The complete, detailed mechanism for a given reaction is to be drawn, and the major product is to be predicted. Concept introduction: Intramolecular reactions are the ones in which the electron-rich and electron-poor sites are present within the same molecule. When ketones or aldehydes are treated with a strong base, they yield β -hydroxycarbonyl compounds via an aldol addition. Under these basic conditions, an enolate anion acts as a nucleophile. An intramolecular reaction is favored when it forms a five or six-membered ring. Intramolecular reactions involving the attack of an aldehyde C=O are favored over ones involving the attack of a ketone C=O . The first step is the formation of an enolate ion. The HO − reversibly deprotonates the alpha carbon to yield an enolate anion. In step two, the newly formed enolate anion, which serves as a nucleophile, attacks the carbonyl carbon present within the same molecule. The product of this step is an alkoxide ion, which is subsequently protonated in step 3. The nucleophilic addition reaction to a ketone is generally less favorable than the addition to an aldehyde because in a ketone, there are two alkyl groups attached to the carbonyl carbon, but in an aldehyde, only one alkyl group is attached. The electron-donating effects from a ketone’s alkyl groups diminish the concentration of positive charge on the carbonyl carbon, making it less susceptible to the nucleophilic attack.

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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 18, Problem 18.32P

Interpretation Introduction

Interpretation:

The complete, detailed mechanism for a given reaction is to be drawn, and the major product is to be predicted.

Concept introduction:

Intramolecular reactions are the ones in which the electron-rich and electron-poor sites are present within the same molecule. When ketones or aldehydes are treated with a strong base, they yield β-hydroxycarbonyl compounds via an aldol addition. Under these basic conditions, an enolate anion acts as a nucleophile. An intramolecular reaction is favored when it forms a five or six-membered ring. Intramolecular reactions involving the attack of an aldehyde C=O are favored over ones involving the attack of a ketone C=O. The first step is the formation of an enolate ion. The HO− reversibly deprotonates the alpha carbon to yield an enolate anion. In step two, the newly formed enolate anion, which serves as a nucleophile, attacks the carbonyl carbon present within the same molecule. The product of this step is an alkoxide ion, which is subsequently protonated in step 3. The nucleophilic addition reaction to a ketone is generally less favorable than the addition to an aldehyde because in a ketone, there are two alkyl groups attached to the carbonyl carbon, but in an aldehyde, only one alkyl group is attached. The electron-donating effects from a ketone’s alkyl groups diminish the concentration of positive charge on the carbonyl carbon, making it less susceptible to the nucleophilic attack.

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A sample of hydrated magnesium sulfate (MgSO4⋅xH2O) is analyzed using thermogravimetric analysis (TGA). The sample weighs 2.50 g initially and is heated in a controlled atmosphere. As the temperature increases, the water of hydration is released in two stages: (a) The first mass loss of 0.72 g occurs at 150°C, corresponding to the loss of a certain number of water molecules. (b) The second mass loss of 0.90 g occurs at 250°C, corresponding to the loss of the remaining water molecules. The residue is identified as anhydrous magnesium sulfate (MgSO4) Questions: (i) Determine the value of x (the total number of water molecules in MgSO4⋅xH2O) (ii) Calculate the percentage of water in the original sample. Write down the applications of TGA.

Answer 2

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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 18, Problem 18.32P

Interpretation Introduction

Interpretation:

The complete, detailed mechanism for a given reaction is to be drawn, and the major product is to be predicted.

Concept introduction:

Intramolecular reactions are the ones in which the electron-rich and electron-poor sites are present within the same molecule. When ketones or aldehydes are treated with a strong base, they yield β-hydroxycarbonyl compounds via an aldol addition. Under these basic conditions, an enolate anion acts as a nucleophile. An intramolecular reaction is favored when it forms a five or six-membered ring. Intramolecular reactions involving the attack of an aldehyde C=O are favored over ones involving the attack of a ketone C=O. The first step is the formation of an enolate ion. The HO− reversibly deprotonates the alpha carbon to yield an enolate anion. In step two, the newly formed enolate anion, which serves as a nucleophile, attacks the carbonyl carbon present within the same molecule. The product of this step is an alkoxide ion, which is subsequently protonated in step 3. The nucleophilic addition reaction to a ketone is generally less favorable than the addition to an aldehyde because in a ketone, there are two alkyl groups attached to the carbonyl carbon, but in an aldehyde, only one alkyl group is attached. The electron-donating effects from a ketone’s alkyl groups diminish the concentration of positive charge on the carbonyl carbon, making it less susceptible to the nucleophilic attack.

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Answer 3

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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 18, Problem 18.32P

Interpretation Introduction

Interpretation:

The complete, detailed mechanism for a given reaction is to be drawn, and the major product is to be predicted.

Concept introduction:

Intramolecular reactions are the ones in which the electron-rich and electron-poor sites are present within the same molecule. When ketones or aldehydes are treated with a strong base, they yield β-hydroxycarbonyl compounds via an aldol addition. Under these basic conditions, an enolate anion acts as a nucleophile. An intramolecular reaction is favored when it forms a five or six-membered ring. Intramolecular reactions involving the attack of an aldehyde C=O are favored over ones involving the attack of a ketone C=O. The first step is the formation of an enolate ion. The HO− reversibly deprotonates the alpha carbon to yield an enolate anion. In step two, the newly formed enolate anion, which serves as a nucleophile, attacks the carbonyl carbon present within the same molecule. The product of this step is an alkoxide ion, which is subsequently protonated in step 3. The nucleophilic addition reaction to a ketone is generally less favorable than the addition to an aldehyde because in a ketone, there are two alkyl groups attached to the carbonyl carbon, but in an aldehyde, only one alkyl group is attached. The electron-donating effects from a ketone’s alkyl groups diminish the concentration of positive charge on the carbonyl carbon, making it less susceptible to the nucleophilic attack.

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Answer 4

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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 18, Problem 18.32P

Interpretation Introduction