Advanced Organic
Chemistry Dr. M. J.
Wieder
Addition of HBr in the dark to 3,3-dimethyl-1-butene yields 2-bromo-3,3-dimethylbutane and 2-bromo-2,3-dimethylbutane. Peroxide-initiated addition of HBr to the same alkene gives only 1-bromo-3,3-dimethylbutane. What conclusions can be drawn from these facts?
In the presence of trace amounts of peroxides, CCl4 adds to RCH=CH2 to give not only RCH(Cl)CH2CCl3 but also significant amounts of RCH(Cl)CH2CH(R)CH2CCl3. Propose a mechanism to account for these facts.
Consider the following reaction:
Product formation occurs via a free radical chain reaction pathway. Propose a plausible mechanism for the chain reaction.
Allylic free radical bromination of cyclohexene labeled with 14C at the C-1 position leads to scrambling of the label in the product, 3-bromo-cyclohexene, as follows: 25% at C-1, 50% at C-2, and 25% at C-3. Explain the data.
Reaction of singlet dichlorocarbene with cyclopentene yields a single addition product. Reaction of singlet bromochlorocarbene with cyclopentene under the same reaction conditions leads to two distinct addition products. Explain.
When a trace of KNH2 is added to a solution of chlorobenzene and potassium triphenylmethide, (C6H5)3C- K+, in liquid ammonia, a rapid reaction takes place to yield a product of formula C25H20. Explain.
When either amine (I) or (II), shown below, is treated with potassium diethylamide in diethylamine solvent, one obtains a good yield of the same product, a compound of formula C9H11N. Explain.
Consider the following photochemically induced decomposition:
Account for the formation of each product from the appropriate radical intermediate(s).
In each of the following examples, provide a plausible mechanism to account for the transformation:
