Integrated Problem 22.86 Get help answering Molecular Drawing questions. Compound A (
) is an amine that does not possess a chirality center. Compound A was treated with excess methyl iodide and then heated in the presence of aqueous silver oxide to produce an alkene. The alkene was further subjected to ozonolysis to produce butanal and pentanal. Draw the structure of compound A.
The Correct Answer and Explanation is:
To determine the structure of Compound A, we will work backward from the ozonolysis products and understand how the reactions lead us to an amine that is not chiral.
Step 1: Ozonolysis Products
The ozonolysis of the alkene yields:
- Butanal (CH₃CH₂CH₂CHO)
- Pentanal (CH₃CH₂CH₂CH₂CHO)
Ozonolysis breaks the double bond in an alkene and replaces it with carbonyl groups on each carbon that was part of the double bond. So, if we got butanal and pentanal, the alkene must have had a double bond between:
- A 4-carbon chain (that gives butanal) and
- A 5-carbon chain (that gives pentanal)
Thus, the alkene formed after elimination was non-symmetrical, with the double bond located between carbon 4 and carbon 5 in a nine-carbon chain.
So the alkene is:
CH₃CH₂CH₂CH=CHCH₂CH₂CH₂CH₃
This is nonene, specifically 4-nonene.
Step 2: Source of the Alkene – Hofmann Elimination
The alkene was produced by heating a quaternary ammonium salt with aqueous silver oxide, which is a Hofmann elimination reaction. In this reaction:
- An amine is methylated with excess methyl iodide to make a quaternary ammonium iodide
- Then it’s converted into a quaternary ammonium hydroxide using Ag₂O and H₂O
- Heating leads to elimination of the least hindered β-hydrogen, forming an alkene
So the starting amine (Compound A) must be a primary or secondary amine with a nine-carbon chain that leads to 4-nonene after Hofmann elimination.
The only structure that fits and has no chirality center is:
4-aminononane → CH₃CH₂CH₂CH(NH₂)CH₂CH₂CH₂CH₂CH₃
But this has a chirality center at carbon 4, so it cannot be Compound A.
Now consider nonylamine (1-aminononane), which is CH₃(CH₂)₈NH₂.
This amine has no chirality center and upon quaternization and Hofmann elimination, elimination occurs at the β-position, favoring the formation of 4-nonene.
✅ Final Answer: Compound A is 1-nonanamine (nonylamine)
Structure: CH₃(CH₂)₈NH₂
This satisfies:
- Being an amine
- Having no chirality center
- Giving 4-nonene after Hofmann elimination
- Producing butanal and pentanal upon ozonolysis
