Polarographische Analyse von Chromatfarben

Baltes, J.; Wiertz, P.

doi:10.1002/lipi.19550570307

Cited by 6 publications

(5 citation statements)

References 1 publication

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“…Less hindered phenols can also yield spiro compounds. Thus, oxidation of 2-i-butyl-4-methoxyphenol (7) gives a dimer which is probably (209) the spiro compound XLVI. Hewgill (140) has recently investigated the oxidation of 2-and 3-i-butyl-4-methoxyphenol as well as their cooxidation.…”

Section: R= Aliphatic R" Alkyl Arylmentioning

confidence: 99%

“…For alkoxy radicals, for example, Gray and Williams (125; also cf. ref 314) list eight modes of reaction: (1) association (dimerization), (2) hydrogen abstraction, (3) addition, (4) rearrangement, (5) decomposition by C-H bond fission, (6) decomposition by C-C bond fission, (7) disproportionation, (8) decomposition by radical attack. These reactions are shown also by carbon radicals and there is an abundance of examples to show that phenoxy radicals react as oxygen or carbon radicals.…”

Section: Phenoxy Radicals In Natural Productsmentioning

confidence: 99%

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The Chemistry of Stable Phenoxy Radicals

Altwicker¹

1967

Chem. Rev.

260

189

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are closely related to phenoxy radicals but have a unique structural feature in that they are radical anions, will be mentioned only briefly. The chemistry of semiquinones has been the subject of an earlier review paper (202; for recent references cf. 58, 208, 313). Stable radicals based on polynuclear phenols (such as naphthols etc.) will be discussed.Electron spin resonance spectroscopy has contributed more than any other tool to the structural analysis of phenoxys and to the characterization of many new radicals. The results from esr work will be introduced where pertinent, but a detailed discussion of the many spectra that have been published is considered beyond the scope of this review. Excellent summaries of the esr method (232,325) and its application to phenoxy radicals have appeared (44,205).The literature has been reviewed through September 1966; a number of later references are included. III. Generation of Phenoxy RadicalsA.

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Section: R= Aliphatic R" Alkyl Arylmentioning

confidence: 99%

Section: Phenoxy Radicals In Natural Productsmentioning

confidence: 99%

The Chemistry of Stable Phenoxy Radicals

Altwicker¹

1967

Chem. Rev.

260

189

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“…The deep purple color of an o,ol-diphenoquinone (4,5) is produced in a very short time when 0.5 g 1. (or 2,4-di-t-butylphenol) are mixed, with shaking, with 0.3 g Ag20 in 20 1111 absolute ether containing 1 g of anhydrous NaZSOe.…”

Section: 2'~4'-tetra-t-blltyl-oo'-diphenoq~ri~zone (Ix)mentioning

confidence: 99%

THE OXIDATION OF PHENOLS: II. THE OXIDATION OF 2,4-DI-t-BUTYLPHENOL WITH PEROXY RADICALS

Horswill¹,

Ingold²

1966

Can. J. Chem.

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Ten p r o d~~c t s f r o m the osidatior~ of 2,4-di-t-butylpher~ol wit11 L-butyl perosy radicals have been identilied. They can be subdivided into three groups, depending on the type of radicalradical coupling reaction by which they are prod~rced or iri which their precursors are forn~ed:(i) pher~oxy-perosy coupling, ( i i ) phenoxjr-phenoxy coupling a t the 6 positior~s, and (iii) phenoxy-phenoxy couplir~g through the oxygen atoll1 of one radical and the 6 positio!~ of the second radical. Products resulting from still other phenosy-phenoxy coupling reactions are undoubtedly formed in 111i11or amounts.The products from the oxidation of 2,4-di-t-butylphenol xrith t-butyl peroxy radicals have been studied as a part of our general investigation into the oxidation of phenols (I). This compound was chosen as a representative 2,1-dialliyl phenol which might be expected to give a simpler mixture of products than a phenol containing a inethyl group, since products coupled through the methyl group (such as dihydroxy bibenzyls and stilbenequinones) would not be formed. In spite of this siinplification 110 less than 10 products were identified, and the thin-layer chromatographic (t.1.c.) plates showed t h a t many others were present. T h e products were separated by coluilln chroillatography on silica ( I ) . Their relative yields depended not only on the exact conditions of the reaction but also on the speed 11-ith nrhich they were separated. The latter variation is due to the fact that inany of the initial products are unstable peroxides which decoinpose on exposure to light and heat and even t o the inildly acidic silica column itself.By analogy with 2,G-dialliyl phenols (I) we inay expect to get products resulting from phenoxy-peroxy and phenoxy-phenoxy radical coupling reactions. Elowever, in the present case, the existence of a hydrogen atom in the 6 positioil leads to products of increased complex it^^ because of the rapid rearrangement of those intermediates \\ ith an o-quinolide structure. For convenience, the overall reaction is divided into three parts.Firstly, combination of the initially forined phenoxy radical with a t-but11 peroxy radical.3,s-Di-t-butyl-o-benzoquinone (11) was one of the major products (-10yo), but its probable precursor (I) \vas not identified. The conversion of I into I1 inay occur either directly (cf. ref. 1) or after rearrangement to an o-peroxy phenol. The 4-peroxy-cyclohexadienone, 111, found in s-lOyO yield, is siinilar to the major products formed fro111 ,3,4,6-trialliyl phenols (1). Co~npound I11 decolnposed slo~vly on the t.1.c. plates to give 2-t-butyl-p-benzoquinone (I\[) and other unidentified products. No compound corresponding t o the addition of the peroxy radical a t the 2 position of the original phenol \\-as identified, nor was its expected decomposition product, 4-t-but)il-o-benzoquinone, detected.Secondly, colllbination of two phenoxy radicals through their carbon atoms in position 6. T h e biphenol V and its precursor mere not identified anlong the products under the s...

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“…After being heated for 20 min on a steam-bath the solution was poured into water and extracted with ether. The extract was washed with aqueous sodium hydrogen carbonate and water, dried, and evaporated to give a residue which was subjected to t. 1 1 785 (enol acetate CO and furanone CO), 1 695 (unsaturated CO), and 1 650 cm-' (C=C); h,,,. (EtOH) 272 (E 9 600), 362 (10 500), and 460sh (3 000).…”

Section: Photosensitized Oxidation Of the Oxepine (3)-(a)mentioning

confidence: 99%

Oxidation by singlet oxygen of 4,7-dimethoxy-2,9-di-t-butyloxepino[2,3-b]benzofuran, an oxidation product of the antioxidant BHA

Byrne¹,

Engelhardt²,

Hewgill³

et al. 1989

J. Chem. Soc., Perkin Trans. 1

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Tetraphenylporphin-sensitized photo-oxidation of 4,7-dimethoxy-2,9-di-t-butyloxepino[2,3-6]benzofuran (3) and reaction of the products with methanol cleaves the oxepine ring, producing the acetal (9) and its isomer (13), which may be derived respectively from the 1,4-endoperoxide and 1,2-dioxetane oxygen adducts of (3). The geometrical isomerization of (9) to (14), and the acidcatalysed hydrolysis of (9), (1 3) and (14) to the dihydrofuranylidenebenzofuranone (1 8) are described.Crystal structures were determined for compounds (9), ( 14), and (18).

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Polarographische Analyse von Chromatfarben

Cited by 6 publications

References 1 publication

The Chemistry of Stable Phenoxy Radicals

The Chemistry of Stable Phenoxy Radicals

THE OXIDATION OF PHENOLS: II. THE OXIDATION OF 2,4-DI-t-BUTYLPHENOL WITH PEROXY RADICALS

Oxidation by singlet oxygen of 4,7-dimethoxy-2,9-di-t-butyloxepino[2,3-b]benzofuran, an oxidation product of the antioxidant BHA

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