Chemical properties, inorganic zinc oxide

Properties of zinc salts of inorganic and organic salts are Hsted in Table 1 with other commercially important zinc chemicals. In the dithiocarbamates, 2-mercaptobenzothiazole, and formaldehyde sulfoxylate, zinc is covalendy bound to sulfur. In compounds such as the oxide, borate, and sihcate, the covalent bonds with oxygen are very stable. Zinc—carbon bonds occur in diorganozinc compounds, eg, diethjizinc [557-20-0]. Such compounds were much used in organic synthesis prior to the development of the more convenient Grignard route (see Grignard reactions). 

Chemical Properties. Zinc oxide is amphoteric it reacts with organic and inorganic acids, and also dissolves in alkalis and ammonia solution to form zincates. It combines readily with acidic gases (e.g., C02, S02, and H2S). It reacts at high temperatures with other oxides to form compounds such as zinc ferrites. 

The tendency of a chemical to partition between soil, water, sediment, air, and biota can be inferred from its physical and/or chemical properties. Zinc occurs in the environment primarily in the +2 oxidation state. It dissolves in acids to form hydrated Zn" cations and in strong bases to form zincate anions (probably Zn[OH]4 ). In most unpolluted waters, zinc exists primarily as the hydrated form of the divalent cation. In polluted waters, the metal often forms complexes with a variety of organic and inorganic ligands (Callahan et al. 1979 ERA 1984b, 1987c). 

To control the heavy losses of crops from insects and other pests, the use of different pesticides has become extensive, and with the passing of time, more of these compounds are being developed and produced on a commercial scale. At present, apart from the inorganic compounds such as zinc phosphide and arsenious oxide, several hundred organic compounds, having widely different chemical constituents and properties, are being used throughout the world. 

Boron compounds such as borax and boric acid are well known fire retardants for cellulosic products [1]. However, the use of boron compounds such as zinc borate, ammonium pentaborate, boric oxide, and other metallo-borates in the plastics industry has become prominent only since the late 1970s. This entry will review the manufacturing, chemical and physical properties, end-use applications, as well as modes of action of major boron compounds as fire retardants in polymers. The subject is also mentioned in the section entitled Flame retardants inorganic oxide and hydroxide systems. ... 

Papers with fire-resistant properties are used for wallpaper, decoration paper, Chi-nese/Japanese lamps and partition walls. Flame retardants are added either at the wet end or by surface treatment in the paper production process. They either release incombustible gases on heating, which prevent the entry of atmospheric oxygen, or when heated produce a nonflammable melt that surrounds the paper. Chemicals for this purpose include calcium chloride, magnesium chloride, diammonium ethyl phosphate, and mixtures of zinc borates, antimony oxides, and organic haloid salts as well as inorganic bromides and oxybromides. 

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