[miss_molecule]

Hi!

I am trying to figure out the chemical shifts for 2-(2-methyl-1,3-dioxolan-2-yl)-1,1-diphenylethanol. The aromatic region confuses me... I have found this formula:

d=7.26+Rorto+Rmeta+Rpara

but the substituent in this case is so complex that none of my tables can help me. I have a C-atom bond to a benzen ring, an alcohol, and an R-group... So which value should I use??

I also try to figure out the coupling trees. I have found the answear online, but I don't want to just copy the answear, I want to understand it... Anyone able to explain it for me?

Then I have one last question: I thought the hydrogens on the ketal would appear as one singlet, but they turned up as two octets! Does this have something to do with the benzene rings? Or did I do something wrong in the lab?

[Squirmy]

Re: the CH2's of your ketal, I suggest reading up on diastereotopic hydrogens...see http://en.wikipedia.org/wiki/Topicity for a discussion. See if you can figure out how this applies to your structure.

Re: splitting trees, there's a nice paper by Hoye (Journal of Organic Chemistry, 1994, 4096) that gives representations of the common splitting patterns, with varying J-values. There is some discussion of creating inverted splitting trees (taking a signal in the spectrum and figuring out the tree that created the splitting pattern). However, I've used that paper more for visual comparison of my splitting patterns with the representative ones.

If you don't have access to JOC, you can probably Google "Hoye Splitting Pattern", it should be the first link.