Flash photolytic generation and study ofp-quinone α-phenylmethide andp-quinone α,α-diphenylmethide in aqueous solution

Autor:	H.‐Q. Zhan, J. A. Chang, A. J. Kresge, Y. Zhu
Rok vydání:	2004
Předmět:	Hydronium ved/biology Organic Chemistry ved/biology.organism_classification_rank.species Protonation Photochemistry Quinone methide Acid dissociation constant Quinone chemistry.chemical_compound chemistry Hydroxide Perchloric acid Physical and Theoretical Chemistry Conjugate acid
Zdroj:	Journal of Physical Organic Chemistry. 17:579-585
ISSN:	1099-1395 0894-3230
DOI:	10.1002/poc.767
Popis:	p-Quinone α-phenylmethide (7) and p-quinone α,α-diphenylmethide (8) were generated by flash photolytic dehydration of p-hydroxy-α-phenylbenzyl alcohol (9, R1 = Ph, R2 = H) and p-hydroxy-α,α-diphenylbenzyl alcohol (9, R1 = R2 = Ph) respectively, and rates of their decay were measured in aqueous perchloric acid and sodium hydroxide solutions and also as in acetic acid, biphosphate ion, tris(hydroxymethyl)methylammonium ion, ammonium ion and bicarbonate ion buffers. The rate profiles for the hydration of these quinone methides that these data provide show hydronium ion and hydroxide ion-catalyzed regions and also ‘uncatalyzed’ water reactions, with saturation of hydronium ion catalysis in dilute solution for the diphenyl-substituted substrate but only in concentrated acid solution for the less basic monophenyl substrate. Both substrates also give inverse hydronium ion isotope effects (kH+/kD+
Databáze:	OpenAIRE
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