PrayogX › Chemistry › Polymers

Mass of a biodegradable condensation copolymer from glycine and 6-aminohexanoic acid

Five short screens: charge the reactor, watch CH3I become glycine one reagent at a time, watch caprolactam's ring unroll into 6-aminohexanoic acid, link the two monomers while every condensation ejects a water, assemble the arithmetic - and then reveal the mass of Z in spray-paint lettering.

Sub-topics covered

• Nitrile route for one-carbon ascent
• Hydrolysis of a nitrile to a carboxylic acid
• Hell-Volhard-Zelinsky alpha-bromination
• Amination of an alpha-halo acid
• Acidic hydrolysis of a lactam and ring opening
• Condensation polymerisation and the water eliminated
• Linear chain: n units give n minus 1 links

What it teaches

• Cyanide displacement is the only step in the sequence that changes the carbon count, which alone fixes X as a two-carbon acid
• Red P with Br2 is the Hell-Volhard-Zelinsky reaction and brominates the alpha carbon of an acid
• Excess ammonia converts an alpha-bromo acid to an alpha-amino acid without alkylating twice
• A lactam is a cyclic amide; hydrolysis adds a water across the C-N bond and opens the ring, so the product is 18 heavier than the lactam
• A polyamide needs an amine at one end and an acid at the other, which is why both monomers must be acyclic
• Condensation polymerisation ejects one small molecule per link, so the polymer is always lighter than the monomers that made it
• A chain of n units with two loose ends has n minus 1 links, not n - the word acyclic in the question is what makes it 999 rather than 1000
• Not every number given in a question is used: bromine appears only in an intermediate and never reaches the answer

Simulation ID

• ADV-2026-P2-CHE-Q14 · revision 1

See this simulation in the library →  ·  open the simulation file on its own