Role of indoles in the oxidative degradation of unstable diesel fuels. The ferric and cupric ion catalyzed oxidation of 1,2,3,4-tetrahydrocarbazole as a model compound study

Abstract This review provides relevant background information about the vulcanization process, as well as the chemistry of thiuram- and sulfenamide-accelerated sulfur vulcanization with emphasis on the role of activators, to lay a base for further research. It commences with an introduction of sulfur vulcanization and a summary of the reaction mechanisms as described in literature, followed by the role of activators, particularly ZnO. The various possibilities to reduce ZnO levels in rubber compounding, that have been proposed in literature, are reviewed. A totally different approach to reduce ZnO is described in the paragraphs about the various possible roles of multifunctional additives (MFA) in rubber vulcanization. Another paragraph is dedicated to the role of amines in rubber vulcanization, in order to provide some insight in the underlying chemical mechanisms of MFA systems. Furthermore, an overview of Model Compound Vulcanization (MCV) with respect to different models and activator/accelerator systems is given. In the last part of this review, the various functions of ZnO in rubber are summarized. It clearly reveals that the role of ZnO and zinc compounds is very complex and still deserves further clarification.

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Chemistry of oxylipin pathways in marine diatoms

Pure and Applied Chemistry ◽

10.1351/pac200779040481 ◽

2007 ◽

Vol 79 (4) ◽

pp. 481-490 ◽

Cited By ~ 80

Author(s):

Angelo Fontana ◽

Giuliana d'Ippolito ◽

Adele Cutignano ◽

Antonio Miralto ◽

Adrianna Ianora ◽

...

Keyword(s):

Higher Plants ◽

Larval Growth ◽

Marine Macroalgae ◽

High Concentration ◽

Marine Diatoms ◽

Fatty Acid Derivatives ◽

The Family ◽

Hydrolysis Of ◽

Catalyzed Oxidation

Oxylipins are important signal transduction molecules widely distributed in animals and plants where they regulate a variety of events associated with physiological and pathological processes. The family embraces several different metabolites that share a common origin from the oxygenase-catalyzed oxidation of polyunsaturated fatty acids. The biological role of these compounds has been especially studied in mammalians and higher plants, although a varied and very high concentration of these products has also been reported from marine macroalgae. This article gives a summary of our results concerning the oxylipin chemistry of marine diatoms, a major class of planktonic microalgae that discourage predation from their natural grazers, zooplanktonic copepods, using chemical warfare. These apparently harmless microscopic cells produce a plethora of oxylipins, including short-chain unsaturated aldehydes, hydroxyl-, keto-, and epoxyhydroxy fatty acid derivatives, that induce reproductive failure in copepods through abortions, congenital malformations, and reduced larval growth. The biochemical process involved in the production of these compounds shows a simple regulation based on decompartmentation and mixing of preexisting enzymes and requires hydrolysis of chloroplast-derived glycolipids to feed the downstream activities of C16 and C20 lipoxygenases.

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Exhaustive laccase-catalysed oxidation of a lignin model compound (vanillyl glycol) produces methanol and polymeric quinoid products

Biochemical Journal ◽

10.1042/bj2290277 ◽

1985 ◽

Vol 229 (1) ◽

pp. 277-279 ◽

Cited By ~ 41

Author(s):

K Lundquist ◽

P Kristersson

Keyword(s):

Model Compound ◽

Polymerization Process ◽

Lignin Biodegradation ◽

Simultaneous Formation ◽

Initial Formation ◽

Lignin Model Compound ◽

Catalysed Oxidation ◽

Visible Spectra ◽

Lignin Model

Laccase-catalysed oxidation of the lignin-related phenol vanillyl glycol results in the initial formation of dimers and subsequent polymerization. The polymerization is accompanied by a liberation of methanol corresponding to 15-20% demethylation. Visible spectra together with reduction experiments suggest the simultaneous formation of o-quinones. The participation of quinone formation in the polymerization process and the possible role of such intermediates in lignin biodegradation is discussed.

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