The Wurtz reaction involves coupling two alkyl halides. To make an alkane with an odd number of carbons, like propane, one would need to use a mixture of two different alkyl halides (e.g., methyl chloride and ethyl chloride), which results in a mixture of three different products (ethane, propane, and butane) that is difficult to separate. [cite: 587, 588, 589, 591, 592]