Chlorine with phosphorus

Analogous chlorinations with phosphorus pentachloride proceed in higher yield and at lower temperature [61] (equation 46). 

Hydrazinotriazine 749 was prepared by the condensation of the respective quinone with thiosemicarbazide followed by sequential cyclization, chlorination with phosphorus oxychloride, and reaction with hydrazine (88JHC1139). Cyclocondensation of 749 with formic acid or carbon disulfide gave triazolotriazines 750 (88JHC1139) (Scheme 156). 

Aryloxymethyl chlorides may be prepared by the reaction of sodium aryloxymethanesulfonates with phosphorus pentachloride. The chlorination of anisole does not, as previously reported, give phenoxymethyl chloride, but rather a mixture of p- and o-chloroanisoles. Similarly, anisole and other unsubstituted methyl aryl ethers undergo ring chlorination with phosphorus pentachloride and chlorine, whereas ring-chlorinated anisoles, such as />-chloroanisole, undergo chlorination at the methyl group with chlorine at 190-195° in the presence of a catalytic amount of phosphorus pentachloride. ... 

Also, the compound is obtained by reaction of dry chlorine with phosphorus trichloride ... 

The most convenient synthesis of halogenopyrazines and -quinoxalines is by halogenation of pyrazinones and quinoxalinones with phosphoryl or other acid halides for example, 5-hydroxy-2-pyrazinecarboxylic acid, rather than 5(477)-pyrazinone-2-carboxylic acid, is chlorinated with phosphorus pentachloride/phosphoryl chloride to afford a 63% yield of 5-chloro-2-pyrazinecarbonyl chloride <1994SL814>. Sato and Narita provided an improved synthesis of various halogenopyrazines in which 2(l//)-pyrazinones were activated with chlorotrimethylsilane to give silyl ethers (Section 8.03.7.3). This procedure is most effective for synthesis of bromopyrazines whose overall yields are 62-81% <1999JHC783>. Bromopyrazine is directly prepared by treatment of 2-(l//)-pyrazinone with phosphoryl... 

Chlorination with phosphorus oxychloride under conditions which minimize dichlorination was reported to give a mixture of products consisting of dichloride 23 and two respective isomeric monochlorides, 4-chloro and 7-chloro 24 and 25 (Scheme IS) <2002JHC889>. 

Heating hydrazinopyrimidine (488) in diethyl oxalate gave 489, which upon chlorination with phosphorus oxychloride yielded (2-ethoxycarbonyl) triazolo[l,5-c]pyrimidine (491). The intermediate hydrazidoyl chloride 490 can be isolated under mild conditions (90T3897) (Scheme 96). 

Imidazo[4,5-c]pyridin-4(5//)-one (150) has been chlorinated with phosphorus oxychloride and thiated with phosphorus pentasulfide to give 4-chloroimidazo[4,5-c]pyridine (149) and imidazo[4,5-c]pyridine-4(5//)-thione (151), respectively (49RTC1013, 65JMC708). 

The 3-amino substituent of various [l,2,4]triazoIo[4,3-a]pyrazines can be acylated (69JCS(C)1593) but it is inert towards normal diazotization procedures (68JHC485). The 3-hydroxy compound could not be chlorinated with phosphorus oxychloride and in the IR spectrum it appeared to exist in both the keto and enol forms (68JHC485). 

The reaction of (1) with hypochlorous acid leads to chlorination at the 5- and 6-positions.30 Oxidative chlorination with phosphorus pentachloride gives the 2,9-dichloro-[l], as well as the 2,3,8,9-tetrachloro-[l]31 Chlorinated-[l] may be converted sequentially through the thiol-[l] to the sulfonato-[l] 32 Several trihalomethyl derivatives, particularly fluorinated phenanthrolines, have also been prepared 33-37... 

Neither [xxm] nor 14-bromocodeinone can be chlorinated with phosphorus pentachloride [31]. 

Cyclization of the unsaturated ester lactone (156) with hydrazine gives the fused furopyridazine derivative (157) which undergoes ring opening on chlorination with phosphorus oxychloride to give the dichloropyridazine (158), (Scheme 121), but the yields are only moderate <88JOC5704>. 

The synthesis of the compound is achieved by condensation of the amide hydrochloride of valine with glyoxal (Jones, 1949), followed by treatment with diazomethane (Seifert et al., 1970) or successive chlorination with phosphorus oxychloride and methoxylation (Murray and Whitfield, 1975). 

Phosphorus pentachloride, sulfur monochloride. The reaction of chlorine with phosphorus pentasulfide leads mainly to these two products ... 

Aldehyde benzoic acid, i.e., the half-aldehyde corresponding to phthalic acid, undergoes condensation with hydrazine to yield the hydrazone hydrazide (lactam-form). The lactim-form of this compound upon chlorination with phosphorus oxychloride gives the corresponding chloro derivative which on first treatment with a further mole of hydrazine and secondly with a calculated amount of hydrochloric acid affords the official compoimd. 

Benzene on nitration yields nitrobenzene which on reduetion gives aniline. /)-Amino benzene sulphonie aeid is obtained by treating aniline with hot coneentrated sulphurie aeid which on chlorination with phosphorus pentachloride gives /(-aminobenzene sulphonyl chloride and this on amination with coneentrated ammonia solution yields sufanilamide. 

The reaction of chlorine with phosphorus produces phosphorus trichloride (PCI3) and pentachloride (PCI5). Wet chlorine attacks most metals to form chlorides. Although titanium 174 0-32-6] is resistant to wet chlorine, it is rapidly attacked by dry chlorine. Tantalum is resistant to both wet and dry chlorine. Most metals are resistant to dry chlorine below 100 °C, but above a specific temperature for each metal, combustion takes place with a flame. This specific temperature, the ignition temperature, also depends on the particle size of the metal so that the following values are only approximate iron at 140 °C, nickel at 500 °C, copper at 200 °C, and titanium at 20 C. 

Pyrimidines used to be prepared via the construction of the heterocyclic ring as shown in Fig. 35. A 4-substituted-cyano-benzene is subjected to treatment with hydrogen chloride gas in an ethanolic solution, after the reaction is complete ammonia is bubbled into the solution to yield the ami-no-imine, which in turn is reacted with a suitably substituted phenyl diethyl malo-nate to give the dihydroxypyrimidine. The hydroxyl groups are removed by chlorination with phosphorus oxychloride followed by hydrogenation over palladium. The first part of this synthetic pathway is relatively straightforward, but the latter stages can result in poor yields if not performed correctly. 

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