9. Alkenes and Alkynes

Propose a mechanism for each of the following reactions:

b.

Which of the following functional groups may be used to form polymers via dehydration reactions?

The dehydration of tertiary alcohols typically occurs by which reaction mechanism?

What type of bond forms between two amino acids during a dehydration reaction?

Predict the product(s) that would result when molecules (a)–(p) are allowed to react under the following conditions: (vi) H₂SO₄. If no reaction occurs, write 'no reaction.'  

(a)

Suggest a mechanism for the following substitution reaction.

A student was studying terpene synthesis, and she wanted to make the compound shown here. First she converted 3-bromo-6-methylcyclohexene to alcohol A. She heated alcohol A with sulfuric acid and purified one of the components (compound B) from the resulting mixture. Compound B has the correct molecular formula for the desired product.

(c) Propose a mechanism for the dehydration of alcohol A to compound B.

Predict the major product of the following elimination reactions.

(a)

Which of the following is an example of a dehydration synthesis reaction?

Propose a mechanism for each reaction.

(a)

(b)

What stereoisomers are formed in the following reactions? Which stereoisomer is the major product?

b. the acid-catalyzed dehydration of 3,4-dimethyl-3-hexanol to 3,4-dimethyl-3-hexene

The following reaction is called the pinacol rearrangement. The reaction begins with an acid-promoted ionization to give a carbocation. This carbocation undergoes a methyl shift to give a more stable, resonance-stabilized cation. Loss of a proton gives the observed product. Propose a mechanism for the pinacol rearrangement.

In a dehydration synthesis reaction, which molecule is typically removed to form a new bond?

Predict the major products of acid-catalyzed dehydration of the following alcohols.

(a)

(b)