Phosphorus hypophosphites

The recommended names for these compounds (phosphinic acid and phosphinates) have not yet gained wide acceptance for inorganic compounds but are generally used for organophosphorus derivatives. Hypophosphites can be made by healing white phosphorus in aqueous alkali ... 

PCA 16 is available as Beldene 161/164 (50/35% w/w solids), Acumer 4161 (50%), and Polysperse (50%). These are low-phosphorus content materials that have found application in boiler FW formulations because of excellent sludge conditioning and particulate dispersion properties. The number 16 represents a 16 1 w/w ratio of acrylic acid and sodium hypophosphite, giving PCA 16 a MW range of 3,300 to 3,900. PCA 16 is particularly effective for the control of calcium carbonate and sulfate deposition. It is usually incorporated with other polymers in formulations and is approved for use under U.S. CFR 21, 173.310. 

Dibasic forms of phosphorus (III) species also have been reported to undergo Michael-type additions to unsaturated substrates. Hypo-phosphorous acid adds to acrylamides to generate free phosphonous acids in good yield,430 as well as to vinyl acetate.431 Further, methyl hypophosphite adds to a variety of unsaturated substrates,432 as does the ammonium salt of mono(2-ethylhexyl) phosphite (Equation 3.27).433... 

TABLE 16.1. Influence of Solution Hypophosphite Concentration on Preferred Orientation and Magnetic Coercivity of Electroless Cobalt-Phosphorus Eilms... 

Electrolessly plated cobalt-phosphorus thin films are usually characterized by low- to medium-coercivity values (300 to 900 Oe). For some apphcations it would be desirable to have films with coercivities greater than 900 Oe. Table 16.1 shows that films with minimum preferred orientation exhibit maximum coercivity values. The ratio of the intensity of the (002) and (101) diffraction rings changes with hypophosphite concentration of the plating solution, with zero preferred orientation obtained at solution hypophosphite concentrations of 5 to 6 wt %. 

By treating sodium hypophosphite, NaH2P02 with an ion-exchange resin. The sodium salt may be produced by boding white phosphorus with a solution of sodium hydroxide, a reaction similar to (1) above. 

Phosphine can be prepared by alkaline hydrolysis of white phosphorus. Thus, a strong aqueous solution of caustic potash when boded with white phosphorus yields hypophosphite with hberation of phosphine ... 

White phosphorus reacts with strong aqueous alkali solution forming hypophosphite with evolution of phosphine, PH3 ... 

The P-H bond is also weak enough to serve in thione-based radical chemistry. The first success was achieved with dialkyl phosphites [40a]. However, hypophosphorous acid and its salts proved to be even better [40b]. In a final paper [40c], the various phosphorus-based reagents were compared. The crystalline salt N-ethylpiperidine hypophosphite was very convenient and has been commercialized 140c]. The use of hypophosphorous acid has the advantages of nontoxicity, cheapness, and ease of removal from the organic reduction products. It already has several industrial applications. 

Pure arsenic has been prepared by reducing carefully purified ammonium dihydrogen arsenate at 1000° C. in a current of ammonia, the arsenic being finally resublimed in a vacuum.7 The element may also be obtained as an amorphous precipitate by reduction of aqueous arsenious acid, for example, by means of sodium hypophosphite,8 or by the addition of a few drops of phosphorus trichloride.9 The reaction in the latter case probably takes the following course ... 

Phosphorus pentachloride also reacts to yield arsenic trichloride.7 Arsenious oxide in aqueous solution is reduced by hypophosphorous acid, especially on boiling, when phosphine is liberated and brown arsenic precipitated.8 The reduction is readily brought about by calcium hypophosphite dissolved in 10 parts of hydrochloric acid (dens. 1-126), this salt being preferable in use to the sodium salt and providing an extremely sensitive reagent, although in the presence of slight traces of arsenic the brown colour may appear only after the lapse of 20 to 30 minutes.9 Arsenious oxide dissolves in arsenic trichloride to form an oxychloride.10... 

Calcium Hypophosphite. CAS 7789-79-9, CalHiPOi) . white solid, snluhilily 15.4 g/100 g HiO at 2VC, formed (I) bv (toiling calcium hydroxide suspension in water and yellow phosphorus, (2) by reaction of calcium carbonate or hydroxide and hypophosphorous acid. 

Sodium hypophosphite NaPO H3. the only sodium hypophosphite. is formed 11) by reaclion of yellow phosphorus and sodium hydroxide solution (phosphine simultaneously fomicdl, (2) by reaclion of hypophosphorous acid and sodium hydroxide, and evaporating. Sodium hypophosphite. upon healing, yields sodium phosphate and sndiutn phosphide. Common tests for ihc hypophosphiles are as follows ... 

Hypophosphite. Potassium hypophosphite, [CAS 7782-87-8], KH2PO2, white solid, soluble, formed (1) by reaction of hypophosphorons add and potassium carbonate solution, and then evaporating. (2) by reaction of potassium hydroxide solution and phosphorus on heating (poisonous phosphine gas evolved). 

A solution of 12.5 g. of sodium arsonoacetate and 30 g. of sodium hypophosphite (NallyPOa-HaO) in 150 cc. of cold 15 per cent sulfuric acid is allowed to stand at room temperature. After two or three days, the yellow precipitate is filtered off, washed with water, and dried in a vacuum over sulfuric acid or phosphorus pentoxide. A second crop is obtained by allowing the mother liquid to stand for two days longer. 

Deposition reactions for some reducing agents are given in Table 1 hydrogen is a principal by-product of each reduction. Elemental phosphorus or boron is codeposited with the reduced metal from hypophosphite, borohydride, or organoborane baths (15). Other minor reactions can also occur (18). All of these reductions can be viewed as dehydrogenation reactions (16,19). 

Electroless nickel—boron baths use sodium borohydride or dimethyl amine borane [74-94-2] in place of sodium hypophosphite (see Boron COMPOUNDS). The nickel—boron alloy is brittle, highly stressed, and much more expensive than nickel—phosphorus alloys. Nickel—boron is mainly used to replace gold in printed circuit board plating. 

---