pyrrole ring

pyrrole ring

[′pī‚rōl ‚riŋ]
(organic chemistry)
A five-member heterocycle containing one nitrogen atom and four carbon atoms in the ring; frequently found in structures of natural products occurring as joined rings or attached to straight chains.
References in periodicals archive ?
Four characteristic peaks could be assigned to C=C stretching vibration of the pyrrole ring, C-N stretching vibration in the ring, and C-H in-plane vibrations, respectively.
1H NMR (300 MHz, CDCl3, 25 AdegC, TMS): I' = 8.835 (8H, s, pyrrole ring), 8.431-8.478 (8H, t, -C6H4), 8.142-8.168(8H, d, carbazole ring C1-H), 8.069-8.096(8H, d, m-C6H4), 7.545 (8H, t, carbazole ring C2,3-H), 7.236-7.276 (16H, t, carbazole ring C4-H), 4.548-4.569 (8H, t, -O-CH2-), 4.221-4.261 (8H, t, --N-CH2-), 2.259- 2.309 (8H, m,-N-C-CH2-), 2.027-2.073 (8H, m, -O-C-CH2-), -2.785 (2H, s, pyrrole N-H).
In all other spectra, the bands observed between 1550 [cm.sup.-1] and 1460 [cm.sup.-1] are assigned to C-C bonds and C-N stretching vibration of the pyrrole ring, respectively.
The occurrence of a wide peak at 3400 [cm.sup.-1] is assigned to the presence of N-H stretching vibrations of pyrrole ring. The weak band at 2100 [cm.sup.-1] is due to C-H stretching.
Table 1 is divided into two sections; the first section shows the local aromaticity of the pyrrole ring whereas the second section lists the local aromaticity of the pyrazinone ring.
2a), there are four possible fracture points during oil shale pyrolysis: 1) C-C bond at position [gamma] in the carbon chain branched to the aromatic ring, 2) C-C bond at position [alpha] in the carbon chain branched to the pyrrole ring, 3) C-C bond at position [beta] near the carboxylic acid species, and 4) C-N bond in the pyrrolic ring.
The gas phase ligand molecule of tetramic acid (Figure 4(a)) is not planar as the calculated dihedral angle between the phenyl and pyrrole ring is about 31[degrees], in accordance with the crystalline structure where there is a twist of 27.42 (8)[degrees] between the mean planes of the two rings.
During one of our current research programs involving experiments with nitrogen heterocycles, utilizing reactions under conditions of phase-transfer catalysis between triethyl-benzylammonium chloride (TEBAC) and a pyrrole ring, it was observed that the catalyst participated as an N-alkylating agent providing a benzylated product.
(a) represents the interaction of Hit1 with the heme by [pi]-[pi] stacked and [pi]-alkyl interactions with pyrrole ring III.
(30) The peak at 1558 [cm.sup.-1] comes from -CC- stretch of pyrrole ring, and the peak at 1033 [cm.sup.-1] is caused by -C-H- in-plane deformation of the pyrrole unit.
This book on the chemistry of pyrroles describes a method for the construction of the pyrrole ring from ketones and acetylene in superbase catalytic systems.
Polycarbazole (PCz) and its derivatives, which have a structure of pyrrole ring with two fused benzene rings, are well known to exhibit good electroactive and photoactive properties [2].