Topic
Benzaldehyde
About: Benzaldehyde is a research topic. Over the lifetime, 8049 publications have been published within this topic receiving 114520 citations. The topic is also known as: Benzoic acid aldehyde & Ethereal oil of bitter almonds.
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TL;DR: All experimental evidence points to a mechanism involving an N-acyliminium ion as the key intermediate, formed by acid-catalyzed condensation of benzaldehyde and urea (or N-methylurea) formed by the Biginelli dihydropyrimidines.
Abstract: The mechansim of the three-component Biginelli dihydropyrimidine synthesis was reinvestigated using 1H and 13C NMR spectroscopy. Condensation of benzaldehyde, ethyl acetoacetate, and urea (or N-methylurea) in CD3OH according to the procedure described by Biginelli produced the expected 6-methyl-2-oxo-4-phenyl-1,2,3,4-tetrahydropyrimidine-5-carboxylates. According to NMR measurements, there is no evidence that the first step in the Biginelli reaction is an acid-catalyzed aldol reaction of ethyl acetoacetate and benzaldehyde leading to a carbenium ion intermediate, as has been suggested previously. In contrast, all experimental evidence points to a mechanism involving an N-acyliminium ion as the key intermediate, formed by acid-catalyzed condensation of benzaldehyde and urea (or N-methylurea). Interception of this iminium ion by ethyl acetoacetate produces open-chain ureides which subsequently cyclize to the Biginelli dihydropyrimidines.
383 citations
TL;DR: After controlled pretreatment, some Zr-terephthalate metal-organic frameworks are highly selective catalysts for the cross-aldol condensation between benzaldehyde and heptanal.
368 citations
TL;DR: The alcohol group of hydroxymethylfurfural (compound 1, HMF) is preferentially oxidized by dioxygen and metal/bromide catalysts [Co/Mn/Br, Co/mn=Br/(Co+Mn) = 1.0 mol/mol] to form the dialdehyde, 2,5-diformylfuran (DFF) in 57% isolated yield as mentioned in this paper.
Abstract: The alcohol group of hydroxymethylfurfural (compound 1, HMF) is preferentially oxidized by dioxygen and metal/bromide catalysts [Co/Mn/Br, Co/Mn/Zr/Br; Co/Mn=Br/(Co+Mn) = 1.0 mol/mol] to form the dialdehyde, 2,5-diformylfuran (compound 2, DFF) in 57% isolated yield. HMF can be also oxidized, via a network of identified intermediates, to the highly insoluble 2,5-furandicarboxylic acid (compound 5, FDA) in 60% yield. For comparison, benzyl alcohol gives benzaldehyde in 80% using the same catalyst system. Over-oxidation (to CO2) of HMF is much higher than that of the benzyl alcohol but can be greatly reduced by increasing catalyst concentration.
337 citations
TL;DR: In this paper, thermal and hydrothermal treatments have been applied to an amorphous TiO2 precursor for obtaining nanosized TiO 2 particles (P11t and P11h, respectively) of different photocatalytic properties.
327 citations
TL;DR: The role of lattice oxygen on the activity and selectivity of the OMS-2 catalyst synthesized by the hydrothermal method was investigated for the catalytic oxidation of toluene.
326 citations