Table 1 Optimization of the photocatalytic sulfinylation of propane with SO2 in flow

From: C(sp3)–H sulfinylation of light hydrocarbons with sulfur dioxide via hydrogen atom transfer photocatalysis in flow

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Entrya

Parameter

Deviation from the standard conditions

Yield [%]b

1

Residence time [h]

0.5/1/2/4

41/48/46/25

2

Catalyst loading [mol%]

0.5/1/2/3

18/48/44/34

3

Gas equivalents

2.5/5/10

19/48/45

4

DT source

TBADT/NaDT

48/59

5

Concentration SO2 [mol/L]

0.1/0.2

43/59

6

BnBr as limiting reagent

BnBr 1 eq.c

95

  1. aReaction conditions: SO2 (0.4 mmol), propane (2.0 mmol), DT catalyst (1 mol%) in CH3CN/H2O (4:1, 2 mL, 0.2 M) irradiated in photoreactor (365 nm, 144 W optical output power) for 1 h. The outflow is collected in a flask containing NaHCO3 (1.0 mmol) and benzyl bromide (0.6 mmol, 1.5 equiv.) and is stirred overnight at room temperature.
  2. bYield determined by 1H-NMR spectroscopy using trichloroethylene as external standard.
  3. cOptimized conditions: SO2 (0.6 mmol), propane (3.0 mmol), DT catalyst (1 mol%) in CH3CN/H2O (4:1, 3 mL, 0.2 M) irradiated in photoreactor (365 nm, 144 W optical output power) for 1 h. The outflow is collected in a flask containing NaHCO3 (1.2 mmol) and benzyl bromide (0.2 mmol, 1 equiv.) and is stirred overnight at room temperature.
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