Water phosphines

The Systems Phosphine/Water, Phosphine/Water/Ammonia, and Phosphine/ Water/Ammonia/Methane... 

Substituting a phosphine with a polyether chain may also make the phosphine water-soluble. However, diphosphines of the type 15 (Structures 15-17) are only soluble in water when n > 15 [24]. This type of materials can also be used to prepare thermally responsive catalysts [58]. Other examples related to 15 are the class of compounds 16 (cf. Section 3.2.2.3 n = 12, 16, 110) and 17 (n= 18) [12, 25]. The number n gives the average value of the degree of polycondensation . So far, these polyether-based diphosphines have mainly been used in asymmetric hydrogenation of prochiral substrates such as a-acetamidocinnamic acid where ee values vary from 11 to 91% depending on the reaction medium and ligand used (cf. Section 4.6.3). 

Substituting a phosphine with a polyether chain may also make the phosphine water-soluble. However, diphosphines of the type 41 (41-43) are only soluble in water when n > 15 [85]. This type of material can also be used to prepare thermally responsive catalysts [86]. 

A variety of palladium(O) and palladium(II) precatalysts are routinely employed, including Pd2(dba)3 (dba = dibenzylideneacetone), Pd(dba)2, Pd2(dba)3 -CHCl3, Pd(OAc)2 and Pd[(allyl)Cl]2. Catalyst loading in the range of 5.0-20 mol% is common. When a pal-ladium(II) precatalyst like Pd(OAc)2 is utilized, phosphines, water or an amine typically reduces the catalyst to the active palladium(O) species [22]. For the asymmetric reaction, the reduction process can consume valuable phosphine ligand, so palladium(O) precatalysts like Pd2(dba)3 are most commonly used. 

Some labile complexes react with alkynes to afford products in which at least one ligand was displaced by an acetylene molecule. Substitution reactions most commonly occur for complexes containing the following ligands CO, halides, phosphines, water, N2, etc. 

Phosphine is a colourless gas at room temperature, boiling point 183K. with an unpleasant odour it is extremely poisonous. Like ammonia, phosphine has an essentially tetrahedral structure with one position occupied by a lone pair of electrons. Phosphorus, however, is a larger atom than nitrogen and the lone pair of electrons on the phosphorus are much less concentrated in space. Thus phosphine has a very much smaller dipole moment than ammonia. Hence phosphine is not associated (like ammonia) in the liquid state (see data in Table 9.2) and it is only sparingly soluble in water. 

With hot water a vigorous but complex reaction occurs, the products including phosphine and phosphoric(V) acid. This disproportionation reaction can be approximately represented as ... 

To a mixture of 100 ml of dry dichloromethane, 0.10 mol of propargyl alcohol and 0.11 mol of triethylamine was added a solution of 0.05 mol of Ph2PCl in 75 ml of dichloromethane in 3 min between -80 and -90°C. The cooling bath was removed, and when the temperature had reached 10°C, the reaction mixture was poured into a solution of 2.5 ml of 362 HCl in 100 ml of water. After vigorous shaking the lower layer was separated and the aqueous layer was extracted twice with 25-ml portions of dichloromethane. The combined solutions were washed twice with water, dried over magnesium sulfate and then concentrated in a water-pump vacuum, giving almost pure allenyl phosphine oxide as a white solid, m.p. 98-100 5, in almost 1002 yield. 

Pd can also be recovered as insoluble complexes such as the dimethylglyox-ime complex, or PdCUiPhiP) by treatment with HCl and PI13P. When water-soluble phosphines are used, the catalyst always remains in the aqueous phase and can be separated from a product in the organic phase, and is used repeatedly. 

Polyphenylene polymers can be prepared by this coupling. For example, the preparation of poly(/i-quaterphenylene-2,2 -dicarboxylic acid) (643) was carried out using aqueous NaHCO and a water-soluble phosphine ligand (DPMSPP)[5I I]. Branched polyphenylene was also prepared[5l2). 

Volatile hydrides, except those of Periodic Group VII and of oxygen and nitrogen, are named by citing the root name of the element (penultimate consonant and Latin affixes. Sec. 3.1.2.2) followed by the suffix -ane. Exceptions are water, ammonia, hydrazine, phosphine, arsine, stibine, and bismuthine. 

The reaction with sodium sulfite or bisulfite (5,11) to yield sodium-P-sulfopropionamide [19298-89-6] (C3H7N04S-Na) is very useful since it can be used as a scavenger for acrylamide monomer. The reaction proceeds very rapidly even at room temperature, and the product has low toxicity. Reactions with phosphines and phosphine oxides have been studied (12), and the products are potentially useful because of thek fire retardant properties. Reactions with sulfide and dithiocarbamates proceed readily but have no appHcations (5). However, the reaction with mercaptide ions has been used for analytical purposes (13)). Water reacts with the amide group (5) to form hydrolysis products, and other hydroxy compounds, such as alcohols and phenols, react readily to form ether compounds. Primary aUphatic alcohols are the most reactive and the reactions are compHcated by partial hydrolysis of the amide groups by any water present. 

These are water-soluble crystalline compounds sold as concentrated aqueous solutions. The methylol groups are highly reactive (118—122) and capable of being cured on the fabric by reaction with ammonia or amino compounds to form durable cross-linked finishes, probably having phosphine oxide stmctures after post-oxidizing. This finishing process, as developed by Albright Wilson, is known as the Proban process. 

In general, peroxomonosulfates have fewer uses in organic chemistry than peroxodisulfates. However, the triple salt is used for oxidizing ketones (qv) to dioxiranes (7) (71,72), which in turn are useful oxidants in organic chemistry. Acetone in water is oxidized by triple salt to dimethyldioxirane, which in turn oxidizes alkenes to epoxides, polycycHc aromatic hydrocarbons to oxides and diones, amines to nitro compounds, sulfides to sulfoxides, phosphines to phosphine oxides, and alkanes to alcohols or carbonyl compounds. 

Semiconductors. Phosphine is commonly used in the electronics industry as an -type dopant for siUcon semiconductors (6), and to a lesser extent for the preparation of gaUium—indium—phosphide devices (7). For these end uses, high purity, electronic-grade phosphine is required normally >99.999% pure. The main impurities that occur in phosphine manufactured by the acid process are nitrogen [7727-37-9] hydrogen [1333-74-0] arsine [7784-42-17, carbon dioxide [124-38-9], oxygen [7782-44-7], methane [74-82-8], carbon monoxide [630-08-0], and water [7732-42-1]. Phosphine is purified by distillation under pressure to reduce the level of these compounds to <1 ppm by volume. The final product is sold as CYPURE (Cytec Canada Inc.) phosphine. 

All phosphoms oxides are obtained by direct oxidation of phosphoms, but only phosphoms(V) oxide is produced commercially. This is in part because of the stabiUty of phosphoms pentoxide and the tendency for the intermediate oxidation states to undergo disproportionation to mixtures. Besides the oxides mentioned above, other lower oxides of phosphoms can be formed but which are poorly understood. These are commonly termed lower oxides of phosphoms (LOOPs) and are mixtures of usually water-insoluble, yeUow-to-orange, and poorly characteri2ed polymers (58). LOOPs are often formed as a disproportionation by-product in a number of reactions, eg, in combustion of phosphoms with an inadequate air supply, in hydrolysis of a phosphoms trihahde with less than a stoichiometric amount of water, and in various reactions of phosphoms haUdes or phosphonic acid. LOOPs appear to have a backbone of phosphoms atoms having —OH, =0, and —H pendent groups and is often represented by an approximate formula, (P OH). LOOPs may either hydroly2e slowly, be pyrophoric, or pyroly2e rapidly and yield diphosphine-contaminated phosphine. LOOP can also decompose explosively in the presence of moisture and air near 150° C. 

Phosphorus(III) Oxide. Phosphoms(III) oxide [12440-00-5] the anhydride of phosphonic acid, is formed along with by-products such as phosphoms pentoxide and red phosphoms when phosphoms is burned with less than stoichiometric amounts of oxygen (62). Phosphoms(III) oxide is a poisonous, white, wax-like, crystalline material, which has a melting point of 23.8°C and a boiling point of 175.3°C. When added to hot water, phosphoms(III) oxide reacts violentiy and forms phosphine, phosphoric acid, and red phosphoms. Even in cold water, disproportionation maybe observed if the oxide is not well agitated, resulting in the formation of phosphoric acid and yellow or orange poorly defined polymeric lower oxides of phosphoms (LOOP). 

The standard heat of formation for crystalline H3PO2 is —608.8 kJ/mol (—145.5 kcal/mol) (39). The acid can be prepared by the oxidation of phosphine by iodine and water. 

Phosphine is prepared commercially from the acid- or base-cataly2ed reaction of elemental phosphoms with water. In the acid-cataly2ed reaction, P4, white phosphoms, converts in part to red phosphoms. The latter is the main reactant (69). 

Phosphine generated by the above procedures is usually contaminated to varying degrees with diphosphine, which renders it spontaneously flammable. Pure phosphine can be produced by hydrolysis of phosphonium iodide [12125-09-6] PH I, which can be made by the action of water on a mixture of phosphoms and diphosphoms tetraiodide [13455-00-0] (71). 

The free phosphine is Hberated upon the removal of the acid catalyst with water. Tri-/-butylphosphine [998-40-3] is prepared by the acid-cataly2ed addition of isobutene to phosphine. 

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