Kinetic Studies on the Reaction of Chlorosulfonyl Isocyanate with Monofluoralkenes: Experimental Evidence for Both Stepwise and Concerted Mechanisms, and a Pre-equilibrium Complex on the Reaction Pathway

Abstract

Chlorosulfonyl isocyanate (CSI) is reported to react with hydrocarbon alkenes by a stepwise dipolar pathway to give N-chlorosulfonyl-Beta-lactams that are readily reduced to Beta-lactams. Substitution of a vinyl hydrogen for a vinyl fluorine changes the dynamics for reaction with CSI so that a concerted pathway is favored. Rate constants were measured for reactions of CSI with monofluoroalkenes and some hydrocarbon alkenes. Activation parameters for two hydrocarbon alkenes and two monofluoroalkenes support this change inmechanism. A plot generated from the natural log of rate constants vs ionization potentials (IP) indicates that fluoroalkenes with IP values >8.9 eV react by a concerted process. Electron-rich monofluoroalkenes with IP values <8.5 eV were found to react by a single-electron transfer (SET) pathway. Hydrocarbon alkenes were also found to react by this dipolar stepwise SET intermediate rather than the previously accepted stepwise dipolar pathway. Data support a pre-equilibrium complex on the reaction pathway just before the rate-determining step of the concerted pathway and a SET intermediate for the stepwise reactions. When the reactions are carried out at lower temperatures, the equilibrium shifts toward the complex or SET intermediate enhancing the synthetic utility of these reactions. Kinetic data also support formation of a planar transition state rather than the orthogonal geometry as reported for ketene [2 + 2] cycloadditions.

Open PDF

Document Details

Document Type
Technical Report
Publication Date
Dec 14, 2012
Accession Number
ADA628561

Entities

People

  • Dale F. Shellhamer
  • Danielle E. Shipowick
  • David J. Vandenbroek
  • Jacob C. Milligan
  • Jerry A. Boatz
  • Kelli R. Hickle
  • Lincoln B. Smith
  • Marc C. Perry
  • Parker C. Horn
  • Summer A. Bunting

Organizations

  • Air Force Research Laboratory

Tags

Communities of Interest

  • Air Platforms

DTIC Thesaurus Topics

  • Air Force
  • Air Force Research Laboratories
  • Alkenes
  • Chemical Reaction Properties
  • Chemical Reactions
  • Chemical Synthesis
  • Chemistry
  • Chlorides
  • Cyclic Hydrocarbons
  • Electron Transfer
  • Electrons
  • Hydrocarbons
  • Ionization
  • Ionization Potentials
  • Isocyanates
  • Organic Chemistry
  • Transitions

Fields of Study

  • Chemistry

Readers

  • Combustion science or combustion engineering.
  • Organic Chemistry

Technology Areas

  • Microelectronics