I started chemistry with a boxed set in 1962. In those days they contained serious amounts of chemicals, but I very soon ran out of most of them. Two discoveries turned what might have been a typical discarded christmas present into a lifelong career and hobby.
Archive for the ‘Historical’ Category
Egon Willighagen recently gave a presentation at the RSC entitled “The Web – what is the issue” where he laments how little uptake of web technologies as a “channel for communication of scientific knowledge and data” there is in chemistry after twenty years or more. It caused me to ponder what we were doing with the web twenty years ago. Our HTTP server started in August 1993, and to my knowledge very little content there has been deleted (it’s mostly now just hidden). So here are some ancient pages which whilst certainly not examples of how it should be done nowadays, give an interesting historical perspective. In truth, there is not much stuff that is older out there!
Following the discussion here of Kekulé’s suggestion of what we now call a vibrational mode (and which in fact now bears his name), I thought I might apply the concept to a recent molecule known as [2.2]paracyclophane. The idea was sparked by Steve Bachrach’s latest post, where the “zero-point” structure of the molecule has recently been clarified as having D2 symmetry.
- H. Wolf, D. Leusser, . Mads R. V. Jørgensen, R. Herbst-Irmer, Y. Chen, E. Scheidt, W. Scherer, B.B. Iversen, and D. Stalke, "Phase Transition of [2,2]-Paracyclophane - An End to an Apparently Endless Story", Chemistry - A European Journal, vol. 20, pp. 7048-7053, 2014. http://dx.doi.org/10.1002/chem.201304972
In the preceding post, a nice discussion broke out about Kekulé’s 1872 model for benzene. This model has become known as the oscillation hypothesis between two extreme forms of benzene (below). The discussion centered around the semantics of the term oscillation compared to vibration (a synonym or not?) and the timescale implied by each word. The original article is in german, but more significantly, obtainable only with difficulty. Thus I cannot access the article directly since my university does not have the appropriate “back-number” subscription.‡ So it was with delight that I tracked down an English translation in a journal that I could easily access. Here I discuss what I found (on pages 614-615, the translation does not have its own DOI).
Continuing my european visits, here are two photos from Bonn. First, a word about how the representation of benzene evolved, attributed to Kekulé.
Not a computer in sight! I refer to a chemistry lab from the 1800s I was recently taken to, where famous french chemists such as Joseph Gay-Lussac, Michel Chevreul and Edmond Fremy were professors. Although not used for chemistry any more, it is an incredible treasure trove of objects. Here are photos of some.