Table 2.

Optimization of the synthesis of THF catalysed by H₃PW₁₂O₄₀^a.

entry	cat. loading (mmol) (%)	T (°C)	time (h)	yield (%)
1	0.05	100	3	70
2	0.1	100	3	98
3	0.2	100	2.5	99
4	0.1	90	10	60
5	0.1	120	3	98
6	0.1	100	1	62
7	0.1	100	2	80

^aReaction conditions: butane-1,4-diol (200 mmol).