Bismuth compounds, reaction

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 Mercury salt catalysts were popular in early formulations, but have been replaced by tin and bismuth compounds. 

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... 

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) ... 

Bi2(SC6F5)6((i-X)] or [Bi3(SC6 F f/ii- Br)2]2 have been obtained by reaction of [Bi(SCf,F5L3] with halide anions.192 The reaction of BiBr3 with PhSeSiMe3 gives clusters, such as [Bi4(p-SePh)5(SePh)g] (20) or [Bi6(p-SePh)6 (SePh)10Br2].193 The use in medicine of bismuth compounds has lead to the... 

Recently, Kobayashi has disclosed significant advances regarding rare-earth and lanthanide triflates as catalysts for Mannich-type reactions [65-68] and there are several reviews available on catalytic Mannich-type reactions [69-73]. High catalytic activity, low toxicity, and low tolerance to moisture and air make lanthanide triflates valuable catalysts. However, the high cost of these catalysts restricts their use. Bismuth compounds are of interest as lower toxicity and cheaper alternatives to such catalysts. 

Cyclic triarylbismuth(III) compounds also undergo the Pd-catalyzed cross-coupling reaction with benzoyl chloride (Scheme 27) [42]. The exocyclic aryl group was selectively transferred to form 4-methylbenzophenone in good yield. Bismuth-containing products could not be isolated except for the cyclic bismuth compound possessing a SO2 moiety, for which cyclic bismuth chloride was isolated in 86% yield. 

Aryl chlorides can also be used as coupling partners for azabismocine reagents 2. In the coupling reaction with aryl chlorides, Pd(PPh3)4 was not an efficient catalyst, and Pd(OAc)2/l,l,-bis(diphenylphosphino)ferrocene (dppf) combination was found to be effective [54]. Not only the arylation, but also methylation, alkenylation and alkynylation reactions can be accomplished by using the corresponding bismuth compounds (Scheme 35). The addition of CsF improved the product yields. However, electron-rich aryl chlorides were unable to be coupled efficiently under these reaction conditions. 

Germanium-bismuth compounds have been prepared by transmetallation reactions,185191 as shown in the previous section (28.15.2.1). 

Phenyl-2-arylethanols, via antimony(III) compounds, 9,428 Phenylations, via Cu-catalyzed bismuth(III) reactions, 9, 443... 

Reduction of bismuth compounds could take place by reaction with polymer radicals propagating the depolymerization of polypropylene, either by electron transfer or ligand transfer which are typical redox reactions between alkyl radicals and metal compounds 59... 

In the case of PI3, this reaction is a convenient synthesis of HI (see Chapter 6). The arsenic trihalides hydrolyze in an analogous way. However, the trihalides of antimony (and the analogous bismuth compounds) react according to the equation... 

These molecules (10-XXXV) are known for all four elements. Older trivial names for these are phosphabenzene, arsabenzene, etc., but the current literature60 favors the names phosphinine, arsinine, stibinine, and bismuthinine. The bismuth compound, C5H5Sb, is extremely unstable and polymerizes at room temperature. Phosphinine and arsinine are thermally stable (distillable) and can be prepared by the reactions ... 

SAFETY PROFILE Moderate fire hazard by spontaneous chemical reaction with powerful oxidizers. Reacts with moisture to evolve a toxic gas. Slight explosion hazard by chemical reaction with powerful oxidizers reacts with moisture. When heated to decomposition it emits toxic fumes of Te. See also BISMUTH COMPOUNDS and TELLURIUM COMPOUNDS. 

Reactions of bismuth compounds with hydrides to form Bi—M-containing compounds are not known . ... 

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