Phosphorus oxides reaction with, phosgene

Triphenylphosphine oxide from the commercial production of vitamin A by a Wittig reaction is recycled by reaction with phosgene to give the phosphine dichloride and reduction of the dichloride to triphenylphosphine with elemental phosphorus (461. Polymeric phosphine oxides have been converted to phosphine dichlorides with oxalyl chloride and then reduced to phosphine with diisobutylaluminum hydride (471. 

Guanidines have been prepared by the reaction between an amine, or an amine salt, and a host of other reagents, such as a thiourea in the presence of lead or mercuric oxide [83, 157, 158], carbodi-imides [140, 174, 175],calcium cyanamide [176, 177], isonitrile dichlorides [178—180], chloroformamidines [181], dialkyl imidocarbonates [182], orthocarbonate esters [183], trichloro-methanesulphenyl chloride [184], and nitro- or nitroso-guanidines [185-188]. Substituted ureas can furnish guanidines, either by treatment with amines and phosphorus oxychloride [189], or by reaction with phenylisocyanate [190] or phosgene [191]. 

HAZARD RISK Dangerous fire hazard when exposed to heat or flame contact with strong oxidizers may cause fire vapors may flow to distant ignition sources and flash back forms explosive mixtures with powdered sodium or phosphorus trichloride and sodium violent reaction with silver perchlorate and dimethyl sulfoxide closed containers exposed to heat may explode decomposition emits toxic gases of hydrogen chloride, phosgene, carbon monoxide, carbon dioxide NFPA Code H 2 F 3 R 0. 

The Wittig reaction is employed industrially as in the BASF syntheses for Vitamin A and jS-carotene. Laboratory methods have to be modified for industrial practice. Triphenylphosphine is obtained by the Wurtz reaction (p. 126). The triphenylphosphine oxide recovered after reaction is reconverted into Ph3P by treatment first with phosgene and then with phosphorus. 

Acidic reagents seem to offer milder conditions. Dehydration reactions forming cyanides can be performed with phosgene [1049-1052], diphosgene [1053-1055], triphosgene [1056], phenyl chloroformate [1057], oxalyl chloride [1058, 1059], tri-chloroacetyl chloride [1060-1062], acetic anhydride [1063-1074], TFAA [1075-1082], phosphorus oxides [1083-1088], phosphorus oxychloride [1089-1098], phosphorus pentachloride [1099], triphenylphosphine/haloalkanes [1100-1103], thionyl chloride [1104-1118], p-tosyl chloride [1119-1124], triflic anhydride [1125-1127], chlorosulfonyl isocyanate [1128], the Burgess reagent [1129], phenyl chloro-thionoformate [1130], cyanuric chloride [1131-1134], carbodiimides [1135, 1136], CDC [1137], PyBOP [1138], AlCU/Nal [1139], and acetonitrile/aldehyde [1140], and by pyrolysis [1141]. 

Ketone Method. In the ketone method, die central carbon atom is derived from phosgene. A diarylketone is prepared from phosgene and a tertiary arylamine and then condenses with another mole of a tertiary arylamine (same or different) in the presence of phosphorus oxychloride or zinc chloride. The dye is produced directly without an oxidation step. Thus, ethyl violet CT Basic Violet 4, is prepared from 4.4 -bis(diethy]amino)benzophenone with diethylaniline in the presence of phosphorus oxychloride. This reaction is very useful for the preparation of unsymmetrical dyes. 

Qiloroacetyl cliloride is manufactured by reaction of cliloroacetic acid with chlorinating agents such as phosphorus oxychloride, phosphorus trichloride, sulfuryl cliloride, or phosgene (42—44). Various catalysts have been used to promote the reaction. Qiloroacetyl cliloride is also produced by chlorination of acetyl cliloride (45—47), the oxidation of 1,1-dichloroethene (48,49), and the addition of chlorine to ketene (50,51). Dicliloroacetyl and trichloroacetyl cliloride are produced by oxidation of tricliloroethylene or tetrachloroethylene, respectively. 

The maiin domain of oxidation with dimethyl sulfoxide is the conver-sionofprimary alcoholsinto aldehydes andofsecondaryalcoholsintoketones. These reactions are accomplished under very mild conditions, sometimes at temperatures well below 0 °C. The reactions require the presence of acid catalysts such as acetic anhydride [713, 1008, 1009], trifluoroacetic acid [1010], trifluoroacetic anhydride [1011, 1012, 1013], trifluorometh-anesulfonic acid [1014], phosphoric acid [1015, 1016], phosphorus pentox-ide [1006, 1017], hydrobromic acid [1001], sulfur trioxide [1018], chlorine [1019, 1020], A -bromosuccinimide [997], carbonyl chloride (phosgene) [1021], and oxalyl chloride (the Swem oxidation) [1022, 1023, 1024], Dimethyl sulfoxide also converts sufficiently reactive halogen derivatives. into aldehydes or ketones [998, 999] and epoxides to a-hydroxy ketones at -78 °C [1014]. 

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