June - 35 years ago; 75 years ago; 80 years ago; 95 years ago; 110 years ago.

35 years ago 

Swiss chemist Paul Karrer died. In 1930 Karrer worked out the chemical structure of carotenoids. He then determined the structure of vitamin A, for which he shared the 1937 Nobel prize for chemistry with Sir Norman Haworth. 

75 years ago 

UK chemist Jesse Boot died. Founder of Boots Company Ltd, Boot started making simple pharmaceuticals in 1888 and was soon controlling the largest pharmaceutical retail trade in the world. 

80 years ago 

Paul Berg was born in New York, US. He was first to construct a recombinant-DNA molecule and his pioneering work initiated genetic engineering. He shared the Nobel prize for chemistry in 1980 with Walter Gilbert and Frederick Sanger for work on recombinant-DNA techniques. 

95 years ago 

US biochemist William Stein was born in New York. Stein, Stanford Moore and Christian Anfinsen worked on the structures of ribonuclease and deoxyribonuclease and won the 1972 Nobel prize for chemistry. 

110 years ago 

Robert Sanderson Mulliken was born in Massachusetts, US. He developed the molecular-orbital theory with Friedrich Hund, and received the 1966 Nobel prize for chemistry for his work on chemical bonds and electronic structure of molecules.