Aromatic protonation. XII. Solvent isotope effects in H/sub 2/O--D/sub 2/O mixtures on the detritiation of trimethoxybenzene

Journal Article · Wed Mar 30 04:00:00 EST 1977 · J. Am. Chem. Soc.; (United States)

DOI:https://doi.org/10.1021/ja00449a036· OSTI ID:7292986

Kresge, A J; Chiang, Y; Koeppl, G W; More O'Ferrall, R A

The problem of kinetic solvent isotope effects in H/sub 2/O--D/sub 2/O mixtures on systems for which proton transfer from H/sub 3/O/sup +/ and some subsequent reaction step are each partly rate determining is considered, and an expression relating the isotope effect to the atom fraction of deuterium in the solvent is derived for a symmetrical isotope exchange process such as acid-catalyzed aromatic hydrogen exchange. This expression is then applied to data presented here for the detritiation of 1,3,5-trimethoxybenzene-2-t as well as to literature values for the same reaction and the detritiation of azulene-l-t. The analysis yields isotopic (Bronsted) exponents, ..cap alpha../sub i/ = 0.67 for trimethoxybenzene and ..cap alpha../sub i/ = 0.57 for azulene, which are not affected substantially by inclusion of corrections for nonadherence to the rule of the geometric mean and which are in good agreement with conventional Bronsted exponents as well as other measures of transition-state structure for these reactions.

• Research Organization: Illinois Inst. of Tech., Chicago
• OSTI ID: 7292986
• Journal Information: J. Am. Chem. Soc.; (United States), Journal Name: J. Am. Chem. Soc.; (United States) Vol. 99:7; ISSN JACSA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400302* -- Organic Chemistry-- Isotope Effects-- (-1987)
AROMATICS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
DEUTERIUM
HYDROGEN ISOTOPES
ISOTOPE EFFECTS
ISOTOPES
LIGHT NUCLEI
NUCLEI
ODD-EVEN NUCLEI
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
RADIOISOTOPES
STABLE ISOTOPES
TRITIUM
YEARS LIVING RADIOISOTOPES