Title: Phosphorus
CAS Registry Number: 7723-14-0
Literature References: P; at. wt 30.973762; at. no. 15; valences 3, 5. Group VA (15). One naturally occurring isotope: 31P; artificial, radioactive isotopes: 28-30; 32-34. Abundance in earth's crust: about 0.12%. Does not occur free in nature; found in the form of phosphates in the minerals chlorapatite [3Ca2(PO4)2.CaCl2], fluorapatite [3Ca(PO4)2.CaF2], vivianite, wavellite and "phosphate rock" or phosphorite; occurs in small quantities in granite rocks; occurs in all fertile soil; an essential constituent of protoplasm, nervous tissue and bones. Discovered in 1669 by Brandt. Prepn: Ullmann, Enzyklopädie der Technischen Chemie 8, 362 (1931); DeWitt, Skolnik, J. Am. Chem. Soc. 68, 2305 (1946); Skolnik et al., ibid. 2310. Lab prepn and purification: Klement in Handbook of Preparative Inorganic Chemistry vol. 1, G. Brauer, Ed. (Academic Press, New York, 2nd ed., 1963) pp 518-525. Reviews: J. R. Van Waser, Phosphorus and Its Compounds 2 vols. (Interscience, New York, 1958, 1961) 2046 pp; Corbridge, "The Structural Chemistry of Phosphorus Compounds" in Topics in Phosphorus Chemistry Vol. 3, E. J. Griffith, M. Grayson, Eds. (Interscience, New York, 1966) pp 57-394; Toy, "Phosphorus" in Comprehensive Inorganic Chemistry Vol. 2, J. C. Bailar, Jr. et al., Eds. (Pergamon Press, Oxford, 1973) pp 389-545; J. R. Van Wazer in Kirk-Othmer Encyclopedia of Chemical Technology vol. 17 (Wiley-Interscience, New York, 3rd ed., 1982) pp 473-490. Review of toxicology and human exposure: Toxicological Profile for White Phosphorous (PB98-101090, 1997) 248 pp.
Properties: Phosphorus exists in three main allotropic forms: white, black, and red. The same liquid is obtained on melting. Caution: Avoid contact with KClO3, KMnO4, peroxides and other oxidizing agents; explosions may result on contact or friction. Phosphorus atoms exist as symmetrical, tetrahedral P4 molecules in the liquid phase and in the vapor phase below 800°; molecules dissociate to P2 above 800°.
Derivative Type: White phosphorus
Properties: Colorless or white, transparent, cryst solid; waxy appearance; darkens on exposure to light. Sometimes called yellow phosphorus; color due to impurities. Two allotropic modifications: a-form exists at room temp; cubic crystals containing P4 molecules; d 1.83. b-Form prepd by conversion of a-form at -79.6°; hexagonal crystals; d 1.88. mp 44.1° (vapor press. 0.181 mm); bp 280°. Volatile; sublimes in vacuo at ordinary temp when exposed to light. When exposed to air in the dark, emits a greenish light and gives off white fumes. Solubilities in water: one part/300,000 parts water; in abs alc: one g/400 ml; in abs ether: one g/102 ml; in CHCl3: one g/40 ml; in benzene: one g/35 ml; in CS2: one g/0.8 ml. Soly in oils: one gram phosphorus dissolves in 80 ml olive oil, 60 ml oil of turpentine, ~100 ml almond oil. Ignites at about 30° in moist air; the ignition temp is higher when the air is dry. Handle with forceps. Keep under water. Poisonous. Combines directly with the halogens to form tri- or pentahalides; combines with sulfur to form sulfides. Reacts with several metals to form phosphides. Yields orthophosphoric acid when treated with nitric acid. Reacts with alkali hydroxides with formation of phosphine and sodium hypophosphite.
Melting point: mp 44.1° (vapor press. 0.181 mm)
Boiling point: bp 280°
Density: d 1.83; d 1.88
Derivative Type: Black Phosphorus
Properties: Polymorphic. Orthorhombic crystalline form: stable in air; resembles graphite in texture; produced from the white modification under high pressures: Bridgman, J. Am. Chem. Soc. 36, 1344 (1914); Jacobs, J. Chem. Phys. 5, 945 (1937); Krebs, Inorg. Synth. 7, 60 (1963). d 2.691. Does not catch fire spontaneously. Insol in organic solvents. Amorphous form prepd at lower pressures: Jacobs, loc. cit. At higher pressure the orthorhombic form undergoes reversible transition to a rhombohedral structure, d 3.56, and a cubic structure, d 3.83: Jamieson, Science 139, 1291 (1963).
Density: d 2.691; d 3.56; d 3.83: Jamieson, Science 139, 1291 (1963)
Derivative Type: Red phosphorus
Literature References: Polymorphism: Roth et al., J. Am. Chem. Soc. 69, 2881 (1947); Corbridge, loc. cit. Crystal structure of one form, Hittorf's phosphorus: Thurn, Krebs, Acta Crystallogr. 25B, 125 (1969).
Properties: Red to violet powder. The properties of red phosphorus are intermediate between those of the white and black forms. Sublimes at 416°, triple point 589.5° under 43.1 atm. d 2.34. Insol in organic solvents. Sol in phosphorus tribromide. Less active than the white form; reacts only at high temp. Yields the white modification when distilled at 290°. Catches fire when heated in air to about 260° and burns with formation of the pentoxide. Burns when heated in an atmosphere of chlorine.
Density: d 2.34
CAUTION: Potential symptoms of acute poisoning by ingestion of white (or yellow) phosphorous are burning pain in throat and abdomen; intense thirst; nausea, vomiting, diarrhea; garlic breath; luminescent vomitus and feces. Direct contact may cause eye and skin burns. May be followed by symptoms of systemic poisoning, including hematemesis; hepatomegaly, jaundice; hemorrhages into skin, mucous membranes, viscera; oliguria, hematuria, albuminuria; cardiovascular collapse; convulsions, confusion, coma. Potential symptoms of chronic poisoning from inhalation or ingestion are cachexia, anemia, bronchitis. general debility, necrosis of mandible. See Clinical Toxicology of Commercial Products, R. E. Gosselin et al., Eds. (Williams & Wilkins, Baltimore, 5th ed., 1984) Section III, pp 348-352; NIOSH Pocket Guide to Chemical Hazards (DHHS/NIOSH 97-140, 1997) p 254.
Use: White phosphorus: manuf rat poisons; for smoke screens, gas analysis. Red phosphorus: pyrotechnics; manuf safety matches; in organic synthesis; manuf phosphoric acid, phosphine, phosphoric anhydride, phosphorus pentachloride, phosphorus trichloride; manuf fertilizers, pesticides, incendiary shells, smoke bombs, tracer bullets. |