Bismuth reactions

The uncatalysed bismuth reaction, which takes place at a significantly lower temperature, gives a distannane ... 

An excess of boiling trifluoroacetic anhydride reacts with sodium arsenite to give the compound NaAs0(CF3C02)2 in good yield, and similar bismuth reactions also take place. Polarographic and potentiometric measurements in aqueous solution point to the formation of a complex [As(OH)2HX]" between arsenic(iii) and nitrilotriacetic acid (HaX). ... 

A modification of this method has been studied in which finely divided thorium from a supernatant mixture of fused chlorides is electrolyti( ally deposited on a molten bi.smuth cathode at the desired temperature [13]. The thorium must be stirred through the interface. Slurries that are satisfactory with respect to thorium content and partiide size and shape have l>een produced by the electrolytic method in batches of up to 10 lb. No e olution of gas has been detected during the thorium-bismuth reaction. 1/iifortunately, the necessary stirring introduces chloride inclu.sions which are difficult to remove completely. Since the.se inclusions would decrea.se... 

A complete set of trihalides for arsenic, antimony and bismuth can be prepared by the direct combination of the elements although other methods of preparation can sometimes be used. The vigour of the direct combination reaction for a given metal decreases from fluorine to iodine (except in the case of bismuth which does not react readily with fluorine) and for a given halogen, from arsenic to bismuth. 

Solutions of many antimony and bismuth salts hydrolyse when diluted the cationic species then present will usually form a precipitate with any anion present. Addition of the appropriate acid suppresses the hydrolysis, reverses the reaction and the precipitate dissolves. This reaction indicates the presence of a bismuth or an antimony salt. 

Patents claiming specific catalysts and processes for thek use in each of the two reactions have been assigned to Japan Catalytic (45,47—49), Sohio (50), Toyo Soda (51), Rohm and Haas (52), Sumitomo (53), BASF (54), Mitsubishi Petrochemical (56,57), Celanese (55), and others. The catalysts used for these reactions remain based on bismuth molybdate for the first stage and molybdenum vanadium oxides for the second stage, but improvements in minor component composition and catalyst preparation have resulted in yields that can reach the 85—90% range and lifetimes of several years under optimum conditions. Since plants operate under more productive conditions than those optimum for yield and life, the economically most attractive yields and productive lifetimes maybe somewhat lower. 

The pyrometaHurgical processes, ie, furnace-kettle refining, are based on (/) the higher oxidation potentials of the impurities such as antimony, arsenic, and tin, ia comparison to that of lead and (2) the formation of iasoluble iatermetaUic compounds by reaction of metallic reagents such as 2iac with the impurities, gold, silver and copper, and calcium and magnesium with bismuth (Fig. 12). 

The purple permanganate ion [14333-13-2], MnOu can be obtained from lower valent manganese compounds by a wide variety of reactions, eg, from manganese metal by anodic oxidation from Mn(II) solution by oxidants such as o2one, periodate, bismuthate, and persulfate (using Ag" as catalyst), lead peroxide in acid, or chlorine in base or from MnO by disproportionation, or chemical or electrochemical oxidation. 

The presence of manganese can be detected by formation of the purple MnO upon oxidation using bismuth or periodate in acidic solution. A very sensitive test is the reaction of and formaldoxime hydrochloride in aqueous alkaline solution, which also leads to the production of a purple MnO ... 

MAA and MMA may also be prepared via the ammoxidation of isobutylene to give meth acrylonitrile as the key intermediate. A mixture of isobutjiene, ammonia, and air are passed over a complex mixed metal oxide catalyst at elevated temperatures to give a 70—80% yield of methacrylonitrile. Suitable catalysts often include mixtures of molybdenum, bismuth, iron, and antimony, in addition to a noble metal (131—133). The meth acrylonitrile formed may then be hydrolyzed to methacrjiamide by treatment with one equivalent of sulfuric acid. The methacrjiamide can be esterified to MMA or hydrolyzed to MAA under conditions similar to those employed in the ACH process. The relatively modest yields obtainable in the ammoxidation reaction and the generation of a considerable acid waste stream combine to make this process economically less desirable than the ACH or C-4 oxidation to methacrolein processes. 

Oxidation Catalysis. The multiple oxidation states available in molybdenum oxide species make these exceUent catalysts in oxidation reactions. The oxidation of methanol (qv) to formaldehyde (qv) is generally carried out commercially on mixed ferric molybdate—molybdenum trioxide catalysts. The oxidation of propylene (qv) to acrolein (77) and the ammoxidation of propylene to acrylonitrile (qv) (78) are each carried out over bismuth—molybdenum oxide catalyst systems. The latter (Sohio) process produces in excess of 3.6 x 10 t/yr of acrylonitrile, which finds use in the production of fibers (qv), elastomers (qv), and water-soluble polymers. 

Minor amounts of tantalum, tin, lead, bismuth, and other elements also occur ia the ferroniobium. After cooling for 12—30 h, the metal is separated from the slag and cmshed and si2ed for shipment. The recovery of niobium ia the alurninothermic reaction is 87—93%. Larger reactions generally give better recoveries. 

Arsenic Peroxides. Arsenic peroxides have not been isolated however, elemental arsenic, and a great variety of arsenic compounds, have been found to be effective catalysts ia the epoxidation of olefins by aqueous hydrogen peroxide. Transient peroxoarsenic compounds are beheved to be iavolved ia these systems. Compounds that act as effective epoxidation catalysts iaclude arsenic trioxide, arsenic pentoxide, arsenious acid, arsenic acid, arsenic trichloride, arsenic oxychloride, triphenyl arsiae, phenylarsonic acid, and the arsenates of sodium, ammonium, and bismuth (56). To avoid having to dispose of the toxic residues of these reactions, the arsenic can be immobi1i2ed on a polystyrene resia (57). 

Al-Pb. Both lead [7439-92-17, Pb, and bismuth [7440-69-9] Bi, which form similar systems (Fig. 17), are added to aluminum ahoys to promote machinahility by providing particles to act as chip breakers. The Al—Pb system has a monotectic reaction in which Al-rich Hquid free2es partiahy to soHd aluminum plus a Pb-rich Hquid. This Pb-rich Hquid does not free2e until the temperature has fahen to the eutectic temperature of 327°C. SoHd solubiHty of lead in aluminum is negligible the products contain small spherical particles of lead which melt if they are heated above 327°C. 

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. 

Other methods for safely cleaning apparatus containing sodium residues or disposing of waste sodium are based on treatment with bismuth or lead (103), inert organic Hquids (104—106), or by reaction with water vapor carried in an inert gas stream (107). 

Solvent for Electrolytic Reactions. Dimethyl sulfoxide has been widely used as a solvent for polarographic studies and a more negative cathode potential can be used in it than in water. In DMSO, cations can be successfully reduced to metals that react with water. Thus, the following metals have been electrodeposited from their salts in DMSO cerium, actinides, iron, nickel, cobalt, and manganese as amorphous deposits zinc, cadmium, tin, and bismuth as crystalline deposits and chromium, silver, lead, copper, and titanium (96—103). Generally, no metal less noble than zinc can be deposited from DMSO. 

Other. Insoluble alkaline-earth metal and heavy metal stannates are prepared by the metathetic reaction of a soluble salt of the metal with a soluble alkah—metal stannate. They are used as additives to ceramic dielectric bodies (32). The use of bismuth stannate [12777-45-6] Bi2(Sn02)3 5H20, with barium titanate produces a ceramic capacitor body of uniform dielectric constant over a substantial temperature range (33). Ceramic and dielectric properties of individual stannates are given in Reference 34. Other typical commercially available stannates are barium stannate [12009-18-6] BaSnO calcium stannate [12013 6-6] CaSnO magnesium stannate [12032-29-0], MgSnO and strontium stannate [12143-34-9], SrSnO. ... 

Catalytic Oxidation. Catalytic oxidation is used only for gaseous streams because combustion reactions take place on the surface of the catalyst which otherwise would be covered by soHd material. Common catalysts are palladium [7440-05-3] and platinum [7440-06-4]. Because of the catalytic boost, operating temperatures and residence times are much lower which reduce operating costs. Catalysts in any treatment system are susceptible to poisoning (masking of or interference with the active sites). Catalysts can be poisoned or deactivated by sulfur, bismuth [7440-69-9] phosphoms [7723-14-0] arsenic, antimony, mercury, lead, zinc, tin [7440-31-5] or halogens (notably chlorine) platinum catalysts can tolerate sulfur compounds, but can be poisoned by chlorine. 

Bismuth triduoride is usually prepared by dissolving either Bi O or BiOF in hydroduoric acid to yield the addition compound bismuth triduoride ttihydroduoride [66184-11-0] 3 HF or H2(BiF ). Caredil evaporation of the solution permits isolation of a grey soHd, which upon heating loses HF to yield BiF. It may be purified by sublimation in a stream of HF at 500°C. Bismuth triduoride may also be prepared by direct duorination of bismuth by (/) reaction of Bi O with sulfiir tetraduoride, SF (2) treatment of metallic bismuth with HF at 350°C and (J) reduction of BiF in a dilute stream of hydrogen. 

Bismuth trichloride shows considerable tendency to form addition compounds. Reaction with ammonia yields the colodess, easily volatili2ed bismuth trichloride triammine [66172-89-2] BiCl ANH, as well as the red, thermally unstable bismuth trichloride hemiammine [66172-90-5] 2BiCl2 NH. Compounds of formula BiCl NO, BiCl 2N02, and BiCl NOCl may be isolated these are stable in dry air but are decomposed by moisture. Bismuth... 

Triarylbismuthines have been synthesized by means of the Nesmeyanov reaction that employs an arenediazonium salt such as the tetrafluoroborate, a bismuth trihahde, and a reduciag agent (51). The decomposition of iodonium salts ia the preseace of bismuth trichloride and metallic bismuth also leads to the formation of triarylbismuthines, Ar Bi (52) ... 

Other methods of preparing tertiary bismuthines have been used only to a limited extent. These methods iaclude the electrolysis of organometaUic compounds at a sacrificial bismuth anode (54), the reaction between a sodium—bismuth or potassium—bismuth alloy and an alkyl or aryl haUde (55), the thermal elimination of sulfur dioxide from tris(arenesulfiaato)bismuthines (56), and the iateraction of ketene and a ttis(dialkylainino)bismuthine (57). 

The reaction of tris(trifluoromethyl)bismuthine with chlorine, bromine, or iodine, however, has been found to yield the corresponding bismuth trihahde and trifluoromethyl hahde (61) ... 

Halobismuthines, Dihalobismuthines, and Related Compounds. Chloro-, dichloro-, bromo-, and dibromobismuthines are best prepared by the reaction of a tertiary bismuthine and bismuth trichloride or tribromide (7,43,45,46,104—107) ... 

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) ... 

Sihcon carbide is comparatively stable. The only violent reaction occurs when SiC is heated with a mixture of potassium dichromate and lead chromate. Chemical reactions do, however, take place between sihcon carbide and a variety of compounds at relatively high temperatures. Sodium sihcate attacks SiC above 1300°C, and SiC reacts with calcium and magnesium oxides above 1000°C and with copper oxide at 800°C to form the metal sihcide. Sihcon carbide decomposes in fused alkahes such as potassium chromate or sodium chromate and in fused borax or cryohte, and reacts with carbon dioxide, hydrogen, ak, and steam. Sihcon carbide, resistant to chlorine below 700°C, reacts to form carbon and sihcon tetrachloride at high temperature. SiC dissociates in molten kon and the sihcon reacts with oxides present in the melt, a reaction of use in the metallurgy of kon and steel (qv). The dense, self-bonded type of SiC has good resistance to aluminum up to about 800°C, to bismuth and zinc at 600°C, and to tin up to 400°C a new sihcon nitride-bonded type exhibits improved resistance to cryohte. 

Chlorination of bismuth or mercuric oxides results in precipitation of relatively insoluble basic chlorides, ie, BiOCl and HgO HgCl2. However, the reaction with is slow and does not produce high concentrations of HOCl (121). With HgO, the HOCl solutions may contain significant amounts of... 

The precipitated copper from this reaction is an important constituent of the slime that collects at the bottom of the electrolytic cells. The accumulation of copper as well as of impurities such as nickel, arsenic, antimony, and bismuth is controlled by periodic bleed-off and treatment in the electrolyte purification section. 

Among arsenic, bismuth, lead, antimony, and sulfur in the concentration range of 5—26 ppm, bismuth had the greatest unit effect (59). A decrease in the annealing temperature prior to cold deformation led to a decrease in the measured unit effectiveness, indicating that at low temperature bismuth is not in sohd solution. Lead lowered the recrystaUization temperature, provided that the samples were aimealed at 700°C or lower. A precipitation reaction between lead and sulfur was proposed (60). 

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