Tuesday, 13 January 2015

The importance of Magnesium

Elizabeth Henderson
Product Development Manager

Magnesium plays a significant role in Itac’s processing of solid polymers. We regularly chip materials such as Neoprene and natural rubber before dissolving them, but unless the chips are coated with powder they will re-agglomerate. Magnesium stearate is sometimes used for this, whereas magnesium oxide is more reactive. It is an effective curing agent and acid scavenger in halogen-containing elastomers. Its mopping-up of excess acid prevents pre-vulcanisation of the rubber in our solutions and helps prevent ‘scorching’ during processing. Magnesium oxide occurs naturally and is known as ‘Magnesia’ as this province of mainland Greece was an early source. It is mined as periclase, crystal system cubic 4/m 3¯ 2/m. The element itself was initially identified by Sir Humphrey Davy.
Magnesium’s most important job on earth is to work in the chlorophyll molecule, capturing energy from the sun. Chlorophyll molecules are porphyrins, all of which have four nitrogen atoms providing a site for a metal ion in the centre. In particular, chorophyll has magnesium in this site, and the molecule absorbs red and blue light for synthesis of sugars from water and carbon dioxide. Without this chemistry, there would be no mechanism for plants to convert energy from the sun into food and chemical fuels.
Most applications of magnesium focus on its physical properties – because it has a low density it is incorporated in casting alloys for racing engines and other applications where weight reduction is crucial, but this can be a source of problems as magnesium metal is highly flammable. Although pieces of the metal are normally covered by a thin layer of inert oxide, if a flame is held to them they burn with a bright white flame. This property means magnesium is a regular constituent of fireworks and safety flares, and was a component of early flash powders for studio photography. It was also built into early flash bulbs, where the foil was ignited electronically to give a bright white flash without releasing any smoke.
Magnesium plays a major role in synthesis of organic compounds, as a component of Grignard reagents. These highly reactive species react with carbonyl groups in molecules such as aldehydes and ketones to form of new carbon-carbon bonds. Grignard reagents can also be used in reactions with groups as diverse as epoxies and nitriles to alkylate a target carbon atom. They have wide applications in the synthesis of molecules for drug intermediates.