Reactions of sulfur atoms. XII. Arrhenius parameters for the addition to olefins and acetylenes

Abstract

The reactions of ground-state (3P2,i,o) atoms of the group Via elements with olefins have received considerable attention in recent years.1-7 Atomic oxygen yields epoxides, the isomeric carbonyl compounds, and various fragmentation products. Sulfur, selenium, and tellurium give only the cyclic adduct which, with the latter two elements, has only transient existence.

Addition of Group VIa atoms to tetramethylethylene. Addition reaction with a negative activation energy

“…constant agrees well with the recently published value11 of (7.2 ± 1) X 10s 1. mol-1 sec-1. The rate constants relative to that of ethylene are in satisfactory agreement with the values obtained from the relative Arrhenius parameters determined from conventional photolysis studies 4.…”

“…(2) Considerable broadening of the pmr signal of the a-and b-methyl protons of 1 and 2 are observed in the DNA complex at 32°. 4 In the case of DNA-2 complex the pmr signal of the c-methyl protons is completely broadened and indistinguishable from base-line noise at 32 and 58°, indicating a restricted tumbling rate of the 4-nitroaniline ring of 2. At 90°, where melting of the DNA helix has occurred,5 sharp resonance lines characteristic of the free reporter molecules are observed for the a-, b-, and c-methyl protons. "…”

The Spin‐Forbidden Reaction of Ground‐State Sulfur Atoms with Ethylene

“…The two data sets together hint at a curved Arrhenius plot. The earliest measurements [4][5][6] are ca. three times higher than these two studies at room temperature.…”

“…Early measurements of reaction were made at room temperature . The experiments by Davis et al at Ar pressures of 67–530 mbar revealed no pressure dependence for k 1 at 298 K and characterized k 1 over 218–442 K mainly at 133 mbar…”

“…Sulfur-hydrocarbon chemistry is also involved in the deposition of diamond-like films [2], the com-bustion of sulfur-containing fuels, and in astrochemistry [3]. Here we present new measurements of the effective second-order rate constant k 1 for the reaction S 3 P J + C 2 H 4 (+Ar) → products (+Ar) (1) Early measurements of reaction (1) were made at room temperature [4][5][6]. The experiments by Davis et al [7] at Ar pressures of 67-530 mbar revealed no pressure dependence for k 1 at 298 K and characterized k 1 over 218-442 K mainly at 133 mbar k 1 = (7.13 ± 0.74) × 10 −12 exp −6.6 ± 0.3 kJ mol −1 /RT cm 3 molecule −1 s −1 (2) An early theoretical study of reaction (1) was made by McKee [8] using semiempirical methods.…”