Discovery phosphorus

The exploration of the chemistry of azirines has led to the discovery of several pyrrole syntheses. From a mechanistic viewpoint the simplest is based upon their ability to behave as a-amino ketone equivalents in reactions analogous to the Knorr pyrrole synthesis cf. Section 3.03.3.2.2), as illustrated in Schemes 91a and 91b for reactions with carbanions. Parallel reactions with enamines or a-keto phosphorus ylides can be effected with electron-deficient 2//-azirines (Scheme 91c). Conversely, electron-rich azirines react with electron deficient alkynes (Scheme 91d). 

For a century after its discovery the only source of phosphorus was urine. The present process of heating phosphate rock with sand and coke was proposed by E. Aubertin and L. Boblique in 1867 and improved by J. B. Readman who introduced the use of an electric furnace. The reactions occurring are still not fully understood, but the overall process can be represented by the idealized equation ... 

Despite its relatively late discovery, phosphorus is the eleventh most abundant element in Earth s crustal rock. It has been estimated that world reserves of phosphate rock are sufficient to last for several hundred years. Virtually all phosphorus deposits contain apatite, whose general formula is Caj (P04)3 X, where X — OH, or Cl. Fluoroapatite is the least soluble, hence most abundant, of the three apatite minerals. Phosphorus Is found in aqueous systems as HPOq and H2 PO4 ions. In biological organisms, phosphorus is a component of nucleic acids and energy-shuttling molecules such as ATP. 

There is no doubt that the element phosphorus occupies a special position in the family of the elements. The Earth s crust (including the oceans), which is about 16 km thick, contains only about 0.04% phosphorus, compared, for example, with 2.4% potassium however, phosphorus is present in all the substances necessary for living processes. It does not occur in elemental form because of its high affinity for oxygen and has been known since its discovery by the alchemist Henning Brand in Hamburg in the course of his search for the philosopher s stone. However, it was many years later that Antoine Lavoisier realized that this new, shining substance was a chemical element. 

The interest of alchemists in urine was driven by a search for a yellow pigment known as India Yellow, which is produced in the urine of cows fed with mango leaves. This interest, then, led to the discovery of elemental phosphorus. 

Metallophosphazenes with Phosphorus-Metal Bonds. Until recently, the chemistry of cyclic and high polymeric phosphazenes was essentially the chemistry of their organic derivatives (Scheme 1). However, a discovery reported in 1979 (31) opened up a new field of metallophosphazene chemistry in which transition metals form the nucleus of the side group structure and are linked to the skeleton through phosphorus-metal bonds. These species are of theoretical and potentially practical importance, and I will summarize briefly some of the main features known at this time. 

In 1841 Jons Jakob BerzeUius (1779—1884), who introduced the term allotropy, transformed white phosphorus to red phosphorous. In 1865 Johann Wilhehn Hittorf (1824—1914) was the first to produce metalhc phosphorus. Brand, however, was given credit for the discovery of phosphorus. 

The discovery that the keto chelates (especially the p ones) are the species controlling the strict alternation of the monomers and the intrinsic copolymerisation rate in ethene/CO propagation has stimulated much research aimed at designing catalytic systems where the keto chelates can be readily opened by CO. These studies have allowed the development of a new generation of more efficient Pd" copolymerisation catalysts based on diphosphines with o-methoxyphenyl groups on the phosphorus atoms [13b, 31-34]. 

In 1677 Charles II invited Kraft to England to demonstrate his phosphorus to the royal court. Kraft replied that he would do so for a fee of a thousand thalers. This was a lot of money, but Charles apparently didn t want to forego witnessing a monumental discovery his continental something had seen, and he agreed. Kraft, after all, was the only person capable of performing such a feat. 

It might seem that not much had been done to advance the science of chemistry. Although a new element had been discovered, it was not recognized as an element, and its main use was to exhibit it as a curiosity. The discovery of phosphorus had impoverished Brandt, while Kraft and Godfrey (ne Hanckwitz) became wealthy. Its discovery had done little but affect a few individual fives. However, the discovery of phosphorus was an important event. Boyle s experiments with the... 

Most importantly, chemists were beginning to realize that they did not yet know the composition of the universe. If one new chemical substance had been found, why could there not be more Who could say what discoveries were yet to be made And they were made. When Brandt first made phosphorus in 1669, no new element had been discovered for more than 150 years. This situation was soon to change, however. Some 15 new elements were to be found during the eighteenth century. 

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