Equal amounts of bromomethane and bromoethane are warmed with sodium in dry ether…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
Equal amounts of bromomethane and bromoethane are warmed with sodium in dry ether.
- How many different alkanes can form?
- Suppose each halide reacts with itself and with the other at the same rate, so that every pairing is equally likely. What percentage of the alkane mixture is propane?
- A chemist uses three different alkyl halides in one flask. How many different alkanes can form?
Why is this reaction useful for making a symmetrical alkane but not an unsymmetrical one?
Need a reminder? The key ideaShow
Hydrogenation and reduction of an alkyl halide keep the number of carbon atoms. The Wurtz reaction doubles the carbon atoms of the halide. Heating a sodium salt with soda lime removes the carboxyl carbon. Kolbe electrolysis joins two alkyl groups, each with the carboxyl carbon removed. An alkane has the formula .
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. Two halides. Call the groups and . They can pair as with , with and with . That is alkanes: ethane, butane and propane.
Step 2. The share of propane. Pick two groups, one after the other. Each pick is equally likely to be or . The four outcomes are then , then , then , and then . Two of the four make propane: .
Step 3. Three halides. Three ways to join a group with itself and three to join two different groups: alkanes.
Answer: , and . With one halide there is only one product, a symmetrical alkane. With two or more, the mixture is hard to separate.
Discussion (0)
Log in to join the discussion.
Loading…