Crum Brown, Alexander

Shortly after the tetravalent nature of carbon was proposed, extensions to the Kekule-Couper theory were made w7hen the possibility of multiple bonding between atoms was suggested. Emil Erlenmeyer proposed a carbon-carbon triple bond for acetylene, and Alexander Crum Brown proposed a carbon-carbon double bond for ethylene. In 1865, Kekule provided another major advance when he suggested that carbon chains can double back on themselves to form rings of atoms. 

With the exception of some unique symbols of William Higgins in 1789, generally, straight lines appeared in published chemical formulas only when Archibald Couper introduced them in 1858 to indicate valences (units of atomicity, saturation capacity, or quantivalence).77 Whereas innocent accent marks or superscript dashes had been used at midcentury to indicate valence or value, straight lines now suggested a less abstract meaning, despite disclaimers like Alexander Crum Brown s that the lines indicated the "chemical," not "physical," positions of atoms. 78... 

Sir James Dewar was born in Kincardine, Scotland, on September 20, 1842, the son of an innkeeper. He attended local schools until he was ten when he suffered a serious case of rheumatic fever lasting two years. During this period he built a violin, and music remained a lifelong interest of his. In 1858 he entered the University of Edinburgh. There he studied physics and chemistry. Dewar, in an early display of his dexterity, developed a mechanical model of Alexander Crum Brown s graphic notation for organic compounds. This was sent to Friedrich Kekule in Ghent who then invited Dewar to spend some time in his laboratory. 

Alexander Crum Brown, Report of the British Association for the Advancement of Science (1874) 46, 49. 

Chemistry was required for admission to medical school, and the Professor of Chemistry, Alexander Crum Brown,75 gave separate lectures to the women students, insisting they were identical to those which he was concurrently giving to the men. Pechey attained third place in the chemistry examinations. Forty years earlier, Hope had instituted awards known as the Hope Scholarships, and these were presented to the top four students in the first-year chemistry examinations. The recipients were entitled to free use of the facilities of the University chemistry laboratory for the next term. The two students above Pechey in the list were repeating the course and were therefore ineligible. 

J.W. (1924). Obituary notices of Fellows deceased Alexander Crum Brown, 1838-1922. Proceedings of the Royal Society of London, Series A 105 i-v. 

The concept of specific receptors and sites of drug action has many origins. However, the work of Thomas Fraser and Alexander Crum Brown of Edinburgh University described in their publication of 1869, "On The Connection Between Chemical Constitution and Physiological Action", provides both a definition of structure-activity relationships and a pioneering example of chemist-pharmacologist collaboration (13). 

Kekule was not the only important protagonist in the rise of the set of ideas that was ultimately consolidated under the rubric "structure theory" for example, in addition to Williamson, Adolphe Wurtz, Emil Erlenmeyer, Hermann Kolbe, and Edward Frankland also played vital roles. At the time of the birth of the theory all of these men occupied respected positions in their field. Chapter 5 looks at four outsiders— Archibald Couper, Joseph Loschmidt, Aleksandr Butlerov, and Alexander Crum Brown—who at this time were relatively new to the science, but who made their marks in sometimes transformative ways during the years 1858-64. All four had definite ideas on how molecules should be conceived by the scientist and best represented for heuristic purposes. A tour of these figures provides a fuller understanding of the range of responses, opportunities, and creative options that were available during these tumultuous years in the science, and suggests par-... 

In chapter 1 we noted the probable influence of the Common-Sense school on Couper s fellow Scots/English chemists Williamson and Graham. In reference to the 1826-27 atomistic formulas of the Glaswegian chemist Thomas Clark, W. V. Farrar has seen "a climate of thought in Scotland favourable to naive structuralism," and argued for a culmination of this trend in the formulas of Couper and Alexander Crum Brown. More broadly, Richard Olson has explored the influence of Scottish Common-Sense philosophy on British physics. This philosophical school arose in Thomas Reid s opposition to the skeptical writings... 

These details come from Dobbin, "Couper Quest" Since Alexander Crum Brown was at Edinburgh University at this time and yet never met Couper, it is likely that Couper never actually reported for work in January 1859 all we know for certain is that he was offered the position, not that he accepted it or fulfilled any duties. 

As we have noted, Loschmidt s booklet contains references to literature that was published throughout the year 1861, but it must have been printed and distributed quickly at the end of the year, for already on 4 January 1862 Kekul4 mentioned in a letter to Erlenmeyer that he had read "Loschmidts Confusionsformeln." This derogatory two-word reference is all we have from the private Kekule, but he also referred once to Loschmidt s formulas publicly (and relatively neutrally), in the 1865 paper in which he first announced his benzene theory the relevant footnote simply states that he regarded his own graphic formulas as preferable to those that had been proposed by Loschmidt and by Alexander Crum Brown. Interestingly, in Loschmidt s very last publication (1890), in which he returned to a theoretical discussion of the structure of benzene, he did not even mention his 1861 booklet or any proposals therein. ... 

So the four tetrahedral faces of carbon in Butlerov s imagined example were not equivalent two were "primary" valences, two "secondary." Such a distinction could explain several curious examples of isomerism that otherwise appeared inexplicable. Alexander Crum Brown examined this hypothesis two years later. He argued from known reaction sequences to demonstrate there was no way to formulate the hypothesis in a self-consistent fashion to explain such isomerisms, unless one were also to assume that primary valences can spontaneously become secondary, and vice versa. Crum Brown had effectively closed down this line of argument. 

Crum Brown, Alexander. On the Theory of Chemical Combination, M.D. thesis. University of Edinburgh, 1861. Published verbatim by Edinburgh Neill, 1879. 

Larder, David. "Alexander Crum Brown and His Doctoral Thesis of 1861." Am-bix 14 (1967) 112-32. 

Ritter, Christopher. "An Early ffistory of Alexander Crum Brown s Graphical Formulas." In Tools and Modes of Representation in the Laboratory Sciences, edited by Ursula Klein, 35-46. Dordrecht Kluwer, 2001. 

W[alker], J. "Alexander Crum Brown." Journal of the Chemical Society 123 (1923) 3422-31. 

At this point, it is instructive to remind ourselves of the prediction made by the Scottish chemist Alexander Crum Brown in 1874 [22] ... 

Alexander Crum Brown (Edinburgh 26 March 1838-28 October 1922), professor of chemistry in Edinburgh (1869-1908), was also proficient in anatomy and engineering and acted as examiner in Japanese. He wrote on the phlogiston theory, on Brodie s system of chemical notation, and the application of mathematics to chemistry. With James Walker he extended Kolbe s electrosynthetic method (see p. 505) to the preparation of esters of dibasic acids from the alkali salts of semi-esters ... 

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