In Jingdezhen an Imperial Kiln was built in 1369 to produce porcelain that was “white as jade, thin as paper, bright as a mirror and tuneful as a bell”. It’s the colours of the glazes that caught my eye, achieved by a combination of oxidative and reductive firing in the kiln, coupled with exquisite control of the temperature.
This post is prompted by the appearance of a retrospective special issue of C&E news, with what appears to be its very own Website: internet.cenmag.org.
This is a little historical essay into the electronic structure of naphthalene, presented as key dates (and also collects comments made which were appended to other posts). 1890[cite]10.1039/pl8900600095[/cite]: Henry Armstrong presents the following structure of naphthalene. Three words need translation into modern usage.
As I have noted elsewhere, Gilbert N. Lewis wrote a famous paper entitled “ the atom and the molecule ”, the centenary of which is coming up.[cite]10.1021/ja02261a002[/cite] In a short and rarely commented upon remark, he speculates about the shared electron pair structure of acetylene, R-X≡X-R (R=H, X=C). It could, he suggests, take up three forms. H-C:::C-H and two more which I show as he drew them.
Sometimes you come across a bond in chemistry that just shouts at you. This happened to me in 1989[cite]10.1039/C39890001722[/cite] with the molecule shown below. Here is its story and, 26 years later, how I responded. To start at the beginning, there was a problem with the measured 1 H NMR spectrum; specifically (Y=H, Z=O) there are supposedly 16 protons, but only 15 could be located. What had happened to the 16th?
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. The first was 60 Stoke Newington High Street in north London, the home of Albert N. Beck, Chemist (or his son;
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.
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.
In the preceding post, a nice discussion broke out about Kekulé’s 1872 model for benzene.[cite]10.1002/jlac.18721620110[/cite] 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.
Continuing my european visits, here are two photos from Bonn. First, a word about how the representation of benzene evolved, attributed to Kekulé. The sausage formula Above is his first effort, made in 1865. The bent bond formula This one above is better, offered in 1866.
