Cupric phosphite

Cupric phosphite, CuHP03,2H20.—A phosphite of this formula is obtained by the interaction of solutions of diammonium hydrogen phosphite and cupric chloride, or of phosphorous acid and cupric acetate.6 It is unstable, but admits of drying at a medium temperature. 

Phosphites and hypophosphites both decolourise acidified potassium permanganate solutions, but only the latter reacts in the cold. Phosphites can be distinguished from hypophosphites by their reaction with copper sulphate solution. The former will give a light blue precipitate of cupric phosphite, while the latter will give a reddish precipitate of copper hydride on warming. 

Smith, T.D., Reaction of dialkyl phosphites with cupric chloride, /. Chem. Soc., 1122, 1962. 

Similarly, copper salts (cupric and cuprous) facilitate the reaction of aryl halides with trialkyl phosphites in the formation of dialkyl arylphosphonates under conditions like those found in nickel systems.37-39 Again, the copper salts appear to undergo an initial reaction with the phosphites to form a complex that subsequently undergoes reaction with the aryl halide. The requirement for copper is also similar to that for nickel saltstonly a catalytic amount is needed. Further, a preference among halides on the aromatic ring is noted iodide is replaced preferentially to other halides (Figure 6.10).40... 

Aliphatic and aromatic sulfides undergo desulfurization with Raney nickel [673], with nickel boride [673], with lithium aluminum hydride in the presence of cupric chloride [675], with titanium dichloride [676], and with triethyl phosphite [677]. In saccharides benzylthioethers were not desulfurized but reduced to toluene and mercaptodeoxysugars using sodium in liquid ammonia [678]. This reduction has general application and replaces catalytic hydrogenolysis, which cannot be used [637]. 

Cupric hypophosphite, Ch HgPOg) —The solution obtained by addition of slightly less than the equivalent proportion of barium hypo-phosphite to a solution of cupric sulphate yields, after removal of the barium sulphate and addition of alcohol, the hypophosphite in the form of white crystals.4 At ordinary temperatures the dry salt does not decompose for several days, but at 90° C. it explodes with evolution of phosphine. On warming in aqueous solution, it decomposes with formation of phosphorous acid, copper, and hydrogen. Its aqueous solution is also decomposed catalytically by palladium ... 

The rates of reaction of hypophosphorous acid with iodine bromine ", chlorine ", iodine chlorides , iodate , selenious and tel-lurous acids, silver nitrate , cupric chloride and mercuric chloride" (all forming phosphorous acid or phosphites) have been measured, and the results of the earlier work summarized clearly" . All the data are consistent with the hypothesis that there is prior transformation to some reactive form (I). This form (I) does not discriminate very effectively between different oxidants and thus the oxidation steps are presumed to have rates close to the diffusion-controlled limit. The rates of formation of I deduced in these studies are close enough to the rates of deuterium and tritium exchange for the residual difference to represent an isotope effect. Mitchell wrote the formula H5PO3 for I. Others have supposed it to be a tautomer e.g. HPO(OH)2. Both the isotopic exchange results and the oxidation studies require that its formation and decomposition be subject to acid catalysis. For the general mechanism... 

The commercial catalyst used for hydrogenation was a palladium on charcoal catalyst (type 37), manufactured by Johnson Matthey (UK)) with metal content 4.89% and supplied as powder. The Pd metal was d osited on the exterior sur ce of the charcoal The Pd/Ii02 catalyst was prepared using sodium tetrachloropalladate (II), supplied by Johnson Matthey (UK) and titanium dioxide, firom Degussa (Germany). The hydrogen gas was supplied by BOC (UK), with >99.98% purity and was used directly fi om cylinder. The reactant, butyne-l,4-diol 99%, was procured firom Aldrich (UK) and water and 2-propanol obtained firom Fisons (UK), were used as solvents. Additives such as lead acetate, quinoline, thiophene and triethyl phosphite were supplied by Aldrich (UK) and cupric acetate, zinc su hate, ferric nitrate and potasaum hydroxide were provided by Fisons (UK). 

OXYGENATION Cupric acetate-amine complexes. 4-Ethyl-2,6,7 -trioxa-1 -phospha-bicyclo[2,2.2] octane. Triphenyl phosphite-Ozone. 

There are many complexes of Cu1 with olefins or other unsaturated compounds, and these are in general rather similar19 to those of Ag+ (page 1051). Although they are usually made by direct reaction with Cu1 halides, they may also be prepared from cupric salts by reduction with trialkyl phosphites in ethanolic solution in presence of the alkene.193 The crystalline compounds obtained when using chelating alkenes such as norbornadiene or cyclic polyalkenes usually have polymeric structures, such as that for the cyclo-octatetraene complex (25-H-V), and only one of the double bonds is normally coordinated. 

Hypophosphites are more powerful reducing agents than phosphites. The acid will reduce sulphur dioxide to sulphur and will precipitate Pt, Au, Ag, Hg and Bi from aqueous solutions of these salts. Hypophosphites reduce cupric salts to cuprous and dichromates to trivalent chromium salts. 

A heterogeneous mixture of diethyl phosphite in GGI4 and anhydrous cupric chloride stirred 4 hrs. at ca. 100° in dry air until the reaction with cacotheline is negative -> diethyl phosphorochloridate. Y 74%. F. e. s. T. D. Smith, Soc. 1962,1122. 

Synthesis.— A review on organocopper compounds and organocuprates in synthesis has appeared these reagents are particularly useful for constructing olefins. Thus stereospecifically trisubstituted alkenes (381) are obtained by alkylation of vinylcopper reagents in the presence of triethyl phosphite and HMPA. The vinylcopper rea nts (382) are obtained by addition of acetylenes to a reagent prepared from R MgX and cupric bromide in ether at — 10 C. Alkylation occurs with retention of configuration... 

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