Pick a search engine, any search engine, type in your favourite keywords - you can use Boolean operators if you like. Regardless of how sophisticated your search tactics you will inevitably get a listing of hundreds if not thousands of sites. Take a chemistry search for online journals, for instance. A typical search engine will provide a listing of numerous sites claiming to provide such a listing. Click a likely link... and...
Oh! It's a dead- end. 'Site under construction, November 1997' or 'Last updated April 1996' are common greetings.
It has been like that since the heady mid-1990s when there were merely hundreds and thousands of sites. Some entries don't bear up to closer scrutiny though having stagnated months after they were started. These CobWebs are making it harder and harder for chemists to fight their way through the net.
Ten years ago, an online resource that claimed to be current for six months would probably be perfectly adequate. But, today with millions of chemical web pages and countless journals online, a site not updated at least every couple of months will not do.
The problem might seem trivial. After all, for every search engine entry that is a little dated, there are surely a dozen more current ones. With the Internet expanding almost exponentially though, it becomes increasingly difficult to wade through the shallows to catch the next wave. To mix a metaphor, the cobwebs are leaving us all at sea.
Without meaning to single out particular webmasters, there are many sites around that leave, cobwebs in their wake to mix metaphors again. For example, the Free University Berlin created one early chemistry web index. The site moved to new premises some years ago to www.chemie.de, but, the latest generation of enthusiastic web-site amateurs keeps on listing the original address. Almost a thousand sites, to be precise, according to a quick link-search on AltaVista.com. If you were a web novice, you might spend many a happy hour trawling through those hundreds of links looking for the FU Berlin site and failing at every click to hit the wave.
This is a growing problem. Another popular resource was begun several years ago by German chemistry student Rolf Claessen. Claessen built up quite a substantial set of links to all kinds of resources from chemistry software to discussion groups. However, while the content has changed, his site has only just settled on a domain name (www.claessen.net) so the search engines are littered with the old web addresses and sub-pages which don't always lead to the current resources. Amazingly, webmasters are still adding these cobwebs to their own lists of links, clogging the system further. There are almost 500 links to a previous incarnation of
Claessen.net.
Closer to home, the Sheffield University ChemDex, for all its fame, is still linked to by users and sites through several outdated addresses rather than the fresher Chemdex.org. If you do not have the new address, you can still find it, eventually, and therein lies the problem with cobwebs. The outdated sites, the links that have changed, and acres of abandoned net real estate really do waste your time.
Although strictly speaking these links to Chemdex are not really cobwebs
in that they have redirect instructions attached to them that do take you
to the proper site, although seeing an old link in a search engine listing
might put you off clicking it if you thought it might likely be out of
date.
So, what's the solution? Well from the web users' perspective, we could e- mail every errant webmaster and alert them to dead links and out of date pages on their site. But, they may not thank you for it. More practically, one can learn by experience that not every link is good and if you are a webmaster make sure your old pages are updated, check those links and include a 'redirect' tag if you move site. Most of all - clean out those cobwebs.
A listing of cobwebs and fully up to date sites are at www.liv.ac.uk/Chemistry/Links/cobwebchemistry.html compiled by Michael Barker of Helsinki University of Technology, Finland.
You might also try Mark Winter's ChemDex.org, Chemindustry.com for arachnid-free surfing and
Jonathan Goodman's Chemistry2000
site, which is
checked monthly and as polished as one would
expect.
UK chemists have developed a new synthetic methodology for the synthesis of pharmaceuticals that avoids the use of noxious organic solvents and reduces waste. They have demonstrated the efficacy of the approach in the synthesis of Pravadoline, which they obtain in high yield.
Kenneth Seddon (right), Martyn Earle and their colleagues at The Queen's University of Belfast have been developing alternatives to volatile organic solvents (VOCs) for several years. Ionic liquids - compounds that although ionic in nature are liquids at room temperature rather than crystalline solids - have been their focus. These materials are non-volatile, non- flammable and can easily be separated from product and catalysts.
Seddon and his team believe that ionic liquids could allow wasteful pharmaceutical processes to be cleaned up and the amount of solvent used reduced. They have demonstrated the potential using Pravadoline. This and its analogues are under investigation as painkillers and neurochemical receptor probes, because they interact agonistically with the cannabinoid receptor in the brain. Their manufacture, however, would be likely to generate large quantities of waste VOCs during each stage of its synthesis.
Seddon points out that Pravadoline is synthesised using a sequence of regioselective nucleophilic displacement reactions and Friedel–Crafts reactions. These, he explains, are two classes of reaction that work very well in ionic liquids and can be extended to many other industrial processes.
The researchers have used 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF6]) as their ionic liquid solvent because it is immiscible with water and alkanes, but readily dissolves many metal catalysts and reagents.
The reaction scheme for Pravadoline synthesis usually involves a dipolar aprotic solvent such as the unpleasant smelling DMF or noxious DMSO using sodium hydride or sodium hydroxide as the base. Neither solvent is easily recyclable and is lost to the environment. Using the ionic liquid process, however, the team was able to easily retrieve it for recycling and the only chemically generated waste is an aqueous solution of potassium chloride. The reaction also occurs without heating and boosts yields from 91% in the VOCs to better than 95% in the ionic liquid.
They report more details in Green Chemistry [[DOI: 10.1039/b006612p]]