Acetylation of Phenols, Anilines, and Thiols Using Silica Sulfuric Acid under Solvent-Free Conditions

Table 5

Comparison of different acylation methods under solvent-free conditions.

Entry	Substrate	Reaction conditions	Ratio; (substrate : acylating agent)	Time (min)	Yield %	The literature reference
1	1-Naphtol	TiCl3(OTf) (1.0 mol%), Ac2O, r.t.	1.0 : 2.0	10	84	[35]
		(NH4)2.5HO.5PW12O40, Ac2O, r.t.	1.0 : 1.0	2.0	92	[34]
		Zn(ClO4)2·6H2O, (1.0 mol%), Ac2O, r.t.	1.0 : 1.0	15	90	[36]
		SSA, Ac2O, r.t.	1.0 : 2.0	2.0	95	Present work
2	Benzylamine	Sulphated zirconia, Ac2O, r.t.	1.0 : 1.0	10	85	[38]
		Bromodimethylsulfonium bromide, Ac2O, r.t.	1.0 : 2.0	20	87	[39]
		SSA, Ac2O, r.t.	1.0 : 2.0	1.0	96	Present work
3	4-Nitrophenol	TiCl3(OTf) (1.0 mol %), Ac2O, r.t.	1.0 : 1.0	60	85	[35]
		Zn(ClO4)2·6H2O, (1.0 mol %), Ac2O, r.t.	1.0 : 1.0	30	93	[36]
		Bromodimethylsulfonium bromide, Ac2O, r.t.	1.0 : 2.0	90	87	[39]
		SSA, Ac2O, r.t.	1.0 : 2.0	12	90	Present work