Phosphorus oxychloride determination

Phosphorus oxychloride content and impurities are determined by gas chromatography analyses. 

A"-Ray structure determinations (see Chapter 11 for details) have been reported for triphenylphosphine oxide, tri-o-tolylphosphine oxide, sulphide, and selenide, and for cw-2,2,3,4,4-pentamethyl-l-phenylphos-phetan-1-oxide (5). Electron spectroscopic studies of phosphorus oxychloride and thiophosphoryl chloride in the gaseous state, and n.m.r., i.r., and u.v. spectra of phosphine sulphides have appeared. Dipole moments have been used to define the stereochemistry of 2-cyanoethylphosphine oxides, such as (6), which is shown in its preferred conformation. 

Methylcarbazole reacted with 2,6-dimethyl-4-pyrone in the presence of phosphorus oxychloride generating the pyrylium salt 170. Xanthydrol and thiaxanthydrol condensed with carbazole and 9-methylcarbazole under acid catalysis and sulfuric acid oxidation to give the colored salts 171 (X = O or S) the process has been used for the colorimetric determination of carbazole. ... 

HNMR data have been used to determine the structure of certain unusual products obtained in the reaction of chlorohydroxypyrimido[4,5-c]pyridazines with phosphorus oxychloride and N,N-dimethylaniline (71CPB1849). NMR has also been used in the structure... 

Acid chlorides are used for the quantitative determination of hydroxyl groups and for acylation of sugars. Industrial applications include the formation of the alkyl or aryl carbonates from phosgene (see Carbonic and chloroformic esters) and phosphate esters such as triethyl, triphenyl, tricresyl, and tritolyl phosphates from phosphorus oxychloride. 

The method to be used is determined by the practicability of the separation of the chloride from the by-products of the reaction, and the excess of the reagent used. Thus, in the laboratory, phosphorus trichloride is used for the lower fatty acids because their chlorides are more volatile than phosphorous acid. The acid, together with 1.5 times the amount of phosphorus trichloride, as indicated in equation (1), is refluxed, and then the acid chloride is distilled from the viscous phosphorous acid and fractionated. Phosphorus pentachloride is used with aromatic acids as shown in equation (2). The dry, finely pulverized potassium or sodium salt of the acid is mixed with a little more than the calculated amount of the pentachloride and heated until the reaction is finished. The resulting oxychloride (POCI3) is removed by distillation. If the boiling points are too close, then the mixture of aryl acid chloride and phosphorus oxychloride is added to finely chopped ice. The oxychloride decomposes instantly, while the aryl acid chloride does not react appreciably at this temperature. The chloride is either separated or extracted with ether, dried, and then fractionated. 

The yields of the pyrimidines 147 and the pyridines 151 are not high and vary greatly, depending on the structure of the starting materials. The latter can also determine the nature of the product. Thus, a mixture of 2,4-dimethyl-6-phenylpyrimidine, 2,4-dimethyl-4,6-diphenyl-4//-l,3-oxazine and 1-chloro-l-phenylethene was obtained by refluxing a 1 3 3 ratio of the acetophenone-benzonitrile-phosphorus oxychloride mixture, followed by treatment of the crude product with sodium carbonate solution .It has been shown that addition of an additional ketone molecule to the iminium intermediate is an alternative to the formation of the A -acylenamines and this route is catalyzed by aluminum chloride. Auricchio and coworkers believe also that the reaction of ketones with nitriles catalyzed with both protic and Lewis acids must be considered as a Ritter reaction (see, however, Section V.C). The cationic intermediate 152 thus formed can undergo either a proton shift giving enamide 153 or addition of another ketone molecule... 

The sultone cycloadducts could be further manipulated by ring-opening with various nucleophiles, such as alcohols and amines, at the y-position [41]. When optically active (S)-(-)-a-methylbenzylamine reacted with the racemic sultone cycloadduct 76 in ethanol at room temperature, one of the diastereomeric ammonium sulfonates precipitated from the reaction mixture (Scheme 17). Although the absolute stereochemistry of 77 had not been determined, cyclization of optically pure 77 with phosphorus oxychloride gave an optically pure sultam 78. Formic acid debenzylation followed by base hydrolysis of the N-formyl group afforded the optically pure sultam 80 in good yield [40]. 

The thioacyl-arylhydrazides (187 R = Me, Et, Pr, or Ph) react with phosphorus oxychloride to yield the iminium salts (189) by way of the suggested intermediates (188). Quantum yields for the photocyclization (190) (191) (R = H, Bu, Ph, OMe, NO2, etc ) have been determined.Oxidation of the phenolic amino-ester (192), i.e. a dopachrome reaction, gives the quinone imine... 

Of the esters, starch phosphate is produced by reaction with phosphorus oxychloride, polyphosphates, or metaphosphates a cross-bonded product results. Total degree of substitution is determined by measuring the phosphorus content, and the mono- to disubstitution ratio can be calculated by potentio-metric titration. Allowance is made for the natural phosphorus content of the starch. Treatment of starch with acetic anhydride produces starch acetate, which has improved paste stability over native starch. The acetyl group is very labile, and hydrolyses readily under mild alkaline conditions. When a known amount of alkali is used, the excess can be titrated and the ester function measured. This is not specific, however, and a method based on an enzymatic measurement of the acetate has been developed in an ISO work group. The modified starch is hydrolyzed under acidic conditions, which releases acetic acid and permits filtration of the resulting solution. Acetic acid is then measured by a commercially available enzyme test kit. Both bound and free acetyl groups can be measured, and the method is applicable... 

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