Easy Access to Coumarin Derivatives Using Alumina Sulfuric Acid as an Efficient and Reusable Catalyst under Solvent-Free Conditions

Table 3

Optimization of temperature in Pechmann condensation of resorcinol (1 mmol) with ethyl acetoacetate (1 mmol) and ASA (0.02 g) in solvent-free conditions.

Entry	Temperature (°C)	Yield (%)
1	80	70
2	90	80
3	100	98
4	110	90