Acetylation of alcohols, phenols and amines using waste plant extract
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Acetylation of alcohols, phenols and amines using waste plant extract Rituparna Chutia1 · Bolin Chetia1 Received: 26 February 2020 / Accepted: 17 August 2020 © Springer Nature Switzerland AG 2020
Abstract The acetylation of alcohols, phenols and amines using water extract of waste plant extract of rice straw ash and seed husk of Vigna mungo ash at room temperature is reported here. The easy availability of plants, high yields, mild reaction conditions, cost effectiveness of the catalyst proved to be an excellent and green protocol for the acetylation reaction. Keywords Acetylation · Green · Waste materials · Vigna mungo · Rice straw · Gram scale synthesis
1 Introduction Acetylation reactions have been an important transformation [1] in organic synthesis. These reactions have been used as protective group reactions in agricultural and pharmaceutical industries [2–4]. The transformation has been usually carried out with acetic acid or acetic anhydride in presence of acidic or basic conditions. Amines with carboxylic acid derivatives such as lachrymatory acetyl chloride, acids or esters undergo N-acetylation reactions. Several methods have been cited in literature for acetylation reaction of alcohols, phenols and amines using different acid or base (Table 1), but they have one or more disadvantages such as the use of harsh reaction conditions, longer reaction time, use of expensive catalyst etc. Recently reported methods includes the use of metal triflates such as Ce(OTf )3 [11], Sc(OTf )3 [12], Cu(OTf )2 [13], indium triflate [14], Gadolinium triflate [15], Al(OTf )3 [16]; metal halides such as TaCl5 [17], InCl3 [18], and ZrOCl2.8H2O [19]; and solid acid catalysts such as heteropoly acids [20], Mg(NTf2)2 [21], aluminum-supported MoO3 [22], BiFeO3 [23], cation-exchanged montmorillonite K-10 clay [24], phosphomolybdic acid [25], sulfamic acid [26], NaHSO4.
SiO2 [27], polystyrene-bound heterogeneous cobalt(II) salen [28], and [ TMBSA][HSO4] ionic liquid [29] for acetylation reactions. The preparation of these catalyst normally require harsh reaction conditions, use of toxic chemicals and poor yields are normally obtained. All these harsh reaction conditions can likely be overcome by using eco-friendly green catalyst for the acetylation reactions. Green chemistry aims at the use of biodegradable, eco-friendly catalyst and the use of plant extracts as catalyst and solvent enhance this application. Plants as green solvents and catalyst offers shorter reaction time, use of non-toxic solvent making an overall extraction process more environment friendly [30]. Thus, owing to the principles of Green Chemistry [31] researchers nowadays are focusing their interest on the use of agricultural waste residues in chemical reactions. These waste plant extract are normally basic in nature, and as cited in literature acetylation reactions is efficiently performed in the presence of base as catalyst. Thus, citing to all the advantages of the plant extracts and considering the increasing pressure from environmentalist we tried
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