The complete, detailed mechanism for the given reaction is to be drawn, which is identical to the one in Equation 10-30, except that Br 2 takes the place of Cl 2 . Concept introduction: Alpha halogenation is the halogenation at the alpha carbon atom of an aldehyde or a ketone under acidic conditions. Under these conditions, a negatively charged enolate ion is highly basic and cannot exist at substantial concentrations. However, the alpha carbon atom of a ketone can still become electron-rich via acid-catalyzed keto-enol tautomerism. Under the acidic conditions, the first step is the protonation of carbonyl oxygen. In the second step, the acetate ions serve as a base and abstract an alpha proton from ketone; this yields an enol form. In the enol form, the alpha carbon is electron rich, due to the small contribution by the resonance structure in which a negative charge and a lone pair of electrons are located on the alpha carbon. Alpha halogenation occurs only once as the electron withdrawing effect of bromine destabilizes the positive charge, if the carbonyl oxygen gets protonated further. This reduces the chances of the second halogenation.

Question

Want to see the full answer?

Answer 1

Question

Definition Definition Organic compounds that have a carbonyl group, C=O, as their functional group. The carbonyl group in aldehydes is placed at the end of the molecular structure, which means the C=O is attached to one hydrogen atom and an alkyl group or a benzene ring. Just like all the other homologous series in organic chemistry, the naming of aldehydes uses the suffix “-al”. The general molecular formula is C n H 2n O.

Chapter 10, Problem 10.9YT

Interpretation Introduction

Interpretation:

The complete, detailed mechanism for the given reaction is to be drawn, which is identical to the one in Equation 10-30, except that Br2 takes the place of Cl2.

Concept introduction:

Alpha halogenation is the halogenation at the alpha carbon atom of an aldehyde or a ketone under acidic conditions. Under these conditions, a negatively charged enolate ion is highly basic and cannot exist at substantial concentrations. However, the alpha carbon atom of a ketone can still become electron-rich via acid-catalyzed keto-enol tautomerism.

Under the acidic conditions, the first step is the protonation of carbonyl oxygen. In the second step, the acetate ions serve as a base and abstract an alpha proton from ketone; this yields an enol form. In the enol form, the alpha carbon is electron rich, due to the small contribution by the resonance structure in which a negative charge and a lone pair of electrons are located on the alpha carbon. Alpha halogenation occurs only once as the electron withdrawing effect of bromine destabilizes the positive charge, if the carbonyl oxygen gets protonated further. This reduces the chances of the second halogenation.

Expert Solution & Answer

Want to see the full answer?

Check out a sample textbook solution

See solution

Students have asked these similar questions

SYNTHESIS REACTIONS. For the following reactions, synthesize the given products from the given reactants. Multiple reactions/steps will be needed. For the one of the steps (ie reactions) in each synthesis, write out the mechanism for that reaction and draw an energy diagram showing the correct number of hills and valleys for that step's mechanism. CI b. a. Use acetylene (ethyne) and any alkyl halide as your starting materials Br C. d. "OH OH III. OH

Calculate the pH and the pOH of each of the following solutions at 25 °C for which the substances ionize completely: (a) 0.200 M HCl

Calculate the pH and the pOH of each of the following solutions at 25 °C for which the substances ionize completely: (a) 0.000259 M HClO4

Answer 2

Question

Definition Definition Organic compounds that have a carbonyl group, C=O, as their functional group. The carbonyl group in aldehydes is placed at the end of the molecular structure, which means the C=O is attached to one hydrogen atom and an alkyl group or a benzene ring. Just like all the other homologous series in organic chemistry, the naming of aldehydes uses the suffix “-al”. The general molecular formula is C n H 2n O.

Chapter 10, Problem 10.9YT

Interpretation Introduction

Interpretation:

The complete, detailed mechanism for the given reaction is to be drawn, which is identical to the one in Equation 10-30, except that Br2 takes the place of Cl2.

Concept introduction:

Alpha halogenation is the halogenation at the alpha carbon atom of an aldehyde or a ketone under acidic conditions. Under these conditions, a negatively charged enolate ion is highly basic and cannot exist at substantial concentrations. However, the alpha carbon atom of a ketone can still become electron-rich via acid-catalyzed keto-enol tautomerism.

Under the acidic conditions, the first step is the protonation of carbonyl oxygen. In the second step, the acetate ions serve as a base and abstract an alpha proton from ketone; this yields an enol form. In the enol form, the alpha carbon is electron rich, due to the small contribution by the resonance structure in which a negative charge and a lone pair of electrons are located on the alpha carbon. Alpha halogenation occurs only once as the electron withdrawing effect of bromine destabilizes the positive charge, if the carbonyl oxygen gets protonated further. This reduces the chances of the second halogenation.

Expert Solution & Answer

Want to see the full answer?

Check out a sample textbook solution

See solution

Answer 3

Question

Definition Definition Organic compounds that have a carbonyl group, C=O, as their functional group. The carbonyl group in aldehydes is placed at the end of the molecular structure, which means the C=O is attached to one hydrogen atom and an alkyl group or a benzene ring. Just like all the other homologous series in organic chemistry, the naming of aldehydes uses the suffix “-al”. The general molecular formula is C n H 2n O.

Chapter 10, Problem 10.9YT

Interpretation Introduction

Interpretation:

The complete, detailed mechanism for the given reaction is to be drawn, which is identical to the one in Equation 10-30, except that Br2 takes the place of Cl2.

Concept introduction:

Alpha halogenation is the halogenation at the alpha carbon atom of an aldehyde or a ketone under acidic conditions. Under these conditions, a negatively charged enolate ion is highly basic and cannot exist at substantial concentrations. However, the alpha carbon atom of a ketone can still become electron-rich via acid-catalyzed keto-enol tautomerism.

Under the acidic conditions, the first step is the protonation of carbonyl oxygen. In the second step, the acetate ions serve as a base and abstract an alpha proton from ketone; this yields an enol form. In the enol form, the alpha carbon is electron rich, due to the small contribution by the resonance structure in which a negative charge and a lone pair of electrons are located on the alpha carbon. Alpha halogenation occurs only once as the electron withdrawing effect of bromine destabilizes the positive charge, if the carbonyl oxygen gets protonated further. This reduces the chances of the second halogenation.

Expert Solution & Answer

Want to see the full answer?

Check out a sample textbook solution

See solution

Answer 4

Question

Definition Definition Organic compounds that have a carbonyl group, C=O, as their functional group. The carbonyl group in aldehydes is placed at the end of the molecular structure, which means the C=O is attached to one hydrogen atom and an alkyl group or a benzene ring. Just like all the other homologous series in organic chemistry, the naming of aldehydes uses the suffix “-al”. The general molecular formula is C n H 2n O.

Chapter 10, Problem 10.9YT

Interpretation Introduction