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Pregled bibliografske jedinice broj: 787267

Časopis

Autori: Cindro, Nikola; Antol, Ivana; Mlinarić-Majerski, Kata; Halasz, Ivan; Wan, Peter; Basarić, Nikola
Naslov: Reactivity of cations and zwitterions formed in photochemical and acid-catalyzed reactions from m-hydroxycycloalkyl substituted phenol derivatives
Izvornik: Journal of organic chemistry (0022-3263) 80 (2015), 24; 12420-12430
Vrsta rada: članak
Ključne riječi: excited state proton transfer (ESPT) ; carbocations ; zwitterions ; DFT ; laser flash photolysis ; m-quinone methide
Sažetak:
Three m-substituted phenol derivatives, each with a labile benzylic alcohol group and bearing either protoadamantyl 4, homoadamantyl 5, or a cyclohexyl group 6, were synthesized and their potential thermal acid-catalyzed and photochemical solvolytic reactivity studied, using preparative irradiations, fluorescence measurements, nanosecond laser flash photolysis, and quantum chemical calculations. The choice of m-hydroxy-substitution was driven by the potential for these phenolic systems to generate m-quinone methides on photolysis which could ultimately drive the excited state pathway, as opposed to forming simple benzylic carbocations in the corresponding thermal route. Indeed, thermal acid-catalyzed reactions gave the corresponding cations which undergo rearrangement and elimination from 4, only elimination from 5, and substitution and elimination from 6. On the other hand, photoexcitation of 4-6 to S1 in a polar protic solvent, proton dissociation from the phenol coupled by elimination of the benzylic OH (as hydroxide ion) gave zwitterions (formal m-quinone methides). The zwitterions exhibit different reactivity from the corresponding cations due to a difference in charge distribution, as shown by DFT calculations. Thus, protoadamantyl zwitterion has a less non-classical character than the corresponding cation so it does not undergo 1, 2-shift of the carbon atom, as observed in the acid-catalyzed reaction.
Projekt / tema: 098-0982933-2911, HRZZ-IP-2014-09-6312, HRZZ-02.05/25
Izvorni jezik: ENG
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bazama podataka:
Current Contents Connect (CCC)
Scopus
SCI-EXP, SSCI i/ili A&HCI
Science Citation Index Expanded (SCI-EXP) (sastavni dio Web of Science Core Collectiona)
Kategorija: Znanstveni
Znanstvena područja:
Kemija
URL Internet adrese: http://pubs.acs.org/doi/abs/10.1021/acs.joc.5b02297
Broj citata:
Altmetric:
DOI: 10.1021/acs.joc.5b02297
URL cjelovitog teksta:
Google Scholar: Reactivity of cations and zwitterions formed in photochemical and acid-catalyzed reactions from m-hydroxycycloalkyl substituted phenol derivatives
Upisao u CROSBI: Enidija Lukša (Enidija.Luksa@irb.hr), 24. Stu. 2015. u 15:14 sati



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