Hydroxide phosphonium

FLALffiRETARDANTS - PHOSPHORUS FLALffi RETARDANTS] (Vol 10) Phosphonium hydroxide [4814-27-8]... 

Anionic Polymerization of Cyclic Siloxanes. The anionic polymerization of cyclosiloxanes can be performed in the presence of a wide variety of strong bases such as hydroxides, alcoholates, or silanolates of alkaH metals (59,68). Commercially, the most important catalyst is potassium silanolate. The activity of the alkaH metal hydroxides increases in the foUowing sequence LiOH < NaOH < KOH < CsOH, which is also the order in which the degree of ionization of thein hydroxides increases (90). Another important class of catalysts is tetraalkyl ammonium, phosphonium hydroxides, and silanolates (91—93). These catalysts undergo thermal degradation when the polymer is heated above the temperature requited (typically >150°C) to decompose the catalyst, giving volatile products and the neutral, thermally stable polymer. 

Kuraray [17] appears to have solved this problem in a very clever way with chemistry that is not well understood. Their solution to the problem can be viewed as having two parts. As rhodium catalyst modifiers, they use both a stoichiometric amount of a bis-phosphine and excess triphenylphosphine. The second part is to use an aqueous extraction of the product. This provides at least two advantages. The first is that the products are not exposed to the type of high temperatures that are associated with vaporizers. The second, and this is speculation, is that the water also removes the phosphonium hydroxide. 

A stereospecific synthesis of aziridine 266 has been reported by Ittah et al. from arene oxide 1 by treatment with sodium azide, followed by tri-phenylphosphine reaction. The reaction proceeds via a phosphonium hydroxide intermediate (267).157... 

Phosphine, as remarked on p. 66, combines with hydrogen iodide, forming a salt, PH4I, phosphonium iodide, resembling ammonium chloride. But as it is decomposed by water into phosphine, PH3, and hydrogen iodide, an attempt to convert it into phosphonium hydroxide, PH4OH. cannot be made. Substituted phosphonium compounds,... 

The primary, secondary and tertiary phosphines are weak bases, stronger, however, than the phosphine itself which is scarcely basic at all. The tetra-alkyl phosphonium hydroxides are strong bases. 

The sulfonated EPDM ionomers were prepared by neutralizing the free acid form of the polymer in solution with the specified quaternary phosphonium hydroxide. The free acid form of the sulfonated EPDM was prepared from a commercial EPDM—Vistalon 2504 manufactured by... 

The phosphonium hydroxides usually give a saturated hydrocarbon and a phosphine oxide, rather than an olefin and a phosphine, viz-... 

Alkyl phosphonium halides are decomposed by strong heating to give tertiary phosphines (6.32), whereas phosphonium hydroxides easily give phosphine oxide and hydrocarbon (6.109). The action of heat on triphenyl ((-alkoxycarbonyl alkyl) phosphonium salts is to produce ylids (6.391) (Section 6.10). 

Cope [147] has described a pyrolysis/gas chromatographic procedure for the determination of tetrakis(hydroxymethyl)phosphonium hydroxide and tris(2,3-dibromo-propyl)phosphate flame retardants on polyesters and surface tris(2,3-dibromopropyl)phosphate have been determined on the surface of retardant polyester fabrics [148]. The technique used to determine these, involved extraction of the fabric with an organic solvent followed by analysis of the solvent by X-ray fluorescence for surface bromine and by high pressure liquid chromatography for molecular tris(2,3-dibromopropyl)phosphate. 

Gu and Yan et al. [76] developed an ionomer, tris(2,4,6-trimethoxyphenyl) polysulfone-methylene quaternary phosphonium hydroxide (TPQPOH), which is soluble in low boiling point and water-soluble solvents such as methanol, ethanol, and n-propanol. The solubility of this kind of ionomer could be ideal for use in... 

There are two possible mechanisms for oxidation of trivalent phosphorus com-ponnds by these oxidizing agents (Routes (a) and (b) in Scheme 11.14). Route (a) involves the initial attack of the phosphorus on the hydroxylic oxygen atom to form the intermediate I while Route (b) involves the phosphonium hydroxide intermediate II. It was reported that reaction of hydroperoxides proceeds via Route (a) based on a tracer study using The mechanism for oxidation of triphenylphosphine... 

Cope has described a pyrolysis - gas chromatographic procedure for the determination of tetrakis(hypropyl)phosphate flame retardants on polyesters and cotton. 

Tris (2,4,6-trimethoxyphenyl) benzyl phosphonium hydroxide shows the highest basicity ever reported. Its HEM has the highest specific hydroxide conductivity among all reported cationic functional group-based HEMs, typically about twice that of trimethyl benzyl ammonium and more than foiu- times that of methyl imidazolium (39 [5], 19 [31], and 8.4mSgcm mmor [32] respectively, with the same polysulfone polymer matrix and homogeneous membrane structure in each case) (Table 6.2). 

Phosphorus is an important foundation industnal raw material of national defense industry, food industry and chemical industry, where it is used to produce red phosphorus, phosphonium hydroxide, phosphorus pentasulfide and phosphoric anhydride[l-2]. 

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