Aniline, 4.65 g, is shaken with an excess of bromine water at room temperature…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
Aniline, , is shaken with an excess of bromine water at room temperature. A white solid forms, 2,4,6-tribromoaniline, . Use C = 12, H = 1, N = 14 and Br = 80 in g/mol. Three bromine molecules react with each aniline molecule, and hydrogen bromide forms. Find the molar mass of the solid. Find the mass formed at a yield of 100 %. Find the amount of bromine used and the mass of that bromine.
Need a reminder? The key ideaShow
The amino group activates the ring and directs to the ortho and para positions. Bromine water gives 2,4,6-tribromoaniline. In strong acid, aniline becomes the anilinium ion, which directs meta. An acetyl group protects the amine: acetylate, react, hydrolyse. The yields of the steps multiply. The ratio of the ion to the free amine is .
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. Molar mass. The solid is : .
Step 2. Mass. .
Step 3. Bromine. of .
Step 4. Its mass. .
Answer: , , and .
Check. The reaction also makes of hydrogen bromide, which stays in the water.
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