Chapter 14, Problem 14.29P

Interpretation Introduction

(a)

Interpretation:

State True or false.

The two most important reactions of alcohols are their acid-catalyzed dehydration to give alkenes and their oxidation to aldehydes, ketones and carboxylic acid.

Concept Introduction:

Chemical reaction is the procedure to transform the chemical substance in the new substance. During this procedure sometimes, acid is involved which is the substance which could either accept electron pairs or donate protons in the reactions.

A catalyst is the molecule which is used to speed up the chemical reaction, not being consumed within the procedure. Acids are used as catalysts are needed for an acid catalyzed hydration.

A dehydration reaction is aeration when any organic substance loses the water molecule to form an alkene.

Answer to Problem 14.29P

True.

Explanation of Solution

Alcohols are organic compounds containing -OH group. It undergoes in the presence of acid to form an alkene. Dehydration is the removal of water from alcohol.

Alcohols undergo oxidation to yield aldehyde, ketone, and carboxylic acid. The primary alcohol in an acid catalyzed oxidation gives an aldehyde and further acid catalyzed oxidation gives a corresponding acid.

The secondary alcohol in an acid catalyzed oxidation fives a ketone.

Therefore, this statement is True.

Interpretation Introduction

(b)

Interpretation:

State True or false.

The acidity of alcohols is comparable to that of water.

Concept Introduction:

Chemical reaction is the procedure to transform the chemical substance in the new substance. During this procedure sometimes, acid is involved which is the substance which could either accept electron pairs or donate protons in the reactions.

A catalyst is the molecule which is used to speed up the chemical reaction, not being consumed within the procedure. Acids are used as catalysts are needed for an acid catalyzed hydration.

A dehydration reaction is aeration when any organic substance loses the water molecule to form an alkene.

Answer to Problem 14.29P

True.

Explanation of Solution

The strength of an acid can be measured by the acid dissociation constant K_a while the pK_a value is logarithmic value of the acid dissociation constant. So, the alcohol has the nearly same pK_a value as of water.

Therefore, this statement is True.

Interpretation Introduction

(c)

Interpretation:

State True or false.

Water-insoluble alcohols and water-insoluble phenols react with string bases to give water soluble salts.

Concept Introduction:

Chemical reaction is the procedure to transform the chemical substance in the new substance. During this procedure sometimes, acid is involved which is the substance which could either accept electron pairs or donate protons in the reactions.

A catalyst is the molecule which is used to speed up the chemical reaction, not being consumed within the procedure. Acids are used as catalysts are needed for an acid catalyzed hydration.

A dehydration reaction is aeration when any organic substance loses the water molecule to form an alkene.

Answer to Problem 14.29P

False.

Explanation of Solution

Alcohol is a water-soluble compound. It is soluble in water because of the hydrogen bonding between oxygen and hydrogen atoms of water and alcohol molecules. Phenol is also water soluble because of hydrogen bonding. Water-soluble alcohol and water-insoluble phenol react with string bases to form water-soluble salt.

Therefore, this statement is False.

Interpretation Introduction

(d)

Interpretation:

State True or false.

Acid catalyzed dehydration of cyclohexanol gives cyclohexene.

Concept Introduction:

Chemical reaction is the procedure to transform the chemical substance in the new substance. During this procedure sometimes, acid is involved which is the substance which could either accept electron pairs or donate protons in the reactions.

A catalyst is the molecule which is used to speed up the chemical reaction, not being consumed within the procedure. Acids are used as catalysts are needed for an acid catalyzed hydration.

A dehydration reaction is aeration when any organic substance loses the water molecule to form an alkene.

Answer to Problem 14.29P

False.

Explanation of Solution

Acid-catalyzed dehydration of cyclohexanol gives corresponding alkene. In the presence of sulfuric acid, cyclohexanol gives cyclohexene.

Therefore, this statement is False.

Interpretation Introduction

(e)

Interpretation:

State True or false.

When the acid-catalyzed dehydration of an alkene can yield isomeric alkenes, the alkene with the greater number of hydrogens in the carbons of the double bond generally predominates.

Concept Introduction:

Chemical reaction is the procedure to transform the chemical substance in the new substance. During this procedure sometimes, acid is involved which is the substance which could either accept electron pairs or donate protons in the reactions.

A catalyst is the molecule which is used to speed up the chemical reaction, not being consumed within the procedure. Acids are used as catalysts are needed for an acid catalyzed hydration.

A dehydration reaction is aeration when any organic substance loses the water molecule to form an alkene.

Answer to Problem 14.29P

False.

Explanation of Solution

Acid-catalyzed dehydration of an alcohol gives an isomeric alkene. The isomeric alkene, which has a lower number of hydrogen atoms in the double bond, has a grater yield. Hence, when butanol undergoes an acid-catalyzed dehydration, 2-butene is the major product.

Therefore, this statement is False.

Interpretation Introduction

(f)

Interpretation:

State True or false.

The acid-catalyzed dehydration of 2-butanol gives predominantly 1-butene.

Concept Introduction:

Chemical reaction is the procedure to transform the chemical substance in the new substance. During this procedure sometimes, acid is involved which is the substance which could either accept electron pairs or donate protons in the reactions.

A catalyst is the molecule which is used to speed up the chemical reaction, not being consumed within the procedure. Acids are used as catalysts are needed for an acid catalyzed hydration.

A dehydration reaction is aeration when any organic substance loses the water molecule to form an alkene.

Answer to Problem 14.29P

False.

Explanation of Solution

An acid catalyzed dehydration of butanol gives predominantly 2-butene. The yield of 1-butene is approximately because in the acid-catalyzed dehydration reaction of an alcohol, the major product has the lower number of hydrogen atoms attached to the carbon atoms with double bonds. Thus, 2-Butene is the major product.

Therefore, this statement is False.

Interpretation Introduction

(g)

Interpretation:

State True or false.

The oxidation of a primary alcohol gives either an aldehyde or a carboxylic acid depending on experimental conditions.

Concept Introduction:

Chemical reaction is the procedure to transform the chemical substance in the new substance. During this procedure sometimes, acid is involved which is the substance which could either accept electron pairs or donate protons in the reactions.

A catalyst is the molecule which is used to speed up the chemical reaction, not being consumed within the procedure. Acids are used as catalysts are needed for an acid catalyzed hydration.

A dehydration reaction is aeration when any organic substance loses the water molecule to form an alkene.

Answer to Problem 14.29P

True.

Explanation of Solution

The oxidation of the primary alcohols gives either aldehyde or carboxylic acid, depending on the experimental condition. For illustration, the primary alcohol in an acid catalyzed oxidation gives an aldehyde and further acid catalyzed oxidation gives a corresponding acid.

Therefore, this statement is True.

Interpretation Introduction

(h)

Interpretation:

State True or false.

The oxidation of a secondary alcohol gives a carboxylic acid.

Concept Introduction:

Chemical reaction is the procedure to transform the chemical substance in the new substance. During this procedure sometimes, acid is involved which is the substance which could either accept electron pairs or donate protons in the reactions.

A catalyst is the molecule which is used to speed up the chemical reaction, not being consumed within the procedure. Acids are used as catalysts are needed for an acid catalyzed hydration.

A dehydration reaction is aeration when any organic substance loses the water molecule to form an alkene.

Answer to Problem 14.29P

False.

Explanation of Solution

The secondary alcohol in an acid-catalyzed oxidation gives ketone. The oxidation of the secondary alcohol gives ketone in the presence of potassium chromate as an oxidizing agent. It does not produce carboxylic acid because it lacks a hydrogen atom.

Therefore, this statement is false.

Interpretation Introduction

(i)

Interpretation:

State True or false.

Acetic acid, CH₃ COOH, can be prepared from ethylene, CH₂ =CH₂, by treatment of ethylene with H₂ O/H₂ SO₄, followed by treatment with K₂ Cr₂ O₇ /H₂ SO₄.

Concept Introduction:

Chemical reaction is the procedure to transform the chemical substance in the new substance. During this procedure sometimes, acid is involved which is the substance which could either accept electron pairs or donate protons in the reactions.

A catalyst is the molecule which is used to speed up the chemical reaction, not being consumed within the procedure. Acids are used as catalysts are needed for an acid catalyzed hydration.

A dehydration reaction is aeration when any organic substance loses the water molecule to form an alkene.

Answer to Problem 14.29P

True.

Explanation of Solution

Ethylene undergoes acid catalyzed hydration to produce ethanol. This, ethanol, in further treatment with potassium dichromate, undergoes oxidation to form acetic acid. The reaction is.

Therefore, this statement is True.

Interpretation Introduction

(j)

Interpretation:

State True or false.

Treatment of propene, CH₃ CH=CH₂, with H₂ O/H₂ SO₄, followed by treatment with K₂ Cr₂ O₇ /H₂ SO₄ gives propanoic acid.

Concept Introduction:

Chemical reaction is the procedure to transform the chemical substance in the new substance. During this procedure sometimes, acid is involved which is the substance which could either accept electron pairs or donate protons in the reactions.

A catalyst is the molecule which is used to speed up the chemical reaction, not being consumed within the procedure. Acids are used as catalysts are needed for an acid catalyzed hydration.

A dehydration reaction is aeration when any organic substance loses the water molecule to form an alkene.

Answer to Problem 14.29P

False.

Explanation of Solution

The hydration of propene with water in the presence of sulfuric acid produces propanol. It is a secondary alcohol. Propanol undergoes oxidation in the presence of potassium chromate and produces propanone. There is no hydrogen atom present in propanone. So, it does not produce propanoic acid in oxidation.

Therefore, this statement is false.