Synthesis of Carboxylic Acid by 2-Hexenal Oxidation Using Gold Catalysts Supported on MnO₂

Table 1

Effect of support on 2-hexenal oxidation.

Catalyst	Conversion%	Selectivity%
		Dimer	2-Hexenoic acid
Graphite	0.7	0	93.1
Au/G	74.5	4.0	86.0
TiO2	0.9	0	96.5
Au/TiO2	68.2	2.9	88.4
MgO	1.1	0	89.3
Au/MgO	54.0	6.2	85.9
SiC	0.7	0	92.1
Au/SiC	69.3	4.1	82.8
MnO2	0.8	0	95.6
Au/MnO2	81.3	8.3	89.1
CeO2	1.2	0	90.5
Au/CeO2	72.8	4.3	84.6
Al2O3	0.4	0	89.0
Au/Al2O3	65.4	4.8	84.2

Reaction conditions: 4.23 g of 2-hexenal, 0.06 g of catalyst, 50°C, 24 h, atmospheric pressure.
Dimer: 4,6-dipropyl-3,4,5,6-tetrahydropyran-2-one-5-carboxaldehyde.