Telluriums oxygen halides

Oxygen halides are dealt with in Chapter 11, p. 334. Sulphur, selenium and tellurium form many halides, and only a brief introduction to the subject is given here. 

Alkali metals Moisture, acetylene, metal halides, ammonium salts, oxygen and oxidizing agents, halogens, carbon tetrachloride, carbon, carbon dioxide, carbon disul-flde, chloroform, chlorinated hydrocarbons, ethylene oxide, boric acid, sulfur, tellurium... 

The chemical properties of selenium fall between sulfur and tellurium. Thus, selenium reacts with oxygen similarly to sulfur, forming two oxides, selenium dioxide, Se02 and trioxide, SeOs. The metal combines with halogens forming their halides. With nonmetals, selenium forms binary compounds exhibiting oxidation states +4 and -i-6. 

Organo tellurium trihalides form complexes with coordinatively unsaturated metal halides and with ligands having nitrogen, oxygen, or sulfur donor atoms. 

Potassium tellurocyanate, prepared from potassium cyanide and tellurium in DMSO, reacts with benzyl halides to produce benzyl tellurium cyanides in good yields. Because of the sensitivity of potassium tellurocyanate to oxygen and of some of the benzyl tellurium cyanides to light, the reactions must be carried out in an inert atmosphere (nitrogen or argon) under red light. 

Allyl phenyl telluriums, prepared from allyl halides and benzenetellurolate, experience oxidative cleavage of the allyl group when treated with hydrogen peroxide, tcrr.-butyl hydroperoxide, sodium periodate, oxygen, or air The allyl group is converted to unsaturated alcohols, aldehydes, and ketones. Before elimination from the molecule the phenyltelluro group is probably oxidized to a telluroxide or a tellurinic ester ... 

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