Fluoroboric acid adsorbed on silica gel as a new and efficient catalyst for acylation of phenols, thiols, alcohols, and amines

Decatungstodivanadogermanic heteropoly acid (H6GeW10V2O40.22H2O): A novel, green and reusable catalyst for efficient acetylation of alcohols and phenols under solvent-free conditions

“…Also, the conversion of benzyl alcohol to benzyl acetate on a 100 mmol scale proceeded just as well as the 5 mmol reaction (22 min, 95%). The scope of this reaction was further extended for the acetylation of phenols (Table 2, entries [30][31][32][33][34][35][36][37][38]. Phenol and differently substituted phenols were acetylated with quantitative yields after a prolonged reaction time in comparison with alcohols.…”

“…Heterogeneous catalysts offer several advantages over homogeneous systems with respect to easy recovery and recycling of catalysts as well as the minimization of undesired toxic wastes. In this framework, several metal oxides and supported systems including YO2-ZrO2 [22], ZnO [23], transition metal oxides [24], montmorillonites [25], HClO4-SiO2 [26], H2SO4-SiO2 [27], AlPW12O40 [28], zeolites [29], Nafion-H [30], HBF4-SiO2 [31], KF-Al2O3 [32], MoO3-Al2O3 [33], NaHSO4-SiO2 [34], sulphated zirconia [35] and (NH4)2.5H0.5PW12O40 [36] [TMBSA][HSO4] ionic liquid [37], silica-bonded cobalt(II) salen [38], and silica-bonded N-propyl sulfamic acid and S-propyl sulfuric acid [39,40] have been used as heterogeneous catalysts for the acetylation of alcohols and phenols. However, each of these methods has advantages and limitations.…”

Air-stable titanocene bis(perfluorooctanesulfonate) as a new catalyst for acylation of alcohols, phenols, thiols, and amines under solvent-free condition

“…A number of Lewis acids such as TMSCl [7], MoO 2 Cl 2 [8], ErCl 3 [9], RuCl 3 [10], ZrOCl 2 [11], Zn(ClO 4 ) 2 [12] TiCl 4 + AgClO 4 [13], Cu(OTf) 2 (Tf = CF 3 SO 2 ) [14], Er(OTf) 3 [15], Al(OTf) 3 [16], TiCl 3 (OTf) [17], Ce(OTf) 3 [18], Sn IV (tpp)(OTf) 2 (tpp = tetra phenylporphyrin) [19], Sc(NTf) 3 [20], have been reported to show catalytic activity towards the acylation of alcohols with acid anhydride. Chakraborti et al also reported a number of good catalytic systems for the acylation reactions [21][22][23][24][25][26][27][28][29]. Particularly, Sc(OTf) 3 [30,31], a commercially available and moisture-stable Lewis acid, is extremely active for this reaction.…”

“…Besides being environmentally friendly, solvent-free reactions in many cases can offer synthetic advantages in terms of yield, selectivity and simplicity of reaction procedure. The use of solvent-free acetylation procedure is limited [21][22][23][24][25][26][27][28][29][35][36][37][38].…”

M(acac)n Covalently Anchored onto Amine Functionalized Silica: Highly Efficient and Recyclable Heterogeneous Catalysts for the Acetylation of Amines, Phenols and Alcohols Under Solvent-Free Conditions

“…These transformations are usually performed with acetic anhydride and/or acetyl chloride in the presence of stoichiometric amounts of either basic or acidic catalysts. A variety of procedures using homogeneous or heterogeneous catalysts [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] have been reported for this transformation. Although these procedures provide an improvement, yet many of these catalysts or activators need long reaction times, drastic reaction conditions or tedious work-up, and the catalysts are moisture sensitive or expensive.…”