HNMR and Synthesis Need Some Help Please!

[Pyar]

1.. Look at the H which has the arrow pointed to it, and find the number of peaks in the signal:

http://img10.imageshack.us/my.php?image=118awin09ps3q4.png

 

I need help with A and D.

 

For A, I can't tell whether it's a nonet (so eight H neighbors+1= 9 peaks=nonet)

or whether it's a quartet (just take one methyl group so 3+1= quarter= 4 peaks)

or whether you just take one methyl group since the other one is in the same env't and then also take that CH2 group..so (3+2 then +1= sextet= six peaks)?

 

For D: there's symmetry so do you look at only one CH2 group so 3 peaks (triplet)

OR do you count both neighbors, so 4+1= pentet

 

 

2. What is the last reagent? I need four and I have 1. BR2 2. NaOAc 3. NaOH but for 4. I don’t know what it would be.

http://img23.imageshack.us/my.php?image=118awin09ps3q5.png

 

3. What are the four reagents used (it has to be in order):

http://img23.imageshack.us/my.php?image=ques10.png

 

Perhaps it's 1. CH3CH2CH2Li 2. PBr3 3. CH3COONa... but what's the 4th reagent? I don't know whether my answers or order is right either.

 

 

 

Finding major products:

 

4. What are the major products?

http://img293.imageshack.us/my.php?image=118awin09ps3q7.png

 

How is it C?

 

5. What are the major products?

http://img23.imageshack.us/my.php?image=118awin09ps3q8.png

 

How is it E?

 

 

6. What are the major products?

http://img166.imageshack.us/my.php?image=118awin09ps3q9.png

 

How is it D?

 

 

7. What are the major products?

http://img232.imageshack.us/my.php?image=118awin09ps3q10.png

 

How is it C? What about D?

 

I have no idea how to do 4-7. Something to do with SN1/SN2? Could someone please help me get the answers?

 

 

Thank you!

[UC]

Yeesh, lots of questions. For proton NMR spectra, all you need to consider are 1: how many equivalent hydrogen are there for the peak (gives the integration, this is where symmetry matters) and how many hydrogen is it coupled to (ignore hydrogen attached to the same carbon, symmetry does not matter).You're first guess is correct, in that it is coupled to 8 hydrogens and thus is a nonet.

 

For part D, you do need to count both methylene groups and thus you have a pentet.

 

For questions 2 and 3, I want you to tell me why you are picking the reagents you picked. what does each do? what are the intermediate products?

 

For 4, because acidified dichromate is a *powerful* oxidant. You can make aldehydes with dichromates, but it's fairly tricky.

 

For 5, http://upload.wikimedia.org/wikipedia/commons/b/b9/PBr3_alcohol_rxn.jpg What kind of mechanism is that and what does it do to stereochemistry?

 

For 6, because neopentyl groups are so hindered that they don't really undergo SN2 reactions. The alternative is SN1, which involves a carbocation and alkyl shifts can occur.

 

For 7, look up zaitsev's rule.