A chemist makes a mixture that holds 0.0100 mol of each of the eight amines of the formula C₄H₁₁N…
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A chemist makes a mixture that holds of each of the eight amines of the formula : four primary, three secondary and one tertiary. Assume that every reaction goes to completion and that the gas behaves ideally. Do not count any nitrogen that stays dissolved in the solution. All eight are aliphatic. A sample of the whole mixture is shaken with sodium nitrite and hydrochloric acid at 273 K. Then, a second sample is treated with benzenesulphonyl chloride in excess aqueous sodium hydroxide. Take the gas volume at 273 K and 1 atm with one mole of gas as . Find the volume of nitrogen gas from the first sample. In the second sample, find the amount of amine that gives an alkali-soluble sulphonamide, the amount that gives an insoluble sulphonamide and the amount that gives none.
Need a reminder? The key ideaShow
The amine lone pair attacks carbon atoms that are short of electrons. Primary and secondary amines are acylated. Only primary amines give the carbylamine reaction. Nitrous acid gives nitrogen gas with a primary aliphatic amine. At 273 K and 1 atm, one mole of gas has a volume of . Hinsberg's reagent gives an alkali-soluble sulphonamide with a primary amine, an insoluble one with a secondary amine and no product with a tertiary amine.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. The classes. The four primary amines are butan-1-amine, butan-2-amine, 2-methylpropan-1-amine and 2-methylpropan-2-amine. The three secondary amines are N-methylpropan-1-amine, N-methylpropan-2-amine and N-ethylethanamine. The tertiary amine is N,N-dimethylethanamine.
Step 2. Nitrogen. Only the primary amines give nitrogen: . The volume is .
Step 3. Soluble sulphonamide. The primary amines: .
Step 4. Insoluble sulphonamide. The secondary amines: .
Step 5. None. The tertiary amine: .
Answer: , , and .
Check. , which is eight amines of each.
Watch out. The tertiary amine neither reacts with nitrous acid to give gas nor forms a sulphonamide, so it is the one that survives both tests.
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