[alison]

I am attempting to study for a final and cannot figure out these practice synthesis problems in spite of my best efforts, does anyone have ideas...all begin with a benzene ring and all require multiple steps.
1) product = benzene ring with sec-butanol attached to it
- however the benzene ring has the double bonds in the resonance structure on the original
- I was thinking just do friedel-crafts alkylation, but then there is no rearrangement in the ring...
2) product = benzene with NO₂ in the 1 position 3 position and 5 position, also there is a CH₃ in the 4 position
- if i add CH₃ again using friedel-crafts, can i do then do nitration w/ 3 eq.? HNO₃/H₂SO₄, this would put everything in the correct ortho/para/meta positions, but I've never seen that done w/ 3 eq. and it doesn't seem right
Last one, starting w/ a 1-methylcyclohexene the product is 2-ethylnonan-2,7-ol (okay I'm bad with nomenclature so there are 9 carbons, and on the 2nd carbon there is an ethyl and an OH, and on the 7th carbon there is an OH).  THis has something to do with Oxidation but if I oxidize with O₃/ HOOH  I still have the double bonds and no extra carbons.
Another totally unrelated question regarding thermodynamics and kinetics in 1,2 and 1,4 reactions like HBr or Br₂.  We are told we cannot go simply by temperature (made that mistake on the last test) to determine the product.  However, is it that the more substitated product will form in greater quantities at higher temperatures, and the least substituated will form in greater quantities at lower temperatures regardless of the 1,2 and 1,4 positions?  From there one can figure out the kinetic or thermodynamic control?
Sorry for the vast amount of questions, any help would be appreciated...

[azmanam]

1) remember - different resonance structures are not individual structures that can be isolated.  the real structure is a hybrid of the various resonance structures.  So if the double bonds are in a different place in the product than you expect, is this necessarily wrong?  are they even necessarily different compounds?

2) I don't think there's anything wrong with this.  do you know what you're making in this synthesis?

3) what is the product when you oxidize with O₃?  You're right that there will still be double bonds, but they're in different places now.  What functional groups will you get after oxidation with O₃?  Only 1 more step is needed after that to get to the product.

4) You can't generalize like that.  It will depend on the specific reaction and reaction conditions used.

[alison]

For #3) I get hexane with double bonded OH and ethane on C1 and double bonded OH on C6, I am still lost!  I also have CO2 and H2O as by-products of the reactions yes?  If I did a Br2 reaction that would give me the additional Cs that I needed on C6, then I don't know what to do with the Br, if I used H+, that would completely take away the OH leaving just single bonds.  Really, I'm just out of ideas here!

[azmanam]

Let me make sure we're both talking about the same transformation before I start giving you misinformation.  Have I drawn the overall transformation correctly below?  And in the op, you mentioned using O₃ as the first step.  In your most recent post, are you describing the structure I have in the bottom reaction?  The overall transformation is correct, but there is no proton on oxygen (oxygen would have a formal positive charge if it did) and there is only a methyl group on "C1".

you can read about ozonolysis here
http://www.cem.msu.edu/~reusch/VirtTxtJml/addene2.htm#add4d

I like ozonolysis as the first step.  Now that we have the correct product of the ozonolysis, what needs to happen to get to the end?  How many carbons, and with what connectivity, do we need to add to get to the product?  Do you know what reaction we need to use to get there?

[alison]

Okay, well that is better, for some reason I think I was attempting (wrongly at that) to do oxidative ozonolysis instead of Ox/reduc.  Anyways, now that is cleared up...it is apparent that I need to add 2 ethyl groups to each side.  So, ahh, no idea, I can do this on the aromatic ring I think, but then oxidation wouldn't be the 1st step...I would add one ethyl with friedel crafts to get it on the carbon with solely the ethyl attached, and then hmm to get the 2nd ethyl...do the same borrowing an H from the methyl in order to make it work?  Then do ozonolysis?  Then I could just rearrange the double bond and use H3O+ to add the H?  How off base am I now?

[azmanam]

start here:

http://www.cem.msu.edu/~reusch/VirtTxtJml/aldket1.htm

[alison]

We really haven't learned any of that except the Grignard....I admit defeat on this question.  Thank you for all of your help and time, it has helped me get my bearings somewhat.

[azmanam]

ok.  we can make the grignard work.  do you see how?

[alison]

2 eq. of CH₂CH₃-MgBr in ether, then use H₃O⁺ to pull the MgBr off the O?

[azmanam]

yup.  good work

[alison]

Thanks for sticking with me!