Entry Solvent condition t Yielda(%)
1b CH2Cl2 Reflux 6h 45
2b THF Reflux 8h 50
3 Neat 60°C 4h 62
4 Neat 80°C 2h 70
5c Ultrasonication,neat 200W 8min 96
6c,d Ultrasonication,neat 200W 8min 25
aThe yields refer to the isolated pure products.
bThe reaction was carried out in 5 mL of solvent.
cThe reaction was irradiated by using ultrasonicator laboratory system.
dThe reaction was carried out in the absence of KHSO4-SiO2.
Table 2: The reaction between 2-naphthol and benzaldehyde using KHSO4-SiO2 as a catalyst under different conditions.