MediumChemistryHigh School (11–12)Organic Compounds with Functional Groups › Alcohols, Phenols and EthersNumerical
Ethyl isopropyl ether (2-ethoxypropane) can be made in two ways: (1) sodium ethoxide with…
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Ethyl isopropyl ether (2-ethoxypropane) can be made in two ways: (1) sodium ethoxide with 2-bromopropane, or (2) sodium propan-2-oxide with bromoethane. Decide which route is better, and give its number. A chemist uses of sodium propan-2-oxide with excess bromoethane, and the yield is . Use for the ether and for sodium bromide. Find the mass of ether and of sodium bromide formed.
Need a reminder? The key ideaShow
The number of ethers of carbons is the number of unordered pairs of alkyl groups with carbons in all. The Williamson synthesis needs a methyl or primary halide. Two alcohol molecules give one ether and one water. Yield .
The worked solution
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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.
Given. Two routes, of alkoxide, yield.
Step 1. The route. The halide in route (1), 2-bromopropane, is secondary, and the strongly basic ethoxide would take a proton and give propene. The halide in route (2), bromoethane, is primary. This is the better route: number 2.
Step 2. The ether. . Mass: .
Step 3. The salt. The same of sodium bromide: .
Check. The ether has a lower molar mass than the salt, but the mass of the ether is still the larger part of what a chemist wants. The salt is washed out with water.
Answer: route 2, and .
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