10. Addition Reactions

Predict the products of reaction of pent-1-yne with the following reagents.

d. H₂, Pd/BaSO₄, quinoline

e. 1 equivalent of Br₂

f. 2 equivalents of Br₂

What is the major product of the reaction of 1 mol of propyne with each of the following reagents?

c. Br₂ (1 mol)/CH₂Cl₂

When alkynes are treated with water and bromine a bromoketone is produced. Provide a plausible arrow-pushing mechanism that accounts for the formation of this product.

Trans addition is heavily favored for the addition of Br₂ and Cl₂ to alkynes. With chlorination, however, more of the syn addition product is formed. Rationalize this fact in light of your answer to Assessments 10.50 and 10.51.

For the alkynes shows here, show the product(s) expected to form when treated under the following conditions: (ix) Br₂ (2 equiv.). If you expect two products, show both.

(c)

Propose a mechanism for the triolefin process using a metal alkylidene as the catalyst.