Why does “fetid fluorite”, a mineral that is found in the Upper Palatinate in Bavaria, Germany, have such an unpleasant sharp smell when it is crushed? Scientists in Munich have now found the solution to this puzzle, not only bringing an end to a controversial discussion that has been going on for about 200 years, but also altering a hard and fast textbook rule.
In the journal Angewandte Chemie, the researchers have demonstrated that the stench is caused by elemental fluorine. This unambiguously proves that despite prior assumptions, elemental fluorine does occur in nature.
Elemental fluorine (F2) is an extremely reactive gas that attacks nearly all materials; it even eats away at laboratory glassware. In contrast, chemically bound fluorine atoms in inorganic or organic compounds are – in proper doses – harmless and actually quite useful, whether in fluoride toothpaste, flame retardant materials, or Teflon. It is no wonder that chemists have so far been convinced that fluorine cannot occur in nature in its elemental form, but only as the fluoride ion, for example in minerals like fluorite (CaF2).
One special form of fluorite is found in the “Maria” mine in Wölsendorf in the Upper Palatinate in Germany. The unusual thing about this mineral is its odor, which pricks the nose as soon as this “fetid fluorite” or “antozonite” is crushed. But what causes the smell? Experts have been arguing about this for almost 200 years. A number of important chemists, including Friedrich Wöhler (1800-1882) and Justus von Liebig (1803-1873), discussed possible different substances that may be responsible for the smell. Over the years, elemental fluorine; iodine; ozone; compounds of phosphorus, arsenic, sulfur, and selenium; chlorine; hypochloric acid; and fluoridated hydrocarbons have all been blamed for the stench.
Florian Kraus of the TU Munich, as well as Jörn Schmedt auf der Günne and Martin Mangstl at the Ludwig Maximilians University in Munich have now obtained direct proof: Elemental fluorine is the guilty party that causes the unpleasant odor. By using 19F nuclear magnetic resonance spectroscopy (NMR spectroscopy), they were able to show for the first time that elemental fluorine is contained in “antozonite”.
How is this possible for such a reactive gas? The researchers explain that “antozonite” contains a tiny amount of uranium that, together with its radioactive daughter nuclides, constantly releases radiation into the surrounding mineral. This causes fluorite to split into calcium and elemental fluorine, forming the calcium clusters that give “antozonite” its dark purple color. The fluorine is contained in tiny enclaves surrounded by nonreactive fluorite, which shields it from the calcium, allowing it to maintain its elemental form.
Angewandte Chemie International Edition, Permalink to the article: http://dx.doi.org/10.1002/anie.201203515
Florian Kraus | Angewandte Chemie
Flow of cerebrospinal fluid regulates neural stem cell division
22.05.2018 | Helmholtz Zentrum München - Deutsches Forschungszentrum für Gesundheit und Umwelt
Chemists at FAU successfully demonstrate imine hydrogenation with inexpensive main group metal
22.05.2018 | Friedrich-Alexander-Universität Erlangen-Nürnberg
So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics
Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...
The historic first detection of gravitational waves from colliding black holes far outside our galaxy opened a new window to understanding the universe. A...
A team led by Austrian experimental physicist Rainer Blatt has succeeded in characterizing the quantum entanglement of two spatially separated atoms by observing their light emission. This fundamental demonstration could lead to the development of highly sensitive optical gradiometers for the precise measurement of the gravitational field or the earth's magnetic field.
The age of quantum technology has long been heralded. Decades of research into the quantum world have led to the development of methods that make it possible...
Cardiovascular tissue engineering aims to treat heart disease with prostheses that grow and regenerate. Now, researchers from the University of Zurich, the Technical University Eindhoven and the Charité Berlin have successfully implanted regenerative heart valves, designed with the aid of computer simulations, into sheep for the first time.
Producing living tissue or organs based on human cells is one of the main research fields in regenerative medicine. Tissue engineering, which involves growing...
A team of scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg investigated optically-induced superconductivity in the alkali-doped fulleride K3C60under high external pressures. This study allowed, on one hand, to uniquely assess the nature of the transient state as a superconducting phase. In addition, it unveiled the possibility to induce superconductivity in K3C60 at temperatures far above the -170 degrees Celsius hypothesized previously, and rather all the way to room temperature. The paper by Cantaluppi et al has been published in Nature Physics.
Unlike ordinary metals, superconductors have the unique capability of transporting electrical currents without any loss. Nowadays, their technological...
02.05.2018 | Event News
13.04.2018 | Event News
12.04.2018 | Event News
18.05.2018 | Power and Electrical Engineering
18.05.2018 | Information Technology
18.05.2018 | Information Technology