Developing skills for searching the patent literature is an essential element of chemical information literacy programs at the university level. The present article creates awareness of patents as a rich source of chemical information. Patent classification is introduced as a key-component in comprehensive search strategies. The free Espacenet patent search interface and classification browser are used in a case study related to the chemistry of graphene. Step-by-step instructions are provided on how to identify search concepts, retrieve classification symbols with keywords, and iteratively refine the chemical concept based search. Instructional material for the use in chemical literature courses is proposed.