Formation of isomeric pyrrolones by flash vacuum pyrolysis of bisaminomethylene derivatives of Meldrum’s acid

Abstract

The bisaminomethylene derivatives, 7a-7c, of Meldrum's acid were made by reaction of appropriate N-methylaniline derivatives with the chloro-compound 15. Under flash vacuum pyrolysis (FVP) conditions (600 °C, 0.005 Torr), 7a-7c were transformed into mixtures of the pyrrolones 10a-10c and 12a-12c. The ratio of 10:12 is essentially independent of the nature of a para-substituent on the aryl ring; the implications of this result on the mechanism of the process are discussed

Synthesis of Nanocrystalline Zirconium Titanate and its Dielectric Properties

“…The isolated organic volatiles consist of three major types of constituents: highly volatile components, isopropanol and water, components with low volatility involving four major fractions identified as pyrrol, pyrazine, methyl-pyrazine and dimethyl-pyrazine, and, finally, a polymeric nitrogen-containing residue which was not volatile under experimental conditions (evaporator temperature, 180 °C). Pyrrols and pyrazines are known as typical products of the thermal decomposition of α-aminoacids (proteins) in a non-oxidative atmosphere (reductive cyclization). − 27a Their formation is facilitated by the presence of polyols, for example, sugars and protic catalysts. The decomposition of a diethanolamine-modified alkoxide follows most probably this type of condensation.…”

“…The zirconium titanate nanoparticles are most probably initially formed through quick high-temperature hydrolysis of the precursor by water released through dehydration of isopropanol in the primary steps of decomposition. The metal oxides play the role of a protic catalyst and facilitate the reactions of dehydration and dehydrogenation and also lead to the polymerization of the unsaturated organic fragments 27b. These organic fragments result finally in the formation of amorphous carbon shells around the metal oxide core.…”