Polyvinylpolypyrrolidoniume Tribromide as an Efficient Catalyst for the Acetylation of Alcohols and Phenols

ZnAl2O4@SiO2 nanocomposite catalyst for the acetylation of alcohols, phenols and amines with acetic anhydride under solvent-free conditions

“…One of the most promising solutions to overcome these problems is the use of heterogeneous solid catalysts [14,15], which can be recovered easily from the reaction mixture by simple filtration and reused to make the process more economical and environmentally viable. Solid catalysts such as HClO4-SiO2 [16], montmorillonites [17][18][19], metal oxides [20][21][22], H2SO4-SiO2 [23], zeolites [24,25], HBF4-SiO2 [26], MoO3-Al2O3 [27], NaHSO4-SiO2 [28], sulphated zirconia [29], (NH4)2.5H0.5PW12O40 [30], silica-bonded Co(II) salen [31], silica-bonded N-and S-propyl sulfamic acids [32,33], poly(4vinylpyridinium) perchlorate [34], polystyrene-supported GaCl3 [35], borated zirconia modified with ammonium metatungstate [36], rice husk [37], V(IV) tetraphenylporphyrin [38], Ti IV (salophen)(OTf)2 [39], polystyrene-bound electron-defi-cient Sn(IV) porphyrin [40], poly(vinylpolypyrrolidoniume) tribromide [41], modified attapulgite [42], succinimide-N-sulfonic acid [43], acylimidazolium acetate [44], Ph3P(OAc)2 [45], poly(4-vinylpyridinium) tribromide [46], sulfonated ordered nanostructured carbon [47], iron oxide nanoparticles [48] and Ni/Silica [49], Cu based metal-organic framework [50] have been used in the acetylation of alcohols, phenols, and amines. However, each of these catalysts or reagents has disadvantages and limitations.…”

Acetylation of alcohols and phenols under solvent-free conditions using iron zirconium phosphate

“…All the acetylated products formed in the current study were characterized by gas chromatography-mass spectrometry (GC-MS, Agilent 5975C), Fourier transform infrared spectroscopy (FT-IR, JASCO FT-IR 680 plus) and 1 H nuclear magnetic resonance (NMR, Bruker-Avance AQS 400 MHz spectrometer). The resulting spectra were compared with data obtained from standard samples or data from the literature [28,44,45,[47][48][49][50][51][52][53].…”

“…A number of different procedures have been developed for the acetylation of alcohols, phenols, amines, and thiols using both homogeneous and heterogeneous catalysts. These have included V IV (TPP)(OTf)2 [27], La(NO3)3•6H2O [29], B(C6F5)3 [30], NSPVPHS [31], ZnCl2 [32], borated zirconia [33], ZnO2 [34], Ce(OTf)3 [35], SiO2-ZnCl2 [36], H3PW12O40 [37], DMAP•HCl [38], Cu(BF4)2 [39], silica-bonded sulfamic acid [40], Cp2ZrCl2 [41] [44], SaSA [45], SBNPSA [46], SuSA [47], P(4-VPT) [48], acylimidazolium acetate [49], polyvinylpolypyrrolidoniume tribromide [50], ZnAl2O4@SiO2 [51], P2O5/Al2O3 [52], [Hmim]HSO4 [53], yttria-zirconia [54], CoCl2 [55], MWCNTs-C-PO3H2 [56], NiCl2 [57], Ni/SiO2 [58], DBSA [59], rice husk [60], anhydrous NiCl2 [61], LaFeO3/SiO2 [62], and Fe/SBA-15 [63]. However, most of these catalysts have both advantages and limitations.…”

In situ generated acylimidazolium acetate as an efficient catalyst and acylating agent for the acetylation of alcohols, phenols, and amines at ambient temperature

“…Functional group protection strategies are essential to the design and implementation of effective organic syntheses and are used extensively in the preparation of multifunctional organic compounds [1,2]. Of the many different protecting methodologies available, the acetylation of alcohols, phenols, and amines with acetic anhydride in the presence of protic acids [3], Lewis acid catalysts [4][5][6][7][8][9][10][11][12][13][14], or basic reagents [15][16][17][18][19][20] is particularly important and one of the preferred approaches for the protection of these functional groups because of the ease with which these transformations can be affected, as well as the stability of the resulting acetates under mild acidic and basic conditions. Furthermore, acetates can be readily deprotected as necessary to afford the parent functionality.…”

“…Furthermore, acetates can be readily deprotected as necessary to afford the parent functionality. Although acylation reactions are traditionally conducted in the presence of a stoichiometric quantity of a base, such as pyridine, 4-(N,Ndimethylamino)pyridine (DMAP), triethylamine or tributylphosphine, which are very toxic in nature and difficult to remove from the product, as well as being flammable and possessing an unpleasant odor, a variety of homogeneous and heterogeneous acidic catalysts [3][4][5][6][7][8][9][10][11][12][13][14] such as simple metal salts, metal triflates, and solid acid catalysts have also been reported to be effective for acetylation reactions involving acetic anhydride. Although these procedures provide an improvement over the traditional methodologies, many of these methods require long reaction times, forcing reaction conditions, tedious workup procedures, moisture sensitive or expensive catalysts, extensive catalyst preparation processes, and the use of halogenated volatile organic solvents, and generally provide poor yields of the desired products.…”