A perspective distilled from seventy years of research

Physical organic chemistry might be regarded as officially recognized as a distinct discipline through the publication of L. P. Hammett's book of that title, although substantial earlier work can be traced back to the turn of the 20th century. Many of the instrumental tools that helped the discipline develop in so many different ways began to appear in the late thirties and during World War II and were soon built to be increasingly operated in the "hands-on" mode. This development became very popular in academia, where instruments are not operated for you by an expert, but even if you are an undergraduate, you can more or less be the expert yourself and take many varieties of data on instruments usually available on a 24 h basis. It has been my privilege and joy to begin research in chemistry just as these waves of change began to grow and to savor the great contribution that the new methods, such as measurement of (14)C, UV-vis, IR, NMR, and hands-on use of computers, made in facilitating our research programs at MIT and later at Caltech. Among those programs, which will be discussed, were (14)C tracing of carbocation rearrangements and benzyne formation, electrical effects of substituents, Grignard reagents, synthesis of small-ring compounds, (2 + 2) cycloaddition reactions of halogenated ethylenes, assisting in development of (19)F, (13)C, and (15)N NMR for conformational analysis, other structural, kinetic, and tracer studies, as well as helping through textbooks to bring Huckel MO theory and the elements of NMR to familiarity for organic chemists. From the very beginning of my research career, I have been the beneficiary of personal mentoring which has been very crucial to my success in research and is an important theme in what follows.