Phosphorus pentasulphide, reaction with

The problems associated with lability of double bonds during the mass spectro-metric examination of monoterpenes have been discussed. The mass spectra of ketones are not as easy to interpret as those of thioketones, the latter having a higher proportion of heteroatom-containing fragments. They are readily available by reaction of the ketones either with phosphorus pentasulphide, or with hydrogen sulphide and dry hydrogen chloride, and are recommended for the study of bicyclic ketones in the norbomane series. ... 

The deoxygenation of some penicillin and cephalosporin sulphoxides has been accomplished by the use of phosphorus pentasulphide.53 The reactive species responsible for deoxygenation was not identified. A particularly mild method for reducing sulphoxides to sulphides involves the reaction of the sulphoxide with 2-chloro-l,3,2-benzodioxaphosphole at room temperature.536 Yields in excess of 80% were reported. 

The reductive formation of C-S bonds via the reaction of carboxylic acids with phosphorus pentasulphide and red phosphorus has been utilized in the synthesis of 3-arylthiophenes starting from 2-arylsuccinic acids [66, 67]. The reaction is catalysed by benzyltriethylammonium chloride, but it has been suggested that co-catalysis with 18-crown-6 is advantageous [67]. 

The former is deposited in yellow crystals, mixed with sulphur when acetoxime is treated with phosphorus pentasulphide in carbon bisulphide soln. the insoluble product extracted with alcohol and the alcoholic soln. heated to boiling the compound separates from cold water in large, transparent, seemingly monoclinic prisms, melts at 146° 150° with decomposition, and is readily soluble in water, but only sparingly in alcohol, and insoluble in ether and carbon bisulphide. It decomposes carbonates, gives a colourless precipitate with lead acetate, and is decomposed by hot dilute nitric acid with separation of sulphur and formation of phosphoric acid it is also decomposed by mercuric oxide, the filtrate from the precipitated mercury sulphide giving all the reactions of phosphoric acid. 

Uses of the Sulphides of Phosphorus.—The pentasulphide of phosphorus is used to replace the oxygen of organic compounds by sulphur thus ethyl alcohol gives ethyl mercaptan, and acetic acid thioacetic acid.4 The reactions, however, are somewhat complex thus with ethyl alcohol the first product has been shown to be diethyl-dithiophosphate, SP(SH)(OEt)s, the mercaptan being produced by a secondary reaction.5 Phosphorus pentasulphide, boiling under atmospheric or other definite pressure, has been recommended for use in constant temperature baths in place of sulphur. The compound P4S3, which is one of the most stable sulphides in diy air, but resembles phosphorus in some respects, is used as a substitute for this element in the manufacture of matches.6... 

This method may be used for the preparation of other perfluorinated alkanesulphonyl-, arenesulphonyl-, and alkanecarbonyl-amides. Several reactions of the pseudohalide were studied, but perhaps the most interesting are the reaction under pressure at 160 °C with phosphorus pentasulphide to give the previously unknown compound CF3SOzNCS, and the reaction with phosphorus pentachloride under the same conditions to give CF3S02NCC12. 

The reaction of phosphorus trihalides with 1,3-dienes and phosphorus pentasulphide leads to a one-step synthesis of the phospholens (41) and (42). 

The compound (102.3), used in the synthesis of a fused pyridine in Section II. I, may also be cyclized to pyrano- or thiopyrano-pyrazole by heating with phosphorus pentoxide-PPA or phosphorus pentasulphide. The presence of ethanol or acetic acid retards the reaction. 

O-Alkyl phosphorotrithioate salts are converted by treatment with hydrogen chloride and a dihydric phenol into the mixed esters (52). Structure (53) has been proposed for the product from reaction of phosphorus pentasulphide with the thiophen derivative (54). Studies on the... 

Various Carbocyclic Fused Systems.—l,3-diphenyl-4//-5,6-dihydrocyclo-penta[c]thiophen-c/5-4,6-dicarboxylic acid has been prepared by the reaction of the appropriate 1,4-diketo-derivative with phosphorus pentasulphide. The reaction of (169) with tolane gave (170). Acylation of 2-methoxy-... 

The reaction of tropone with phosphorus pentasulphide provides thiotropone [233]. It is very unstable in solution. It appears to form a mercaptotropylium ion in concentrated sulphuric acid. 

Reaction of diphenyl eyelopropenone with phosphorus pentasulphide converts it into diphenylcyclopropenethione [119], Similar conversions of cyclopropenones into cyclopropenethiones have also been accomplished. using thioacetic acid in the presence of tetrafluoro-boric acid or perchloric acid [151]. ... 

The carbonyl group has been converted into a gew -dichloro group by means of thionyl chloride [53], phosgene [118] or phosphorus penta-chloride [119] and into a thione group by reaction with phosphorus pentasulphide [119],... 

The thionation of amides with phosphorus pentasulphide constitutes a traditional synthetic route to thioamides, which have been found to be especially useful for the synthesis of heterocyclic thiones containing the thiolactam grouping.However, thioformylhydroxylamine and some thioamides derived from 2-furanoic acid and anthranilic acid have also been obtained by this reaction. In the latter case, the reaction was performed in pyridine, and the authors were able to isolate the intermediate... 

The reactions of y-diketones with phosphorus pentasulphide constitute a well-known route to thiophens, but Trebaul and Teste have nevertheless observed that y-diketones of the type (262) react with phosphorus pentasulphide in boiling xylene to form 2,5-disubstituted 3-ethoxythio-carbonylfurans (263). Apparently, the ester group that is present facilitates an initial ring-closure of (262) to the furanoic ester (264), which then... 

Dewar para localization energies for some anthracene analogues have been computed. Another route to heterocyclic analogues of triptycene (433) is through the reaction of (432) with phosphorus pentasulphide. The starting material (432) was prepared by the Diels-Alder reaction of anthracenes with dibenzoyl- or diacetyl-ethylenes. ... 

Thieno[2,3-6]indoles (532) have been prepared through the reaction of (533) with phosphorus pentasulphide. The system (532) underwent an interesting Diels-Alder reaction, i.e. to (534), with dimethyl acetylene-dicarboxylate. ... 

Ri =s R2 = Ph). 4-Aryl-l,2-dithiolium salts of type (36 R = Me or Ph, R = H) yield 1,2-dithiolylidene ketones (37) when heated in ethanol, but this reaction fails when the dithiolium salt has a 5-amino-substituent (36 R = NRa). The 5-amino-compounds have been found to give 1,3-dithiole derivatives on treatment with phosphorus pentasulphide in pyridine. The structure of one of the products (38) was established by conversion into the 6a-thiathiophthen (39), which was also prepared by sulphurization of the dithiolylidene ketone (37 R = Ar = Ph, R = MeaN) obtained by the triethylamine-acetic acid route. 

An effective synthesis of 3-aryl-1,2-dithioisocoumarins has been described. 3-Aryl-l-thioisocoumarins (65) react with secondary amines to give thioamides (66) which, on treatment with phosphorus pentasulphide, give high yields of the dithioisocoumarins (67). The reactions of these... 

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