John D. Roberts (1918-2016).

John D. (“Jack”) Roberts, Professor of Chemistry, Emeritus, at the California Institute of Technology (Caltech), died on 29 October at the age of 98. Roberts led organic chemistry's transition from a field that studied what reactions did to one that also studied how reactions happened. He was an explorer with boundless curiosity who was untiring in his efforts to bring new and useful ideas, tools, and experimental designs to chemistry. He thrived on convincing chemists that his opinions on both science and scientific standards were correct (or at least worth arguing about, usually strenuously). He was not the only parent of physical-organic chemistry, but he was its best teacher. Roberts began his independent career in the time immediately after World War II. Before the war, chemistry had been concerned primarily with combining small molecules to make larger, more complicated ones. The war had produced a flood of new ideas and instrumental techniques in physical chemistry, ranging from theories of electronic structure to new spectroscopic tools. Organic synthetic chemistry and physical/analytical chemistry were culturally distinct, and interactions between them were limited. The war also resulted in the formation of the similarly distinct petrochemical industry and system of U.S. research universities that quickly came to support academic science. Roberts was completely indifferent to these boundaries between scientific ideologies. He went where his curiosity led him, and if there were obstacles that might have deterred others (for example, if he understood nothing about the subject), he simply charged on (boldly, or incautiously, depending upon one's point of view). When he discovered a good new idea, or a new technique, he did everything he could to teach other chemists about it. He became simultaneously an organic chemist, a physical chemist, an academic scientist, an inveterate teacher, and an active industrial consultant. As a scientist, his greatest contribution was to the formation of physical-organic chemistry, the field that studies organic reactions using combinations of physical and synthetic methods. In addition to introducing methods of simple quantum mechanics and new forms of spectroscopy [especially nuclear magnetic resonance (NMR)] to the field, Roberts showed how to infer the existence and structure of “transitory intermediates”: molecular structures that exist fleetingly (and are often, even now, invisible to direct observation) between the starting materials and products. In doing so, he made clear that focusing only on stable, long-lived reactants and products misses much of what goes on during the course of chemical reactions. The understanding of reaction mechanisms and intermediates that Roberts and others developed has been invaluable both in improving synthesis and in understanding the critical reaction networks making up processes ranging from metabolism in living cells to the formation of hydrocarbon fuels in petroleum refineries. ![Figure][1] PHOTO: NSF COLLECTION Roberts taught by doing, but he also taught by teaching. He wrote a number of books—from a widely used first-year organic chemistry text to short books on NMR spectroscopy and molecular-orbital theory (which he claimed to have dictated in his car while commuting). These books introduced the philosophy of physical-organic chemistry to both students and senior scientists. Born in 1918 in Los Angeles, California, Roberts received his B.A. (1941) and Ph.D. (1944) degrees from the University of California, Los Angeles (UCLA). After short appointments at UCLA, Harvard, and MIT, he moved to Caltech in 1952, where he spent the remainder of his career. After 1980, he became vice president, provost, and dean of the faculty at Caltech, but he continued to teach courses for many years. I joined his research group as a graduate student in 1960, when his research career was in its most active phase. Roberts was an unwavering supporter of young scientists (and, long before others, of women in science). He worked tirelessly and invisibly—insofar as he could manage it—to support and encourage younger colleagues. During the time I was a student, I almost never saw him in person (he later told me that I was a porcupine best left alone), but he devoted countless hours to editing my work. I would write a draft of a paper, he would correct it in word-for-word detail (in red pen), I would rewrite it, he would correct it again, and so on, seemingly ad infinitum. This style of directing graduate research was splendid for improving scientific standards, logic, grammar, style, and punctuation. It was even better as a lesson in the scientific method and, perhaps best of all, for building a (partially illusory) sense of independence. Years later, no longer a beginner, I wrote a report for a U.S. National Academy of Sciences committee, and Roberts was the reviewer. As in the past, we went through six or seven rounds of detailed editing (his, of course, in red pen) before he was satisfied. One comes to realize that—as a writer or scientist—one can have no better friend and teacher than a demanding editor. Roberts loved to argue, and did not discriminate between arguments in private and in public. For decades, he was the voice of conscience in the U.S. National Academy of Sciences and in other musty halls of Washington, DC, science. His arguments were always elitist. To him, only “quality” mattered. There could be no compromise on standards (and, fortunately, he had a clear and unwavering view of what these standards should be). His arguments were also loud. He was hard of hearing, and he loved combat. Every discussion proceeded at high volume. But it was always worth thinking about what he said. Jack Roberts was someone who was almost impossible not to love. To deal with—even for those of us who knew him well—he was gruff, argumentative, difficult or impossible to convince, and stubborn to a fault. He was also extraordinarily generous (he never took credit for a student's idea), incorrigibly curious, addicted to new ideas, warm and loyal to his friends, devoted to his family, students, and colleagues, and deeply and genuinely protective of science and its institutions. [1]: pending:yes