in your element A flash of Magnesium is commonly found in rocks and sea water as well as living organisms. Paul Knochel relates how this element has also sparked a great deal of interest among .

ne of the most abundant elements world immediately applied his procedure on Earth (the sixth in order of — Grignard subsequently had problems Oweight abundance), magnesium finding enough examples of applications occurs naturally in crustal rocks, mainly in of his reagents that were still unpublished the form of insoluble carbonates, sulfates to complete his PhD thesis. This key and silicates. Its name derives from the discovery, for which he was awarded Magnesia district of Thessaly, where the a in 1912, revolutionized soft white mineral steatite talc — a hydrated organic chemistry. magnesium silicate — was found in ancient Organometallic compounds bearing a Greece. Magnesium was first isolated in carbon–magnesium bond are now among pure form in 1808 by Sir Humphry Davy, the most popular nucleophilic reagents. who used an electrolytic method that More than 100,000 publications dealing had been previously developed by the with the reactivity of these intermediates Swedish chemists Jöns Jakob Berzelius and have now appeared in the chemical Magnus Martin Pontin to isolate sodium, literature. Why such popularity? The barium, potassium, strontium and calcium, reactivity of a carbon–magnesium bond between 1807–1808. Elemental magnesium can be readily tuned by appropriate is a fairly strong, silvery white, light-weight transmetallations with many metallic salts, metal. It tarnishes slightly in air, and is thus increasing its use in synthesis dramatically. protected against further oxidation by a thin ions are also widely present in the basic Furthermore, the carbon–magnesium impermeable layer of oxide. nucleic acid chemistry of life. It is vital to bond possesses an intrinsic reactivity that Magnesium reacts exothermically the cells or enzymes of living organisms is compatible with the presence of many with most acids, and with water at room for synthesizing adenosine triphosphate, important organic functional groups in the temperature to give magnesium hydroxide DNA and RNA, as well as to green plants same molecule. Now, methods for preparing and hydrogen. It is a very flammable — chlorophylls, which are responsible for polyfunctional aryl and heteroaryl metal, able to burn in both nitrogen and photosynthesis, are magnesium-centred magnesium compounds bearing an ester, carbon dioxide, and famously creates a porphyrins. This also means that it is a a nitrile or an aromatic are also brilliant white light on burning in air. common additive in fertilizers, and is used available, which further increases the scope This resulted in its use as a source of in medicine. For example ‘milk of magnesia’, of Grignard reagents in . illumination in early photography. It a white aqueous solution of magnesium Moreover, the low price and low toxicity is still employed in flash bulbs, and in hydroxide, is commonly used as a laxative of magnesium makes these compounds fireworks to produce brighter sparks. Its and an antacid. suitable intermediates for large-scale very low density (1.74 g cm–3) makes it Magnesium also has a central position applications in industry. Important drugs an attractive component for alloys — for in organic and . such as tamoxifen citrate, a non-steroidal example, the best magnesium alloy weighs Although organomagnesium compounds oestrogen antagonist used in the treatment only a quarter as much as steel — and have been known since the last decades of of advanced breast cancer, are prepared because its metallurgy is simpler than that the nineteenth century, their insolubility industrially using Grignard reagents. of other metals, it is also popular in the initially precluded general applications. Although magnesium captured the construction and the aircraft industries, In 1900, the young French PhD student attention of chemists more than a century and for optical and electronic devices. Victor Grignard (1871–1935) had the ago in the form of Grignard reagents, it In China, the large-scale production idea to prepare these elusive reagents will certainly continue to have a key role in of magnesium metal is achieved by in solution; this was a new concept. many research fields, including materials ‘silicothermal reduction’ of dolomite The reaction of various organic halides science, biochemistry and synthetic (MgO·CaO), but the process used in with magnesium ribbons (often called organic chemistry. ❐ the USA is the electrolysis of hydrated turnings) in ether led to stable solutions

MgCl2, abundant in sea water. Magnesium of organomagnesium reagents that PauL KnOChEL is in the Chemistry bear Grignard’s name. In fact, his first Department, Ludwig-Maximilians-university publication in 1900 was so successful Munich, D-81377 Munich, Germany. that many organic chemists around the e-mail: [email protected] F Ne Na Mg Al Si P S Cl Ar K Ca Sc Ti V Cr Mn Fe Co Ni Cu

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