Carbonate de césium
Caesium carbonate or cesium carbonate is a white crystalline solid compound. Caesium carbonate has a high solubility in polar solvents such as water, alcohol and DMF. Its solubility is higher in organic solvents compared to other carbonates like potassium and sodium carbonates, although it remains quite insoluble in other organic solvents such as toluene, p-xylene, and chlorobenzene. This compound is used in organic synthesis as a base. It also appears to have applications in energy conversion. Caesium carbonate can be prepared by thermal decomposition of caesium oxalate. Upon heating, caesium oxalate is converted to caesium carbonate with emission of carbon monoxide. Cs2C2O4 → Cs2CO3 + CO It can also be synthesized by reacting caesium hydroxide with carbon dioxide. 2 CsOH + CO2 → Cs2CO3 + H2O Caesium carbonate facilitates the N-alkylation of compounds such as sulfonamides, amines, β-lactams, indoles, heterocyclic compounds, N-substituted aromatic imides, phthalimides, and other similar compounds. Research on these compounds has focused on their synthesis and biological activity. In the presence of sodium tetrachloroaurate (NaAuCl4), caesium carbonate is very efficient mechanism for aerobic oxidation of different kinds of alcohols into ketones and aldehydes at room temperature without additional polymeric compounds. There is no acid formation produced when primary alcohols are used. The process of selective oxidation of alcohols to carbonyls had been quite difficult due to the nucleophilic character of the carbonyl intermediate. In the past Cr(VI) and Mn(VII) reagents have been used to oxidize alcohols, however, these reagents are toxic and comparatively expensive. Caesium carbonate can also be used in Suzuki, Heck, and Sonogashira synthesis reactions. Caesium carbonate produces carbonylation of alcohols and carbamination of amines more efficiently than some of the mechanisms that have been introduced in the past. Caesium carbonate can be used for sensitive synthesis when a balanced strong base is needed.
