Reactivity phosphinic

In one family of experiments, a pair of phosphine reagents was used to evaluate the relative reactivities of PyO towards the peroxo intermediate. The reactivity ratio proved to be independent of the PyO used, consistent with the absence of the Py group in the intermediate. The most reactive phosphines were those with electron-donating substituents (57). 

Me-P = CH2 is a reactive phosphine and the freshly prepared species reacts with isoprene to give Diels-Alder adducts of phophinines with six-membered phosphorus heterocycles 17-20 (Scheme 6). 

In addition to aerosol age, phosphorus aerosol speciation is also affected by the humidity of the ambient environment (Van Voris et al. 1987). Washout and rainout processes transport both the reaction products of vapor phase phosphorus and unreacted particles of phosphorus to water and land (Berkowitz et al. 1981). Because of its lower water solubility, physical state (gas), and slower reactivity, phosphine formed during the combustion of white phosphorus or released to the atmosphere from other media persists in the atmosphere longer than other reaction products. 

A different approach toward preparation of phosphinous and phosphonous iodides uses the reaction of iodoalkanes with either PI3 or PI5. This reaction is specific for iodoalkanes and phosphorus iodides and is not applicable to other halides. From the resultant highly reactive phosphinous and phosphonous iodides, the full range of the parent acid derivatives may be prepared (esters, other acid halides, anhydrides, amides). We will not be concerned here with these preparations of derivatives of the parent acids, topics that are considered in other reports. ... 

The interaction of a (2-halogenoethyl)phosphinate (129) with less than one molar proportion of a chiral base [(—)-quinine, (+)-quinidine, (+)-l-phenyl-ethylamine, and (—)-A -methylephedrine, were each used] results in elimination to give (130) with concurrent enrichment of the less reactive phosphinate enantiomer (129). The leaving group evidently plays a significant role in the... 

The C2-symmetric trienes 7 and 9 readily derived from D-marmitol underwent a symmetrical cleavage via a domino process featuring two ring-dosing metathesis (RCM) events to afford the enantiopure lactones 8 and 10, respectively (Scheme 2.2) [4]. While the second-generation Grubbs catalyst 2 led to an effident conversion of the p,Y-unsaturated diester 9, the more reactive phosphine-ffee catalyst 4 was required for a dean transformation of the a,fi-unsaturated diester 7. 

There may be many targets within cells where reactions with reactive phosphines could be destructive. In the next sections we will consider some possible reactions of phosphines in biological systems. It is interesting to note that PH3 itself is highly toxic and is widely used as a pesticide. 

The problem of the synthesis of highly substituted olefins from ketones according to this principle was solved by D.H.R. Barton. The ketones are first connected to azines by hydrazine and secondly treated with hydrogen sulfide to yield 1,3,4-thiadiazolidines. In this heterocycle the substituents of the prospective olefin are too far from each other to produce problems. Mild oxidation of the hydrazine nitrogens produces d -l,3,4-thiadiazolines. The decisive step of carbon-carbon bond formation is achieved in a thermal reaction a nitrogen molecule is cleaved off and the biradical formed recombines immediately since its two reactive centers are hold together by the sulfur atom. The thiirane (episulfide) can be finally desulfurized by phosphines or phosphites, and the desired olefin is formed. With very large substituents the 1,3,4-thiadiazolidines do not form with hydrazine. In such cases, however, direct thiadiazoline formation from thiones and diazo compounds is often possible, or a thermal reaction between alkylideneazinophosphoranes and thiones may be successful (D.H.R. Barton, 1972, 1974, 1975). 

The diazonium salts 145 are another source of arylpalladium com-plexes[114]. They are the most reactive source of arylpalladium species and the reaction can be carried out at room temperature. In addition, they can be used for alkene insertion in the absence of a phosphine ligand using Pd2(dba)3 as a catalyst. This reaction consists of the indirect substitution reaction of an aromatic nitro group with an alkene. The use of diazonium salts is more convenient and synthetically useful than the use of aryl halides, because many aryl halides are prepared from diazonium salts. Diazotization of the aniline derivative 146 in aqueous solution and subsequent insertion of acrylate catalyzed by Pd(OAc)2 by the addition of MeOH are carried out as a one-pot reaction, affording the cinnamate 147 in good yield[115]. The A-nitroso-jV-arylacetamide 148 is prepared from acetanilides and used as another precursor of arylpalladium intermediate. It is more reactive than aryl iodides and bromides and reacts with alkenes at 40 °C without addition of a phosphine ligandfl 16]. 

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. 

Alkylation of phosphines by alkyl hahdes exhibits reactivity relative to the base strength, ie, PH is the least reactive and tertiary phosphines the most. This reactivity reflects the difficulty in using alkylation to prepare anything except quaternary phosphonium hahdes. 

Conventional triorganophosphite ligands, such as triphenylphosphite, form highly active hydroformylation catalysts (95—99) however, they suffer from poor durabiUty because of decomposition. Diorganophosphite-modified rhodium catalysts (94,100,101), have overcome this stabiUty deficiency and provide a low pressure, rhodium catalyzed process for the hydroformylation of low reactivity olefins, thus making lower cost amyl alcohols from butenes readily accessible. The new diorganophosphite-modified rhodium catalysts increase hydroformylation rates by more than 100 times and provide selectivities not available with standard phosphine catalysts. For example, hydroformylation of 2-butene with l,l -biphenyl-2,2 -diyl... 

Chemical Reactivity - Reactivity with Water Reacts vigorously with water, generating phosphine, which is a poisonous and spontaneously flammable gas Reactivity with Common Materials Can react with surface moisture to generate phosphine, which is toxic and spontaneously flammable Stability During Transport Stable if kept dry Neutralizing Agents for Acids and Caustics Not pertinent Polymerization Not pertinent Inhibitor of Polymerization Not pertinent. 

The more reactive fluoroketones also react with reagents prepared by the action of carbon tetrachloride on a tnalkylphosphine to form a vinyl phosphine oxide [id] (equation 29)... 

Important and widely used variants of the Wittig reaction are based on carbanionic organophosphorus reagents, and are known as the Wadsworth-Emmons reaction, Wittig-Horner reaction or Horner-Wadsworth-Emmons reaction. As first reported by Horner, carbanionic phosphine oxides can be used today carbanions from alkyl phosphonates 13 are most often used. The latter are easily prepared by application of the Arbuzov reaction. The reactive carbanionic species—e.g. 14 —is generated by treatment of the appropriate phosphonate with base, e.g. with sodium hydride ... 

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