PART ONE: A STUDY OF UNIMOLECULAR GAS PHASE REACTIONS NEAR THE LIMITING FIRST ORDER REGION. PART TWO: THE HYDROGEN ISOTOPE EFFECT IN THE THERMAL DECOMPOSITION OF CYCLOBUTANE. Thesis

Thesis/Dissertation · Tue Jan 01 00:00:00 UTC 1963

OSTI ID:4118855

Carr, Jr, R W

The thermal decomposition of cyclobutane and the thermal isomerization of cyclobutene were investigated at pressures greater than those at which the first-order rate constants begin to fall appieciably from their high pressure limit. The thermal decomposition of cyclobutane at pressures up to 1500 mm Hg over the temperature range 418 to 460 deg C was found to be a first order, homogeneous process yielding ethylene as the only product of any significance. At 449 deg C the experimental first-order rate constants for the decomposition do not change detectably with pressure from 100 to 1500 mm Hg, showing that the high pressure limit of this reaction was essentially reached The activation energy with 650 to 1500 mm Hg initial pressure was found to be 62.5 plus or minus 0.4 kcal/mole. The experimentally determined rate constant at 650to 1500 mm Hg is representative of the high pressure limit and may be expressed as k = 4,24 x 10/ sup 15/ exp(-62,500/RT) sec/sup -1/. At 1500 mm Hg the thermal isomerization of cyclobutene produces 1,3-butadiene by a first-order process, which is free of significant side reactions. Rate measurements over the range from 50to 1500 mm Hg at both 150 deg C and 175 deg C indicated that the increase in initial pressure produces very little change in the first-order rate constants in this region. The temperature dependence of the isomerization was studied at pressures near 100 and 1500 mm Hg. The activation energy was observed not to change over this pressure range, and the value at the high pressure limit is most probably 32.6 plus or minus 0.5 kcal/mole. The thermal decomposition of mixtures of cyclobutane and cyclobutane-d/sub 8/ was studied. The value of the isotope effect (k/sub H//k/sub D/) at 449 deg C and 100 mm Hg is 1.39. The isotope effect is pressure dependent. The ratio (k/sub H//d/sub D//) reaches a value of unity near 0.1 mm Hg, and at even lower pressures an inverse isotope effect was observed. The temperature dependence of the isotope effect can be expressed as k/ sub H//k/sub D/ = 0.45 exp (1600/RT). (M.P.G.)

• Research Organization: Originating Research Org. not identified
• DOE Contract Number: NONE
• NSA Number: NSA-18-012136
• OSTI ID: 4118855
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

ACTIVATION ENERGY
BUTADIENE
BUTANE
BUTYLENE
CHEMISTRY
CYCLOALKANES
CYCLOALKENES
DECONTAMINATION
DEUTERIUM
ETHYLENE
HEATING
HYDROGEN
ISOMERS
ISOTOPE EFFECTS
PRESSURE
REACTION KINETICS
TEMPERATURE