Phosphorus halides water

The reaction of chromone-2-carboxylic acid with thionyl chloride or phosphorus halides gives the trihalide (400). This compound readily loses one of its geminal chlorine atoms and with water, for example, affords 4-chlorocoumarin through the simultaneous loss of carbon monoxide (Scheme 131) (63JGU1806). 

Concentrating phosphoric acid leads to polyphosphoric acid, a mixture of several polymeric species, a good catalyst and dehydrating agent. Polyphosphate salts are used as water softeners in detergents or as buffers in food. Small quantities of elemental phosphorus are used to make matches, and phosphorus halides to prepare specialty chemicals for the pharmaceutical and agrochemical industries. 

Thiophosphoryl chloride dissolves sulphur and phosphorus freely when hot, but only sparingly when cold.2 Since the liquid is immiscible with water the hydrolysis proceeds only on the surface at first, as is usual with phosphorus halides. In this case the products are phosphoric acid, hydrogen chloride and sulphide and a little sulphur. It reacts with ethyl alcohol, giving ethyl chloride and ethyl thiophosphate ... 

Another time-honored reaction is the acylation-dehydration of thiosemicarbazides. The acylation is generally performed with an acid chloride, and elimination of water from the intermediate 1-acylthio-semicarbazide is conveniently elFected with cold concentrated sulfuric acid or with 100 % phosphoric acid. Phosphorus halides have... 

Phosphorus has been determined40 in phosphosilico organic compounds (POSi bonds) by dissolving the sample in water, leaving for 4-5 h to hydrolyse (or for 30-40 min at 80°) and titrating the alkylphosphinic acid so produced with 0.1 M-alkali to the thymolphthalein end-point. A method has been described41 for the simultaneous determination of free phosphorus, combined phosphorus and silicon in the reaction products of tetraalkoxysilanes with phosphorus halides. 

Reactive impurities are substances that can react with the monomers, the growing chain-ends, or the acid acceptor to terminate the polymerization prematurely. They can be introduced with the solvent or with the intermediates. The acid chloride may contain impurities originating in its synthesis or storage such as hydrogen chloride, thionyl chloride, phosphorus halides, or monoacid halides. The diamine may contain monoamines, water, or carbonates. It may degrade oxidatively in air or absorb moisture and carbon dioxide. The degree of interference caused by these impurities depends on both the quantity of the impurities as well the relative reaction rates of the desired polymerization vs. those of the impurities. 

The phosphorus halides hydrolyze on contact with water. The reactions occur readily, and most of the phosphorus halides fume in air because of reaction with water vapor. In the presence of excess water the products are the corresponding phosphorus oxyacid and hydrogen halide ... 

Phosphorus halides react with water to form phosphoric acid and the corresponding hydrogen halide. For example, PCI3 reacts with water. 

Phosphorus exists as white and red phosphorus. The former allotrope may be preserved in the dark at low temperatures but otherwise reverts to the more stable red form. The white form is a waxy, translucent, crystalline, highly-toxic solid subliming at room temperature and inflaming in air at 35°C, so it is handled under water. The red form is a reddish violet crystalline solid which vaporizes if heated at atmospheric pressure and condenses to give white phosphorus. The red form ignites in air at 260°C. Both are insoluble in water, and white phosphorus can be stored beneath it. Phosphorus forms a host of compounds such as phosphine, tri- and penta-halides, tri-, tetra- and penta-oxides, oxyacids including hypophosphorous, orthophosphorous and orthophosphoric acids. 

B. By Hydrolysis Reactions.—Details have appeared of the synthesis of dibenzophosphorin oxides (15) from 5-alkyldibenzophospholes, by reaction with methyl propiolate in the presence of water, and of confirmatory syntheses from phosphinic acid chlorides, as shown below. Evidence for the suggested mechanism of the ring-expansion reaction is presented. The hydrolysis of enamine phosphine oxides is an efficient, although somewhat indirect, method for the preparation of j8-ketoalkylphosphine oxides (16) [see Section 3(iii), for the preparation of enamine oxides]. Reasonable yields (48—66%) of trialkylphosphine oxides (17) have been obtained by the alkaline hydrolysis of the products from the pyrolysis at 220 °C of red phosphorus with alkyl halides, in the presence of iodine. 

Phosphorus haiides violently react with water by producing the corresponding hydrogen halide. In the case of phosphorus trichloride, the following reaction equation is postulated ... 

For example, direct treatment of red phosphorus with potassium hydroxide in a mixture of dioxane and water with a phase-transfer catalyst (benzyltriethylammonium chloride) allows direct reaction with primary haloalkanes to form the trialkylphosphine oxide in moderate (60-65%) yield.1415 Allylic and benzylic halides are similarly reported to generate the corresponding tertiary phosphine oxides. When the reaction is performed with a,(o-dihalides, cyclic products are generated only with four- and five-carbon chains the third site... 

In the instances of phosphorous and phosphonous acid systems, the generation of a new C-P bond via the classical Michaelis-Arbuzov reactions as noted above leads to products that are esters themselves. Isolation of the free acid product requires cleavage of the ester linkage in a separate reaction step, generally after isolation and purification of the initial product. The advent of silyl phosphorus reagents for the Michaelis-Arbuzov reaction allowed free acid products to be isolated simply by water workup of the reaction system. Further, since the byproduct was a silyl-halide, the general concern that the by-product halide would participate in an extraneous Michaelis-Arbuzov reaction was obviated. 

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