Quinones Derivatives

CgHgNa. While crystals m.p. 147 C, b.p. 267"C, darken rapidly in air. Prepared by reducing p-nitroaniline or aminoazobenzene. Oxidizing agents convert it to quinone derivatives, hence it cannot be diazotized with nitric acid. 

There is a fair amount of work reported with films at the mercury-air interface. Rice and co-workers [107] used grazing incidence x-ray diffraction to determine that a crystalline stearic acid monolayer induces order in the Hg substrate. Quinone derivatives spread at the mercury-n-hexane interface form crystalline structures governed primarily by hydrogen bonding interactions [108]. 

Within the cubane synthesis the initially produced cyclobutadiene moiety (see p. 329) is only stable as an iron(O) complex (M. Avram, 1964 G.F. Emerson, 1965 M.P. Cava, 1967). When this complex is destroyed by oxidation with cerium(lV) in the presence of a dienophilic quinone derivative, the cycloaddition takes place immediately. Irradiation leads to a further cyclobutane ring closure. The cubane synthesis also exemplifies another general approach to cyclobutane derivatives. This starts with cyclopentanone or cyclohexane-dione derivatives which are brominated and treated with strong base. A Favorskii rearrangement then leads to ring contraction (J.C. Barborak, 1966). 

Oxidation of P-nicotinamide adenine dinucleotide (NADH) to NAD+ has attracted much interest from the viewpoint of its role in biosensors reactions. It has been reported that several quinone derivatives and polymerized redox dyes, such as phenoxazine and phenothiazine derivatives, possess catalytic activities for the oxidation of NADH and have been used for dehydrogenase biosensors development [1, 2]. Flavins (contain in chemical structure isoalloxazine ring) are the prosthetic groups responsible for NAD+/NADH conversion in the active sites of some dehydrogenase enzymes. Upon the electropolymerization of flavin derivatives, the effective catalysts of NAD+/NADH regeneration, which mimic the NADH-dehydrogenase activity, would be synthesized [3]. 

Synthesis of p-quinones, derivatives of fused systems including heterocyclic fragments through oxidation of phenol derivatives 98OPP603. 

In aromatic diazonium compounds containing an ionized hydroxyl group ( —O-) in the 2- or 4-position, it is necessary to consider delocalization of electrons and, therefore, two mesomeric structures (1.7a-1.7b) (see Sec. 4.2). This fact has implications for nomenclature compounds of this type are considered as quinone derivatives following IUPAC Rule C-815.3 (Exception) compounds of this class are called quinone diazides. As a specific compound 1.7a-1.7b is indexed in Chemical Abstracts as 4-diazo-2,5-cyclohexadien-l-one. If reference is made specifically to mesomeric structure 1.7b, however, it is called 4-diazoniophenolate. 

Iodine addition to the ter- [13] tiary nitrogen of the opium alkaloids and to the OCH3 group of the brucine with formation of an o-quinone derivative, probably ring opening in the case of phenylbutazone, ketazone and trimethazone detection by IR... 

The oxidation of reduced jS-nicotinamide adenine dinucleotide (NADH) by quinone derivatives (Q) by has been investigated extensively, since the reaction was considered to be essential in the proton transport and the energy accumulation occurring at the mitochondrial inner membrane [2]. However, most of fundamental work in this field has been done in homogeneous solutions [48-52] though the reaction in living bodies has been believed to proceed at the solution membrane interface. 

TABLE 1 Tetra-alkylammonium Ion, R4N, Transferred from W to DCE by the Coupling with the Redox Reaction Between NADH in W and a Quinone Derivative in DCE. Results After Shaking W Containing 10 M NADH and 10 M (R4N )2 SO4 with DCE Containing 10 M Quinone [Q Chloranil (CQ) or Toluquinone (TQ)] for 1 h. TPenA, TBA, and TEA Denote Tetrapentylammonium, Tetrabutylammonium, and Tetraethylammonium ions. Respectively... 

Terashima, I. Suzuki, N. Shibutani, S. Mutagenic properties of estrogen quinone-derived DNA adducts in simian kidney cells. Biochemistry 2001, 40, 166-172. 

The oxygen-consuming reaction between a quinone derived from a simple catechin and a quinone derived from a gallocatechin results in the formation of a theafiavin. These compounds possess the benztropolone group that is based on a seven-membered ring. Figure 4 illustrates the formation of theaflavins. 

Photodimerizations of quinone derivatives are quite common. Representative examples are as follows<87,88) ... 

An other example of Salvia quinone is salvicine, a structurally modified diterpenoid quinone derived from Salvia prionitis, which is cytotoxic against multidrug-resistant cancer cell lines of topoisomerase II inhibition by trapping the DNA-topoisomerase II complex (49). 

The interstellar dust was shown to contain quinone derivatives as well as oxygen-rich condensed aromatic compounds the quinones were present in both hydrated and carboxylated form. Very little nitrogen was present in the compounds detected. The cometary material, however, contained condensed nitrogen heterocycles. Hardly any oxygen was detected in the solid phase of the cometary dust it possibly evaporates from the tail of the comet in the form of water or oxidized carbon compounds. The authors assume that these analytical results could lead to a reconsideration of the current biogenesis models (Kissel et al 2004 Brownlee, 2004). 

Inubushi s synthesis of racemic serratinine commences with a Diels-Alder reaction of butadiene with substituted quinone derivative 26 (available in four steps from 25,... 

The reaction products depend on the ring substituents of the thione and the dienophile. If the dienophile is 2,5-norbornadiene,107 4 affords a new ben-zothiopyran by reaction with a further molecule of 4, 4,4 -dimethylthiobenzo-phenone yields a [4+2] cycloadduct, and 4,4 -dimethoxythiobenzophenone, a quinone derivative via the [4+2] cycloadduct. 

Michael addition of di- and tri-hydric phenols to /V-cinnamoylimidazoles followed by a lactonisation offers a route to 4-aryI-3,4-dihydrocoumarins and their [/]-benzologues <00S123>. The lactonisation of the naphthoquinone derivative 66 is sensitive to the acidic cyclising medium and it is possible to obtain the thermodynamically less stable o-quinone derivative exclusively (Scheme 44) <00TL3007>. Some related quinones have been obtained from 1-benzylisoquinolines via an arylnaphthoquinone <00T6O23>. 

The bleaching powder reaction is peculiar to aniline the dye which is formed is a complex quinone derivative the constitution of which is not yet known with complete certainty. The other experiments, about to be described, are group reactions for primary aromatic amines. 

Enzymatic browning. Phenol-oxidizing enzymes (such as tyrosinase and peroxidase) oxidize tyrosine residues into reactive quinone derivatives, which will condense into colored polymers (melanins). Melanins are rich in carboxyl groups and therefore have high affinity for divalent metal ions such as calcium. 

Reactions of various l-(l,2-propadienyl)cyclopropanols having a substituent at the 1- or 3-position of the propadienyl moiety 55 proceed smoothly at between 0°C and room temperature with 1.1 mole amounts of Co2(CO)8 in either THF or ethyl acetate, and various 2-monosubstituted or 2,3-disubstituted 1,4-hydro-quinone derivatives 58 are obtained in good yields (Scheme 25). In particular, 1-(1,2-propadienyI)cycIopropanoI having the ferf-butyldimethylsilyl group at the 1-position of the 1,2-prop adienyl moiety gives a high yield of the silylated hydroquinone. 

Many naturally occurring antioxidants are derivatives of phenol and hindered phenols, such as di-tert-butyl paracresol (Equation 15.14). It has the ability to act as a chain transfer agent forming a stable free radical that does not initiate chain radical degradation. However, the phenoxy free radical may react with other free radicals producing quinone derivatives. 

In 1984, Giibble et al. reported for the first time a novel l,10-bis-(6-methyl-5H-benzo[fc]carbazol-ll-yl)decane (469) which has potential bifunctional nucleic acid intercalating properties (406). To function as anti-tumor active drugs, one of the most important cytostatic mechanisms of action of coplanar annelated polycyclic compounds is their intercalation with DNA (405). Ten years later, Kucklander et al. studied a series of 5H-benzo[ 7]carbazole quinone derivatives for their cytotoxic activity against colon and lung cancer cells, and found that the heteroannelated 5H-benzo[ 7]carbazole quinone derivative 470 was the most active among the various analogs (407) (Scheme 4.2). 

Many quinones derived from aromatic compounds are used as dienophiles in the Diels-Alder reaction, and functionalized hydroxyquinones are extensively used as anti-oxidants in the photo industry and as polymeric materials. 

Oxidation of ortho-xylene. The spectra of the adsorbed species arising from interaction of ortho-xylene with the surface of the vanadia-titania catalyst in the presence of oxygen are shown in Figure 4. The spectra show some parallel features with respect to those discussed above concerning the oxidation of toluene and meta- and para-xylene. Also in this case the o-methyl-benzyl species begins to transform above 373 K, with production of adsorbed o-tolualdehyde (band at 1635 cm 0 and of a quinone derivative (band at 1670 cm. Successively bands likely due to o-toluate species (1530,1420 cm 0 grow first and decrease later with production of CO2 gas. 

OTHER TESTS OF CONNECTIVITY THEORIES 7.1. m-Quinone Derivatives... 

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