The Reaction of O(3P) with C2Cl4

1974 ◽  
Vol 52 (23) ◽  
pp. 3870-3878 ◽  
Author(s):  
Eugenio Sanhueza ◽  
Julian Heicklen
Keyword(s):  
Reaction Mechanism ◽  
Quantum Yield ◽  
Chain Length ◽  
Rate Coefficient ◽  
Chain Process ◽  
Reaction Conditions ◽  
Text Production ◽  
Competitive Kinetics ◽  
A Chain ◽  
Cl Atom

The reaction of O(3P), prepared from Hg photosensitization of N2O with C2Cl4 was studied at 25 °C. The exclusive products of the reaction in the absence of O2 were CCl2O and polymer (as well as N2 from the N2O). The quantum yield of CCl2O production, Φ{CCl2O}, was 0.19 independent of the C2Cl4 pressure or the absorbed intensity, Ia. There was no evidence for CO, Cl2, c-C3Cl6, CCl3CCl(O), or [Formula: see text] production. The reaction mechanism is[Formula: see text]with k12a/k12 = 0.19. The CCl2 radical dimerizes and the energetic C2Cl4O* intermediate polymerizes. By competitive kinetics, the ratio k12/k13 was found to be 0.10, where k12 ≡ k12a + k12b and k13 is the rate coefficient of the O(3P) + C2F4 reaction.In the presence of O2, a chain process is involved in which CCl3CCl(O) and CCl2O are the major products. They are formed in a ratio of 2.0 independent of reaction conditions, but the chain length is proportional to [C2Cl4]/Ia1/2. Also produced is CO with a quantum yield of ∼0.18. The ratio Φ{CCl3CCl(O)}/Φ{CCl2O} = 2.0 is similar to that of 2.5 found in the Cl atom initiated oxidation. This result is interpreted to mean that chlorine atoms are involved in the chain. The reaction which initiates monoradicals in the system is[Formula: see text]

The photolysis of ozone by ultraviolet radiation. I. The photolysis of pure, dry ozone

1965 ◽  
Vol 288 (1413) ◽  
pp. 200-211 ◽  
Keyword(s):  
Reaction Mechanism ◽  
Quantum Yield ◽  
Light Intensity ◽  
Ultraviolet Radiation ◽  
Oxygen Molecule ◽  
Inert Gases ◽  
Ozone Variation ◽  
Photochemical Decomposition ◽  
A Chain ◽  
Limiting Value

The photochemical decomposition of dry ozone has been studied at λ = 2537 Å. The quantum yield for the photolysis of pure ozone was proportional to the pressure of ozone; the highest quantum yield recorded was 16.7 at a pressure of 5 cmHg ozone. Variation of light intensity did not markedly affect the quantum yield, and some evidence was found for a wall termination reaction. A reaction mechanism is proposed in which O( 1 D ) atoms, formed in the primary photolysis, initiate a chain propagated by energy-rich oxygen molecules. A discussion of the nature of the energy-rich molecules is presented. Addition of inert gases to the pure ozone reduces the quantum yield to a limiting value of two. This is explained in terms of the deactivation of the energy-rich oxygen molecule. In the presence of oxygen, the quantum yield tends to zero, as a result of the reverse reaction O + O 2 + M → O 3 + M .

The Chlorine Atom Sensitized Oxidation and the Ozonolysis of C2Cl4

1974 ◽  
Vol 52 (23) ◽  
pp. 3852-3862 ◽  
Author(s):  
Eckart Mathias ◽  
Eugenio Sanhueza ◽  
I. C. Hisatsune ◽  
Julian Heicklen
Keyword(s):  
Free Radicals ◽  
Chain Length ◽  
Chlorine Atom ◽  
Chain Process ◽  
Chain Mechanism ◽  
A Chain ◽  
A Minor ◽  
Long Chain

The chlorine atom initiated oxidation of C2Cl4 was studied both in the absence and presence of O3 at 24 and 32 °C. In the absence of O3, the products are CCl3CCl(O) and CCl2O, and they are produced in a long-chain process in a ratio of 2.5 at 24 °C and 3.0 at 32 °C. The product producing step involves the decay of C2Cl5O radicals[Formula: see text]The ratio k6a/k6b is 5.0 at 24 °C and 6.0 at 32 °C since CCl3 reacts with O2 to produce another CCl2O molecule. In the presence of O3 the ratio Φ{CCl3CCl(O)}/Φ{CCl2O} drops, [Formula: see text] is produced, and the chain length is reduced. The change in Φ{CCl3CCl(O)}/Φ{CCl2O} is a function of [O3]/[O2] and is attributed to the additional reactions[Formula: see text]The epoxide yield is a function of [C2Cl4]/[O3] and is attributed to the reaction of ClO with C2Cl4. The ClO is produced by the reaction of Cl• with O3[Formula: see text]which competes with[Formula: see text]The ratio k2/kl0 = 6.7. The reduction in yield as O3 is added results from the terminating reaction[Formula: see text]The ClO2 reacts further with O3 to produce Cl2O7.The reaction of O3 with C2Cl4 at 24 °C also produces mainly CCl3CCl(O) and CCl2O with [Formula: see text] as a minor product. Other minor products detected after extended conversions included Cl2, CO, and CO2. However c-C3Cl6 was not found. The ratio [CCl3CCl(O)]/[CCl2O] is < 1. Moreover, the addition of O2 retarded the reaction, indicating a long chain mechanism in which both free radicals (species with an odd number of electrons) and CCl2 were absent. A diradical chain mechanism is presented which explains the main features. The chain step is the addition of CCl2O2 to C2Cl4[Formula: see text]The adduct then reacts with O3 in a chain regenerating step or with O2 in a chain terminating step.

The Hg 6(3P)-Photosensitized Oxidation of C2Cl4

1974 ◽  
Vol 52 (23) ◽  
pp. 3863-3869 ◽  
Author(s):  
Eugenio Sanhueza ◽  
Julian Heicklen
Keyword(s):  
Quantum Yield ◽  
Chlorine Atom ◽  
Quantum Yields ◽  
Chain Process ◽  
Reaction Conditions ◽  
Radical Chain ◽  
Detailed Mechanism ◽  
Chain Oxidation ◽  
Atom Chain ◽  
Radical Chain Process

The Hg 6(3P) sensitized photolysis of C2Cl4 was studied at 25 °C both in the absence and presence of N2O and O2. For C2Cl4 alone, the only products are polymer and Hg2Cl2. The quantum yield of C2Cl4 disappearance, −Φ{C2Cl4} ∼ 1. Thus, the photolysis produces C2Cl3 radicals and Hg2Cl2, the C2Cl3 radicals dimerize, and the resultant 1,3-C4Cl6 polymerizes. The relative quenching of Hg 6(6P) by C2Cl4 compared to N2O is 3.0.In the presence of O2 the products are CCl3CCl(O) and CCl2O which are formed in a radical chain process in a ratio of 2.6 independent of reaction conditions. CO is also produced with a quantum yield of unity. The quantum yields of the chlorine-containing products are independent of the O2 pressure and the absorbed intensity, but are proportional to the C2Cl4 pressure, the proportionality constants being 1.4 and 3.7 Torr−1, respectively, for CCl2O and CCl3CCl(O). A detailed mechanism, based on the chlorine atom chain oxidation, is presented, and appropriate rate constant ratios are evaluated.

scholarly journals Ring-Opening Copolymerization of Cyclohexene Oxide and Cyclic Anhydrides Catalyzed by Bimetallic Scorpionate Zinc Catalysts

Polymers ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 1651
Author(s):  
Felipe de la Cruz-Martínez ◽  
Marc Martínez de Sarasa Buchaca ◽  
Almudena del Campo-Balguerías ◽  
Juan Fernández-Baeza ◽  
Luis F. Sánchez-Barba ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Reaction Mechanism ◽  
Catalytic System ◽  
Phthalic Anhydride ◽  
Ring Opening ◽  
High Selectivity ◽  
Zinc Complexes ◽  
Cyclohexene Oxide ◽  
Reaction Conditions ◽  
Cyclic Anhydrides

The catalytic activity and high selectivity reported by bimetallic heteroscorpionate acetate zinc complexes in ring-opening copolymerization (ROCOP) reactions involving CO2 as substrate encouraged us to expand their use as catalysts for ROCOP of cyclohexene oxide (CHO) and cyclic anhydrides. Among the catalysts tested for the ROCOP of CHO and phthalic anhydride at different reaction conditions, the most active catalytic system was the combination of complex 3 with bis(triphenylphosphine)iminium as cocatalyst in toluene at 80 °C. Once the optimal catalytic system was determined, the scope in terms of other cyclic anhydrides was broadened. The catalytic system was capable of copolymerizing selectively and efficiently CHO with phthalic, maleic, succinic and naphthalic anhydrides to afford the corresponding polyester materials. The polyesters obtained were characterized by spectroscopic, spectrometric, and calorimetric techniques. Finally, the reaction mechanism of the catalytic system was proposed based on stoichiometric reactions.

Local structural changes in polyamorphous (Ni,Fe)Ox electrocatalysts suggest a dual-site oxygen evolution reaction mechanism

2021 ◽  
Author(s):  
Martin Schon ◽  
Oliver Calderon ◽  
Nick Randell ◽  
Santiago Jimenez Villegas ◽  
Katelynn M. Daly ◽  
...  
Keyword(s):  
Reaction Mechanism ◽  
Oxygen Evolution ◽  
Oxygen Evolution Reaction ◽  
Structural Changes ◽  
Mixed Metal Oxides ◽  
Reaction Conditions ◽  
Nickel Iron ◽  
Alkaline Reaction ◽  
Dual Site ◽  
Economical Alternative

Amorphous nickel-iron mixed metal oxides have been shown to be extremely efficient oxygen evolution reaction (OER) electrocatalysts with good stability in alkaline reaction conditions. Thus, they offer an economical alternative...

scholarly journals The relationship between lymphangion chain length and maximum pressure generation established through in vivo imaging and computational modeling

2017 ◽  
Vol 313 (6) ◽  
pp. H1249-H1260 ◽  
Author(s):  
Mohammad S. Razavi ◽  
Tyler S. Nelson ◽  
Zhanna Nepiyushchikh ◽  
Rudolph L. Gleason ◽  
J. Brandon Dixon
Keyword(s):  
Nitric Oxide ◽  
Smooth Muscle ◽  
Minimally Invasive ◽  
Chain Length ◽  
Maximum Pressure ◽  
Computational Simulations ◽  
A Chain ◽  
Lymphatic Pumping ◽  
The Relationship

The intrinsic contraction of collecting lymphatic vessels serves as a pumping system to propel lymph against hydrostatic pressure gradients as it returns interstitial fluid to the venous circulation. In the present study, we proposed and validated that the maximum opposing outflow pressure along a chain of lymphangions at which flow can be achieved increases with the length of chain. Using minimally invasive near-infrared imaging to measure the effective pumping pressure at various locations in the rat tail, we demonstrated increases in pumping pressure along the length of the tail. Computational simulations based on a microstructurally motivated model of a chain of lymphangions informed from biaxial testing of isolated vessels was used to provide insights into the pumping mechanisms responsible for the pressure increases observed in vivo. These models suggest that the number of lymphangions in the chain and smooth muscle cell force generation play a significant role in determining the maximum outflow pressure, whereas the frequency of contraction has no effect. In vivo administration of nitric oxide attenuated lymphatic contraction, subsequently lowering the effective pumping pressure. Computational simulations suggest that the reduction in contractile strength of smooth muscle cells in the presence of nitric oxide can account for the reductions in outflow pressure observed along the lymphangion chain in vivo. Thus, combining modeling with multiple measurements of lymphatic pumping pressure provides a method for approximating intrinsic lymphatic muscle activity noninvasively in vivo while also providing insights into factors that determine the extent that a lymphangion chain can transport fluid against an adverse pressure gradient. NEW & NOTEWORTHY Here, we report the first minimally invasive in vivo measurements of the relationship between lymphangion chain length and lymphatic pumping pressure. We also provide the first in vivo validation of lumped parameter models of lymphangion chains previously developed through data obtained from isolated vessel testing.

A New Simple Procedure for the Synthesis of Heptamethyl Cyclohepta-1,3,5-triene-1,2,3,4,5,6,7-heptacarboxylate

Synlett ◽  
2018 ◽  
Vol 29 (09) ◽  
pp. 1157-1160 ◽  
Author(s):  
Alexander Belyy ◽  
Dmitry Platonov ◽  
Rinat Salikov ◽  
Anastasiya Levina ◽  
Yury Tomilov
Keyword(s):  
Reaction Mechanism ◽  
Nmr Spectroscopy ◽  
Simple Procedure ◽  
Reaction Conditions

A new and simple procedure for the synthesis of heptamethyl cyclohepta-1,3,5-triene-1,2,3,4,5,6,7-heptacarboxylate in a 51% yield is presented. An optimization of the reaction conditions was performed, and a convenient protocol for the isolation of the reaction product was developed. The structure of the key electrophilic intermediate was determined by means of NMR spectroscopy, and a plausible reaction mechanism is proposed.

scholarly journals Enzyme catalysis as a chain reaction

1991 ◽  
Vol 279 (3) ◽  
pp. 855-861 ◽  
Author(s):  
S E Szedlacsek ◽  
R G Duggleby ◽  
M O Vlad
Keyword(s):  
Reaction Mechanism ◽  
Kinetic Mechanism ◽  
Point Of View ◽  
Simple Type ◽  
Chain Reaction ◽  
Proposed Model ◽  
New Type ◽  
A Chain ◽  
Theoretical Considerations ◽  
Classical Mechanism

A new type of enzyme kinetic mechanism is suggested by which catalysis may be viewed as a chain reaction. A simple type of one-substrate/one-product reaction mechanism has been analysed from this point of view, and the kinetics, in both the transient and the steady-state phases, has been reconsidered. This analysis, as well as literature data and theoretical considerations, shows that the proposed model is a generalization of the classical ones. As a consequence of the suggested mechanism, the expressions, and in some cases even the significance of classical constants (Km and Vmax.), are altered. Moreover, this mechanism suggests that, between two successive enzyme-binding steps, more than one catalytic act could be accomplished. The reaction catalysed by alcohol dehydrogenase was analysed, and it was shown that this chain-reaction mechanism has a real contribution to the catalytic process, which could become exclusive under particular conditions. Similarly, the mechanism of glycogen phosphorylase is considered, and two partly modified versions of the classical mechanism are proposed. They account for both the existing experimental facts and suggest the possibility of chain-reaction pathways for any polymerase.

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