pyrrolen.

1835 F. F. Runge in Rec. Gen. Sci. 1 48 Pyrrol (red oil) in a pure state is a gaseous body possessing the odour of turnips.

1857 H. Watts tr. L. Gmelin Hand-bk. Chem. XI. 264 [An oil which] diffuses vapours which impart a dark purple colour to deal shavings moistened with hydrochloric acid (the pyrrhol described by Runge).

1865 G. W. Gesner A. Gesner's Pract. Treat. Coal (ed. 2) v. 94 Besides the foregoing compounds, derived from coal tar, phenyle, pyrrole,..and others have been described.

1944 M. B. Jacobs Chem. & Technol. Food & Food Products I. ix. 319 Pyrrhol derivatives include the coloring matters of plant green and of logwood.

1972 J. M. Tedder et al. Basic Org. Chem. IV. ix. 454 On reduction with hydriodic acid haem yields eight comparatively simple pyrroles.

2002 D. K. O. Chan & Z. Xi in K. Schellander et al. Genomics & Biotechnol. Livestock Breeding 120 Pyrazines, pyridines and pyrroles in cooked chicken meat are generated by high temperature and low moisture.

1853 T. Anderson in Trans. Royal Soc. Edinb. 20 249 A series of bases..to which I shall afterwards refer under the provisional name of pyrrol bases.

1931 Jrnl. Amer. Chem. Soc. 53 188 To 10 cc. of pyrrole base in 100 cc. of absolute alcohol, [etc.].

1991 J. B. Harborne in R. T. Palo & C. T. Robbins Plant Defenses against Mammalian Herbivory iii. 48 The mammalian detoxification of pyrrolizidine alkaloids..can produce..a more toxic product, a pyrrole base which binds to DNA in the liver.

1889 Proc. Royal Soc. 46 214 The isomerides in which the substitution occurs in the pyrrole nucleus of indole.

1913 A. G. Bloxam & S. J. Lewis Bloxam's Chem. (ed. 10) 782 The metals are not present as bases, but as integral parts of the complex molecules, probably exercising their subsidiary valencies, and uniting a number of pyrrol nuclei.

1992 Jrnl. Org. Chem. 57 4452 The significant role of the pyrrole nucleus in conducting the intramolecular general base catalysis in the amine oxidation is discussed.

1857 T. Anderson in Trans. Royal Soc. Edinb. 21 593 Pyrrol Red..is produced whenever pyrrol is boiled with an excess of acid.

1950 Thorpe's Dict. Appl. Chem. (ed. 4) X. 337/2 Pyrrole..is only slowly dissolved by dilute acids in the cold; on warming, it polymerises to pyrrole-red.

1994 Jrnl. Org. Chem. 59 585/1 ‘Pyrrole-red’ species are known to form in the presence of strong acids, though their structures have not been determined.

1903 Lancet 7 Mar. 656/2 Ehrlich believed that the methylene group of the reagent joined with the unknown body in the urine, which he believed contained a pyrrol ring.

1970 R. W. McGilvery Biochemistry xxi. 494 The basic unit of porphyrins is the pyrrole ring, with four of these linked to form the large porphyrin ring.

1989 New Scientist 18 Feb. 32/1 All porphyrins consist of four small circular molecules—each called pyrrole rings. These rings contain four carbon atoms and one nitrogen atom.

1909 Cent. Dict. Suppl. Pyrrolic, derived from or related to pyrrol.

1912 Chem. Abstr. 6 2749 Pyrrolic α-, β- and γ-diketones.

1955 Endeavour July 135/2 (caption) Porphobilinogen, the simplest pyrrolic substance known to be a precursor of haem and porphyrins.

1994 Tetrahedron Lett. 35 3679 (title) Fluorination of pyrrolic compounds with xenon difluoride.