Phosphorus reactivity

Reactivity. Chemicals that react violently with air or water are considered hazardous examples are sodium metal, potassium metal, and phosphorus. Reactive materials also include strong oxidizers such as perchloric acid, and chemicals capable of detonation when subjected to an initiating source, such as solid, dry < 10% H2O picric acid, benzoyl peroxide, or sodium borohydride. Solutions of certain cyanide or sulfides that could generate toxic gases are also classified as reactive. The potential for finding such chemicals in a refinery is... 

Of equal importance to phosphorus reactivity are the steric propcrtie.s of the OP with respect to the active site gorge of the enzyme. Unless an OP molecule can diffuse into the active site gorge and form a stable Michaelis ct>mplex. 

The modification of conventional polymers with small amounts of phosphorus, reactives, or comonomers to impart flame retardancy (1,4,6) or improve other properties has become commercially significant, and is discussed separately below in connection with the polymer class being modified. 

Black phosphorus is formed when white phosphorus is heated under very high pressure (12 000 atmospheres). Black phosphorus has a well-established corrugated sheet structure with each phos phorus atom bonded to three neighbours. The bonding lorces between layers are weak and give rise to flaky crystals which conduct electricity, properties similar to those ol graphite, it is less reactive than either white or red phosphorus. 

White phosphorus is very reactive. It has an appreciable vapour pressure at room temperature and inflames in dry air at about 320 K or at even lower temperatures if finely divided. In air at room temperature it emits a faint green light called phosphorescence the reaction occurring is a complex oxidation process, but this happens only at certain partial pressures of oxygen. It is necessary, therefore, to store white phosphorus under water, unlike the less reactive red and black allotropes which do not react with air at room temperature. Both red and black phosphorus burn to form oxides when heated in air, the red form igniting at temperatures exceeding 600 K,... 

Sulphur is less reactive than oxygen but still quite a reactive element and when heated it combines directly with the non-metallic elements, oxygen, hydrogen, the halogens (except iodine), carbon and phosphorus, and also with many metals to give sulphides. Selenium and tellurium are less reactive than sulphur but when heated combine directly with many metals and non-metals. 

Bromine has a lower electron affinity and electrode potential than chlorine but is still a very reactive element. It combines violently with alkali metals and reacts spontaneously with phosphorus, arsenic and antimony. When heated it reacts with many other elements, including gold, but it does not attack platinum, and silver forms a protective film of silver bromide. Because of the strong oxidising properties, bromine, like fluorine and chlorine, tends to form compounds with the electropositive element in a high oxidation state. 

It is very poisonous, 50 mg constituting an approximate fatal dose. Exposure to white phosphorus should not exceed 0.1 mg/ms (8-hour time-weighted average - 40-hour work week). White phosphorus should be kept under water, as it is dangerously reactive in air, and it should be handled with forceps, as contact with the skin may cause severe burns. 

Black phosphorus Black powder Black reactive dyes Black Rubber 3773... 

See also phosphorous acid.) [PHOSPHORUS COMPOUNDS] (Vol 18) Phosphomc acid reactive dyes... 

Phosphorus compounds exhibit an enormous variety of chemical and physical properties as a result of the wide range ia the oxidation states and coordination numbers for the phosphoms atom. The most commonly encountered phosphoms compounds are the oxide, haUde, sulfide, hydride, nitrogen, metal, and organic derivatives, all of which are of iadustrial importance. The hahde, hydride, and metal derivatives, and to a lesser extent the oxides and sulfides, are reactive iatermediates for forming phosphoms bonds with other elements. Phosphoms-containing compounds represented about 6—7% of the compound hstiugs ia Chemical Abstracts as of 1993 (1). 

Phosphorus and Silicon in Waters, Effluents and Sludges [e.g. Phosphorus in Waters, Effluents and Sludges by Spectrophotometry-phosphomolybdenum blue method. Phosphorus in Waters and Acidic Digests by Spectrophotometry-phosphovanadomolybdate method. Ion Chromatographic Methods for the Determination of Phosphorus Compound, Pretreatment Methods for Phosphorus Determinations, Determination of silicon by Spectrophotometric Determination of Molybdate Reactive Silicon-1 -amino-2-naphthol-4, sulphonic acid (ANSA) or Metol reduction methods or ascorbic acid reduction method. Pretreatment Methods to Convert Other Eorms of Silicon to Soluble Molybdate Reactive Silicon, Determination of Phosphorus and Silicon Emission Spectrophotometry], 1992... 

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