Question

1. Write out the balanced equation for the oxidation of hydrobromic acid by hydrogen peroxide.
2. How many stereoisomers of stilbene dibromide can exist?
3. A possible definition of a meso compound is: “while possessing 2 or more assignable
stereocenters, a meso compound is superimposable (identical to) its mirror image in at least
one conformation”. In other words, it is identical to its would-be enantiomer except for the fact
that the molecule contains… what? What physical characteristic arises in meso compounds
that results in the above definition?
4. Let us assume a cut-and-dry, black-and-white case that the mechanism does only one of 2
things when each molecule of product is produced: (1) goes entirely bromonium-ion/antiaddition;
or (2) goes through a fully-fledged planar carbocation intermediate with absolutely
no selectivity.
a. If you were to find by quantitative analysis that exactly 50% of your product mixture
was the meso stilbene dibromide and the other 50% was racemic stilbene dibromide,
then is mechanism case (1) or (2) favored? If so, qualitatively, by how much?
b. Think again. Question (a) is a mind-bender. I want to know what you originally /
immediately thought, and what you eventually came to. If they are not different, you
are either a genius or need to think more. Write out all the possibilities…
c. If you find, qualitatively, that >95% of the product is meso, what does this imply about
the mechanism? What percent of the time does the mechanism go by scenario (1)…
greater than what number?
5. Describe a more likely blend of mechanisms that could have produced your estimated product
distribution