Sn2 E2 and electrophoresis

[Dencology]

what take precedent over SN2 or E2?
also, which moves faster in electrophoresis, protein with a higher molecular weight or with a lower MW? according to destroyer it says that protein with the higher MW moves faster so i am not sure. this just does not make sense! if it talks about comparing the polarity then i understand that the polar molecule moves slower b/c of the polarity. the agar gel is polar so polar molecule with stick it. but what about size?

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[Mstoothlady2012]

what take precedent over SN2 or E2?
also, which moves faster in electrophoresis, protein with a higher molecular weight or with a lower MW? according to destroyer it says that protein with the higher MW moves faster so i am not sure. this just does not make sense! if it talks about comparing the polarity then i understand that the polar molecule moves slower b/c of the polarity. the agar gel is polar so polar molecule with stick it. but what about size?

I don't understand your first question.

For the second question, I thought smaller fragments (lower MW) move faster.

 

[Dencology]

yes. that is what i thought but in destroyer bio #324, 303 in both problems is says that the molecule with the smaller MW stays that the bottom of the agar gel. i am not sure about this? what do you think.

also for the first q. i wanted to know when do you go E2 and when do you go SN2? is is when you have a bulky base we choose E2?

 

[Mstoothlady2012]

yes. that is what i thought but in destroyer bio #324, 303 in both problems is says that the molecule with the smaller MW stays that the bottom of the agar gel. i am not sure about this? what do you think.

also for the first q. i wanted to know when do you go E2 and when do you go SN2? is is when you have a bulky base we choose E2?

sorry but I only have questions upto 278.

Yea you are right! when you have bulky bases, E2 is prefered

 

[PreDent2009]

The smaller fragments are at the bottom of the gel plate because they have moved the furthest.

E2 and SN2 are in competition with eachother when you have a strong base reacting with a alkyl halide, etc. You always look at the E2 products first. If an E2 product is a stable alkene, with 3 C-C bonds around the Double Bond, then elimination will be favored. If there are 2 C-C bonds around the double bond, you will get a mixture of E2 and SN2. This is when reaction conditions make a difference. Heat will force E, while low temp can help favor SN2. If you get 0 or 1 C-C bond around your double bond then SN2 will predominate. The statement about the bulky base is correct as well, it will favor E because of steric hinderance factors.

yes. that is what i thought but in destroyer bio #324, 303 in both problems is says that the molecule with the smaller MW stays that the bottom of the agar gel. i am not sure about this? what do you think.

also for the first q. i wanted to know when do you go E2 and when do you go SN2? is is when you have a bulky base we choose E2?