Phosphorus pentachloride, formation

Similarly, von Braun and Schmitz found that A-benzoylconiine, on distillation with phosphorus pentachloride, underwent ring scission with elimination of the nitrogen atom and formation of the dichlorooctane, CH2CI. (CH2)3. CHCl. CHa. CH. CH3. 

The formation of the dichlorides is aided by increased temperature (60-80°C) and by an excess of PCI5 (2-2.3 moles/mole of 4-acetylpyrazole). With a larger excess of PCI5, further chlorination of the compounds occurs. With 3 moles of phosphorus pentachloride at 80°C in benzene, ketones 12a-d gave pyrazolyl-trichloroethylenes 16a-d in 75% yield. Then dichlorides 17a-d were converted quantitatively into pyrazolyltrichloroethylenes 16a-d in 1 h under the same conditions. 

It yields a chloride, thujyl chloride, Cj H jCl, by the action of phosphorus pentachloride, which on treatment with aniline yields up HCl, with the formation of the terpene thujene. 

In a 2-1 three-necked flask equipped with a stirrer, a reflux condenser, and a dropping funnel (Note 1) 832 g (4 0 moles) of phosphorus pentachloride is stirred with 250 ml. of phosphorus oxychloride (Note 2) To this is added with stirring 264 g (272 ml, 4 4 moles) of methyl formate (Note 3). During the addition the reaction vessel is cooled in an ice bath to maintain a reaction temperature of 10-20° The addition requires about 1.75 hours When the addition is complete, the solution is stirred at a temperature under 30° until all the phosphorus pentachloride has dissolved (about 1 hour) Then the stirrer is removed, the reflux condenser is replaced by a distilling head, and the reaction... 

Dichloromethyl methyl ether has been prepared by the chlorination of chlorodimethyl ether in the liquid5-4 or gas phase,5 by the reaction of chlorodimethyl ether with sulfuryl chloride and benzoyl peroxide,6 7 and by the treatment of methyl formate with phosphorus pentachloride.8-10... 

B. Reactions.—This year has seen the publication of a number of papers on the reactions of olefins and acetylenes with phosphorus pentachloride, to produce new phosphorus-carbon bonds. An investigation into the structural requirements of trisubstituted olefins (40) undergoing the above reaction has shown that both steric and electronic factors are important, e.g. an adduct forms with (40 X = CH3) but no reaction occurs for (40 X = Ph). Further examples of the reactions of unsaturated ethers include the formation and decomposition of adducts from a-methoxystyrene... 

B. From Cyano-compounds and Phosphorus(v) Halides.—Continued reports of the reactions of alkyl cyanides with phosphorus pentachloride appear. With dicyanides the formation of phosphazenes occurs via a series of intermediates whose stability varies with the nature of X ... 

It also detonates in the presence of phosphorus, sulphur and carbon monoxide. With a chlorine/phosphorus pentachloride mixture the resulting detonation was explained by the hypothetical formation of chlorine monoxide. 

The traditional method for transforming carboxylic acids into reactive acylating agents capable of converting alcohols to esters or amines to amides is by formation of the acyl chloride. Molecules devoid of acid-sensitive functional groups can be converted to acyl chlorides with thionyl chloride or phosphorus pentachloride. When milder conditions are necessary, the reaction of the acid or its sodium salt with oxalyl chloride provides the acyl chloride. When a salt is used, the reaction solution remains essentially neutral. 

An alternative method of synthesis of N3P3Cl6 has been developed recently, based on the reaction of tris (trimethylsilyl) amine and phosphorus pentachloride (40). This reaction either preferentially leads to the formation of N3P3C16 or to an N-silylated phosphoranimine intermediate C13P - NSiMe3, depending on the reaction conditions used. Thus the reaction between tris (trimethylsilylamine) and PC15 in methylene chloride at 40° C affords a mixture of cyclo and linear phosphazenes, which has been shown by an NMR analysis to contain up to 76% of N3P3C16 (Eq. 2). 

Contact between phosphorus pentachloride and a mixture of chlorine and chlorine dioxide (previously considered to be dichlorine trioxide) usually causes explosion, possibly owing to formation of the more sensitive chlorine monoxide. 

Phosphorus pentachloride, in conversion of D,L-10-camphorsulfonic acid to add chloride, 45,14 reaction with methyl formate to yield dichloromethyl methyl ether, 47, 47... 

Phosphorus containing 32P (of the order of 1 g.) was converted into the trichloride. This small-scale conversion presented considerable and unexpected difficulties, the most serious feature being the very ready production of phosphorus pentachloride. (All the reliable descriptions of the preparation of phosphorus trichloride are on a basis of ca. 200 g. of phosphorus.)6 This tendency to pentachloride formation was checked by the correct geometry of the apparatus and by the method of manipulation. 

Condensed 4-halo-1,2,3-triazines are a virtually unknown class of compounds and are apparently very unstable. Reaction of 1,2,3-benzo-triazin-4-one (10, R = H) with a mixture of phosphorus oxychloride and phosphorus pentachloride, for example, results in formation of o-chlorobenzonitrile, presumably via formation and then decomposition of the 4-chlorotriazine (137) to give the diazonium salt (138), subsequent... 

The isomeric tricyclo[3.3.2.0 ]decane hydrocarbon (396) has also recently yielded to synthesis Thus, reaction of 394a with either thionyl chloride or phosphorus pentachloride led to rearrangement and formation of chloride 395a. Alternatively,... 

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. 

Scheme 2.1 Formation of cyclophosphazenes by cyclocondensation of phosphorus pentachloride and ammonium chloride.

Various other processes can be made to yield sulphur monoehloride. The distillation of sulphur with stannous chloride or mercuric, chloride yields sulphur monochloride and, indeed, may be regarded as a modification of the method first given. The action of phosphorus pentacliloridc on sulphur or on metallic sulphides and the action of chlorine on metallic sulphides form closely analogous processes, especially in view of the formation of chlorine as a dissociation product from phosphorus penta-chloride. With phosphorus pentachloride tire phosphorus is found finally as sulphochloride. Of other methods there may be mentioned the interaction of sulphur or of phosphorus sulphide with thionyl chloride,6 and the action of dry chlorine on a hot or boiling solution of... 

Phosphorus pentachloride effects a gradual removal of one atom of oxygen from sulphuryl chloride, with formation of tliionyl chloride,... 

Like sulphuryl chloride, pyrosulphuryl chloride can convert many elements, e.g. sulphur, phosphorus, antimony and mercury, into the corresponding chlorides, with simultaneous formation of sulphur dioxide and trioxide.2 In the reaction between pyrosulphuryl chloride and phosphorus pentachloride or trichloride, there are obtained phosphorus oxychloride, sulphur dioxide and chlorine. 

Whilst the formation of thionyl chloride by the action of phosphorus pentachloride on an alkali sulphite favours a symmetrical structure for the latter, the interaction of an alkali sulphite with ethyl iodide, as mentioned already, is directly opposed to this evidence, as also is the production of sodium sulphite on reducing sodium dithionate with sodium.5 The remaining inorganic evidence is little more satisfactory. 

Japanese workers218 report the formation of 2-alkyl-3-halopyrazolo[l,5-ajpyridines from the corresponding 3-acyl derivatives, whereas attempted perchlorination of 5 with phosphorus pentachloride in a steel bomb gave a 48% yield of perchloropyridine.219... 

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