Bismuth compounds

Bismuth is the fifth member of the nitrogen family of elements and, like its congeners, possesses five electrons in its outermost shell, In many 

The +3 oxidation state is exhibited by bismuth in the vast majority of its compounds. A few inorganic and a variety of organic compounds, however, contain the element in the +5 state. Other rarer oxidation states reported for bismuth include +2, +1, and —3. Bismuth also forms polynuclear ionic species with oxidation states that ate usually fractional and range from —1 to +1. 

Technical information concerning bismuth and its compounds is distributed periodically by the Bismuth Institute, a nonprofit organisation incorporated in La Pas, BoUvia, that has an information center in Bmssels. 

The United States consumed 1500 metric tons of bismuth in 1988 and exported 147 t (1). The average domestic dealer price was 12.74/kg. The world mine output, excluding the United States, was estimated to be 2770 t in 1988 the world refinery production was estimated as 3510 t. Of the bismuth consumed in the United States, 679 t was used for industrial and laboratory chemicals, cosmetics (qv), and pharmaceuticals (qv) 333 t for fusible alloys 493 t for metaHurgical additives 12 t for other alloys and 15 t for miscellaneous purposes. 

For the deterrnination of trace amounts of bismuth, atomic absorption spectrometry is probably the most sensitive method. A procedure involving the generation of bismuthine by the use of sodium borohydride followed by flameless atomic absorption spectrometry has been described (6). The sensitivity of this method is given as 10 pg/0.0044M, where M is an absorbance unit the precision is 6.7% for 25 pg of bismuth. The low neutron cross section of bismuth virtually rules out any deterrnination of bismuth based on neutron absorption or neutron activation. 

Bismuth compounds are used as an antidiarrheal. Topical applications are used in skin disorders. Overdose may cause acute bismuth intoxication but gastric lavage, purgation, use of chelating agents, 2,3-dimercapto-l-propane sulfonic acid, and hemodialysis are steps to be taken.170-172 

Attempts have been made to obtain blsmabenzene (blsmln) (3) by reacting 1,4-dihydro-1,1-dibutylstannabenzene (1) with bismuth trichloride to give 1,4-dihydro-1-chlorobismabenzene (2), which on treatment with 1,5-diazabicyclo[4.3.0]non-5-ene loses hydrogen chloride exothermically to yield polymeric material. The addition of hexafluorobutyne at low temperature, after precipitation of the hydrochloride (2) affords a 1 1 adduct (4) (A.J. Ashe and M.D. Gordon, J. Amer. chem. Soc., 1972, 94, 7596). 

The H-nmr spectroscopic detection at low temperatures of bismabenzene (3) and its dimer (5) have been reported (Ashe, Tetrahedron Letters, 1976, 415) along with photoelectron spectral data (J. Bastide et al., ibid., p.411). The former shows very low field signals for the a-protons due to the very large diamagnetic anisotropy of the bismuth atom (Ashe, T.R. Diephouse, and M.Y. El-Sheikh, J. Amer. chem. Soc., 1982, 104, 5693). 

4-AlkyIbismabenzenes have been prepared and although 4--methylbismabenzene (6) is more stable towards polymerisation than bismabenzene (3) it is still in mobile egulibrium in tetrahydrofuran with its head to head Diels-Alder dimer (7). 

On cooling solutions of 4-tert-butylbismabenzene (8) in tetrahydrofuran no dimer could be detected and they were stable for several hours at 0°C (Ashe, Diephouse, and El-Sheikh, toa. ait.). 

Attempts to form molybdenum-carbonyl complexes of bismabenzene have been unsuccessful because of its extreme lability (Ashe and J.C. Colburn, J. Amer. chem,. Soc., 1977, 99, 8099). 

---

One-part urethane sealants (Table 3) are more compHcated to formulate on account of an undesirable side reaction between the prepolymer s isocyanate end and water vapor which generates carbon dioxide. If this occurs, the sealant may develop voids or bubbles. One way to avoid this reaction is to block the isocyanate end with phenol and use a diketamine to initiate cure. Once exposed to moisture, the diketamine forms a diamine and a ketone. The diamine reacts with the isocyanate end on the prepolymer, creating a cross-link (10). Other blocking agents, such as ethyl malonate, are also used (11). Catalysts commonly used in urethane formulations are tin carboxylates and bismuth salts. Mercury salt catalysts were popular in early formulations, but have been replaced by tin and bismuth compounds. 

Georgius Agricola, a German scientist of the sixteenth century, was the first to mention bismuth detailing the melting of bismuth from ore (1). It was ia the sixteenth century that bismuth compounds were first discovered to have a soothing effect on stomach disorders. Bismuth compounds are stiU widely used ia preparations to reheve this condition. Not until the 1800s was bismuth refined and proven to be an element. Until that time, bismuth was usually referred to as one of the other elements with which it is associated ia ores such as antimony, silver, lead, and tin. 

Bismuthides. Many intermetaUic compounds of bismuth with alkafl metals and alkaline earth metals have the expected formulas M Bi and M Bi, respectively. These compounds ate not saltlike but have high coordination numbers, interatomic distances similar to those found in metals, and metallic electrical conductivities. They dissolve to some extent in molten salts (eg, NaCl—Nal) to form solutions that have been interpreted from cryoscopic data as containing some Bi . Both the alkafl and alkaline earth metals form another series of alloylike bismuth compounds that become superconducting at low temperatures (Table 1). The MBi compounds are particularly noteworthy as having extremely short bond distances between the alkafl metal atoms. 

Quaternary Bismuth Compounds. Although earher attempts had been made to prepare quaternary bismuth compounds, it was not until 1952 that tetraphenylbismuth bromide [66173-02-2], C24H2QBiBr, was obtained from pentaphenjlbismuth [3049-07-8], C2QH25Bi, and one molar equivalent of bromine at —70 C (162) ... 

Quaternary bismuth compounds have not found extensive use ia industry or ia organic synthesis. In manifold studies of organobismuth(V) compounds as oxidi2ing and arylating agents, such quaternary bismuth compounds as (CgH )4Bi02CCH2, (CgH )4Bi02SCgH4CH2-4, and... 

Quinquenary Bismuth Compounds. No pentaalkylbismuth compounds have been reported, but a number of pentaarylbismuth compounds are known. Pentaphenjlbismuth [3049-07-8] C2QH25Bi, was first prepared by means of the reaction (162) ... 

Pentaphenylbismuth is a violet-colored, crystalline compound that decomposes spontaneously after standing for several days in a dry nitrogen atmosphere. With a variety of agents, eg, hydrohahc acids, halogens, and triphenylboron, one phenyl group is cleaved to form quaternary bismuth compounds. 

Bismuth compounds were once employed for the treatment of amoebic dysentery, certain skin diseases, and several spirochetal diseases besides syphilis, but these substances are now seldom considered the dmgs of choice. Various insoluble preparations of bismuth, especially the subcarbonate, subnitrate, subgaHate, subcitrate, and subsahcylate, are stiU employed for the treatment of ulcers and other gastrointestinal disorders, even though use for these purposes is often supported largely by tradition. With a few possible exceptions, it is now difficult to justify the presence of bismuth compounds in a modem therapeutic armamentarium. A review of the biological activity of organobismuth compounds has been pubHshed (179). 

Tripotassium dicitratobismuthate [57644-54-9] (bismuth subcitrate), De-Nol is a buffered aqueous suspension of a poorly defined, water-insoluble bismuth compound. It is said to very effective for the treatment of gastric and duodenal ulcers (180,184). There have not yet been any reports of bismuth encephalopathy following the use of this dmg. 

Bhmingham Metal Company Ltd., 207 Bis(2-chloroisopropyl) ether, 25 Bis(chloromethyl) ether, 25 Bis(chloromethyl) ketone, 25 Bis(2-EthyUiexyl) phthalate, 25 Bismuth and Bismuth Compounds, 25 Bismuth Institute, 256 Bismuth telluride, 26 Bisphenol-A, 26 Bithionol, 26 Bitmac Ltd., 207, 236 Bitoscanate, 26 Bitoumina SA, 167... 

Supplementary Work, Vol 24 Perfluorohnloorganic Compounds of Mam Group Elements Part 3 Phosphorus, Arsenic, Antirnon and Bismuth Compounds Perfhiorohaloorganic Compounds of Main Group Elements Part 5 Compounds oj Nitrogen (Heteroc clrc Compounds)... 

Kirk-Othmer Encyclopedia of Chemical Technology, 4th edn., Vol. 3, Wiley, New York, 1992 Arsenic and arsenic alloys (pp. 624-33) Arsenic compounds (633-59) Antimony and antimony alloys (367 - 81) Antimony compounds (382-412) Bismuth and bismuth alloys (Vol. 4, 1992 (pp. 237-45) Bismuth compounds (246-70). 

---