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Titolo:
Investigation of porphyrin-forming reactions. Part 1. Pyrrole plus aldehyde oligomerization in two-step, one-flask syntheses of meso-substituted porphyrins
Autore:
Geier, GR; Lindsey, JS;
Indirizzi:
N Carolina State Univ, Dept Chem, Raleigh, NC 27695 USA N Carolina State Univ Raleigh NC USA 27695 pt Chem, Raleigh, NC 27695 USA
Titolo Testata:
JOURNAL OF THE CHEMICAL SOCIETY-PERKIN TRANSACTIONS 2
fascicolo: 5, , anno: 2001,
pagine: 677 - 686
SICI:
1472-779X(2001):5<677:IOPRP1>2.0.ZU;2-G
Fonte:
ISI
Lingua:
ENG
Soggetto:
FLIGHT MASS-SPECTROMETRY; ACID-CATALYZED CONDENSATION; CHLORIN BUILDING-BLOCKS; POLYDISPERSE POLYMERS; RATIONAL SYNTHESIS; TRANS-PORPHYRINS; DIPYRROMETHANES; DESORPTION/IONIZATION; TETRAPHENYLPORPHYRINS; DISCRIMINATION;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
38
Recensione:
Indirizzi per estratti:
Indirizzo: Lindsey, JS N Carolina State Univ, Dept Chem, Box 8204, Raleigh, NC 27695 USA N Carolina State Univ Box 8204 Raleigh NC USA 27695 27695 USA
Citazione:
G.R. Geier e J.S. Lindsey, "Investigation of porphyrin-forming reactions. Part 1. Pyrrole plus aldehyde oligomerization in two-step, one-flask syntheses of meso-substituted porphyrins", J CHEM S P2, (5), 2001, pp. 677-686

Abstract

A deep understanding of the two-step, one-flask synthesis of meso-substituted porphyrins requires characterization of the acyclic oligomers, which typically constitute greater than or equal to 50% of the products. We have employed laser desorption mass spectrometry (LD-MS) to obtain a qualitative yet high resolution view of the oligomer content of crude oxidized reaction mixtures. This methodology complements other analytical methods which provide information regarding yields of porphyrin, other macrocyclic products, and unreacted aldehyde. Our findings include the following. (1) Crude oxidized porphyrin reaction mixtures provided peaks in the LD-MS spectrum which were readily assigned to oligomers (m/z 100-2000) derived from pyrrole-aldehyde condensation. The oligomers comprised one of four series depending on the ratio of pyrrole and aldehyde units. (2) Quite disparate reaction conditions that gave good yields of porphyrin also afforded a similar oligomer composition. (3) The change in the nature of the oligomers over time was readily monitored. (4) The maximum yield of porphyrin and the maximum diversityof the oligomer composition were attained at similar times. (5) The decline in yield of porphyrin at long reaction time was accompanied by truncation, not elongation, of oligomers. (6) The onset of the truncation of oligomers and the decline in yield of porphyrin were accompanied by a decrease of the aldehyde to low levels. (7) Pyrrole was incorporated into the growing oligomers more rapidly than aldehyde. Taken together, these studies show how various conditions alter the course of the pyrrole-aldehyde condensation.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 21/09/20 alle ore 15:20:57