In an effort to repurpose expired guaifenesin tablets, experiments devised for practical instruction are reported for the preparation and isolation of the guaifenesin acetonide using a microscale kit. The laboratory experiment successfully utilizes a waste chemical in lieu of a fine chemical to illustrate the principles behind protecting groups in organic synthesis. Oxidative cleavage is used to demonstrate the stability of the acetonide protecting group. Lastly, methanolysis of the acetal demonstrates the reversibility of the functional group transformation.