In this reaction the arene p-xylene is the starting aromatic compound. In this case the p-xylene is more reactive than the starting material, n-propyl chloride and aluminum chloride, so multiple substitutions can take place. The p-xylene is present in excess to prevent multiple alkylations of the reaction to take place.
Rearrangements such as carbocation rearrangements and methyl/hydride shifts can result in different alkyl arenes as products. The alkyl halides, with an exception to methyl and ethyl, undergo these rearrangements. Usually, under the Friedel-Crafts alkylation conditions, primary alkyl halides rearrange to either secondary or tertiary carbocations that are much more stable. The reactant in this experiment is n-propyl chloride. The products in this experiment from the p-xylene are the unrearranged n-propyl group attached to the p-xylene (1,4-Dimethyl-2-n-propylbenzene) and the rearranged isopropyl group attached to the p-xylene (1,4-Dimethyl-2-isopropylbenzene). The aluminum chloride is the Lewis acid catalyst in the reaction and combines with the chloride ion of the n-propyl chloride to form the Friedel-Crafts complex.
Gas chromatography will be used to decide the quantitative product distribution of the resulting compounds.
The purpose of this experiment is to carry out the Friedel-Crafts alkylation of p-xylene. Also the...