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De‐ tert ‐butylation of poly( N ‐ tert ‐butyl‐ N ‐ n ‐propylacrylamide): Stereochemical analysis at the triad level
Author(s) -
Hirano Tomohiro,
Sugiura Misato,
Endo Ryuya,
Oshimura Miyuki,
Ute Koichi
Publication year - 2020
Publication title -
journal of polymer science
Language(s) - English
Resource type - Journals
eISSN - 2642-4169
pISSN - 2642-4150
DOI - 10.1002/pol.20200473
Subject(s) - triad (sociology) , tacticity , diad , polymer , chemistry , polymer chemistry , carbon 13 nmr , proton nmr , racemization , methylene , copolymer , stereochemistry , organic chemistry , polymerization , psychology , psychoanalysis
The stereochemical analysis of polymers derived from N , N ‐disubstituted acrylamides is usually difficult. The diad tacticity can be determined from the 1 H nuclear magnetic resonance (NMR) signals of the main‐chain methylene groups. However, the splitting because of the configurational sequences is poor, even in 13 C NMR, which does not allow determination of the tacticity at the triad level. In contrast, the stereochemical analysis of polymers derived from N ‐monosubstituted acrylamides is easily conducted and the triad tacticity can be determined from the 13 C signals of the main‐chain methine groups. Thus, stereochemical analysis of N , N ‐disubstituted polymers should be able to be conducted if the polymers are transformed into N ‐monosubstituted polymers with retention of the configurational sequence. Poly( N ‐ tert ‐butyl‐ N ‐ n ‐propylacrylamide) was radically prepared, and de‐ tert ‐butylation was conducted by treatment with scandium triflate in a mixed solvent of CH 3 CN and 1,4‐dioxane at 50, 80, and 110°C. 1 H NMR analysis of the resulting polymers indicated quantitative conversion after 72 hr, regardless of the temperature. 13 C NMR analysis of the transformed polymers confirmed that the configurational sequences were retained during the reaction. Thus, the triad stereochemical analysis of N , N ‐disubstituted polymers was successfully conducted by de‐ tert ‐butylation as a polymer reaction, followed by 13 C NMR analysis of the transformed polymers.