Phosphorus pentachloride with phenols

The procedure is not usually applicable to aminosulphonic acids owing to the interaction between the amino group and the phosphorus pentachloride. If, however, the chlorosulphonic acid is prepared by diazotisation and treatment with a solution of cuprous chloride in hydrochloric acid, the crystalline chlorosulphonamide and chlorosulphonanilide may be obtained in the usual way. With some compounds, the amino group may be protected by acetylation. Sulphonic acids derived from a phenol or naphthol cannot be converted into the sulphonyl chlorides by the phosphorus pentachloride method. 

Reactions. Saligenin [90-01-7] undergoes the typical reactions of phenols and benzyl alcohol. When heated above 100°C, it transforms into a pale yellow resinous material. Amorphous condensation products are obtained when saligenin reacts with acetic anhydride, phosphorus pentachloride, or mineral acids. Upon boiling with dilute acids, saligenin is converted into a resinous body, saliretin, a condensed form of saligenin. Condensation reactions of saligenin with itself in the absence of any catalysts and in the presence of bases have also been studied. 

General methods for the preparation of acid halides from aliphatic carboxylic acids are described in Section 5.12.1, p. 692. Phosphorus pentachloride is the preferred chlorinating agent for aromatic acids which contain electron-withdrawing substituents, and which do not react readily with thionyl chloride. The preparation of both p-nitrobenzoyl chloride and 3,5-dinitrobenzoyl chloride is described in Expt 6.161. These particular acid chlorides are valuable reagents for the characterisation of aliphatic alcohols and simple phenols, with which they form crystalline esters (see Section 9.6.4, p. 1241 and Section 9.6.6, p. 1248). 

Phenoxy-5,13-pentacenequinone (IV) was obtained by the replacement of chlorine atoms with phenoxy groups in 5-chloro-6,13-pentacenequinone in a phenol-phenoxide melt (Scheme 7).57 5-Chloro-6,13-pentacenequinone was synthesized by cyclization of 2-(l-chloro-2-naphthoyl)-3 naphthoic acid, which was prepared by acylation of a-naphthol with anhydrous naphthalene-2,3-dicarboxylic acid and by the subsequent treatment of the resultant 2-(l-oxy-2-naphthoyl)-3 naphthoic acid with phosphorus pentachloride. 

An oxidant. Combusdble when exposed to heat and flame. Moderate explosion hazard when exposed to heat or flame. Explosive reacdon with solid or concentrated alkali + heat (e.g., sodium hydroxide or potassium hydroxide), aluminum chloride + phenol (at 120°C), aniline + glycerol + sulfuric acid, nitric + sulfuric acid + heat. Forms explosive mixmres with aluminum chloride, oxidants (e.g., fluorodinitromethane, uranium perchlorate, tetranitromethane, sodium chlorate, nitric acid, nitric acid + water, peroxodisulfuric acid, dinitrogen tetraoxide), phosphorus pentachloride, potassium, sulfuric acid. Reacts violendy with aniline + glycerin, N2O, AgC104. To fight fire, use water, foam, CO2, dry chemical. Incompadble with potassium hydroxide. When heated to decomposidon it emits toxic flames of NOx. See also NITRO COMPOUNDS OF AROMATIC HYDROCARBONS. 

Derivation Heating salicylic acid and phenol with phosphorus pentachloride or other dehydrating agent. 

Treatment of 14-hydroxydihydrocodeine-B with thionyl chloride results only in chlorination of the aromatic nucleus (cf. the corresponding reaction with the four dihydrocodeine isomers, Chap. IV), but treatment with phosphorus pentachloride affords 14-hydroxy-6-chlorodihydrocodide [xrx], That the hydroxyl group at C-6 is the one that is replaced by chlorine is revealed by the fact that reduction of [xrx] by sodium amalgam and alcohol is attended by rupture of the cyclic ether link, giving 14-hydroxydihydrodesoxycodeine-C [xx], which is readily reduced catalytically to 14-hydroxytetrahydrodesoxy-codeine [xm]. All attempts to reduce [xrx] to a non-phenolic base, or to secure elimination of hydrogen chloride with production of a substance of the desoxycodeine-C type failed [6]. 

Isoflavones (3-aryl-chromones) can also be prepared in this way boron trifluoride-catalysed Friedel-Crafts acylation of a reactive phenol with an aryl acetic acid is followed by reaction with dimethylfor-mamide and phosphorus pentachloride. ... 

EXPLOSION and FIRE CONCERNS combustible liquid NFPA rating Health 3, Flammability 2, Reactivity 1 moderate explosion hazard reacts explosively with solid or concentrated sodium hydroxide and heat, potassium hydroxide and heat, aluminum chloride and phenol ( at 120°C), sulfunc and nitric acid and heat, and sulfuric acid and aniline and glycerol violent reaction with aniline and glycerin, silver perchlorate, and dinitrogen oxide forms explosive mixtures with aluminum chloride, fluorodinitromethane, tetranitromethane, sodium chlorate, nitric acid, nitric acid and water, dinitrogen tetraoxide, phosphorus pentachloride, potassium, and sulfuric acid products of combustion include oxides of nitrogen use carbon dioxide, dry chemical, foam, or water spray for firefighting purposes. 

Other inorganic esters are generally prepared by the reaction of an acid chloride with a hydroxy cmppound or its sodium salt. Phosphates are prepared by the reaction of phosphorus pentachloride or phosphorus oxji chloride with the appropriate alcohol or phenol. If the sulfur analogue of phosphorus oxychloride, PSCls, is baused to react with an alcohol, or its sulfur analogue, a mercaptan, the corresponding thioester is obtmned. 

Phosphorus pentachloride reacts with phenol to give triphenoxy di chloro phosphorane (6.496), which may also be obtained by direct chlorination of triphenyl phosphite (6.497), or by Equation 6.487. This compound readily dissociates into a series of anions and cations of general formulae... 

Depsides and Tannins. In forming depsides (poljnmers of phenol carboxylic adds) and tannin (sugar esters of phenol carboxylic acids), Fischer prepared the alkyl carbonates of the phenol carboxylic acids. Treatment of these products with phosphorus pentachloride gave the corresponding acid chlorides the latter were useful in preparing depsides and tannins. Using such reagente. 

The general method for producing the phenyl esters is heating the salicylic acid with the corresponding phenol derivatives in the presence of phosphorus oxychloride [58-66], phosphorus pentachloride [61, 67], phosphorus trichloride [61, 64, 66], phosgene, or thionyl chloride [61]. 

We first sought to convert the primary phosphines into dichlorophosphines (Rg. 1.9) these are typically reactive electrophilic reagents and enantiopure examples would be especially valuable for synthetic operations [36]. A library of phosphonites [58-60] could then be prepared by reaction of these dichlorophosphines with the appropriate alcohols and phenols in the presence of a tertiary amine base, and our exemplar targets were phosphonites based on enantiopure binol as shown in Fig. 1.10. Treatment of (R)-5 and (5)-6 with phosphorus pentachloride [61] in toluene yielded (/ )-16 and (5)-17 in almost quantitative conversion. 

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