Chlorozincate(II) acidic ionic liquid: Efficient and biodegradable silylation catalyst

Abstract

A practical and highly efficient silylation of alcohol and phenol derivatives with hexamethyldisilazane (HMDS) using acidic ionic liquids under mild reaction conditions is described. A series of Brønsted as well as Brønsted–Lewis acidic ionic liquids were prepared and their performance investigated for the silylation of a wide variety of alcohols and phenols with HMDS. Imidazole‐ as well as N‐methyl‐2‐pyrrolidone‐based acidic ionic liquids have a higher catalytic activity for the protection of sensitive, hindered alcohols and phenols, thus providing an environmentally begin and versatile alternative to current acid catalysts. In addition, the acidic ionic liquids are reusable, being recovered easily and reused several times without significant deterioration in catalytic activity.

A new approach for the synthesis of α‐ketothioamides from methyl ketone, pyrrolidine/piperidine and elemental sulfur using recyclable magnetic catalyst

“…13 Halometalate ILs play an important role in many organic synthesis processes due to their Lewis acidity, which results in faster and more efficient reactions. [14][15][16][17] Some of the halometalate ILs of interest are zincate ILs, which are prepared by combining ZnCl 2 with pyridium, 18 imidazolium salts [19][20][21] or quaternary ammonium salts such as choline chloride. [22][23][24][25] Despite the aforementioned superiority, these halometalate ILs require complex catalytic recovery and product isolation methods.…”

Recent advances in catalytic silylation of hydroxyl‐bearing compounds: A green technique for protection of alcohols using Si–O bond formations

“…Affording the corresponding trimethylsilyl (TMS) ethers requires applying HMDS which is an inexpensive reagent for the protection of alcohols or phenols. [72] HMDS produces NH 3 when reacting with alcohols or phenols as the only by-product which can be readily removed from the reaction mixture. HMDS was also used as a nitrogen source in reactions with carbonyl compounds.…”

A Highly Effective Route to Si−O−Si Moieties through O‐Silylation of Silanols and Polyhedral Oligomeric Silsesquioxane Silanols with Disilazanes

“…Amongt his group, disilazanes, especially hexamethyldisilazane (HMDS), seem to be very effective for the silylationo fÀOH groups and have several advantages over other silylating agents, including mild reaction conditions as well as the formation of ammonia as sole byproduct. Although inorganic materials, [19][20][21][22] alcohols, [23][24][25][26][27][28][29][30] phenols, [26][27][28][29] carbohydrates, [29] carboxylic acids, [31] oximes, [32] ande ven thiols [33] have been successfully silylated by various disilazanes, the use of these silylatinga gents in O-metalation of simple silanols and polyhedralo ligomeric silsesquioxane (POSS) silanols has never been comprehensivelys tudied.T herea re only few examples: Lebedeve tal. synthesized two unsymmetricald isiloxanes by utilizingd isilazanes in ar eactionw ith two compounds such as triphenylsilanol and diphenylsilanediol.…”