Predicting the outcome of an “opposite side attack” SN2 reaction can be confusing at first, but animations can help. Check out the SN2 animation at chemtube3D.com. To operate the animation, find the drawing of the chemical reaction and click on the forward reaction arrow.
Try to understand the simple reaction from multiple perspectives: 1) the C seems to push its way through its 3 H neighbors to get from leaving group to nucleophile, OR 2) the 3 H neighbors seem to back away from the approaching nucleophile and move to the leaving group’s side of the molecule. You can rotate the animation as it plays so that you can see it from different angles.
Another SN2 animation to watch: HS(-) + (S)-PhCHClCH3
The models you need can be downloaded here:
Click on the link to download a Spartan EDF2/6-31G** model of ethanol monomer and ethanol dimer. The models have been combined in a single file (a ‘list’ model) and they already contain calculated IR spectra, so do not replace them with SSPD models.
Note: the IR frequencies in these models are unscaled and do not reproduce experimental values.
Computers – source of endless entertainment or endless drudgery? A little of both, right.
Why not turn your computer into a mood enhancer by making some music with the Tonematrix audio tool. 2 minutes will put you in another world. And who knows? When you come back to our world, you might be just a little more able to dip into organic chemistry. Or become the next Philip Glass.
This post has nothing to do with o chem, but you have a long weekend ahead of you and I don’t want you miss something really special: the swarming and roosting of 5000+ small Vaux swifts in the Chapman School chimney in NW Portland. This is one of the best FREE displays of urban wildlife you will ever see (and you don’t need binoculars).
Fortunately, the timing and location are perfect for Reed students. Head towards the Chapman Elementary school in NW Portland (#15 Bus will get you very close) on any night in early-mid September. Arrive about 30-60 minutes before sunset (7:00-7:30 arrival during Labor Day weekend) if you are just going to see the birds. Arrive a little earlier if you plan to bring a picnic, a ball or frisbee, and hang out in the park next to the school. The birds put on their show according to a timing that only they know so don’t be late (Wed, Sept 2, they were all settled in the chimney by 8:10. Thurs they were finished 10 minutes earlier.) The warm late-summer evenings are perfect for an outdoors off-campus adventure.
This event is not to be missed
- Directions: The chimney is located at the west end (hilly side) of Chapman Elementary school. The school is located next to Wallace Park on NW 25th between NW Pettygrove & NW Raleigh. After you see the swifts, you can walk over to NW 23rd for dessert – many many establishments will be happy to serve you between 8-10 PM. Map
- Best viewing: Get there about 20 minutes before sunset and watch the birds collect and feed. It takes awhile for all of them to go into the chimney so you’ll be there after sunset (full moon tonite). Most people watch from the hillside on NW Pettygrove, and it can get kind of noisy, so be considerate to the neighbors who live nearby.
Learn more at Swift Watch – Portland Audubon
Nearly all of the lab reports have been graded so you can expect to see graded lab reports turning up in your inbox over the next week or so.
The lab reports contain three grades: notebook, lab work, report. 99+% of the lab work grades were satisfactory, but this was not the case for notebook and report grades.
Because unsatisfactory grades on notebooks/reports were fairly frequent, and because it is natural to assume the worst concerning such grades, I want to clear up any concerns that you might have about unsatisfactory marks.
This lab experiment lasts 3 weeks. Students finished varying amounts of lab work during the first week so planning the remaining work is a little complicated. I’ve written up a two-page set of instructions to guide you. Please read this well ahead of your lab day and prepare accordingly.
General anesthetics, the chemicals that temporarily ‘put you under,’ have transformed surgery, but doctors and scientists are still learning how these chemicals work. Continue reading
I saw this article (C&ENews, 12 Oct 2015, p. 38) about the molecules that make Halloween pumpkins look and taste and smell the way they do:
There seems to be a little confusion about how to interpret your experimental IR spectra and how to use Spartan’s calculated spectrum. I hope the following will help clarify things a little (I recall that I had to interpret about 30-40 IR spectra as a student over a couple of years before this began to feel routine):