Chem 201 Archive – Alan Shusterman

Month: November 2013

  • “Like ketchup on sushi”

    Reed chemistry alum and medical school student, Hassan Ghani ’08, just sent me this story from yesterday’s NY Times, “How to get an A- in Organic Chemistry” by Barbara Moran. Like so many others, Ms. Moran has decided a mid-life career change is in order, but her search for professional fulfillment has taken an unusual tack: at the tender age of 42, and with parental responsibilities for two small children, she finds herself enrolled in organic chemistry so that she can become a doctor.

    Her story about the joys of “orgo” includes observations on the necessity of mastering electron pushing (draw a “zillion” curved arrows and you will eventually develop the kind of “intuition” that makes a poorly placed arrow seem as unpleasant as “ketchup on sushi”), similarities in the type of reasoning (“inductive generalization”) used by organic chemists and doctors, and the all-important life lesson that, even though our life compass points towards the Land of Perfection, it is not a place that we can ever visit.

  • Some tips for Exam 3

    As you prepare for Exam 3, make sure that you learn to quickly identify the roles that different molecules might play in a chemical reaction. The sooner you can decide that a molecule is probably an acid (or base, nucleophile, electrophile, solvent), and that certain atoms in the molecule are proton donors (or proton acceptors, electron donors, electron acceptors, or leaving groups), the sooner you can move on to solving the problem.

    Lists of acidic functional groups have been provided, but how efficiently can you recognize basic functional groups? How about nucleophiles? (Sorrell Tables 6.2 & 6.3) Or aprotic and protic solvents? (Sorrell Figure 6.7) Sorrell’s chapters often end with a useful Reaction Summary (see p. 233-4). Here’s a link to a summary that I handed out to students in 2012. A tip for the future: as you study (this means work an activity, read the book, …), you should build your own summary of ‘things to know’. It isn’t enough to answer a couple of questions that illustrate a principle like primary RX react with Nu faster than secondary RX. You need to summarize this principle for yourself.

    Mitsunobu Reaction. I didn’t say much about this reaction in class because I ran out of time, but you need to know the reaction (i.e., know how to ‘predict-plan-explain‘) for the next exam. You don’t need to know all of the subtleties of its mechanism, however. Just focus on these 3 points: What is the nucleophilic substitution step, SN1 or SN2? What is the ionization state of the Nu? What is the leaving group? There is considerable disagreement about the details of the mechanism, e.g., the steps leading to the formation of an OPPh3 leaving group. If you’re interested, compare Sorrell’s (poorly drawn) mechanism with alternative (and more plausible) mechanisms presented in Wikipedia and at the Organic Chemistry Portal.

  • NMR & IR slides from lab lecture

    A few of you were unable to attend last night’s lab lecture. Here are slides from the lab lecture (bonus prize: GC data for a ‘standard’ mixture of isopentyl alcohol and isopentyl acetate):