A novel zeolite based stationary phases for in situ synthesis and evaluation of porphyrins and calix (4) pyrroles

The application of zeolite based molecular sieves as catalysts and sorbents in thin layer chromatography (TLC) has been investigated for a single step evaluation of porphyrins and calix (4) pyrroles by in situ synthesis from pyrrole with aromatic aldehydes and ketones under microwave irradiation. The molecular sieves used were microporous zeolites such as HZSM-5, HY, Hβ and mesoporous MCM-41 material and the results are compared. Among the various sorbents studied, MCM-41 proves to be the potential candidate and offered quantitative conversions. This glass-backed zeolite coated TLC plate presumably acted as a reactor and facilitated simultaneous chromatographic separation of the macrocycles as well. The process is simple, economically viable, rapid, selective, solvent free and finds a novel application in high through put parallel synthesis and chromatographic screening in a single step.

The present study, using a novel concept of reaction cum separation on a single plate for efficient evaluation of porphyrins and calix (4) pyrroles by in situ synthesis from pyrrole with aromatic aldehydes and ketones, respectively, over zeolite based molecular sieve catalysts as sorbents in thin layer chromatography (TLC) was accomplished in one step with microwave heating. The design and methodology of this glass-backed zeolite coated TLC, which acted as a micro reactor as well as separator for the in situ synthesis and evaluation of macrocycles is described. Figure optionsDownload as PowerPoint slide