Question Details

In the following reaction sequence, major products X and Y are acyclic monomers.

CH3I 1. KCN 2. H+ , Δ 3. RedP , Br2 , NH3 (excess) X
Caprolactam H 3 O+ , Δ Y
500 mol of X completely reacts with 500 mol of Y to give 1 mol of a single biodegradable acyclic copolymer Z as the only product.
The amount of Z formed in grams is .
Given: Atomic mass (in amu): H = 1, C = 12, N = 14, O = 16, Br = 80

Show Answer

Correct Answer :

85018

Solution :

The correct answer is 85018.

Let us determine the chemical structure of products X and Y step-by-step from the given reaction sequence.

Step 1: Formation of Product X
Starting material is methyl iodide (CH3I).
1. Nucleophilic substitution with KCN yields acetonitrile:
CH3I+KCNCH3CN+KI
2. Acidic hydrolysis (H+,Δ) of acetonitrile converts the nitrile group to a carboxylic acid, forming acetic acid:
CH3CNΔH+CH3COOH
3. Reaction with Red P, Br2 followed by excess NH3 is the Hell-Volhard-Zelinsky (HVZ) reaction followed by amination. This converts acetic acid to 2-bromoacetic acid and then to glycine (aminoacetic acid, X):
CH3COOH2.NH3(excess)1.RedP,Br2H2N-CH2-COOH
Thus, X is Glycine (H2N-CH2-COOH).

Step 2: Formation of Product Y
Acidic hydrolysis (H3O+,Δ) of Caprolactam opens the seven-membered cyclic amide ring to yield 6-aminohexanoic acid (Y, aminocaproic acid):
CaprolactamΔH3O+H2N-(CH2)5-COOH
Thus, Y is 6-aminohexanoic acid (H2N-(CH2)5-COOH).

Step 3: Formation of Copolymer Z
Glycine (X) and 6-aminohexanoic acid (Y) undergo condensation copolymerization to form Nylon-2-nylon-6, a biodegradable acyclic copolymer.
Reaction of 500 mol of X with 500 mol of Y forms 1 mol of copolymer Z:
500X+500Y1Z+(500+500-1)H2O
Since a single acyclic chain polymer Z is formed from 1000 monomer units (500 units of X + 500 units of Y), the total number of peptide bond formations involves the elimination of (500+500-1)=999 molecules of water (H2O).

Step 4: Molar Mass Calculations
Let us calculate the molar masses of X, Y, and H2O using the given atomic masses (H = 1, C = 12, N = 14, O = 16):
1. Molar mass of Glycine (X, C2H5NO2):
MX=(2×12)+(5×1)+14+(2×16)=24+5+14+32=75g/mol
2. Molar mass of 6-aminohexanoic acid (Y, C6H13NO2):
MY=(6×12)+(13×1)+14+(2×16)=72+13+14+32=131g/mol
3. Molar mass of Water (H2O):
MH2O=(2×1)+16=18g/mol

Step 5: Mass Balance Calculation for Z
By conservation of mass:
Mass of Z=Mass of 500molX+Mass of 500molY-Mass of 999molH2O
Mass of Z=(500×75)+(500×131)-(999×18)
Mass of Z=37500+65500-17982
Mass of Z=103000-17982=85018g

Therefore, the amount of copolymer Z formed is 85018 grams.

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