An Efficient One-Pot Green Protocol for the Synthesis of 5-Unsubstituted 3,4-Dihydropyrimidin-2(1H)-Ones Using Recyclable Amberlyst 15 DRY as a Heterogeneous Catalyst via Three-Component Biginelli-Like Reaction

Table 6

Physical properties of Amberlyst 15 DRY.

Physical form	Opaque beads
Ionic form as shipped	Hydrogen
Concentration of acid sites	≥4.7 eq/Kg
Water content	≤1.5% (H^+ form)
Shipped weight	610 g/L (38 lbs/ft)
Fines content	<0.300 mm: 1.0% max
Surface area	45 m^2/g
Average pore diameter	250 Å
Swelling
60 to 70% (dry to Water)
10 to 15% (dry to hexane)
10 to 15% (dry to toluene)
15 to 20% (dry to ethylene dichloride)
30 to 40% (dry to ethyl acetate)
60 to 70% (dry to ethyl alcohol, 95%)
15 to 20% (dry to phenol)
3 to 5% (dry to benzene)