Detroyer: Org. Chem Question #91!!

[s0chon02]

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Hey guys,

I'm not sure if question 91 is the same on all books since they update it pretty often. Anyways, i'll give it a shot.

On question 91, they rotated the molecule twice in order to have the hydrogen atom pointed away in R-S configuration. I'm kinda lost on the rotation.

Any help would be appreciated!!
🙂

 

[whoaaitzkyle]

I think you're talking about option b right? There's a rule, if the H isn't pointing outwards (with the dash) then what you can do is switch 2 different groups and then look at the configuration again to determine the configuration. Personally, I think it's a heck of a lot easier to just look at the molecule and if the H isn't pointing away from you then if it is R you just assume the opposite.

In your case, question 91, part b if you determine the configuration originally it would be the R configuration. Since you know the Hydrogen isn't pointing away, it is the S configuration. The method they used in the solutions manual is just a technique to use to determine configuration that's all 🙂 Hope that helps!

 

[s0chon02]

Thanks, i see it now.

but what about option a? the hydrogen is not dashed, are they assuing it is pointed away since it's in the back?