Phosphorus trichloride chlorination

Phosphorus pentachloride purchased as pure is occasionally of inferior quality and gives poor results. It is not a difficult matter to prepare in the laboratory a product suitable for this reaction. To 1000 g. of phosphorus trichloride, chlorine is added until the increase in weight is 500 g. The gas should be added above the surface of the liquid, which is stirred occasionally during the addition. The stirring should not be continuous, however, as this tends to allow the formation of the pentachloride in the tube, which thus becomes clogged. At the end of the reaction the mixture becomes practically solid. 

The necessary condition for chlorination is that the reaction should take place in an excess of free phosphorus with its lack phosphorus trichloride chlorinates to form pentachloride. The formed PCI5 interacts with free... 

Phosphorus and chlorine combine directly to form either the trichloride or the pentachloride depending on the relative amounts of phosphorus and chlorine used. 

The trichloride is obtained as a liquid, boiling point 349 K, when a jet of chlorine burns in phosphorus vapour. Care must be taken to exclude both air and moisture from the apparatus since phosphorus trichloride reacts with oxygen and is vigorously hydrolysed by water, fuming strongly in moist air. The hydrolysis reaction is ... 

Phosphorus trichloride reacts with chlorine in excess to give phosphorus pentachloride, an equilibrium being set up ... 

Phosphorus pentachloride is prepared by the action of chlorine on phosphorus trichloride. To push the equilibrium over to the right, the temperature must be kept low and excess chlorine must be present. Hence the liquid phosphorus trichloride is run dropwise into a flask cooled in ice through which a steady stream of dry chlorine is passed the solid pentachloride deposits at the bottom of the flask. 

Hydroxylamine Barium oxide and peroxide, carbonyls, chlorine, copper(II) sulfate, dichromates, lead dioxide, phosphorus trichloride and pentachloride, permanganates, pyridine, sodium, zinc... 

Bischloromethyl ether has been prepared by saturation of formalin with dry hydrogen chloride by the reaction of paraformaldehyde with phosphorus trichloride or phosphorus oxychloride, by solution of paraformaldehyde in concentrated sulfuric acid and treatment with ammonium chloride or dry hydrogen chloride, and by suspension of paraformaldehyde in seventy or eighty percent sulfuric acid and treatment with chlorosulfonic acid. It is formed together with the asymmetrical isomer when methyl ether is chlorinated and when paraformaldehyde is treated with chlorosulfonic acid. The present method has been published. ... 

Phosphorus Trichloride (Phosphorous chloride). PCI3, mw 270.73 colorl, clear fuming liq, mp —111.8°, bp 76°, d 1.547g/cc. Decomps rapidly in moist air. -Dissolves in w or ale with decompn and liberation of much heat. Sol in benz, chlf, eth and C disulfide. Prepd by passing a current of dry chlorine over gently heated P, which ignites. The trichloride, admixed with some pentachioride, distills over. A small amt of Pis added and the whole distilled (Refs 9 10)... 

M.2 Phosphorus trichloride, PCI(, is produced from the reaction of white phosphorus, P4, and chlorine P4(s) +... 

Elements that can expand their valence shells commonly show variable covalence, the ability to form different numbers of covalent bonds. Elements that have variable covalence can form one number of bonds in some compounds and a different number in others. Phosphorus is an example. It reacts directly with a limited supply of chlorine to form the toxic, colorless liquid phosphorus trichloride ... 

The Lewis structure of the PCI, molecule is shown in (22), and we see that it obeys the octet rule. However, when phosphorus trichloride reacts with more chlorine (Fig. 2.10), phosphorus pentachloride, a pale yellow crystalline solid, is produced ... 

FIGURE 2.10 Phosphorus trichloride is a colorless liquid. When it reacts with chlorine (the pale yellow-green gas in the flask), it forms the very pale yellow solid phosphorus pentachloride (at the bottom of the flask). 

Self-Test 6.11A When 0.231 g of phosphorus reacts with chlorine to form phosphorus trichloride, PC1 , in a constant-pressure calorimeter of heat capacity 216 J-(°C)1, the temperature of the calorimeter rises by 11.06°C. Write the thermochemical equation for the reaction. 

Suppose that we place 3.12 g of PCls in a reaction vessel of volume 500. ml, and allow the sample to reach equilibrium with its decomposition products phosphorus trichloride and chlorine at 250.°C, when K = 78.3 for the reaction PCl3(g) PCI. (g) + Cl2(g). All three substances are gases at 250°C. Use the general procedure set out in Toolbox 9.1 to find the composition of the equilibrium mixture in moles per liter. 

Phosphorus trichloride, PCI, and phosphorus pentachloride, PC15, are the two most important halides of phosphorus. The former is prepared by direct chlorination... 

C04-0007. Phosphoms trichloride is produced from the reaction of solid phosphorus and chlorine gas ... 

Dichloroethylphosphine has been shown to react with methyl vinyl ketone to form 2-ethyl-5-methyl-A -l,2-oxaphospholen-2-oxide (25), which has been converted to (26) by chlorination in the presence of base. The same phosphine adds to methyl acrylate in the presence of acetic acid to give the phosphine oxide (27). Further examples have appeared of the reactions of the phenylhydrazones of methyl ketones with phosphorus trichloride to produce the heterocycles (28). 

A. Synthetic Methods.—Electrophilic addition of P compounds to olefinic compounds is a well-established route to phosphonic acids, although yields are often disappointing. With phosphorus pentachloride it has been found that yields are greatly improved when phosphorus trichloride is added to the reaction mixture. Since the orientation of the addition implies that electrophilic addition to phosphorus rather than chlorine is the initial step, it seems likely that the trihalide participates by decreasing the free concentration of chlorine rather than by a more active role. This... 

Dangerous materials may require special equipment. Chlorination with gaseous chlorine requires quite expensive storage facilities. Chlorination with chlorine, thionyl chloride, sulphuryl chloride, phosphorus oxychloride, phosphorus trichloride, or phosphorus pentachloride, all of which are fairly hazardous, requires off-gas treatment. Some of these reactants can be recycled. Pyrophoric solids such as hydrogenation catalysts, anhydrous aluminium trichloride for Friedel-Crafts reactions, or hydrides used as reducing agents should usually be handled using special facilities. Therefore, all of the above proce.sses are usually carried out in dedicated plants. 

Both yellow and red phosphorus ignite on contact with fluorine and chlorine red ignites in liquid bromine or in a heptane solution of chlorine at 0°C. Yellow phosphorus explodes in liquid bromine or chlorine, and ignites in contact with bromine vapour or solid iodine [1]. Interaction of bromine and white phosphorus in carbon disulfide gives a slimy by-product which explodes violently on heating [2], Interaction of phosphorus and iodine in carbon disulfide is rather rapid [3], A less hazardous preparation of diphosphorus tetraiodide from phosphorus trichloride and potassium iodide in ether is recommended [4],... 

Phosphorus trichloride is obtained by the reaction of excess phosphorus with chlorine. 

With f-butylmagnesium chloride the substitution of only one chlorine atom of the phosphorus trichloride is possible, giving dichloro-t-butylphosphine (65-70%). 

After a large number of experiments, we found that the preparation could be run virtually as a one-stage process. The whole process consists simply in adding phosphorus trichloride to isopropyl alcohol, dissolved in a solvent such as carbon tetrachloride, without external cooling. The crude product (still in the solvent) is chlorinated and then heated with an inorganic fluoride, e.g. sodium fluoride. After filtration, the solvent is distilled off and the pure di-isopropyl phosphorofluoridate distilled. ... 

The water passing through the condenser C was then cut off, and a stream of nitrogen substituted for the chlorine. This swept the phosphorus trichloride into D, where it was trapped. The next stage of the operation was to sweep the phosphorus trichloride from D into the graduated vessel E, the latter being cooled in liquid air while D was gently warmed. When the transference was complete, the temperature of E was allowed to rise to room temperature and the volume of phosphorus trichloride produced measured on the scale. Yield, ca. 90 per cent. 

As previously stated (p. 53) di-(2-chloroethyl) phosphoro-fluoridate can be prepared by the action of phosphorus oxydi-chlorofluoride on ethylene chlorohydrin. The compound can also be prepared by the fluorination of di (2-chloroethyl) phos-phorochloridate, prepared from di-(2-chloroethyl) hydrogen phosphite (XVIII), obtained by the action of phosphorus trichloride on ethylene chlorohydrin. This partial fluorination was effected by means of sodium fluoride, although the yield was not high. The chlorine atoms of the 2-chloroethyl groups were not affected by this procedure, a fact which falls into line with the observations of Saunders and Stacey (p. 12) that ethylene chlorohydrin is not readily fluorinated by sodium fluoride, but only by potassium fluoride under pressure in a rotating autoclave.1... 

From phosphorus trichloride, benzyl alcohol and 2 mol. of a tertiary base, dibenzyl hydrogen phosphite (XIV), is obtained which on treatment with chlorine or a chlorinating agent (e.g. sulphuryl chloride)4 gives the phosphorochloridate (XV). Although not isolated, (XV) is almost certainly obtained by treatment of (XIV) with a polyhalogen hydrocarbon because reaction in the presence of an alcohol or of a primary or secondary amine gives a triester (XVI) or a phosphoramidate. 

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