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 00:00:00 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), Vol. 99:7
• Country of Publication: United States
• Language: English

Related Subjects

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