ChemWeb Newsletter

Not a subscriber? Join now.November 1, 2005


The Alchemist this week turns his attention to plastic metals with metallic strength but cool plastic properties, golden catalysts for hydrocarbon oxidation, a Russian test for corrosive sulfur contaminants in gasoline, DNA with a twist, and finally pyrethroids lead further than down the garden path.

NASA, Caltech, and the US DoE have formed a research amalgam to develop new materials they call "liquid metals". These alloys contain three or more metals and have properties similar to plastic in that they cool and solidify quickly, but have strength on a par with more conventional metals. One of the materials, dubbed Vitreloy, is composed of a blend of zirconium, titanium, nickel, copper, and beryllium, and goes from a liquid to a solid at room temperature. Instead of having to quickly cool a liquid metal to become solid, it cooled and hardened itself at room temperature. These materials are resistant to stress without losing their shape but are also three times more elastic than conventional alloys. The materials could have applications in the construction industry, sports equipment and in military armor.

UK and US researchers have developed a new type of tunable catalyst based on gold that can promote selective oxidation of hydrocarbons even under mild conditions. Graham Hutchings of Cardiff University, Wales, and colleagues point out that the oxidation reactions that underpin synthetic schemes for making chemical intermediates for high-value fine chemicals, agrochemicals, and pharmaceuticals are often inefficient. Gold catalysis has been used successfully in alcohol oxidation, but Hutchings and his colleagues have now found they can oxidize hydrocarbons to their epoxides efficiently too, using a macrocrystalline catalyst and air as the oxidant. They also demonstrate that no sacrificial reductant is needed as was the case with earlier work.

A small portable device can measure sulfur levels in gasoline, thanks to Russian scientists. Chemists at St. Petersburg State University and the EKROS Scientific Production Association also in St. Petersburg have built a hand-held device that can determine mercaptans, the main sulfur components of petroleum in real-time and so enable a much simpler alternative to current labor-intensive and time-consuming manual tests. Since mercaptans are corrosive to metals, their removal from vehicle fuel oils is desirable. The new device will allow more timely analysis of the refining process and so allow the petrochemical engineers to respond more immediately and so remove more sulfur impurities for their product.

X-ray diffraction results have revealed how normally right-handed DNA can kink and twist like a telephone handset cord to form a left-handed spiral. The results will not only explain certain biological properties of DNA and how it behaves but could be put to use in nano-scale devices based on DNA. MIT biologist Alexander Rich and Yang-Gyun Kim of Chung-Ang University and Kyeong Kyu Kim of Sungkyungkwan University, both in South Korea, and their co-workers have shown that the breaking of a single base pair, which then flips out of the double helix is enough to produce a junction between the right-handed form of DNA and the left-handed form. The researchers suggest the formation of this junction conserves both energy and helical structure.

The pyrethroid insecticides once touted as a safer alternative to the likes of DDT for domestic and garden use have been detected in suburban stream sediments by Donald Weston of the University of California, Berkeley, and colleagues. Pyrethroids are indeed less of a hazard to human health than many other insecticides but surprisingly little is known about their environmental fate and whether or not they might accumulate in ecosystems and cause problems for aquatic systems. Weston and colleagues say that their findings suggest long-overdue environmental monitoring for these materials should now be made a priority.