By Selenium-Metal Exchange

Synthesis of Organometallics Bearing an a-Seleno Carbanion by Selenium-Metal Exchange... 

Synthesis of a-selenoalkyllithiums by selenium-lithium exchange 2.6232 Synthesis of a-selenovinyl metals by selenium-metal exchange... 

Synthesis of a-selenovinyl metals by selenium-metal exchange... 

Synthesis of 1-Seleno eyclopropyllithiums by Selenium-Metal Exchange from Selenoacetals of Cyclopropanones... 

Synthesis of 1-Vinyl Cyclopropyllithiums by Selenium-Metal Exchange from 1-Seleno-l-vinyl cyclopropanes... 

Metallated polystyrenes are versatile intermediates for the preparation of a number of polystyrene derivatives. Metallated polystyrene has been prepared from haloge-nated polystyrenes by halogen-metal exchange [41,42,65,66] and by direct metallation of polystyrene [67-69] (see Chapter 4). Electrophiles suitable for the derivatization of metallated polystyrene include carbon dioxide, carbonyl compounds, sulfur, trimethyl borate, isocyanates, chlorosilanes, alkyl bromides, chlorodiphenylphosphine, DMF, oxirane, selenium [70], dimethyldiselenide [71], organotin halides [69], oxygen [72], etc. [41,42,65-67],... 

Hi) Synthesis of a-selenoalkyl metals by selenium- netal exchange... 

For removing low levels of priority metal pollutants from wastewater, using ferric chloride has been shown to be an effective and economical method [41]. The ferric salt forms iron oxyhydroxide, an amorphous precipitate in the wastewater. Pollutants are adsorbed onto and trapped within this precipitate, which is then settled out, leaving a clear effluent. The equipment is identical to that for metal hydroxide precipitation. Trace elements such as arsenic, selenium, chromium, cadmium, and lead can be removed by this method at varying pH values. Alternative methods of metals removal include ion exchange, oxidation or reduction, reverse osmosis, and activated carbon. 

---