Posts Tagged ‘Imperial College’

Revisiting (and maintaining) a twenty year old web page. Mauveine: The First Industrial Organic Fine-Chemical.

Thursday, February 2nd, 2017
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Almost exactly 20 years ago, I started what can be regarded as the precursor to this blog. As part of a celebration of this anniversary,[1] I revisited the page to see whether any of it had withstood the test of time. Here I recount what I discovered.

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References

  1. P.W. May, S.A. Cotton, K. Harrison, and H.S. Rzepa, "The ‘Molecule of the Month’ Website—An Extraordinary Chemistry Educational Resource Online for over 20 Years", Molecules, vol. 22, pp. 549, 2017. http://dx.doi.org/10.3390/molecules22040549

500 chemical twists: a (chalk and cheese) comparison of the impacts of blog posts and journal articles.

Friday, June 3rd, 2016
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The title might give it away; this is my 500th blog post, the first having come some eight years ago. Very little online activity nowadays is excluded from measurement and so it is no surprise that this blog and another of my "other" scholarly endeavours, viz publishing in traditional journals, attract such "metrics" or statistics. The h-index is a well-known but somewhat controversial measure of the impact of journal articles; here I thought I might instead take a look at three less familiar ones – one relating to blogging, one specific to journal publishing and one to research data.

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Global initiatives in research data management and discovery: searching metadata.

Monday, March 7th, 2016
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The upcoming ACS national meeting in San Diego has a CINF (chemical information division) session entitled "Global initiatives in research data management and discovery". I have highlighted here just one slide from my contribution to this session, which addresses the discovery aspect of the session.

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The 2015 Bradley-Mason prize for open chemistry.

Friday, June 26th, 2015
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Open principles in the sciences in general and chemistry in particular are increasingly nowadays preached from funding councils down, but it can be more of a challenge to find innovative practitioners. Part of the problem perhaps is that many of the current reward systems for scientists do not always help promote openness. Jean-Claude Bradley was a young scientist who was passionately committed to practising open chemistry, even though when he started he could not have anticipated any honours for doing so. A year ago a one day meeting at Cambridge was held to celebrate his achievements, followed up with a special issue of the Journal of Cheminformatics. Peter Murray-Rust and I both contributed and following the meeting we decided to help promote Open Chemistry via an annual award to be called the Bradley-Mason prize. This would celebrate both “JC” himself and Nick Mason, who also made outstanding contributions to the cause whilst studying at Imperial College. The prize was initially to be given to an undergraduate student at Imperial, but was also extended to postgraduate students who have promoted and showcased open chemistry in their PhD researches.

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Mechanism of the Lithal (LAH) reduction of cinnamaldehyde.

Wednesday, April 1st, 2015
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The reduction of cinnamaldehyde by lithium aluminium hydride (LAH) was reported in a classic series of experiments[1],[2],[3] dating from 1947-8. The reaction was first introduced into the organic chemistry laboratories here at Imperial College decades ago, vanished for a short period, and has recently been reintroduced again. The experiment is really simple in concept; add LAH to cinnamaldehyde and you get just reduction of the carbonyl group; invert the order of addition and you additionally get reduction of the double bond. Here I investigate the mechanism of these reductions using computation (ωB97XD/6-311+G(d,p)/SCRF=diethyl ether).

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References

  1. R.F. Nystrom, and W.G. Brown, "Reduction of Organic Compounds by Lithium Aluminum Hydride. I. Aldehydes, Ketones, Esters, Acid Chlorides and Acid Anhydrides", Journal of the American Chemical Society, vol. 69, pp. 1197-1199, 1947. http://dx.doi.org/10.1021/ja01197a060
  2. R.F. Nystrom, and W.G. Brown, "Reduction of Organic Compounds by Lithium Aluminum Hydride. II. Carboxylic Acids", Journal of the American Chemical Society, vol. 69, pp. 2548-2549, 1947. http://dx.doi.org/10.1021/ja01202a082
  3. F.A. Hochstein, and W.G. Brown, "Addition of Lithium Aluminum Hydride to Double Bonds", Journal of the American Chemical Society, vol. 70, pp. 3484-3486, 1948. http://dx.doi.org/10.1021/ja01190a082

The mechanism of diazo coupling: more hidden mechanistic intermediates.

Saturday, March 8th, 2014
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The diazo-coupling reaction dates back to the 1850s (and a close association with Imperial College via the first professor of chemistry there, August von Hofmann) and its mechanism was much studied in the heyday of physical organic chemistry.[1] Nick Greeves, purveyor of the excellent ChemTube3D site, contacted me about the transition state (I have commented previously on this aspect of aromatic electrophilic substitution). ChemTube3D recruits undergraduates to add new entries; Blue Jenkins is one such adding a section on dyes.

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References

  1. S.B. Hanna, C. Jermini, H. Loewenschuss, and H. Zollinger, "Indices of transition state symmetry in proton-transfer reactions. Kinetic isotope effects and Bronested's .beta. in base-catalyzed diazo-coupling reactions", Journal of the American Chemical Society, vol. 96, pp. 7222-7228, 1974. http://dx.doi.org/10.1021/ja00830a009

Blasts from the past and present: altmetrics.

Sunday, October 13th, 2013
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I reminisced about the wonderfully naive but exciting Web-period of 1993-1994. This introduced the server-log analysis to us for the first time, and hits-on-a-web-page. One of our first attempts at crowd-sourcing and analysis was to run an electronic conference in heterocyclic chemistry and to look at how the attendees visited the individual posters and presentations by analysing the server logs.

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Computers 1967-2013: a personal perspective. Part 5. Network bandwidth.

Wednesday, June 5th, 2013
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In a time of change, we often do not notice that Δ = ∫δ. Here I am thinking of network bandwidth, and my personal experience of it over a 46 year period.

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Digital repositories. An update.

Saturday, July 21st, 2012
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I blogged about this two years ago and thought a brief update might be in order now. To support the discussions here, I often perform calculations, and most of these are then deposited into a DSpace digital repository, along with metadata. Anyone wishing to have the full details of any calculation can retrieve these from the repository. Now in 2012, such repositories are more important than ever. 

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Confirming the Fischer convention as a structurally correct representation of absolute configuration.

Tuesday, March 13th, 2012
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I wrote in an earlier post how Pauling’s  Nobel prize-winning suggestion in February 1951 of an (left-handed) α-helical structure for proteins was based on the wrong absolute configuration of the amino acids (hence his helix should really have been the right-handed enantiomer). This was most famously established a few months later by Bijvoet’s definitive crystallographic determination of the absolute configuration of rubidium tartrate, published on August 18th, 1951 (there is no received date, but a preliminary communication of this result was made in April 1950). Well, a colleague (thanks Chris!) just wandered into my office and he drew my attention to an article by John Kirkwood (DOI: 10.1063/1.1700491) published in April 1952, but received July 20, 1951, carrying the assertion “The Fischer convention is confirmed as a structurally correct representation of absolute configuration“, and based on the two compounds 2,3-epoxybutane and 1,2-dichloropropane. Neither Bijvoet nor Kirkwood seem aware of the other’s work, which was based on crystallography for the first, and quantum computation for the second. Over the years, the first result has become the more famous, perhaps because Bijvoet’s result was mentioned early on by Watson and Crick in their own very famous 1953 publication of the helical structure of DNA. They do not mention Kirkwood’s result. Had they not been familiar with Bijvoet’s result, their helix too might have turned out a left-handed one!

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