The reaction of 1‐cyano‐1‐methylethyl radical with antidegradant ethoxyquin and its aminyl and nitroxide derivatives

Abstract

6-Ethoxy-2,2,4-trimethyl-l,2-dihydroquinoline (ethoxyquin, I) does not react with the model alkyl radical, 1-cyano-1-methylethyl, in an inert atmosphere. On the other hand, its aminyl derivative (II) reacts readily with the model alkyl radical; the main product of this reaction is 6-ethoxy-8-(1 -cyano-1 -methylethyl)-2,2,4-trimethyl-l,2-dihydroquinoline (V), while 6-ethoxy-1-( l-cyano-l-methylethyl)-2,2,4-trimethyl-l,2-dihydroquinoline (VI) is formed as a by-product. 6-Ethoxy-2,2,4-trimethyl-1 ,Zdihydroquinoline-N-oxyl (111) also effectively deactivates the model alkyl radical to form 6-ethoxy-8-( 1 -cyano-1 -methylethoxy)-2,2,4-trimethyl-l,2-dihydroquinoline (X).It follows from these results that I is an ineffective antidegradant in oxygen-free atmosphere. However, at very low oxygen concentrations, I becomes capable of deactivating alkyl radicals. Together with its ability to deactivate alkylperoxide radicals, this explains the high antifatigue activity of I.In the presence of silica gel, V is readily cyclized to 8-ethoxy-l,2,3,4-tetrahydro-2imino-l,1,4,4,6-pentamethylpyrrolo[3,2,l-ij]quinoline (VIII). VI undergoes thermal decomposition into its components, i. e., aminyl I1 and the model radical. Photodecomposition of X on silica gel yields 6-ethoxy-2,2,4-trimethyl-8-quinolone (XIII). ZUSAMMENFASSUNG 6-Ethoxy-2,2,4-trimethyl-1,2-dihydrochinolin (Ethoxyquin, I) reagiert nicht mit dem Modell-Alkylradikal 1 -Cyan-1 -methylethyl in inerter Atmosphare. Sein Aminylderivat (11) reagiert dagegen leicht mit dem Modellalkyl; dabei wurden 6-Ethoxy-8-( 1 -cyan-1methylethyl)-2,2,4-trimethyl-1,2-dihydrochinolin (V) als Hauptprodukt und 6-Ethoxy-1-(1 -cyan-1 -methylethyl)-2,2,4-trimethyl-l,2-dihydrochinolin (VI) als Nebenprodukt erhalten. Auch 6-Ethoxy-2,2,4-trimethyl-1,2-dihydrochinolin-N-oxyl(III) desaktiviert wirksam die Modellradikale unter Bildung von 6-Ethoxy-8-(1 -cyan-1 -methyl-ethoxy)-2,2,4-trimethyl-1,2-dihydrochinolin (X). CCC OOO3-3146/93/$05.00 199 L. Taimr, M. Smelhausova, M. PrusikovaIn Abwesenheit von Sauerstoff ist I als Antidegradant ganz unwirksam. Jedoch schon eine sehr niedrige Konzentration von Sauerstoff befahigt I, Alkylradikale zu desaktivieren. Seine hohe alterungsschutzende Aktivitat ist also durch die Fahigkeit erklart, sowohl Alkyl-als auch Alkylperoxyradikale zu desaktivieren.V cyclisiert leicht auf Kieselgel unter Bildung von 8-Ethoxy-l,2,3,4-tetrahydro-2-imino- I ,1,4,4,6-pentamethylpyrrolo[3,2,1-ij]-chinolin (VIII). VI spaltet sich bei hoherer Temperatur in seine Komponenten -Aminyl I1 und das Modellradikal. X spaltet sich unter Lichtwirkung auf Kieselgel unter Entstehung von 6-Ethoxy-2,2,4-trimethyl-8chinolon (XIII).

Activity Mechanisms of Amines in Polymer Stabilization

“…The recombination of 2b and 2c with R* irreversibly yields alkylates. The process was proved by using low-molecular weight R" (12,14). Structure 8 is a typical alkylate (JO).…”

“…The process was proved by using model alkyls in the DPA and DHQ series (10,14,22). Com pounds such as 19 or 20 are formed.…”

10.1007/s10975-008-2008-z

“…Note that the main body of the experimental results obtained in [2,3] does not contradict the DHQ photolysis mechanism established later. Besides the practical importance of ethoxyquin as an effective nontoxic antioxidant [9][10][11][12], the other reason why we chose this DHQ is that the intermediate species generated in its photolysis in protic solvents are substantially less active than in the case 1 [7]. Along with the results for the photolysis of 2,2,4,6-tetramethyl-1,2-dihydroquinoline ( 1 ) obtained earlier and in this study, new data on the photolysis of 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline ( 2 , ethoxyquin) and 6-ethoxy-1,2,2,4-tetramethyl-1,2-dihydroquinoline ( 3 ) in CTAB micellar solution are presented here.…”