A graduate student was following a procedure to make 3-propylcyclohexa-1,4-diene. During

Chapter 15, Problem 15-32

(choose chapter or problem)

A graduate student was following a procedure to make 3-propylcyclohexa-1,4-diene. During the workup procedure, his research adviser called him into her office. By the time the student returned to his bench, the product had warmed to a higher temperature than recommended. He isolated the product, which gave the appropriate =C-H stretch in the IR, but the C=C stretch appeared around \(1630\ cm^{-1}\) as opposed to the literature value of \(1650\ cm^{-1}\) for the desired product. The mass spectrum showed the correct molecular weight, but the base peak was at M-29 rather than at M-43 as expected. Because of the anomalous IR spectrum, he took a UV spectrum that showed \(\lambda_{max}\) at 261 nm.

(a) Should he have his IR recalibrated or should he repeat the experiment, watching the temperature more carefully? What does the \(1630\ cm^{-1}\) absorption suggest?

(b) Draw the structure of the desired product, and propose a structure for the actual product.

(c) Show why he expected the MS base peak to be at M-43, and show how your proposed structure would give an intense peak at M-29.