The relative reaction thermodynamics for the probable pathways
leading to alkene
epoxidation, cis-dihydroxylation, and C−C cleavage as well
as alkenylation of aldehydes
have been investigated for the reaction of ethylene with
LReO3, L = CH3, Cl, OH,
OCH3,
O-, C5H5(Cp), and
C5(CH3)5 (Cp*). We find
the reaction pathway exothermicities to be quite
sensitive to the ligand. For ClReO3,
CH3ReO3, HOReO3,
CH3OReO3, and
O-ReO3, reaction
with ethylene is endothermic with metallaoxetane preferred over
dioxylate formation. For
CpReO3 and Cp*ReO3, the reaction with ethylene
is exothermic but nearly thermoneutral
with dioxylate formation preferred. The π-binding attributes of
the ligand are found to
correlate with thermodyanmic preference.
In no case did we obtain a product melting as low as -20°. The solutions for infrared work were obtained by dissolving the freshly prepared crystalline -hydroxyethyl peracetate in cold chloroform.Infrared spectra. A Baird-Atomic infrared spectrophotometer Model 4-55 was used in this work. The chloroform solution of peroxide was introduced immediately after preparation into the previously cooled low-temperature cell10 at 0°. A variable-path length cell was used in the reference beam to compensate for the chloroform absorption. A Teflon spacer cut from 0.020 mm. sheet was used in the cell since the normal lead spacer rapidly decomposed the peroxide.The decomposition of -hydroxyethyl peracetate at 0°to acetic acid was followed by allowing the solution to remain in the cell and scanning the carbonyl region periodically. Spectra of several reference compounds were obtained at ambient temperature except for acetaldehyde which was obtained at 0°. The compounds and the position (in microns) of their carbonyl bands are: peracetic acid (5.68); acetic acid (5.82); i-butyl peracetate (5.64); -butyl acetate (5.79); and acetaldehyde (5.80).Acknowledgment. We wish to thank Professor II. H. Wasserman of Yale University for helpful discussions and criticism, and to acknowledge the technical assistance of Mr.
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