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(inorganic chemistry)
Salt of phosphorous acid; contains the radical PO33-; an example is normal sodium phosphite, Na3PO3.



any of the salts or esters of phosphorous acid (H3PO3). The salts may be monosubstituted, for example, NaH2PO3·2.5H2O.or disubstituted, as in Na2HPO3·5H2O. Most phosphites are difficultly soluble in water; this is not true, however, of phosphites of alkali metals. When calcined, phosphites decompose into the corresponding phosphates and phosphorus derivatives with lower oxidation states, the process including the formation of phosphine (PH3). Phosphites are oxidized in aqueous solutions by halogens and mercury salts, for example, HgCl2, to phosphates. Phosphites are formed when phosphorous acid is neutralized by hydroxides. They are used as reducing agents in inorganic syntheses. Lead phosphite serves as a light stabilizer in the production of polyvinyl chloride.

The esters of phosphorous acid may be mono-[ROP(O)HOH], di-[(RO)2P(O)H], or tri-substituted [(RO)3P], They are obtained from the reactions of phosphorus trichloride with alcohols and alcoholates:

PCl3 + 3ROH → (RO)2P(O)H

PCl3 + 3RONa → (RO)3P

Phosphites are used as stabilizers of polymer plastics and oils and as intermediates in the synthesis of organophosphorus compounds.

References in periodicals archive ?
The company says the product "looks, handles, and functions" like Weston tris(nonylphenyl) phosphite (TNPP) AOs but is higher in phosphorous, so lower loadings (up to 18% lower) provide equivalent performance.
The next generation of nonylphenol-free phosphite technology from US-based Addivant (Middlebury, Connecticut; www.
Weston polymer additives include various liquid and solid organic phosphites that function as hydroperoxide decomposers, metal-complexing agents, and antioxidants and offer increased resistance to heat and light.
Phosphites probably do not have sufficient nutritional effects to increase crop productivity.
Most phosphorus on Earth exists as oxidised phosphate, but many microbes prefer a rarer, partially oxidised phosphorus - phosphite.
Among the range of phosphites used in the market, Ciba Irgafos 126 is the one providing the best initial color in TPU (figure 2).
Aryl phosphites are known to undergo hydrolysis and, depending on the type of aryl substituent, may contribute to the thermal stabilisation by the release of sterically-hindered phenols.
Based, on proprietary-chemistry, the new liquid phosphite, Weston 705, reportedly outperforms standard solid phosphites such as the company's Alcanox 240 in stabilizing narrow-MWD polymers.
Auxiliary antioxidants are phosphites and thioesters.
Naugard antioxidants include hindered phenolics, aromatic amines, and phosphites.
Model Reaction Studies of Commercial and Developmental Phosphites - Daryl Stein, Don Stevenson, and Michael Jakupca, Dover Chemical Corp.