[aspiringphysician]

For the questions in the attached picture, the answer key states that both of the answers are "A", but I don't understand exactly why. I would appreciate it if someone would explain to me why one alkoxide/halide pair is preferred over the other to make the target ether. Does it have to do with nucleophilicity? I'm very confused!  Thanks in advance! 

[Babcock_Hall]

What do you recall about good versus poor electrophiles in SN2 reactions?

[aspiringphysician]

What do you recall about good versus poor electrophiles in SN2 reactions?

In SN2 reactions, the less substituted the electrophile (substrate), the better it is, so a primary electrophile is a "better" electrophile than a tertiary one, is that correct?

[Babcock_Hall]

That is true, and there are side reactions possible with tertiary alkyl iodides.  A second thing to consider is the geometry of the transition state in the SN2 process, which is that the ideal angle between the nucleophile and the leaving group is 180 degrees.  See if you can apply this to one of the syntheses.

[aspiringphysician]

That is true, and there are side reactions possible with tertiary alkyl iodides.  A second thing to consider is the geometry of the transition state in the SN2 process, which is that the ideal angle between the nucleophile and the leaving group is 180 degrees.  See if you can apply this to one of the syntheses.

Ooohhh...that explains a lot! I think I get it now...thanks so much!