Table 1.

Selective aerobic oxidation of benzyl alcohol (1a) to benzaldehyde (2a)^a

Entry	Catalyst	Yield (%)	Particle size (nm)
			Before use	After use
1	Au-TOASiW9	75	2.9	2.8
2	Au-TOASiW9b	92	2.9	2.9
3	Au-TOASiW10	17	3.4	3.3
4	Au-TOASiW11	24	2.9	3.0
5	Au-TOASiW12	4	3.2	4.3
6	Au-TOAB	3	2.5	5.6
7	Au-dodecanethiol	<1	2.6	2.7
8	Au-dodecanethiolb	<1	2.6	Precipitationc
9	TOASiW9	<1	–	–
10	Au-TOASiW9, Ard	<1	2.9	−

^aReaction conditions: 1a (0.25 mmol), 3 mL toluene solution of colloidal gold nanoparticles (Au: 4 mol%), K₂CO₃ (0.5 mmol), room temperature (~25 °C), O₂ (1 atm), 24 h.

^bCs₂CO₃ (0.5 mmol) was used instead of K₂CO₃ (0.5 mmol).

^cDisulfide was detected in the reaction solution after the reaction.

^dUnder Ar (1 atm). All the reaction yields were determined via GC analysis using biphenyl as an internal standard.