91Ó°ÊÓ

Draw the possible products resulting from addition of 1 equivalent of HCl to 1-phenyl-1,3-buta-di-ene. Which would you expect to predominate, and why?

Predict the products of the following Diels-Alder reaction:

Predict the products of the following Diels-Alder reaction:

(b)

Di-tert-butyl-1,3-butadiene does not undergo Diels-Alder reactions. Explain.

Show the structure, including stereochemistry, of the product from the following Diels-Alder reaction:

Question: 1,3,5-Hexatriene has ${\mathrm{λ}}_{max}$=258 nm. In light of your answer to Problem

14-48, approximately where would you expect 2,3-dimethyl-1,3,5-hexatriene to absorb?

Question:$\mathrm{β}$Ocimene is a pleasant-smelling hydrocarbon found in the leaves of

certain herbs. It has the molecular formula and a UV absorption

maximum at 232 nm. On hydrogenation with a palladium catalyst,

2,6-dimethyloctane is obtained. Ozonolysis of $\mathrm{β}$Ocimene, followed by

treatment with zinc and acetic acid, produces the following four

fragments:

(a)How many double bonds does $\mathrm{β}$ocimene have?

(b)Is $\mathrm{β}$ocimene conjugated or non-conjugated?

(c)Propose a structure for $\mathrm{β}$ocimene.

(d)Write the reactions, showing starting material and products.

Predict the product of the following Diels–Alder reaction:

Draw a segment of the polymer that might be prepared from 2-phenyl-1,3-butadiene.

Show the mechanism of the acid-catalyzed polymerization of 1,3-butadiene.