Showing papers by "Raymond Bonnett published in 1981"
TL;DR: The components of haematoporphyrin derivative have been separated by preparative h.p.c. and identified by comparison with authentic porphyrindicarboxylic acids as discussed by the authors.
Abstract: The components of haematoporphyrin derivative (a preparation used as a photosensitiser in clinical applications, and made by treating haematoporphyrin with sulphuric acid–acetic acid) have been separated by preparative h.p.l.c. and identified by comparison with authentic porphyrindicarboxylic acids. The composition of the mixture is some-what variable but the main components are O,O′-diacetylhaematoporphyrin (6) and O-acetylhaematoporphyrin (2)/(3) with smaller amounts of the 8(3)-(1-acetoxyethyl)-3(8)-vinyldeuteroporphyrin isomers (7) and (8) and the corresponding alcohols (4) and (5).
86 citations
TL;DR: Isoindole is a white solid which becomes discolored and resinous at room temperature, especially in the presence of air as discussed by the authors, and exhibits a series of strong bands in the near ultraviolet region extending in cases of further conjugation almost into the visible region.
Abstract: Publisher Summary This chapter discusses the properties and synthesis of isoindoles. Isoindole is a white solid which becomes discolored and resinous at room temperature, especially in the presence of air. It may be handled for short periods using vacuum techniques, or in solution under an inert atmosphere. The synthesis of isoindoles includes: (1) syntheses from isoindolines, (2) retro-cycloadditions, (3) syntheses from phthalimidines and related compounds, (4) syntheses from ortho-disubstituted benzenes, (5) routes from pyrroles, and (6) rearrangements and other reactions. The absorption spectra of isoindoles exhibits a series of strong bands in the near ultraviolet region extending in cases of further conjugation almost into the visible region. The kinetic instability of isoindoles dominates the chemistry of the simple systems and is principally to be ascribed to autoxidation and self-condensation reactions. Many isoindoles readily form Diels–Alder adducts by reaction across the electron-rich 1,3-positions with dienophiles. Isoindoles are readily oxidized; as with pyrroles, the products are often colored, poorly characterized, polymeric materials.
80 citations
TL;DR: In this paper, a synthesis of octaethylbilindione from 3,4-diethylpyrrole is described, which is suitable for the preparation of this valuable model compound in quantity.
Abstract: A synthesis of the octaethylbilindione (1) from 3,4-diethylpyrrole is described which is suitable for the preparation of this valuable model compound in quantity.
36 citations
TL;DR: In this article, the distribution of the metallic elements in various fractions has been determined, and it is possible that the iron porphyrins are derived directly (i.e. without demetallation-metallation) from biological precursors.
Abstract: Some of the metal compounds that occur in coal are soluble in organic solvents and are extracted in coal liquefaction processes. The material made by the extraction of coal with hydrogenated anthracene oil has been fractionated by sequential Soxhlet extraction with low-boiling solvents, and the distribution of the metallic elements in the various fractions has been determined. Extraction of Daw Mill coal (92 kg) with acidic methanol furnishes 17.8 mg of a mixture of gallium complexes of homologous porphyrins (C 27 -C 32 ). Similar metalloporphyrin concentrates are obtained from a variety of British bituminous coals, the amount detected being about 1 pg/g, but falling off as coal rank increases. Various lignites and a range of Polish coals have also been surveyed: here, iron porphyrins and (in one case) manganese porphyrins have been observed. The iron porphyrins tend to be confined to coals of lower rank : in the lignites, metal-free tetrapyrroles are also detected. The metalloporphyrins are thought to be derived from the chlorophylls and haems of the biological precursors. Indeed, it is possible that the iron porphyrins are derived directly (i.e. without demetallation-metallation) from biological and microbiological haem compounds.
28 citations