Exam 9: Alkynes: an Introduction to Organic Synthesis

Exhibit 9-2 To answer the following question(s),consider the information below: ​ The heat of hydrogenation of 1,4-pentadiene is 254.4 kJ/mol.The heat of hydrogenation of 1-pentyne is approximately 292.9 kJ/mol. -Refer to Exhibit 9-2.Show the energy differences between the hydrogenation of 1,4-pentadiene and 1-pentyne on a reaction energy diagram.

Exhibit 9-1 The compound below has been isolated from the safflower plant.Consider its structure to answer the following question(s). ​ -Refer to Exhibit 9-1.What is the molecular formula for this natural product?

Draw: acetylene

Exhibit 9-1 The compound below has been isolated from the safflower plant.Consider its structure to answer the following question(s). ​ -Refer to Exhibit 9-1.Provide the name for this unusual natural product.

What is the skeletal formula for the product of the reaction when the following is treated with BH₃ in THF followed by H₂O₂?

An acetylide anion is more stable than either a vinylic or alkyl anion due to

Name:

When the following substance is treated with 1 equivalent of Br₂, The product of the reaction is

Draw the structure(s) of the product(s) formed when the following substance is treated with NaNH₂/NH₃ and 1-bromo-3-methylhexane.

Exhibit 9-3 Consider an unknown with the molecular formula C₄H₆. -Refer to Exhibit 9-3.Draw six of the nine possible structures with this formula.

Draw: 4-bromo-3,3-dimethyl-1-hexen-5-yne

Exhibit 9-5 To answer the following question(s) consider this reaction: ​ -Refer to Exhibit 9-5.The key intermediate in the electrophilic addition reaction shown above is called:

Consider the following compound. This compound

​Draw the mechanism of the lithium/ammonia reduction of 2-butyne to produce trans-2-butene.

​Draw the mechanism of the bromination of acetylene.

Exhibit 9-1 The compound below has been isolated from the safflower plant.Consider its structure to answer the following question(s). ​ -Refer to Exhibit 9-1.What is the degree of unsaturation for this compound?

Draw: ethynylcyclopropane

Name:

Draw the skeletal formula for the reactant and product that correspond to the enol formed in a hydroboration/oxidation reaction.Atoms other than carbon and hydrogen are labeled.

Exhibit 9-2 To answer the following question(s),consider the information below: ​ The heat of hydrogenation of 1,4-pentadiene is 254.4 kJ/mol.The heat of hydrogenation of 1-pentyne is approximately 292.9 kJ/mol. -Refer to Exhibit 9-2.Which structure is more stable,1,4-pentadiene or 1-pentyne? Briefly explain your answer.