Conformations

A Modest Proposal

A Modest Proposal

October 2, 2012

Right around this time of year, tens of thousands of organic chemistry students are learning about the cyclohexane chair. It looks like this: It’s more of a deck chair than a wingback. See why we call it a chair? It’s got a “headrest” and a “footrest”? The cyclohexane chair form is more stable than flat [...]

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Khan Academy for Organic Chemistry – Part 2

September 21, 2012

Khan Academy for Organic Chemistry, Part 2: Bonding, Conformations, and Stereochemistry This second  installment of the guide to Khan Academy organic chemistry videos covers videos 13 to 26, covering the topics of chemical bonding, conformational analysis, and stereochemistry. It also goes into the naming conventions for alkenes. Video #13 Title: “sp3 Hybridized Orbitals And Sigma [...]

Tagged as: cahn-ingold-prelog, chirality, entgegen, isomers, khan academy, newman projections

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How To Do Bond Rotations

How To Do Bond Rotations

July 6, 2012

Bond rotation can be a tricky skill for first timers, and it’s a subject that doesn’t really lend itself to a text-laden blog post. You just have to “see it in action”. This video walks through it using the “steering wheel” analogy. Hope it’s useful to students out there who are having difficulty with this [...]

Tagged as: bond rotations, conformations, stereochemistry, stereoisomers, video

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The Ups and Downs of Cyclohexanes

March 16, 2011

Drawing cyclohexane chair forms can be a tricky business. While it’s often intuitive to pick out which groups are up and down when they’re axial (i.e. pointing straight up or down), it’s tougher for beginners to see that equatorial groups (the ones pointing “somewhat up” or “somewhat down”) can be considered up or down too. [...]

Tagged as: boats, chair flips, chairs, conformations, cyclohexanes, dashes, drawing, steric hindrance, wedges

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The World’s Cheapest Molecular Model Kit

February 11, 2011

I see a lot of students who have trouble visualizing how molecules appear from different directions.  Probably the best way to solve this problem is to buy and practice with a model kit, which really helps to make structures more concrete. However, as much as people like me nag their students to buy (and use) [...]

Tagged as: dashes, model kits, newman projections, rotations, tips, wedges

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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 enantiomer), congratulations. If not, you just fell into The Meso Trap. The Meso Trap is a common feature on exams and tests to [...]

Tagged as: diastereomers, enantiomers, exam tips, exams, exceptions, fischer projection, meso, r/s, rotations, trick questions

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Org 1 Review Quizzes

January 7, 2011

This past semester after every tutorial session I would send an email to my student with a list of topics that we discussed, and then a list of questions intended to stimulate thinking about the key concepts we talked about. I still do this: I think it’s helpful for both me and the student to [...]

Tagged as: help, org 1, problems, quizzes, resources, review

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On Cats, Part 3: Newman Projections

November 22, 2010

Do you know where the saying “there’s more than one way to skin a cat” comes from? Me neither. But I do know one thing: there is more than one way to draw cat conformations. Last time I introduced the Cat Line Diagram and showed how we can use it to depict these 3-dimensional creatures [...]

Tagged as: cats, conformations, eclipsed, newman proejctions, rotation, staggered, stereocenters

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On Cats, Part 2: Cat Line Diagrams

November 15, 2010

When this blog was about organic chemistry, I’d never stoop so low as to put cute pictures of cats on my website to drive traffic. Now that it’s all about cat science, I’ve lost any compunctions I might have had earlier.  Want gratuitous cat pictures? You bet. Introducing the Cat Line Diagram But this blog [...]

Tagged as: cat line diagram, cats, configuration, constitutional, fun, isomers, rotation

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On Cats, Part 1: Conformations and Configurations

November 11, 2010

[NOTE: this has been amended to correct some confusion on my part on the difference between configurational and constitutional isocats. Thanks to Prof. Gary Weisman (UNH) for making me aware of the error] As I said earlier, I’ve given up writing about organic chemistry. If you’re expecting to read a post about concepts in organic [...]

Tagged as: cats, configurational, configurations, conformations, constitutional, fun, isomers

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