Oxidation And Reduction Reactions

Reactions of D-Glucose

(a) Reaction of D-glucose with HCN

When D-glucose is treated with hydrogen cyanide (HCN), it undergoes cyanohydrin formation. The reaction occurs at the aldehyde group, resulting in the formation of D-glucose cyanohydrin.

(b) Reaction of D-glucose with Br water

When D-glucose is treated with bromine water (a mild oxidizing agent), it specifically oxidizes the aldehyde group at C-1 to a carboxylic acid, producing gluconic acid.

These reactions demonstrate the aldehydic nature of glucose and its ability to undergo addition and oxidation reactions.

To solve the problem, we need to determine the structures of intermediates A, B, and C in the given reaction sequences.

Sequence (a):

1. Reaction of CH₃COOH with SOCl₂:
Acetic acid (CH₃COOH) reacts with thionyl chloride (SOCl₂) to form acetyl chloride (A):


A: (Acetyl chloride)

2. Reduction of Acetyl Chloride with H₂/Pd-BaSO₄:
Acetyl chloride (CH₃COCl) is reduced to acetaldehyde (B) using hydrogen gas and palladium on barium sulfate (Rosenmund reduction):


B: (Acetaldehyde)

3. Reaction of Acetaldehyde with Hydrazine (H₂N-NH₂):
Acetaldehyde reacts with hydrazine to form acetaldehyde hydrazone (C):


C: (Acetaldehyde hydrazone)

Sequence (b):

1. Reduction of CH₃CN with DIBAL-H:
Acetonitrile (CH₃CN) is reduced by diisobutylaluminum hydride (DIBAL-H) to form acetaldehyde (A):


A: (Acetaldehyde)

2. Aldol Condensation with Dilute NaOH:
Acetaldehyde undergoes aldol condensation in the presence of dilute NaOH to form 3-hydroxybutanal (B):


B: (3-Hydroxybutanal)

3. Dehydration upon Heating (Δ):
3-Hydroxybutanal undergoes dehydration upon heating to form crotonaldehyde (C):


C: (Crotonaldehyde)

Final Answers:

Sequence (a):
A: (Acetyl chloride)
B: (Acetaldehyde)
C: (Acetaldehyde hydrazone)

Sequence (b):
A: (Acetaldehyde)
B: (3-Hydroxybutanal)
C: (Crotonaldehyde)

To solve the problem, we need to explain the given reactions and provide their chemical equations.

1. Wolff-Kishner Reduction:
This reaction reduces aldehydes or ketones to hydrocarbons by treating their hydrazone derivatives with a strong base (e.g., KOH) and hydrazine ( ) at high temperatures. It proceeds via the formation of a hydrazone intermediate, which decomposes to form a hydrocarbon and nitrogen gas.

General equation:
.
Example: Acetone to propane:
.

2. Etard Reaction:
This reaction oxidizes toluene or its derivatives (with an alkyl side chain) to aldehydes using chromyl chloride ( ) in , followed by hydrolysis. The reaction forms a complex intermediate that decomposes to the aldehyde upon hydrolysis.

General equation:
.
Example: Toluene to benzaldehyde:
.

3. Cannizzaro Reaction:
Aldehydes lacking α-hydrogens (e.g., formaldehyde, benzaldehyde) undergo this reaction in the presence of a strong base (e.g., NaOH). One molecule is reduced to an alcohol, and another is oxidized to a carboxylic acid salt.

General equation:
.
Example: Benzaldehyde:
.

Final Answer:
(a) Wolff-Kishner reduction converts aldehydes/ketones to hydrocarbons: .
(b) Etard reaction oxidizes toluene to benzaldehyde: .
(c) Cannizzaro reaction involves disproportionation of aldehydes: .

To solve the problem, we need to calculate the mass of glucose in one litre of its solution that is isotonic with a solution containing 15 g of urea per litre, given the molar masses of urea (60 g mol ) and glucose (180 g mol ).

1. Understand Isotonic Solutions:
Isotonic solutions have the same osmotic pressure. Osmotic pressure ( ) is given by , where is the molar concentration, is the gas constant, and is the temperature. For isotonic solutions at the same temperature, .

2. Calculate Molar Concentration of Urea:
Mass of urea = 15 g, molar mass = 60 g mol , volume = 1 L.

Moles of urea = .
Concentration of urea = .

3. Set Concentration of Glucose Equal to Urea:
Since the solutions are isotonic, .

4. Calculate Mass of Glucose:
Molar mass of glucose = 180 g mol , volume = 1 L.

Moles of glucose = .
Mass of glucose = .

Final Answer:
The mass of glucose present in one litre of its solution is .