Complex sentence: Minieri's contribution to organic chemistry was clear while attending graduate school as he is remembered for a thesis on the Ritter reaction which he wrote as a graduate student at N.Y.U. working under the guidance of Professor John J. Ritter.
Split into simpler sentences: Minieri's contribution to organic chemistry was clear while attending graduate school. He is remembered for a thesis on the Ritter reaction which he wrote as a graduate student at N.Y.U. working under the guidance of Professor John J. Ritter.