Borohydride Reduction of Camphor

oxidation

loss of electron density on carbon

reduction

gain of electron density on carbon

what occurs during redox rxns?

loss of H on carbon or cleavage of a C-O, C-N, or C-X bond (oxidation)

gain of H on a carbon or cleavage of a C-O, C-N, or C-X bond (reduction)

what are the 2 common reductants?

LiAlH4/Lithium Aluminum Hydride (LAH) and NaBH4/Sodium Borohydride

LiAlH4 characteristics

the hydride (H-) is added to the carbonyl and is very powerful indiscriminate reduction

NaBH4

the hydride (H-) is added to the carbonyl and is mild only reducing aldehydes and ketones

what steps were used when doing the reduction of camphor?

1. reduction

2. isolation

3. recrystallization mixed-solvent

4. IR, TLC, and NMR (analysis)

what must u keep a mind on w/the reduction of camphor?

steric hinderance

what does exo addition of camphor give?

the endo product, borneol

what does endo addition of camphor give?

the exo product, isoborneol

what’s the difference be the endo and exo product of camphor ?

endo has H in the equatorial position and exo has H in the axial position

how does the NaBH4 attack camphor during an exo addition ?

it attacks from the top to break the carbonyl

how does the NaBH4 attack camphor during an endo addition ?

it attacks from the carbonyl from the bottom

what is the minor product for the reduction of camphor?

borneol (endo product)

what is the major product for the reduction of camphor?

isoborneol (exo product)

diastereotopic protons are…

essentially the same compound but chemically different

what is the 1H NMR shift of borneol and isoborneol’s diastereotopic protons?

borneol’s is 4.00 ppm and isoborneol’s is 3.61 ppm

what factors can be determined with functional group stretches for the reduction of camphor?

carbonyl and Oh stretched are very distinct being a 1715 cm^-1 sharp peak vs a 3500 cm^-1 broad peak

what factors can be determined with NMR chemical environment for the reduction of camphor?

the ratio of isoborneol and borneol 1H as well as the carbonyl and C-OH peaks

what is the C13 ppm for carbonyl in camphor?

200 ppm

what is the C13 ppm for the OH in isoborneol/ borneol?

60 ppm