Of quinonic compounds

Doong R-A, H-C Chiang (2005) Transformation of carbon tetrachloride by thiol reductants in the presence of quinone compounds. Environ Sci Technol 39 7460-7468. 

Tendille, G., C. Gervai, and T. Gaborit Variations in the amounts of quinone compounds and of tocopherol in various chlorophyll-containing plant tissues under the influence of factors affecting the chlorophyll content Ann. Physiol. Veg. 8 (1966) 270-283. 

Chemotaxonomic Study Based on the Variation of Quinone Compounds in the Heartwood of Javanese Teak Using GC-MS... 

NAD (P)+-dependent enzymes, electrically contacted with electrode surfaces, can provide efhcient bioelectrocatalysis for the NAD(P)H oxidation. For example, diaphorase (DI) was applied to oxidize NADFl, using a variety of quinone compounds, several kinds of flavins, or viologens as mediators between the enzyme and electrode [217, 218]. The bimolecular reaction rate constants between the enzyme and mediators whose redox potentials are more positive than -0.28 V at pH 8.5 can be as high as 10 s , suggesting that the reac-... 

Vitamin K, known as the antihemorrhagic vitamin, is necessary for the synthesis of prothrombin and other biood ciot-ting factors in the iiver. Presentiy, the term vitamin K is used to describe a chemicai group of quinone compounds, rather than a singie entity, which have characteristic antihemorrhagic effects. 

The first attempt to use organic cathode materials for lithium batteries started 40 years ago when Williams et al. [18] proposed dichloroisocyanuric acid, a positive N-chloro compound with carbonyl functionalities, as a high energy density material for a primary lithium battery. Later, Alt et al. [33] investigated the possibility of quinone compounds with carbonyl functionalities as secondary (i.e. rechargeable) battery cathode materials. Since then, lots of carbonyl compounds have been investigated for cathode or anode materials in lithium batteries [21, 34—... 

Alt H, BindCT H, Kohling A et al (1972) Investigation into the use of quinone compounds-for battery cathodes. Electrochim Acta 17(5) 873-887... 

The Perox process was developed in Germany after World War 11, and was the first process to utilize the redox properties of quinone compounds in the removal of hydrogen sulfide from coke-oven gas. As early as 1956, it was reported that three commercial units with a combined capacity of approximately 30 million cu ft per day were operating in Germany (Reinhardt, 1956). 

The Unisulf process is quite similar to the Stretford process, as is apparent from a cursory inspection of the flow diagram shown in Figure 9-29. The principal difference is the absence of quinone compounds in the Unisulf solution. Instead, carboxylated complexing agents (for example, sodium l-hydroxybenzene-4-sulfonate and sodium 8-hydroxyquinoline-5-sul-fonate) are used (Fenton and Gowdy, 1981). 

The decline in immune function may pardy depend on a deficiency of coenzyme Q, a group of closely related quinone compounds (ubiquinones) that participate in the mitochondrial electron transport chain (49). Concentrations of coenzyme Q (specifically coenzyme Q q) appear to decline with age in several organs, most notably the thymus. 

Synthesis by oxidation remains the first choice for commercial and laboratory preparation of quinones the starting material (1) provided the generic name quinone. This simple, descriptive nomenclature has been abandoned by Chemicaly hstracts, but remains widely used (2). The systematic name for (2) is 2,5-cyclohexadiene-l,4-dione. Several examples of quinone synonyms are given in Table 1. Common names are used in this article. 1,2-Benzoquinone (3,5-cydohexadiene-l,2-dione) (3) is also prepared by oxidation, often with freshly prepared silver oxide (3). Compounds related to (3) must be prepared using mild conditions because of their great sensitivity to both electrophiles and nucleophiles (4,5). 

The close electrochemical relationship of the simple quinones, (2) and (3), with hydroquinone (1,4-benzenediol) (4) and catechol (1,2-benzenediol) (5), respectively, has proven useful in ways extending beyond their offering an attractive synthetic route. Photographic developers and dye syntheses often involve (4) or its derivatives (10). Biochemists have found much interest in the interaction of mercaptans and amino acids with various compounds related to (3). The reversible redox couple formed in many such examples and the frequendy observed quinonoid chemistry make it difficult to avoid a discussion of the aromatic reduction products of quinones (see Hydroquinone, resorcinol, and catechol). 

Reactions of acetylene and iron carbonyls can yield benzene derivatives, quinones, cyclopentadienes, and a variety of heterocycHc compounds. The cyclization reaction is useful for preparing substituted benzenes. The reaction of / fZ-butylacetylene in the presence of Co2(CO)g as the catalyst yields l,2,4-tri-/ f2 butylbenzene (142). The reaction of Fe(CO) and diphenylacetylene yields no less than seven different species. A cyclobutadiene derivative [31811 -56-0] is the most important (143—145). 

In the benzene and naphthalene series there are few examples of quinone reductions other than that of hydroquinone itself. There are, however, many intermediate reaction sequences in the anthraquinone series that depend on the generation, usually by employing aqueous "hydros" (sodium dithionite) of the so-called leuco compound. The reaction with leuco quinizarin [122308-59-2] is shown because this provides the key route to the important 1,4-diaminoanthtaquinones. 

Aromatic ethers and furans undergo alkoxylation by addition upon electrolysis in an alcohol containing a suitable electrolyte.Other compounds such as aromatic hydrocarbons, alkenes, A -alkyl amides, and ethers lead to alkoxylated products by substitution. Two mechanisms for these electrochemical alkoxylations are currently discussed. The first one consists of direct oxidation of the substrate to give the radical cation which reacts with the alcohol, followed by reoxidation of the intermediate radical and either alcoholysis or elimination of a proton to the final product. In the second mechanism the primary step is the oxidation of the alcoholate to give an alkoxyl radical which then reacts with the substrate, the consequent steps then being the same as above. The formation of quinone acetals in particular seems to proceed via the second mechanism. ... 

The redox properties of quinones are crucial to the functioning of living cells, where compounds called ubiquinones act as biochemical oxidizing agents to mediate the electron-transfer processes involved in energy production. Ubiquinones, also called coenzymes Q, are components of the cells of all aerobic organisms, from the simplest bacterium to humans. They are so named because of their ubiquitous occurrence in nature. 

In the modern formulation, but ignoring the quinone diazide mesomerism (see Sec. 4.2), his diazotization is shown in Scheme 1-1 yielding 1.2. For the centenary of the discovery of diazo compounds Wizinger (1958) and Cliffe (1959) wrote accounts of its history. More recently Zahn (1989) summarized the life and work of Peter Griess. 

In conclusion, with regard to the structure of benzenediazonium compounds with electron donor substituents in the 2- or 4-position, the most recent experimental data, mainly X-ray analyses and 13C and 15N NMR data, are consistent with 4.4 as the dominant mesomeric structure of quinone diazides, as proposed by Lowe-Ma et al. (1988). For benzenediazonium salts with a tertiary amino group in the 4-position the data are consistent with the quinonoid structure 4.20 as the dominant mesomeric form. 

The Gomberg-Bachmann reaction is a method for arylation of aromatic compounds and quinones (Gomberg and Bachmann, 1924). Originally this reaction involved adding aqueous sodium hydroxide slowly to an intimate mixture of an aqueous solu-... 

The first examples of macrocyclization by enyne RCM were used in Shair s impressive biomimetic total synthesis of the cytotoxic marine natural product longithorone A (429) [180]. This unique compound features an unusual hep-tacyclic structure which, in addition to the stereogenic centers in rings A-E, is also chiral by atropisomerism arising from hindered rotation of quinone ring G through macrocycle F (Scheme 85). It was assumed that biosynthesis of 429 could occur via an intermolecular Diels-Alder reaction between [12]paracy-... 

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