The puzzle provides a list of chemical reactions which add or remove a functional group from a molecule. The key to the solution is figuring out what functional group gets added or removed and then making the same change to the appropriate reactant word.

The descriptions of the reactions suggest that an extra element needs to be added in order to complete the change from the reactant to the product words. These additional elements from the periodic table are shown on the left and spell CALL IN AMBER BEER when read in the reaction order.