Kinetic solvent isotope effects in the additions of bromine and 4-chlorobenzenesulfenyl chloride to alkenes and alkynes

Journal Article · Fri Nov 23 04:00:00 EST 1979 · J. Org. Chem.; (United States)

DOI:https://doi.org/10.1021/jo01338a001· OSTI ID:5738168

Modro, A; Schmid, G H; Yates, K

The rates of bromination of selected alkenes and alkynes in methanol/methanol-d, acetic acid/acetic acid-d, and formic acid/formic acid-d have a nearly constant value of k/sub H//k/sub D/ = 1.23 +- 0.02. This kinetic solvent isotope effect is attributed to specific electrophilic solvation of the incipient bromide anion by hydrogen bonding in the rate-determining transition state. The rates of bromination were measured in two solvents having the same values of the solvent parameter Y but different nucleophilicities in order to assess the importance of nucleophilic solvation. Significant nucleophilic solvent assistance is found for only alkylacetylenes. The kinetic solvent isotope effects of the addition of 4-chlorobenzenesulfenyl chloride to selected alkenes and alkynes in acetic acid/acetic acid-d vary from 1.00 to 1.28. These data are consistent with two mechanisms: one involves a tetravalent sulfur intermediate while the second is the sulfur analogue of the S/sub N/2 mechanism.

• Research Organization: Univ. of Toronto, Ontario
• OSTI ID: 5738168
• Journal Information: J. Org. Chem.; (United States), Journal Name: J. Org. Chem.; (United States) Vol. 44:24; ISSN JOCEA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400302* -- Organic Chemistry-- Isotope Effects-- (-1987)
ACETIC ACID
ALCOHOLS
ALKENES
ALKYNES
BROMINATION
CARBOXYLIC ACIDS
CHEMICAL REACTIONS
DECOMPOSITION
DEUTERIUM
FORMIC ACID
HALOGENATION
HYDROCARBONS
HYDROGEN ISOTOPES
HYDROXY COMPOUNDS
ISOTOPE EFFECTS
ISOTOPES
LIGHT NUCLEI
METHANOL
MONOCARBOXYLIC ACIDS
NUCLEI
ODD-ODD NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
SOLVOLYSIS
STABLE ISOTOPES