“…The data in the figure show that at least 80% of the cis isomer has converted to trans -DBA in 2 h, and the solution has almost completely recovered in 3 h. The solid lines are exponential fits with a decay time of 67 min (rate 1.5 × 10 -3 min -1 ). This value is in good agreement with other thermal isomerization rates observed for substituted azobenzenes in solution. ,, 4 Thermal isomerization of cis - to trans -DBA in DCE solution. Absorbances at 365 nm (filled circles) and 440 nm (open circles) of DBA in DCE solution at room temperature are plotted as a function of time after the solution had been illuminated with 365 nm light.…”
The surface-sensitive spectroscopic technique of optical second
harmonic generation (SHG) is employed to
study the adsorption and photochemistry of surfactant molecules at the
water/1,2-dichloroethane (DCE)
interface. Resonant SHG measurements at 730 nm are used to monitor
the adsorption of the azobenzene
surfactant 4-[[(dodecyloxy)benz-4-yl]azo]benzoic
acid (DBA) from DCE solution to the interface at an
aqueous
pH of 8 or greater. The concentration and pH dependence of the
resonant SHG from the adsorbed monolayer
indicates that the DBA exists in its anionic (carboxylate) form at the
interface. In a series of combined
photochemical/SHG experiments the trans/cis
photoisomerization of the adsorbed DBA anions is examined.
SHG measurements demonstrate that illumination of the surface with
light at 365 nm converts the adsorbed
trans-DBA molecules to the cis isomer. The
cis-DBA anion is found to be unusually stable at the
liquid/liquid interface, and the entire photoactive monolayer (total area 4
cm2) can be photochemically converted in
approximately 450 s with an illumination spot of 0.12 cm2.
This relatively short conversion time is attributed
to surface-tension-induced convection effects that occur during the
photochemical conversion of the monolayer.
Illumination of the cis-DBA anions with light at 440 nm
reconverts the entire surfactant monolayer back to
the trans-DBA form in the same time frame.
“…The data in the figure show that at least 80% of the cis isomer has converted to trans -DBA in 2 h, and the solution has almost completely recovered in 3 h. The solid lines are exponential fits with a decay time of 67 min (rate 1.5 × 10 -3 min -1 ). This value is in good agreement with other thermal isomerization rates observed for substituted azobenzenes in solution. ,, 4 Thermal isomerization of cis - to trans -DBA in DCE solution. Absorbances at 365 nm (filled circles) and 440 nm (open circles) of DBA in DCE solution at room temperature are plotted as a function of time after the solution had been illuminated with 365 nm light.…”
The surface-sensitive spectroscopic technique of optical second
harmonic generation (SHG) is employed to
study the adsorption and photochemistry of surfactant molecules at the
water/1,2-dichloroethane (DCE)
interface. Resonant SHG measurements at 730 nm are used to monitor
the adsorption of the azobenzene
surfactant 4-[[(dodecyloxy)benz-4-yl]azo]benzoic
acid (DBA) from DCE solution to the interface at an
aqueous
pH of 8 or greater. The concentration and pH dependence of the
resonant SHG from the adsorbed monolayer
indicates that the DBA exists in its anionic (carboxylate) form at the
interface. In a series of combined
photochemical/SHG experiments the trans/cis
photoisomerization of the adsorbed DBA anions is examined.
SHG measurements demonstrate that illumination of the surface with
light at 365 nm converts the adsorbed
trans-DBA molecules to the cis isomer. The
cis-DBA anion is found to be unusually stable at the
liquid/liquid interface, and the entire photoactive monolayer (total area 4
cm2) can be photochemically converted in
approximately 450 s with an illumination spot of 0.12 cm2.
This relatively short conversion time is attributed
to surface-tension-induced convection effects that occur during the
photochemical conversion of the monolayer.
Illumination of the cis-DBA anions with light at 440 nm
reconverts the entire surfactant monolayer back to
the trans-DBA form in the same time frame.
“…| 2) = 0.95 ± 0.05 at 5 Torr for the trans and { 2| = 0.93 ± 0.05 at 4 Torr for the cis isomer. Evidence was given in favor of a triplet biradical Intermediate, and the mechanism outlined is shown in Scheme XI.…”
Section: Scheme VIIImentioning
confidence: 94%
“…140 Wellington et al134 tabulated the Arrhenius parameters, and they are listed in Table VII. They correlated the kinetic and molecular parameters for the decomposition reaction and postulated that the driving force of the reaction was the resonance energy of the product formed in each case. An important role H2C-CH2 Factor of 4 uncertainty.…”
Section: Monoolefinsmentioning
confidence: 99%
“…Wu and Heicklen150 studied the photolysis of 0.05 to 4.7 Torr of pyrrole vapor at 213.9 nm and room temperature. The main products were CH3CCH (methylacetylene), CH2CCH2 (aliene), 4, H2, and C2H2. Minor products were CH4 and C3H6, which were secondary products resulting from the reaction of H atoms with the C3H4 products.…”
The gas phase thermal decomposition of triallylamine was studied in the temperature range 531 to 620 K. The major products observed in the reaction were propylene and 3‐picoline. The first order rate constants for depletion of triallylamine, obtained using the internal standard technique, are found to be independent of pressure and conversion, and fit the Arrheniusrelationship
The reaction appears to be homogeneous, as a 15‐fold change in thc surface‐to‐volume ratio of the vessel left the rate constants unchanged. The Arrhenius parameters are consistent with a molecular elimination reaction involving a six‐center transition state, yielding propylene and N‐allyl‐prop‐2‐enaldimine. It is proposed that the latter product undergoes a 1,5‐hydrogen transfer, followed by a ring closure reaction to yield dihydropicoline, which in turn reacts forming 3‐picoline via a self‐initiated decomposition reaction.
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