[1] Holbrook was born in St. Louis, Missouri, and studied chemical engineering at the University of Michigan where he received his BS (1931), MS (1932), and Ph.
He then joined Du Pont, by 1939 was head of new products research at Jackson Laboratory, and in 1943 its assistant director.
In 1949 Holbrook was appointed general superintendent of product development at Chambers Works, then the world's largest chemical plant.
After a brief leave for government service - as deputy director and then director of the Chemical, Rubber, and Forest Products Bureau of the National Production Authority - Holbrook resumed his prior Du Pont work but also chaired Du Pont's Corporate Committee for Educational Fellowships and Grants.
In 1958 he was further promoted to vice president, director, and member of the Executive Committee.