Chapter 19, Problem 19.54P

Interpretation Introduction

(a)

Interpretation:

The product of the given reaction is to be predicted, considering one molar equivalent of ${\text{H}}_{\text{2}}$ reacts.

Concept introduction:

The C=C functional group of an alkene or the $\text{C}\equiv \text{C}$ functional group of an alkyne can be removed via catalytic hydrogenation. Catalytic hydrogenation is a reaction in which ${\text{H}}_{\text{2}}$ adds to a molecule in the presence of a metal catalyst such as Pt, Pd, or Ni. Catalytic hydrogenation readily reduces an alkene or an alkyne to an alkane. The reduction of an alkyne to an alkene via catalytic hydrogenation favors production of the cis isomer over the trans. Catalytic hydrogenation using a poisoned catalyst (a Lindlar catalyst) reduces an alkyne to a cis alkene. The functional groups in alkenes, alkynes, and aldehydes can be selectively reduced over those in ketones, nitriles, and amides.

Answer to Problem 19.54P

The product of the given reaction is

Explanation of Solution

The given reaction is

The given reaction condition correlates to catalytic hydrogenation; it reduces alkene’s C=C over ketone’s C=O. Thus, the ${\text{H}}_{\text{2}}$ molecule added over the C=C double bond converts the C=C double bond to C-C single bond.

Therefore, the product of the given reaction is

Conclusion

The product of the given reaction is predicted using the given reaction conditions.

Interpretation Introduction

(b)

Interpretation:

The product of the given reaction is to be predicted, considering one molar equivalent of ${\text{H}}_{\text{2}}$ reacts.

Concept introduction:

The C=C functional group of an alkene or the $\text{C}\equiv \text{C}$ functional group of an alkyne can be removed via catalytic hydrogenation. Catalytic hydrogenation is a reaction in which ${\text{H}}_{\text{2}}$ adds to a molecule in the presence of a metal catalyst such as Pt, Pd, or Ni. Catalytic hydrogenation readily reduces an alkene or an alkyne to an alkane. The reduction of an alkyne to an alkene via catalytic hydrogenation favors production of the cis isomer over the trans. Catalytic hydrogenation using a poisoned catalyst (a Lindlar catalyst) reduces an alkyne to a cis alkene. The functional groups in alkenes, alkynes, and aldehydes can be selectively reduced over those in ketones, nitriles, and amides.

Catalytic hydrogenation is more favored at a less sterically hindered multiple bond than at a more sterically hindered one.

Answer to Problem 19.54P

The product of the given reaction is

Explanation of Solution

The given reaction

The given reaction condition correlates to catalytic hydrogenation. The substrate in the given reaction have two sites for catalytic hydrogenation, one C=C bond and another $\text{C}\equiv \text{C}$ bond.

Catalytic hydrogenation is more favored at a less sterically hindered multiple bond than at a more sterically hindered one.

In the given reaction, the C=C bond is sterically less hindered; therefore the ${\text{H}}_{\text{2}}$ molecule adds over the C=C double bond and converts the double bond to single bond. Therefore, the product of the given reaction is

Conclusion

The product of the given reaction is predicted using given reaction conditions.

Interpretation Introduction

(c)

Interpretation:

The product of the given reaction is to be predicted, considering one molar equivalent of ${\text{H}}_{\text{2}}$ reacts.

Concept introduction:

The C=C functional group of an alkene or the $\text{C}\equiv \text{C}$ functional group of an alkyne can be removed via catalytic hydrogenation. Catalytic hydrogenation is a reaction in which ${\text{H}}_{\text{2}}$ adds to a molecule in the presence of a metal catalyst such as Pt, Pd, or Ni. Catalytic hydrogenation readily reduces an alkene or an alkyne to an alkane. The reduction of an alkyne to an alkene via catalytic hydrogenation favors production of the cis isomer over the trans. Catalytic hydrogenation using a poisoned catalyst (a Lindlar catalyst) reduces an alkyne to a cis alkene. The less sterically hindered C=C or triple bond is selectively reduced.

Answer to Problem 19.54P

The product of the given reaction is

Explanation of Solution

The given reaction is

The given reaction condition correlates to catalytic hydrogenation. The substrate in the given reaction have two sites for catalytic hydrogenation, two C=C bonds.

Catalytic hydrogenation is more favored at a less sterically hindered multiple bond than at a more sterically hindered one.

In the given reaction, the C=C bond is at bottom is sterically less hindered; therefore the ${\text{H}}_{\text{2}}$ molecule adds over the C=C double bond and converts the double bond to a single bond. Therefore, the product of the given reaction is

Conclusion

The product of the given reaction is predicted using the given reaction conditions.

Interpretation Introduction

(d)

Interpretation:

The product of the given reaction is to be predicted, considering one molar equivalent of ${\text{H}}_{\text{2}}$ reacts.

Concept introduction:

The C=C functional group of an alkene or the $\text{C}\equiv \text{C}$ functional group of an alkyne can be removed via catalytic hydrogenation. Catalytic hydrogenation is a reaction in which ${\text{H}}_{\text{2}}$ adds to a molecule in the presence of a metal catalyst such as Pt, Pd, or Ni. Catalytic hydrogenation readily reduces an alkene or an alkyne to an alkane. The reduction of an alkyne to an alkene via catalytic hydrogenation favors production of the cis isomer over the trans. Catalytic hydrogenation using a poisoned catalyst (a Lindlar catalyst) reduces an alkyne to a cis alkene. The functional groups in alkenes, alkynes, and aldehydes can be selectively reduced over those in ketones, nitriles, and amides.

Answer to Problem 19.54P

The product of the given reaction is

Explanation of Solution

The given reaction is

The given reaction condition correlates to catalytic hydrogenation. The substrate in the given reaction has two sites for catalytic hydrogenation, one $\text{C}\equiv \text{C}$ bond and another the amide group.

The functional groups in alkenes, alkynes, and aldehydes can be selectively reduced over those in ketones, nitriles, and amides. Thus, the ${\text{H}}_{\text{2}}$ molecule is added over the $\text{C}\equiv \text{C}$ triple bond. Catalytic hydrogenation using a poisoned catalyst (a Lindlar catalyst) reduces an alkyne to a cis alkene, as one molar equivalent of ${\text{H}}_{\text{2}}$ reacts.

Therefore, the product of the given reaction is

Conclusion

The product of the given reaction is predicted using the given reaction conditions.

Interpretation Introduction

(e)

Interpretation:

The product of the given reaction is to be predicted, considering one molar equivalent of ${\text{H}}_{\text{2}}$ reacts.

Concept introduction:

The C=C functional group of an alkene or the $\text{C}\equiv \text{C}$ functional group of an alkyne can be removed via catalytic hydrogenation. Catalytic hydrogenation is a reaction in which ${\text{H}}_{\text{2}}$ adds to a molecule in the presence of a metal catalyst such as Pt, Pd, or Ni. Catalytic hydrogenation readily reduces an alkene or an alkyne to an alkane. The reduction of an alkyne to an alkene via catalytic hydrogenation favors production of the cis isomer over the trans. Catalytic hydrogenation using a poisoned catalyst (a Lindlar catalyst) reduces an alkyne to a cis alkene. The functional groups in alkenes, alkynes, and aldehydes can be selectively reduced over those in ketones, nitriles, and amides.

Answer to Problem 19.54P

The product of the given reaction is

Explanation of Solution

The given reaction is

The given reaction condition correlates to catalytic hydrogenation. The substrate in the given reaction has two sites for catalytic hydrogenation, one C=C bond and another the nitrile group.

The functional group ketones can be selectively reduced over nitriles. Thus, the ${\text{H}}_{\text{2}}$ molecule is added over the C=O double bond and converted to the OH (alcoholic group).

Therefore, the product of the given reaction is

Conclusion

The product of the given reaction is predicted using the given reaction conditions.

Interpretation Introduction

(f)

Interpretation:

The product of the given reaction is to be predicted, considering one molar equivalent of ${\text{H}}_{\text{2}}$ reacts.

Concept introduction:

The C=C functional group of an alkene or the $\text{C}\equiv \text{C}$ functional group of an alkyne can be removed via catalytic hydrogenation. Catalytic hydrogenation is a reaction in which ${\text{H}}_{\text{2}}$ adds to a molecule in the presence of a metal catalyst such as Pt, Pd, or Ni. Catalytic hydrogenation readily reduces an alkene or an alkyne to an alkane. The reduction of an alkyne to an alkene via catalytic hydrogenation favors production of the cis isomer over the trans. Catalytic hydrogenation using a poisoned catalyst (a Lindlar catalyst) reduces an alkyne to a cis alkene.

Answer to Problem 19.54P

The product of the given reaction is

Explanation of Solution

The given reaction is

The given reaction condition correlates to catalytic hydrogenation. The substrate in the given reaction has two sites for catalytic hydrogenation, one C=C bond and another the aldehyde group.

Aldehydes and alkenes have similar reactivity toward catalytic hydrogenation, but the aldehyde group in the above substrate is less sterically hindered; thus ${\text{H}}_{\text{2}}$ molecule will add over the aldehyde group and convert it to aldehyde.

Therefore, the product of the given reaction is

Conclusion

The product of the given reaction is predicted using the given reaction conditions.

Interpretation Introduction

(g)

Interpretation:

The product of the given reaction is to be predicted, considering one molar equivalent of ${\text{H}}_{\text{2}}$ reacts.

Concept introduction:

The C=C functional group of an alkene or the $\text{C}\equiv \text{C}$ functional group of an alkyne can be removed via catalytic hydrogenation. Catalytic hydrogenation is a reaction in which ${\text{H}}_{\text{2}}$ adds to a molecule in the presence of a metal catalyst such as Pt, Pd, or Ni. Catalytic hydrogenation readily reduces an alkene or an alkyne to an alkane. The reduction of an alkyne to an alkene via catalytic hydrogenation favors production of the cis isomer over the trans. Catalytic hydrogenation using a poisoned catalyst (a Lindlar catalyst) reduces an alkyne to a cis alkene.

Answer to Problem 19.54P

The product of the given reaction is

Explanation of Solution

The given reaction is

The given reaction condition correlates to catalytic hydrogenation. The substrate in the given reaction has two sites for catalytic hydrogenation, one $\text{C}\equiv \text{C}$ bond and another the amide group.

The functional groups in alkenes, alkynes, and aldehydes can be selectively reduced over those in ketones, nitriles, and amides. Thus, the ${\text{H}}_{\text{2}}$ molecule is added over the $\text{C}\equiv \text{C}$ triple bond. Catalytic hydrogenation using a poisoned catalyst (a Lindlar catalyst) reduces an alkyne to a cis alkene, but the reaction condition favors one more step as ${\text{H}}_{\text{2}}$ is present in excess. Hence one more mol of ${\text{H}}_{\text{2}}$ molecule is added over C=C double bond and converts it to C-C single bond.

Therefore, the product of the given reaction is

Conclusion

The product of the given reaction is predicted using the given reaction conditions.