, incapable of having an enantiom…

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On Cats, Part 8: Moe the Meso Cat

On Cats, Part 8: Moe the Meso Cat

December 24, 2010

I got a very excited call from Walter yesterday. He was looking out the window of his apartment in Talbieh and spied a freaky looking cat with each of his two heads buried in a separate dumpster, happily chewing on so…

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On Cats, Part 7: The Fischer Projection

On Cats, Part 7: The Fischer Projection

December 22, 2010

Last weekend while parts of North America and Europe were getting buried in snow,  my wife and I went to Tel Aviv to pick up some gifts and dip our feet in the sea one last time. There are worse ways to spend a weeke…

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On Cats, Part 6: Stereocenters

On Cats, Part 6: Stereocenters

December 15, 2010

Let’s recap what we’ve talked about so far. Sawhorse cat and Freaky Sawhorse cat are constitutional isocats. But Freaky Sawhorse Cat has a mirror image of himself crawling around somewhere – a cat t…

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On Cats, Part 5: Enantiocats vs. Diastereocats

On Cats, Part 5: Enantiocats vs. Diastereocats

December 6, 2010

I was out for a walk the other day and I saw 3 of the weirdest/ugliest looking cats I’d ever seen.Even weirder than Freaky Sawhorse cat. Luckily I got pictures because nobody would believe me if I described them…

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Ephedrine and Pseudoephedrine

Ephedrine and Pseudoephedrine

May 26, 2010

These molecules make the news quite a bit. Some questions to think about: What’s the (R),(S) designation for the stereocenters of ephedrine and pseudoephedrine, as drawn? What’s best way to describe the re…

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A simple trick: The (R)-(S) Toggle

A simple trick: The (R)-(S) Toggle

March 13, 2010

Instead of redrawing the whole molecule, just leave the hydrogen (or other 4th ranked substituent) in front and figure out whether the substituents ranked 1,2, and 3 go clockwise or counterclockwise. Then toggle (i.…

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