Pyrrole Pigments

Linear oligopyrroles and bile pigments, chemistry of 89MI19. 

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Diketo-pyrrolo-pyrrol, pigment for plastics, 7 367t... 

Expectedly, the pyrrole pigments chlorophyll, as well as pheophytln a and b, have been characterized In Gossypium (, ). 

Two groups of elements appear in significant concentrations in the original crude oil, associated with well-defined types of compounds. Zinc, titanium, calcium, and magnesium appear in the form of organometallic soaps with surface-active properties, adsorbed in the water-oil interfaces, and act as emulsion stabilizers. However, vanadium, copper, nickel, and part of the iron found in crude oils seem to be in a different class and are present as oil-soluble compounds (Reynolds, 1997). These metals are capable of complexing with pyrrole pigment... 

Figure 1 shows the general structure of calixpyrroles. The basic ring structure resembles that of porphyrin. In the past, four pyrrole rings linked by methylene groups to form colourless macrocycles (that feature in the biosynthetic pathways to pyrrole pigments) were referred to as porphyrinogens [22], The term calix[4]pyrrole was later ascribed to these macrocycles and their synthetic derivatives because of their relation to calix[4]arenes [23],... 

Pyrrole pigments, biosynthesis, and total synthesis 84MI33 90CRV1261. 

Later, Falk [66] used TET to explain the photoisomerization of pyrrole pigments. Markov [67] applied the theory to photoketonization of dicarbonylic compounds. Hamanoue [68] showed that TET predictions were consistent with the relative reactivity of (n, n ) and (n, Tt ) states of an-thraquinones. Following a suggestion by Isaacs [69], Okamoto [70] claimed that the increase in the KIE of the H abstraction of methanol by benzo-phenone was evidence for a nuclear tunnelling mechanism, but this claim is not entirely consistent with the predictions of Isaacs. Shizuka [71] proposed TET could be used to explain excited state proton transfers, but this may only be the case for intramolecular proton transfers or reactions in apolar solvents, otherwise the system effective reduced mass will be too high [72]. 

Bile pigments, stereochemistry and photochemistry of 83AG670. Molecular mechanisms of neonatal jaundice phototherapy 84ACR417. Pyrrole pigments from seaweed 81 MI 13. 

Murakami Y, Yamada S, Matsuda Y, Sakata K (1978) Transition-metal complexes of pyrrole pigments XV coordination of pyridine bases to the axial sites of cobalt corroles. Bull Chem Soc Jpn 51 123-129... 

L. Knorr, Annalen, (236), 1886, 318 see also A.H. Jackson, The total Synthesis of Pyrrole Pigments, in The Total Synthesis of Natural,Products, (ed. J. ApSimon), Voll,1973,... 

N-Methylation yields the monomethyl derivative sarcosine and also dimethylglycine, compounds that may function as osmoprotectants (Box 20-C). Many bacteria produce sarcosine oxidase, a fla-voprotein that oxidizes its substrate back to glycine and formaldehyde, which can react with tetrahydro-folate. The formation of porphobilinogen and the various pyrrole pigments derived from it and the synthesis of the purine ring (Chapter 25) represent two other major routes for glycine metabolism. 

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