P-Naphthoquinone

Fig. 3 Electrochemical and homogeneous standard free energies of activation for self-exchange in the reduction of aromatic hydrocarbons in iV.A -dimethylformamide as a function of their equivalent hard sphere radius, a. 1, Benzonitrile 2, 4-cyanopyridine 3, o-toluonitrile 4, w-toluonitrile 5, p-toluonitrile 6, phthalonitrile 7, terephthalonitrile 8, nitrobenzene 9, w-dinitrobenzene 10, p-dinitrobenzene 11, w-nitrobenzonitrile 12, dibenzofuran 13, dibenzothiophene 14, p-naphthoquinone 15, anthracene 16, perylene 17, naphthalene 18, tra 5-stilbene. Solid lines denote theoretical predictions. (Adapted from Kojima and Bard, 1975.)...

Side reactions that occur with intramolecular cycloaddition, such as linear oligomerization or dimerization of the nitrile oxide, are not very common when shorter chain lengths n < 1) are used due to the entropically favored intramolecular process. A rather unusual result in this regard involves the formation of a fused cyclooctane instead of the less-strained six-membered ring (also fused) in the cycloaddition of the nitrile oxide derived from p-naphthoquinone (Scheme 6.43). This result is consistent with the effect of electron-withdrawal in the enedione part, leading to increased reactivity (247), and also reflects the known sluggishness of cyclohexenes towards nitrile oxides (cf. Section 6.2.1.2). 

Kinetics of the addition of PI13P to p-naphthoquinone in 1,2-dichloromethane, using the initial rate method, revealed the order of reaction with respect to the reactants the rate constant was obtained from pseudo-first-order kinetic studies. A variable time method using UV-visible spectrophotometry (at 400 nm) was employed to monitor this addition, for which the following Arrhenius equation was obtained log k = 9.14- (13.63/2.303RT). The resulting activation parameters a, AH, AG, and Aat 300 K were 13.63, 14.42 and 18.75 kcalmol-1 and —14.54 calmol 1K 1,... 

Cyclic a-diketones and o-quinones give, under comparable conditions, dicarboxylic acids. P-Naphthoquinone is converted in 83% yield into o-carboxyallocinnamic acid by 9% peroxyacetic acid in an exothermic reaction [277] (equation 393). 

K. Matsumoto, H. Ukeda, and Y. Osajima, Flow Injection Analysis of Reduced Nicotinamide Adenine Dinucleotide Using p-Naphthoquinone-4-Sulfonate as a Mediator. Agric. Biol. Chem., 48 (1984) 1879. 

Sodium p-naphthoquinone-4-suitonate Sodium 3,4-dihydro-3,4-dioxo-1-naphthaienesuitonate CioHsNaOsS 621-24-4 260.199 287 dec ... 

Both singlet and triplet reactions give higher yields of (h-h) products in the more polar acetonitrile than in benzene the (h-h) orientation should actually correspond to the highest dipole moment in the dimer. p-Naphthoquinone can react with olefins under irradiation in benzene at... 

CAS 524-42-5 EINECS/ELINCS 208-360-2 Synonyms 1,2-Naphthalenedione 1,2-Naphthaquinone P-Naphthoquinone... 

C-1. By oxidation with oxygen or with ferric ions, the correspond- The reaction of gossypol with proteins has been used to ing 0- and p-naphthoquinones arise, which mutually polymerise detoxify cottonseed oil. Gossypol in milled seeds reacts with seed... 

Stable o- and p-naphthoquinone methides leading to (316) have been obtained by a two-stage process, starting with 6-methoxy-l,3,8-tri-hydroxynaphthalene, and studies on the stability conferred on ylides by the phenylimino-group (PhN=) have led to the synthesis shown in Scheme 41 for the formation, in high yield, of the ylide (317) from 2-anilino-3-methylthio-1,4-naphthoquinone (318). 

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