Table 2. Optimization of reaction conditions ^a .

Entry	P(H2)/P(CO2) (atm)	KOH (M)	Yield b (%)	TON c (×103)
1	30/30	1	81	81
2	20/20	1	35	35
3	40/20	1	99	99
4	50/10	1	99	99
5 d	40/20	1	20	200
6 d	40/20	2	34	340
7 d	40/20	5	45	450

^aGeneral reaction conditions: 5 mL aqueous KOH solution, 0.001 mol% iridium catalyst 1b relative to KOH in 100 μL THF, under the desired CO₂ : H₂ pressure, 140 °C, 20 h.

^bYield, which represents conversion of the added KOH, based on ¹H NMR analysis with sodium 3-(trimethylsilyl)-1-propanesulfonate as an internal standard.

^cTON = turnover number; number of moles of product formed per mole of catalyst.

^dCatalyst loading was 0.0001 mol% relative to KOH.