Homework 6

Question 1. Which of the two possible radical products shown below, A or B, is most likely to be formed as a result of reaction of benzophenone triplet with isopropanol? Give your reasoning.

Question 2. Write a mechanism for the following transformation. The product is quenched upon addition of 1,3-pentadiene. Data are given in the file "hw61.txt". What information can you obtain about the lifetime of the important excited state involved in the reaction? Provide any appropriate graphical analysis of the data.
hw61.txt

Question 3. Irradiation of acetone in the presence of trans-dicyanoethylene yields mainly the oxetane cycloadduct at high concentrations of the alkene, and mainly the cis-dicyanoethylene at low concentrations of the alkene (at low conversion). Give a mechanism that accounts for this observation.

Question 4. Irradiation of the ketone shown below results in no detectable fluoresence, but an intermediate is observed by transient absorption, X. X has a lifetime of ca. 75 ns and reacts with pentadiene only very slowly, but reacts with dimethylviologen at close to the diffusion controlled rate as shown. Give the structure of X and give the other product of reaction with dimethylviologen.