Electronic Impacts on the Solvent-Free Mechanochemical Synthesis of Salophen Ligands in Ball Mill

Table 3

Comparison of current azomethine synthesis to different reported methods.

Entry	Diamine (1 mol)	Aldehyde (2 mol)	Solvent	Technique	Time	% yield
1			Ethanol	Stir [18]	4 h	67.96 (Cl)
						63.52 (Br)
2			Ethanol	Reflux [33]	3–4 h	—
3			Ethanol	Reflux [13]	2 h	95
			Ethanol/H2O	Reflux [13]	2 h	85
4			Ethanol	Reflux [20]	5 h	—
5			Ethanol	Reflux [39]	30 min	63.63
6			Ethanol	Reflux [19]	2 h	76
7			Ethanol	Reflux [5]	1 h	89.8
8			MeOH	Ball mill (LAG) [23]	1 h	60
9			Neat	Ball mill [32]	1 h	89.9
10			Neat	Ball mill [1]	2 h	98
11			Ethanol	Stir [34]	9 h	60
12			Ethanol	Reflux [35]	2 h	68
13			Ethanol	Reflux [36]	2 h	68
14			Ethanol	Reflux [37]	2 h	79.7
15			Hot ethanol	Stir [38]	2 h	90
16			Neat	Ball mill (in this work)	1 h	86