Abstract
We report for the first time 100% benzyl alcohol yield from the liquid phase (T = 353 K, P = 9 bar) hydrogenation of benzaldehyde over Au/Al2O3. Under the same reaction conditions, a benchmark Pt/Al2O3 catalyst promoted the formation of toluene and benzene as hydrogenolysis by-products. Reaction kinetics was subjected to a Hammett treatment and the reaction constant (ρ = 0.9) was found to be consistent with a nucleophilic mechanism. A solvent (alcohol, water and alcohol + water) effect is demonstrated and ascribed to competitive adsorption where solvation by polar (water) facilitates benzaldehyde activation.Graphic
Highlights
The production of benzyl alcohol by the selective reduction of benzaldehyde is an important commercial process with multiple applications as solvent for inks, paints and lacquers [1]
The liquid phase (T = 353 K, P = 9.0 bar) hydrogenation of benzaldehyde over (1% w/w) Au on Al2O3 was fully selective with 100% yield of the target benzyl alcohol
Exclusive –C=O reduction extended to a range of p-substituted (–OCH3, –CH3, –CH2CN, –CN) benzaldehydes
Summary
The production of benzyl alcohol by the selective reduction of benzaldehyde is an important commercial process with multiple applications as solvent for inks, paints and lacquers [1]. Drelinkiewicza et al [26] concluded that acetophenone hydrogenation was more influenced by solvent polarity than H 2 solubility Organic solvents such as ethanol [3, 4, 9, 10, 13], dioxane [5] and alkanes (n-octane [3] and dodecane [31]) have been used in the liquid phase hydrogenation of benzaldehyde. Water as a benign green reaction medium has not been considered to any great extent It is worth flagging the work of Wang and co-workers [32] who demonstrated higher activity in the chemoselective hydrogenation of α, β-unsaturated carbonyl compounds over Au/CeO2 in water relative to organic solvents (ethanol, isopropanol, dioxane and cyclohexane). Given the established application of supported Pt in benzaldehyde hydrogenation [8, 10, 11], we employed a commercial Pt/ Al2O3 as a suitable benchmark catalyst
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
