stereochemistry switches r/s configuration 2010 destroyer problem

[yankeefan86]

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Ok I was looking at the other thread about configurations and I thought I understood it, but after doing a problem in destroyer I clearly don't. I understand which groups have priority in R and S. What I don't understand is why we have to "switch." Is the switching so we don't skip over atoms in determining r and s? Need major help. Preferably on 2010 destroyer problem #130. Or is someone can make a good diagram with microsoft paint or something that would be awesome!!! 😎

 

[RCLEE]

What do you mean by "switch?"

Configuration will change from R to S in an Sn2 rxn because of rear end attack.

If you meant switching by rotation or flipping over by 180 degrees, then that's a different story.

I think the switch meaning that switch from R to S configuration because the "Lowest priority" is not in the vertical orientation (fisher's projection). H should be on top or bottom in order to retain its configuration. If H is on the left or right side, then you will have to switch the configuration. This is due to the fact that the Newman? projection and the fisher's projections rule. You imagine for example to have both of your hands hold on to the left and right arms of the cross and those will point toward you (out of the page). The top and bottom into the page.

Remember that H should always be pointed away from you. If H is on the left or right of the Fishers projection, then H is toward you; therefore, your configuration should be switched.

 

[bharat008]

Ok I was looking at the other thread about configurations and I thought I understood it, but after doing a problem in destroyer I clearly don't. I understand which groups have priority in R and S. What I don't understand is why we have to "switch." Is the switching so we don't skip over atoms in determining r and s? Need major help. Preferably on 2010 destroyer problem #130. Or is someone can make a good diagram with microsoft paint or something that would be awesome!!! 😎

It would be great if you could scan it and post it here..
I don't have 2010 destroyer so can't help u unless u post the pic..👎thumbdown