Arsines General

In many CVD processes, toxic, explosive, and corrosive materials are produced as one component of the vapor phase reaction co-product. In order to remove them prior to atmospheric venting, scrubbers are employed, which must be appropriate for the process used. For example, halides frequently are neutralized in a water scrubber. Carbon monoxide and hydrogen often are burnt. Arsine generally is removed by heating the exhaust gas in a cracking furnace. Charcoal canisters often are used to absorb vapor phase species. Sulfur has been employed to getter thallium. Very fine particle filters also are used to catch a diversity of solids entrained within the exhaust stream. 

The more troublesome problem is the biotransformation of arsenic into arsine gas. Four common soil fungi, two anaerobic bacteria and algae in surface water can generate a methylated version of arsine. Generally, see Arsenic Speciation in the Enviromnent by W. R. Cullen and K. J. Reimer, Chemistry Review (1989) Arsenic in the Soil Environment by E. Smith, R. Naidu, and A. M. Alston, Advances in Agronomy (1998) and Arsenic Chemistry in Soils An Overview of Thermodynamic Predictions and Field Observations by Muhammed Sadiq, Water Air and Soil Pollution (1997). 

Arsonic and Arsinic Acids. The arsonic acids, compounds of the type RAsO(OH)2, are among the most important organic arsenicals. The ahphatic arsonic acids are generally prepared by the Meyer reaction ie, heating an alkyl haUde with As O in alkaline solution ... 

Organo-metallic compounds, on the other hand, behave very much like organic compounds, e.g. they can be redistilled and may be soluble in organic solvents. A note of caution should be made about handling organo-metallic compounds, e.g. arsines, because of their potential toxicities, particularly when they are volatile. Generally the suppliers of such compounds provide details about their safe manipulation. These should be read carefully and adhered to closely. If in any doubt always assume that the materials are lethal and treat them with utmost care. The same safety precautions about the handling of substances as stated in Chapter 4 should be followed here (see Chapter 1). 

Arsenic exists as grey, yellow and black forms of differing physical properties and susceptibilities towards atmospheric oxygen. The general chemistry is similar to that of phosphorus but whereas phosphorus is non-metallic, the common form of arsenic is metallic. Traces of arsenides may be present in metallic residues and drosses these may yield highly toxic arsine, ASH3, with water. 

A considerable number of the tertiary phosphine and arsine complexes of iridium(III) have been synthesized [4, 8] they generally contain 6-coordinate iridium and are conventionally prepared by refluxing Na2IrCl6 with the phosphine in ethanol or 2-methoxyethanol [154]... 

Mass effects due to some ions in salts. It is generally observed that there is a greater instability amongst compounds containing heavy atoms compared with elements in the first periods of the periodic tabie.This can be observed by analysing enthalpies of formation of ammonia, phosphine, arsine and stibine (see previous table for the last three). In the same way, it is easier to handle sodium azide than lead azide, which is a primary explosive for detonators. It is exactly the same with the relatively highly stable zinc and cadmium thiocyanates and the much less stable mercury thiocyanate. 

Recently Teles found that cationic gold(l) complexes of the general type [L-Au ] (where L is a phosphine, a phosphite or an arsine) were excellent catalysts for the ad-... 

The symptoms of inhalation of this mixture are not well known. However, Arsine is an extremely toxic gas that destroys red blood cells and can cause widespread organ injury. Inhalation may cause headache, dilirium, nausea, vomiting, general malaise, tightness in the chest, and pain in the abdomen and loins. Arsine may discolor urine to red or a darkened color, and the skin to a bronze or jaundiced color. Symptoms may not occur until several hours after exposure. 

These precursors are generally prepared by alkane elimination (Equation (7a)) or—especially useful with bulkier substituents—the coupling of metal chlorides with lithium pnictides or silyl arsines (Equation (7b)) or salt elimination or silyl halide elimination reactions (Equation (7c)) ... 

However, with soft electron pair acceptors such as Pt2+, Ag+, and Ir+, phosphines are stronger Lewis bases than are NH3 and amines, so phosphines and arsines interact better with class B metals than do amines. Generally, phosphines and arsines form stable complexes with second- and third-row transition metals in low oxidation states. 

Consistent with the human responses to arsine exposure, observations in several animal species (rats, mice, and hamsters) indicated hematologic involvement. Cumulative exposures of 540-1,800 ppm-min produced decreases in hematocrit levels, RBC counts, packed cell volumes, and increases in absolute and relative spleen weights (consistent with erythrocyte damage). For acute exposures, the exposure-response curve is steep generally less than a 10-fold difference between no-effect and lethality exposures. 

The chemistry of these compounds has not been investigated in detail. Scheme 12 summarizes some of the chemistry that has been established for the ruthenium complex RugClCO) (192). In general, the octahedral metal-carbido skeleton is maintained, substitution reactions occurring with phosphine, phosphites, and arsine ligands. Base attack leads to the production of the anion [Ru8C(CO)16P, which is... 

The hydrogen produced by this process is generally very pure, but, depending on the purity of the zinc, it is liable to contain arsine. As the gas is alkaline, owing to the caustic soda carried in suspension, it requires to be scrubbed to make it suitable for balloons and airships. 

Domino-Heck Reactions-General Procedure 5.6 mg (25 pmol) of palladium(II) acetate and 55 pmol of the arsine ligand were dissolved in 3 ml of dry dimethyl formamide and the solution was stirred at 65°C (40°C for trimethylsilylacetylene) for 15 mitt Then, 127 mg (1.35 mmol) N-Benzoyl-2-azabicyclo[2.2.1]hept-5-en-3-one, 1 mmol of the aryl compound. Four hundred and eighty-eight microliters (3.50 mmol) of triethylamine, and 3.00 mmol of the phenylacetylene (or silylmethyl-acetylene) were added rapidly in one portion. The mixture was heated at the same temperature for 24 h. After cooling down to room temperature 50 ml of brine were added, the reaction mixture was extracted with ethyl acetate and dried over MgSO. The solvent was evaporated, the residue purified by column chromatography (n-Hexan-Ethyl acetate 4 1). 

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