Quantitative solid–solid synthesis of azomethines

Abstract

Twenty preparatively useful azomethines have been quantitatively (100% yield at 100% conversion) obtained as hydrates by grinding together solid anilines with solid benzaldehydes without passing through liquid phases. Unlike (acid catalyzed) azomethine syntheses in solution, the solid-solid condensations proceed 'waste-free'. The solid-state mechanisms have been elucidated by atomic force microscopy (AFM) and in part by scanning near-field optical microscopy (SNOM) in three cases. The results indicate long distance migration of the aldehydes into the lattice of the aniline derivatives. Stumpy protrusions are formed at the direct points of contact but also close distance sublimation (100 nm range) is successful in the case of p-chlorobenzaldehyde and p-nitroaniline. Long-range flow of 4-hydroxybenzaldehyde molecules on its (010)-face into contacting crystals of p-toluidine or p-anisidine occurs along two different cleavage planes. Steep hills and valleys are left behind. The molecular migrations through the sites of contact are interpreted in terms of crystal packing. The ease of these solid-solid condensation reactions relies on the crystal packing.

Crystal structure of N-(3,4-dichlorobenzylidene)-4-methylaniline, C14H11Cl2N

“…The product was synthesized by solvent-free method [1,2]. The raw materials 3,4-dichlorobenzaldehyde (98%) and pmethylaniline (98%) were purchased from J&K SCIENTIFIC LTD. Equimolar 3,4-dichlorobenzaldehyde and p-nitroaniline were stirred uniformly at rst.…”

Synthesis, Spectral Correlations and Antimicrobial Activities of 2-Pyrimidine Schiff’s Bases

“…Schiff's bases are widely studied and used in the fields of organic synthesis and metal ion complexation [7] for a number of reasons: their physiological and pharmacological activities [8] their use in ionselective electrodes [9] in the determination of heavy metals ions in environmental samples [10] and in the extraction of metals ions [11,12] and their many catalytic applications (e.g. for epoxidation of olefins, alkene cyclopropanation [13,14] trimethylsilylcyanation of ketones [15] asymmetric oxidation of methyl phenyl sulfide enantioselective epoxidation of silylenol [16] and ring-opening polymerization of lactide [17]. In recent years, correlation analysis has been applied by chemists for solving the effect of substituents on Schiff's bases through spectral data.…”

Synthesis, Characterization and Antibacterial Activity of Macrocyclic Schiff Bases Based on 1,3-Docarbonyl Phenyl Dihydrazide, 1,4-Docarbonyl Phenyl Dihydrazide

“…for epoxidation of olefins, alkene cyclopropanation [15,16] trimethylsily-lcyanation of ketones [17] asymmetric oxidation of methyl phenyl sulfide enantioselective epoxidation of silylenol [18] and ring-opening Polymerization of lactide [19]. Hydrazones are special group of compounds in the Schiff bases family.…”