[LEFT] Maraschino cherry ice cream made at Penn State. [CENTER] An artist's rendition of a DNA structure. [RIGHT] Mildred Cohn
The article titled “The Dream in the Machine” (Summer 2010, p. 17) about my “favorite computer,” the IBM 701, was indeed flattering and is mostly factual. However, I write to correct the impression that our theoretical work with the 701 had any significant impact on the commercial success of Dacron.
Upon my arrival at DuPont’s Jackson Laboratory in late 1950, I was almost the only physical chemist among perhaps 200 organic chemists, many of whom were engaged in creating dyes for the “new” fibers, such as Dacron, Orlon, and the earlier Nylon. I had proposed to provide guidance to this synthetic effort by elucidating the relationships between color and structure through use of molecular orbital theory. This effort, in collaboration with my consultant and former teacher, Robert G. Parr, led to the development of the PP (Pariser, Parr) molecular orbital theory, which was later added to by John Pople, and is now known as PPP.
Although the use of PP provided occasional guidance to the synthetic dye effort at Jackson Laboratory, I am sure that it was not a factor in the commercial success of these fibers. However, the publications of PP theory were extremely well-received worldwide, resulting in these papers being among the five most cited in chemistry or physics during 1961–1977. They likely had influence over various other applications, such as fluorescent dyes, organic LEDs, and conductive polymers.
Rudolph Pariser (via e-mail)
“The Dream in the Machine” implies that DuPont’s Dacron was a new fiber. Poly (ethylene terephthalate) was first produced by Calico Printers and was commercialized by Imperial Chemical Industries in the United Kingdom. DuPont cross-licensed nylon 6,6 to ICI in return for a polyester license. DuPont built a plant in Kinston, North Carolina, to produce Dacron, their version of ICI’s Terylene. The U.S. Justice Department did not look favorably on DuPont using one patent monopoly (Nylon) to gain another and so DuPont granted a nylon license to Chemstrand, a fledgling fiber company originally formed to produce an acrylic fiber (Acrilan). Acrilan was shut down several years ago and the nylon business sold to SK Partners. DuPont is also out of the polyester and nylon businesses except for the aromatic nylons Nomex and Kevlar.
Jim Masson (via e-mail)
I enjoyed reading your article on Mildred Cohn, “A First Lady of Chemistry” (Summer 2010, p. 13). While academic tenure was not granted to Dr. Cohn until she moved to the University of Pennsylvania, the opportunity for her career to flourish as an independent research scientist began during her time at Washington University in St. Louis in the Cori department. Her connection with the American Heart Association began in 1953 as one of the early recipients of the AHA’s Established Investigator Awards. She appeared as first or second author on all but one of the 14 papers that she published while at Washington University. At the time of her departure she held the title of Research Associate Professor. On a separate point, her research did not help to determine the structure of ATP but rather to determine the mechanism of reactions that use ATP.
Michael A. Grayson (via e-mail)
One aspect of John William Draper’s life (“Across the Spectrum,” Summer 2010, p. 8) is little known. Draper was married to a Brazilian woman whose British father was a professor of chemistry in Rio de Janeiro and whose mother was a lady-in-waiting to the Portuguese queen. In 1808 the Portuguese royal family, fleeing Napoleon’s invasion, took refuge in Brazil, thus making Rio de Janeiro the de facto capital of the Portuguese Empire. They remained in Brazil for 13 years, during which time many institutions were created, several of them dealing with science. This includes the Royal Military Academy, where the first regular course of chemistry in the country was set up in 1810. The professor appointed to the chair of chemistry was Daniel Gardner, who married a lady-in-waiting and namesake of the Portuguese queen, Carlota Joaquina de Paiva Pereira Gardner. After Gardner’s retirement in 1825 the family went to England, where their daughter, Antônia Caetana de Paiva Pereira Gardner, would later marry John William Draper.
Carlos A. L. Filgueiras, Department of Chemistry – UFMG (Belo Horizonte - MG Brazil)
Editors’ Note: On page 30 (“Chemical Relations,” Summer 2010) Walter Hückel is listed as the theoretician who proposed a general theory based on the number of electrons in a ring compound. In fact, it was his brother Erich who proposed the theory. We regret the error.
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