Bismuth Compounds

Abstract

AbstractBismuth is the fifth member of the nitrogen family of elements and like its congeners possesses five electrons in its outermost shell, (6s2)(6p3). In many compounds, the bismuth atom utilizes only the three 6pelectrons in bond formation and retains the two 6selectrons as an inert pair. Compounds are also known where bismuth is bonded to four, five, or six other atoms. Many bismuth compounds do not have simple molecular structures and exist in the solid state as polymeric chains or sheets. Inorganic compounds of bismuth include bismuthine, bismuthides, bismuth halides, bismuth oxide halides, bismuth oxides and bismuthates, higher oxides of bismuth and related compounds, sulfides and related compounds, and bismuth salts. In a manner similar to phosphorus, arsenic, and antimony, the bismuth atom can be either tri‐ or pentacovalent. One primary and one secondary bismuthine, methylbismuthine, CH3BiH2, and dimethylbismuthine, (CH3)2BiH, respectively, are prepared by the lithium aluminum hydride reduction of methyldichlorobismuthine, CH3BiCl2, and dimethylchlorobismuthine, respectively. Tertiary bismuthines appear to have a number of uses in synthetic organic chemistry and for a number of other industrial purposes. Chloro‐, dichloro‐, bromo‐, and dibromobismuthines are best prepared by the reaction of a tertiary bismuthine and bismuth trichloride or tribromide. Tetraalkyl‐ and tetraaryldibismuthines can be obtained by the reaction of a sodium dialkyl‐ or diarylbismuthide and a 1,2‐dihaloethane. Dibismuthines tend to be thermally unstable. They also are very sensitive to oxidation. Organobismuth(V) compounds have found considerable use as oxidizing agents. After the tertiary bismuthines, the triarylbismuth dihalides constitute the most important class of organobismuth compounds and are by far the largest class of compounds containing pentacovalent bismuth. Two trialkylbismuth dihalides have been prepared,cis‐tripropenylbismuth dibromide, C9H15BiBr2, andtrans‐tripropenylbismuth dibromide, C9H15BiBr2. In addition to use in organic synthesis and limited industrial use, triarylbismuth dihalides have been used as catalysts for the carbonation of epoxides to form cyclic carbonates. A number of bismuthonium ylides, have been prepared and their reactions studied. A number of pentaarylbismuth compounds are known. Pentaphenylbismuth, C30H25Bi, is a violet‐colored, crystalline compound that decomposes spontaneously after standing for several days in a dry nitrogen atmosphere. It has been studied as a reagent in organic synthesis where it can act either as an oxidizing or an arylating agent. Antibiotics have made bismuth compounds completely obsolete for the treatment of syphilis. Bismuth subsalicylate, Pepto‐Bismol, is a basic salt of varying composition, corresponding approximately too‐HOC6H4CO2(BiO). Like a number of other insoluble bismuth preparations, it is not currently approved in the United States for the treatment of peptic ulcer disease but is under active investigation for this purpose. It does appear to be effective for the relief of mild diarrhea and for the prevention of travelers' diarrhea. Bismuth subcarbonate (basic bismuth carbonate) is a white or pale yellow powder that has been widely used as an antacid. De‐Nol, tripotassium dicitratobismuthate (bismuth subcitrate), is said to be very effective for the treatment of gastric and duodenal ulcers. Bismuth subnitrate (basic bismuth nitrate) has been used as an antacid and in combination with iodoform as a wound dressing. Bismuth subgallate (basic bismuth gallate), Dermatol, a bright yellow powder has been employed as a dusting powder in some skin disorders and for the treatment of hemorrhoids.