[brizznook]

I'm going through some problems in my Organic Book and I'm having trouble differentiating between the Sn2 and E2 reactions when it comes to secondary carbons.

The question I am looking at specifically is:

Give the product when (2R)-2-hexonal undergoes a series of rxns.

First with TsCl and pyridine. This one I can follow. The Ts bonds to the Oxygen to form a good leaving group and the pyridine strips the Hydrogen from the oxygen.

The next is with methoxide anion, CH30-.

I'm having trouble seeing why it doesn't undergo both Sn2 and E2 rxns and give a mixture, as my book says only the Sn2 product is formed. I'm thinking it should be a mixture because the alcohol is on a secondary carbon and as far as I know, -OCH3 is a nucleophile and a base. If I am incorrect on the nucleophile vs. base, could someone please explain to me why?

Note: It gives no solvent for the second reaction.

[orgopete]

Complicated question. Why does your textbook only give SN2 product? I'm guessing your book is concentrating a discussion of SN2 reactions so elimination reactions have been overlooked. I am only guessing. If your book indicated the reaction gave a 93% yield of (2S)-product, then I'm wrong.

If you were using Brown, Foote, and Iverson, then their rule of thumb that bases with a pKa of greater than 12 (of the conjugate acid), give elimination. If that rule of thumb were applied, then elimination would be expected. I don' know what the product is. I would expect both. Can anyone look up this or a similar example to test my theory?

[brizznook]

You know, I'm not entirely sure. The problem must be focusing on it, although it is in a section about alcohol reactions with various different compounds so I was expecting it to be a mixture. I just wanted to make sure I wasn't crazy essentially.