His main field of interest was terpenes and camphor as well as optical activity.

He continued his studies at the University of Strasbourg under Rudolf Fittig and then in 1887 in Munich under Adolf von Baeyer.

Rupe received his PhD in 1889 at Munich for his dissertation Über die Reduktionsprodukte der Dichloromuconsäure.

During his time as a professor, he supervised nearly 150 students and published over 250 scientific articles.

[1] In 1907, he married Margrit Hagenback, daughter of Eduard Hagenbach-Bischoff with whom he had three children.