Alexander Shulgin created and personally tested more than 200 psychedelic drugs, describing their effects according to his personal Shulgin rating scale.
In 1976, he developed a new synthesis method for MDMA, also known as ecstasy. He described being “overcome by the profundity of the experience” when he first took MDMA.
His research popularised the drug for recreational use, and among some psychotherapists it was used as a treatment in marriage guidance.
One described it as “penicillin for the soul”.
Mr Shulgin studied organic chemistry at Harvard in his teens and earned a PhD in biochemistry from the University of California, Berkeley.
He worked at Dow Chemical Company, where he developed the world's first biodegradable pesticide.
His wife, Ann, who was also his research partner, said he died in California “surrounded by family and caretakers and Buddhist meditation music”.