Conversion of these compounds to thioketals with 1,3-propanedithiol was also examined in detail. The reaction between 1,3-propanedithiol and 1,5-biscarbethoxybicyclo[3.2.2]nonane-6.8-dione generated an equilibrating system of 4 compounds. Three of these are shown to be the monothioketal, the bisthioketal, and a mixed thioketal-vinylthioether.Canadian Journal of Chemistry, 48, 1219Chemistry, 48, (1970 For the purposes of continuing our study (I, 2) the former compounds had been documented into the relationship between the structure of (3, 4), syntheses for the latter compounds were condensation polymers and their physical prop-incomplete (4, 5). It seemed logical, however, erties, it became necessary to prepare bifunctional that the synthetic sequence employed for the bridgehead derivatives of bicyclo [2.
In connection with a complex investigation of the transformations of stabilizers during the ageing of polymers, the photooxidation of 2,6‐di‐tert‐butyl‐4‐methylphenol (IV) sensitized with methylene blue in methanol was investigated. If the reaction takes place in a dilute solution, phenol(IV) is oxidized with singlet oxygen forming 2,6‐di‐tert‐butyl‐4‐methyl‐4‐hydroperoxy‐2,5‐cyclohexadiene‐1‐one (V). In a concentrated solution phenol (IV) is attacked by an excited sensitizer which gives rise to a corresponding aryloxy radical; transformations of the latter yield 2,6‐di‐tert‐butyl‐4‐methoxymethylphenol (VI). The further reaction of phenol (IV) is slower, but similar to phenol (IV): by a reaction with singlet oxygen 2,6‐di‐tert‐butyl‐4‐methoxymethyl‐4‐hydroperoxy‐2,5‐cyclohexadienel‐one (VIII) is formed, while a reaction with the excited sensitizer again gives rise to the corresponding aryloxyl. Transformations of the latter produce 3,5‐di‐tert‐butyl‐4‐hydroxybenzaldehyde (X). Under oxidizing conditions the compounds (VIII) and (X) undergo further transformation to yield 2,6‐di‐tert‐butyl‐1,4‐benzoquinone (IX).
In connection with the study of the mechanism of antioxidant action of 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline (ethoxyquin, I) and of its ecological responses in stabilized polymers we studied its oxidation with some selected agents and the properties of products thus obtained. The oxidation of I with silver oxide or lead dioxide proceeds by two main routes. One of them leads to 8-(6-ethoxy-2,2,4-trimethyl-1 ,2-dihydro-l-quinolinyl)-6-ethoxy-2,2,4-trimethyl-l ,2-dihydroquinoline (IV), which is further oxidized to the blue compound 8-(6-ethoxy-2,2,4-trimethyl-l,2-dihydrol-quinolinyl)-2,2,4-trimethyl-6-quinolone (IX). In the second route position 6 is attacked and 2,2,4-trimethyl-6-quinolone (VII) is formed, which is stable under the conditions used, but is oxidized further with m-chloroperbenzoic acid, giving rise to 2,2,4-trimethyl-6-quinolone-N-oxide (VIII). The oxidation of ethoxyquin with potassium permanganate also gives rise to dimer IV and not to 1,l'-bis(6-ethoxy-2,2,4-trimethyl-1 ,2-dihydroquinoline) (III) reported in the literature. Potassium nitrosodisulfonate oxidizes I with formation of 6-ethoxy-2,2,4-trimethyl-8-quinolone @). The oxidation of ethoxyquin with m-chloroperbenzoic acid gives rise to 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline-N-oxide (V) and dimer IV. Nitroxide V was obtained in the crystalline state. In the presence of acids, and particularly on the surface of silica gel it decomposes to ethoxyquin and nitrone VIII. Nitroxide V is readily reduced to the starting ethoxyquin. The transitionally formed 6-ethoxy-1 -hydroxy-2,2,4-trimethyl-1 ,2-dihydroquinoline (XIV) readily disproportionates to I and V. ZUSAMMENFASSUNG: Das Antioxidans 6-Ethoxy-2,2,4-trimethyl-l,2-dihydrochinolin (Ethoxyquin, I) wurde mit ausgewahlten Reagenzien oxidiert und die Reaktionsprodukte charakterisiert. Die Oxidation mit Silberoxid oder Blei(1V)-oxid verlauft auf zwei verschiedenen ' CCC 0003-3146/91/$03.00 53 L. lkimr, M. Prusikovh, and 3. PospiSilWegen. Ein Reaktionsweg fuhrt zur Bildung des Dimeren 8-(6-Ethoxy-2,2,4-trimethyl-1 ,Zdihydro-I -chinolinyl)-6-ethoxy-2,2,4-trimethyl-1 ,2-dihydrochinolin (IV), das weiter zum blauen 8-(6-Ethoxy-2,2,4-trimethyl-l ,2-dihydro-1 -chinolinyl)-2,2,4-trimethyl-6-chinolon (IX) oxidiert wird. Der zweite Weg fuhrt zum Angriff des Ethoxyquins in Position 6, wobei 2,2,4-Trimethyl-6-chinolon (VII) gebildet wird, das unter den gegebenen Bedingungen bestandig ist, aber mit m-Chlorperbenzoesaure weiter zu 2,2,4-Bimethyl-6-chinolon-N-oxid (VIII) oxidiert werden kann. Bei der Oxidation von I mit Kaliumpermanganat entsteht ebenfalls IV und nicht das in der Literatur beschriebene l,l'-Bis(6-ethoxy-2,2,4-trimethyl-1,2-dihydrochinolin) (111). Kaliumnitrosodisulfonat oxidiert I zu 6-Ethoxy-2,2,4-trimethyl-8-chinolon (X). 6-Ethoxy-2,2,4-trimethyl-I ,2-dihydrochinolin-N-oxid (V) und das Dimere IV entstehen bei der Oxidation von I mit m-Chlorperbenzoesaure. Das Nitroxid V wurde als kristalline Substanz erhalten; es zersetzt sich in Gegenwart von Sauren und besonders auf der Oberflache ...
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