laboratory synthesis of caffeine based on US 2,785,162
<a href="//commons.wikimedia.org/wiki/User:%D0%94.%D0%98%D0%BB%D1%8C%D0%B8%D0%BD" title="User:Д.Ильин">Д.Ильин</a>: vectorization, translation
<a href="//commons.wikimedia.org/wiki/File:Caffeine_synthesis.tif" title="File:Caffeine synthesis.tif">File:Caffeine synthesis.tif</a> by <a href="//commons.wikimedia.org/wiki/User:Boghog" title="User:Boghog">Boghog</a>