[lrw281]

Just a bit stuck on this set of questions, any guidance would be great:
Oxidation of cis-4-tertbutylcyclohexanol to 4-tert-butylcyclohexanone proceeds faster than the corresponding trans isomer. Account for the difference in rates and suggest the rate-determining step.
Jones oxidation - RDS is loss of hydrogen and chromate group. As for why the cis isomer is faster - strain in the axial alcohol is relieved in forming the corresponding ketone. Also maybe the greater accessibility of the equatorial hydrogen?

How could you confirm the RDS using labelling experiments. Draw the molecules you would use and propose syntheses from 4-tertbutylcyclohexanone (reagents and conditions, mechanisms not required)
Substitute the hydrogen for deuterium (one attached to same carbon as -OH group) if the C-D bond is broken during the rate-determining step, primary kinetic isotope effects will be observed.
Not clear on how I would make deuterium substituted 4-tertbutylcyclohexanol from 4-tertbutylcyclohexanone. If I used LiAlH₄ and them D₂O this would put the deuterium on the oxygen.

Under acidic conditions of chromic acid oxidation reaction E2 elimination is a significant side reaction. Would you expect cis- or trans-4-tertbutylcyclohexanol would you expect to undergo elimination faster?
Is this not the same answer as to the first question?

[lrw281]

Or is the last question the dehydration of the alcohol to form an alkene due to the acid used? And the trans isomer would proceed faster because it's more stable? The question after that is to suggest non-metal based oxidising agents that could accomplish this transformation which confuses me and I'm sure I'm just being stupid here.

[C-hemCards]

Those are very good questions about the Jones oxidation.

For the second question, reagents like LiAlD4 and NaBD4 are relatively easy to come by.

The third question is a question about stereoelectronics. Consider the required orientation of a proton and leaving group and then look at the two chromate ester intermediates.

There are several non-metal based oxidation reactions out there. As a hint, many of them use DMSO.

[zsinger]

DMSO and Oxalyl chloride....investigate !!!!!

    -Zack

[lrw281]

Thanks! So would the cis isomer undergo the elimination faster as in the the intermediate the chromate group is anti periplanar to a hydrogen, and in the trans isomer it isn't?

[AlphaScent]

Swern stinks...

[orgopete]

Thanks! So would the cis isomer undergo the elimination faster as in the the intermediate the chromate group is anti periplanar to a hydrogen, and in the trans isomer it isn't?

That would be my guess.

[zsinger]

Alpha,
Swern is HORRIBLE, but necessary in some instances.
       -Zack