Mercury silvering methods. The technique was also used in Asia, for example "tokin" plating in Edo-period Japan. Mercury silvering Mercury silvering or fire gilding is a silvering technique for applying a thin layer of precious metal such as silver or gold (mercury gilding) to a base metal object. The process was invented during the Middle Ages and is documented in Vannoccio Biringuccio's 1540 book "De la pirotechnia". An amalgam of mercury and the precious metal is prepared and applied to the object which is then heated, sometimes in oil, vaporizing most of the mercury. The technique is dangerous since mercury is highly
Michaelis–Arbuzov reaction The displaced halide anion then usually reacts via another S2 reaction on one of the R carbons, displacing the oxygen atom to give the desired phosphonate (4) and another alkyl halide (5). This has been supported by the observation that chiral R groups experience inversion of configuration at the carbon center attacked by the halide anion. This is what is expected of an S2 reaction. Evidence also exists for a carbocation based mechanism of dealkylation similar to an S1 reaction, where the R group initially dissociates from the phosphonium salt followed by attack of the anion. Phosphite esters with tertiary