http://www.chem.uic.edu/web1/OCOL-II/WIN/STEREO.HTM

http://www.cliffsnotes.com/WileyCDA/Cliffs...rticleId-22667.html

Here's plenty of stereo practice and review for everyone on these sites.

Good luck tommorow morning everybody.

Ty - you have to consider whether the reverse reaction is a viable process. Think about the acid-base reactions and how relative stability on both sides dictated whether the reaction was reversible or not. You'll see plenty more about how to figure that out next term and I won't expect too much this semester.

Chris - you crafty old bugger, posting from beyond the grave again eh? You'll have to teach me that trick for future reference. If it isn't R, it's S, words to live by. Good lad.

For S & R ..what would be higher priority a carbon attached to another carbon and OH or a carbon attached to 3 carbons?

Kara - the C-OH would win. Have a look at Table 5.1 in the book, which is where we first encountered these rules. Some good examples there.

As far as describing the stereochemical outcome or the optical rotation there is quite a bit of info on the exam answer key. Would it be alright to just talk about the main points or do you want the answer in detail as it is on the answer sheet

dr. norris, as i'm doing the practice tests, when we have to draw the structures, there are different ways in which to write those compared to what you have on the answer key, correct?

Alan - good point. My answer keys are an attempt to answer the exam questions but to also provide enough information to future generations (i.e. you) about where those answers come from. Diagrams really help cut down the amount of writing that you need to do on a test, however a few judicious words can help complete the answer without having to write an essay.

Ochem - we saw in Chapters 3 and 7 that there are many ways of writing or drawing the same molecule depending upon the angle at which you are looking so yes, your depiction may be be quite different to the one shown in the answer key but may be equally correct.

Dr Norris, the only question I have is concerned with Exam 3 from 2006 (question 6.e): how are the ketone substituents formed from the water and zinc molecules?

why on exam 3 from 2006, question 6a, the Na is attached to the first reaction product, but on exam 3 from 2007, question 2f,the first reaction product is an anion? would it be wrong if we attached the Na?

Zane - we don't cover the mechanism for that step. It actually involves Zn metal dumping in 2 electrons to the malozonide, protonation from water, then collapse to the ketone products, but it's dull so we don't draw a mechanism.

Anon1 - the Na is a spectator ion an displays no role in he organic chemistry there so we usually ignore it. There's a lot more to worry about than Na+ at this stage.

Dr. Norris, Going by the same train of thought in the response to Lauren's question about 2007 4C. On the same exam, question 3c, why is the second carbon (with the methyl group facing you)given an R designation? If the C attached to the OH group is 1, the C attached to the methyl is 2, and the CH2 in the cycle is 3, with the H facing away from you, should it not be S?

Ken - the C with the O attached is 1, the CH2 of the ring is 2, the CH3 is 3, it works out to be R.

Well, that's it from me. Good luck tomorrow.

To clear the head -

http://www.youtube.com/watch?v=X4mxsIAziRQ