Green Synthesis of Natural Benzaldehyde from Cinnamon Oil Catalyzed by Hydroxypropyl-β-Cyclodextrin

• Published in: Tetrahedron 2010-12, Vol.66 (52), p.9888-9893
• Main Authors: Chen, Hongyan, Ji, Hongbing, Zhou, Xiantai, Wang, Lefu
• Format: Article
• Language: English
• Subjects: 2-hydroxypropyl-β-cyclodextrin; Benzaldehyde; Binding; Carbohydrates with 4, 5, 6, ... C atoms, dissacharides and oligosaccharides; Carbohydrates. Nucleosides and nucleotides; Chemistry; Cinnamaldehyde; Exact sciences and technology; Fluorescence; Formations; inclusion complex; Kinetics and mechanisms; natural benzaldehyde; Noncondensed benzenic compounds; Organic chemistry; Preparations and properties; Reactivity and mechanisms; Solubilization; Synthesis (chemistry); Tetrahedrons
• ISSN: 0040-4020; 1464-5416
• DOI: 10.1016/j.tet.2010.10.063

The efficient synthesis of natural benzaldehyde from natural cinnamon oil catalyzed by 2-hydroxypropyl-β-cyclodextrin (2-HPβ-CD) in water under rather mild conditions has been developed. Various analysis methods e.g. DSC, UV-vis, 1H NMR, ROESY and fluorescence measurements had been utilized to demonstrate formation of the 1:1 (molar ratio) complexes between 2-HPβ-CD and cinnamaldehyde. The inclusion equilibrium constant K a was 928 M −1 at 298K. The inclusion complex activated the substrate and promoted the reaction selectivity. The yield for benzaldehyde could reach 70% under the optimized conditions (323 K, 5h, 2% NaOH (w/v), cinnamaldehyde: 2-HPβ-CD = 1: 1 (molar ratio)). Further investigation on kinetics and solubilization revealed that the binding ability between 2-HPβ-CD and cinnamaldehyde is primarily responsible for the catalytic effects. [Display omitted]