Catalytic Methods for Imine Synthesis

Abstract

This Focus Review describes different methods that have been reported for the synthesis of imines. It is organized according to the methods used for imine synthesis starting with metal catalysis, including Ru, Au, V, Cu, Mn, Co and Pd catalysis. Other methods, such as photocatalysis, electrocatalysis, organocatalysis, and so on, are also emphasized. Ample information on the condensation of carbonyl compounds/alcohols with amines and direct oxidation of amines to give imines is discussed. Furthermore, among various metal‐catalyzed reactions, specific attention has been paid to copper‐catalyzed imine synthesis, as copper is less toxic than other heavy metals, comparatively inexpensive, and is easily accessible.

Insights into the Ligand Shell, Coordination Mode, and Reactivity of Carboxylic Acid Capped Metal Oxide Nanocrystals

“…Under the same conditions as the nanocatalysis (40 min at room temperature, [oleylamine]=0.076 m, [acetone]=10 m ), the reaction only proceeded 13 or 14 %, with or without dodecanoic acid, respectively ([dodecanoic acid]=0.0076 m ), on the basis of 1 H NMR spectroscopy data. This result confirms that ZrO 2 and HfO 2 NCs are acting as nanocatalysts in the condensation reaction, as it is well known that the synthesis of imines from carbonyl compounds can be acid‐catalyzed . The control experiment with dodecanoic acid suggests that the reaction might be more likely to be catalyzed by the Lewis acid (hafnium or zirconium) surface sites rather than by the Brønsted acidity of adsorbed carboxylic acids, although the influence of hydrogen bonding cannot be excluded.…”

Visible light-induced selective photocatalytic aerobic oxidation of amines into imines on Cu/graphene

“…[3,4] For example, Furukawa et al found that intermetallic Pd 3 Pb supported on Al 2 O 3 can act as an efficient heterogeneous catalyst for the oxidation of various amines. [2] Recently, selectively photocatalytical oxidation of amines has received increased attention because it allows the oxidation reactions to occur at lower temperature and use O 2 as oxidant under renewable solar light irradiation. [2] Recently, selectively photocatalytical oxidation of amines has received increased attention because it allows the oxidation reactions to occur at lower temperature and use O 2 as oxidant under renewable solar light irradiation.…”

A new biocatalyst employing pyrenecarboxaldehyde as an anodic catalyst for enhancing the performance and stability of an enzymatic biofuel cell

“…Namely, the imine groups produced by the reaction released H + into the environment and pH values of the catalytic structures decreased. 20,25 To prove this phenomenon, we measured local pH of the three catalysts and confirmed that the local pH of CNT/PEI/[PCA/ GOx] shifted negatively (the local pH values of CNT/PEI/GOx, CNT/[PCA/GOx] and CNT/PEI/[PCA/GOx] were 7.52, 7.88 and 7.05, respectively). These data are also included in the Supplementary Information (Supplementary Figure S3).…”