Synthesis of synthetic detergent with Friedel Crafts Acylation
Your synthesis looks reasonable, and it is correct to perform sulfonation as the very last step, because the alkanoyl group would be meta-directing for the reason you have provided.

You can simplify your synthesis by reducing the carbonyl group away in one step with the Clemmensen reduction, which works well for aryl-alkyl ketones produced by Friedel-Crafts acylation.



Alternatively, the Wolff-Kishner or Mozingo reaction could be used. Reducing the number of steps in your synthesis would in practice have the benefit of increased overall yield for the final product, as the yield of each single step is usually &lt; 100 %.