scholarly journals Relative Rates of Bond Rotation and Ring Closure in the Photocycloaddition Intermediates from Fullerene-C60 and the Isomeric 2,4-Hexadienes

2019 ◽  
Author(s):  
Wendell Dilling
Keyword(s):  
Relative Rate ◽  
Product Distribution ◽  
Fullerene C60 ◽  
Ring Closure ◽  
Trans Conformation ◽  
Bond Rotation ◽  
Product Distributions

<p>Photocycloaddition of fullerene-C<sub>60 </sub>to the isomeric 2,4-hexadienesreported by Orfanopoulos and co-workers gave a series of 2 + 2 cycloadducts in which bond rotation had occurred in some products. Relative rates of bond rotation and ring closure in the biradical intermediates were calculated from the product distributions using equations developed by Bartlett and co-workers. These data are reinterpreted to show that the ratio of the rate of bond rotation in the intermediate to the rate of ring closure to the cyclobutane product is ~70 for the <i>trans</i>-1-propenyl intermediate formed in the initial cis conformation. Data are inconsistent for the analogous <i>cis</i>-1-propenyl intermediate. The relative rate for the <i>trans</i>-1-propenyl intermediate formed in the initial trans conformation is ~9. Accurate relative rate determinations are highly dependent on very accurate product distribution determinations.</p>

scholarly journals Relative Rates of Bond Rotation and Ring Closure in the Photocycloaddition Intermediates from Fullerene-C60 and the Isomeric 2,4-Hexadienes

2019 ◽  
Author(s):  
Wendell Dilling
Keyword(s):  
Relative Rate ◽  
Product Distribution ◽  
Fullerene C60 ◽  
Ring Closure ◽  
Trans Conformation ◽  
Bond Rotation ◽  
Product Distributions

<p>Photocycloaddition of fullerene-C<sub>60 </sub>to the isomeric 2,4-hexadienesreported by Orfanopoulos and co-workers gave a series of 2 + 2 cycloadducts in which bond rotation had occurred in some products. Relative rates of bond rotation and ring closure in the biradical intermediates were calculated from the product distributions using equations developed by Bartlett and co-workers. These data are reinterpreted to show that the ratio of the rate of bond rotation in the intermediate to the rate of ring closure to the cyclobutane product is ~70 for the <i>trans</i>-1-propenyl intermediate formed in the initial cis conformation. Data are inconsistent for the analogous <i>cis</i>-1-propenyl intermediate. The relative rate for the <i>trans</i>-1-propenyl intermediate formed in the initial trans conformation is ~9. Accurate relative rate determinations are highly dependent on very accurate product distribution determinations.</p>

scholarly journals Effect of NO<sub><i>x</i></sub> on 1,3,5-trimethylbenzene (TMB) oxidation product distribution and particle formation

2019 ◽  
Vol 19 (23) ◽  
pp. 15073-15086 ◽  
Author(s):  
Epameinondas Tsiligiannis ◽  
Julia Hammes ◽  
Christian Mark Salvador ◽  
Thomas F. Mentel ◽  
Mattias Hallquist
Keyword(s):  
Urban Areas ◽  
Organic Molecules ◽  
Flow Reactor ◽  
Organic Aerosol ◽  
Product Distribution ◽  
Particle Formation ◽  
Product Distributions ◽  
Tropospheric Aerosol ◽  
Volatile Organic ◽  
Free Environment

Abstract. Secondary organic aerosol (SOA) represents a significant fraction of the tropospheric aerosol and its precursors are volatile organic compounds (VOCs). Anthropogenic VOCs (AVOC) dominate the VOC budget in many urban areas with 1,3,5-trimethylbenzene (TMB) being among the most reactive aromatic AVOCs. TMB formed highly oxygenated organic molecules (HOMs) in an NOx-free environment, which could contribute to new particle formation (NPF) depending on oxidation conditions where elevated OH oxidation enhanced particle formation. The experiments were performed in an oxidation flow reactor, the Go:PAM unit, under controlled OH oxidation conditions. By addition of NOx to the system we investigated the effect of NOx on particle formation and on the product distribution. We show that the formation of HOMs, and especially HOM accretion products, strongly varies with NOx conditions. We observe a suppression of HOM and particle formation with increasing NOx/ΔTMB ratio and an increase in the formation of organonitrates (ONs) mostly at the expense of HOM accretion products. We propose reaction mechanisms and pathways that explain the formation and observed product distributions with respect to oxidation conditions. We hypothesise that, based on our findings from TMB oxidation studies, aromatic AVOCs may not contribute significantly to NPF under typical NOx/AVOC conditions found in urban atmospheres.

scholarly journals Atmospheric sink of methyl chlorodifluoroacetate and ethyl chlorodifluoroacetate: temperature dependent rate coefficients, product distribution of their reactions with Cl atoms and CF2ClC(O)OH formation

RSC Advances ◽  
2016 ◽  
Vol 6 (57) ◽  
pp. 51834-51844
Author(s):  
María B. Blanco ◽  
Ian Barnes ◽  
Peter Wiesen ◽  
Mariano A. Teruel
Keyword(s):  
Relative Rate ◽  
Product Distribution ◽  
Rate Coefficients ◽  
Gas Phase Reactions ◽  
Temperature Dependent ◽  
Dependent Rate ◽  
P Rate ◽  
Distribution Studies ◽  
First Time ◽  
Cl Atoms

Rate coefficients as a function of temperature and product distribution studies have been performed for the first time for the gas-phase reactions of chlorine atoms with methyl chlorodifluoracetate (k1) and ethyl chlorodifluoroacetate (k2) using the relative rate technique.

Product Distribution From Flash Pyrolysis of Coal in a Fast Fluidized Bed

2003 ◽  
Author(s):  
Lijie Cui ◽  
Jianzhong Yao ◽  
Weigang Lin ◽  
Zheng Zhang
Keyword(s):  
Particle Size ◽  
Pyrolysis Temperature ◽  
Pyrolysis Product ◽  
Product Distribution ◽  
Gaseous Product ◽  
Flash Pyrolysis ◽  
Product Distributions ◽  
Liquid Products ◽  
Liquid Yield ◽  
Increasing Temperature

The flash pyrolysis of Huolinhe coal was carried out in a fast-entrained bed reactor. The investigation focuses on the effects of pyrolysis temperature and particle size on pyrolysis product distributions and gas and liquid compositions. Increasing temperature results in an increase of the gaseous product. There is an optimum temperature on the maximum liquid yield, which is around 650°C. An increase in particle size leads to a decrease of liquid products. Some amount of phenol group was found in the liquid products, which may produce the chemicals with high value. The results provide fundamental data and optimal conditions to maximize light oils yields for the coal topping process.

Reactions of Alkyl Halides in Fused Salt Media

1971 ◽  
Vol 49 (1) ◽  
pp. 1-6 ◽  
Author(s):  
R. A. Bailey ◽  
S. F. Prest
Keyword(s):  
Organic Molecules ◽  
Product Distribution ◽  
Exchange Reactions ◽  
Cyclization Reactions ◽  
Composition Effects ◽  
Carbonium Ion ◽  
Product Distributions ◽  
Halide Exchange ◽  
Melt Composition ◽  
Acid Character

Passage of C1 to C5 haloalkanes through SnCl2–KCl melts results in halide exchange reactions, alkene formation, and rearrangement (including cyclization) reactions of the organic molecules. Relative reactivities, product distributions and melt composition effects are consistent with a carbonium ion mechanism in which the melt functions as a halide ion acceptor. Some control of product distribution by choice of Lewis acid character of the melt seems possible.

Reduction of Vicinal Dihalides. I. The Electrochemical Reduction of meso and (±)-1,2-Dibromo-1,2-diphenylethane

1990 ◽  
Vol 43 (8) ◽  
pp. 1421 ◽  
Author(s):  
P Fawell ◽  
J Avraamides ◽  
G Hefter
Keyword(s):  
Electrochemical Reduction ◽  
Intermediate Stage ◽  
Stepwise Mechanism ◽  
Bond Rotation ◽  
Reduction Potentials ◽  
Product Distributions

The mechanism of the electrochemical dehalogenation of organic vicinal dihalides has been examined in acetonitrile by using meso- and (�)-1,2-dibromo-1,2-diphenylethane. Reduction potentials and product distributions obtained from the isomeric dibromides could not be accommodated within a mechanism involving a concerted addition of two electrons. However, these results can be explained by a stepwise addition of electrons, allowing the possibility of bond rotation at an intermediate stage. The product distributions obtained from the reduction of the (�)- dibromide were found to be potential-dependent, a result not previously observed for this compound, but consistent with a stepwise mechanism.

Aerobic liquid-phase oxidation of p-xylene over metalloporphyrins

2007 ◽  
Vol 11 (07) ◽  
pp. 524-530 ◽  
Author(s):  
Quan Jiang ◽  
Hai-Yang Hu ◽  
Can-Cheng Guo ◽  
Qiang Liu ◽  
Jian-Xin Song ◽  
...  
Keyword(s):  
Liquid Phase ◽  
Terephthalic Acid ◽  
Oxidation Process ◽  
Product Distribution ◽  
Oxidation Products ◽  
Reaction Parameters ◽  
Efficient Catalyst ◽  
Product Distributions ◽  
Phase Oxidation ◽  
Intermediate Oxidation

The five metalloporphyrins ( T (p- Cl ) PPM , M = Fe , Mn , Co , Cu , Zn ) with different metal nuclei were synthesized, and their catalytic aerobic liquid-phase oxidations of p-xylene into p-toluic acid, p-toluic aldehyde and terephthalic acid using a low concentration of acetic acid as solvent without any halide additives, were studied. The p-xylene conversions and the oxidation product distributions were found to be affected by the structures and concentration of the metalloporphyrins as well as the reaction parameters such as time, temperature and air pressure. The formation of some intermediate oxidation products in the oxidation process also influenced the reaction conversions and the product distribution. Among the metalloporphyrins used, tetrakis(p-chlorophenylporphinato)manganese chloride ( T (p- Cl ) PPMnCl ) was the most efficient catalyst for the oxidation of p-xylene. Under the conditions of 180 °C and 2.0 MPa, 44% conversion of p-xylene and 85% selectivity of p-toluic acid were obtained. Based on the results obtained, a preliminary mechanism of the oxidation of p-xylene over metalloporphyrins was proposed.

Kinetische Analyse zur Umwandlung von Oxirenen oder Thiirenen und ihren offenkettigen Valenzisomeren / Kinetic Analysis for the Conversion of Oxirenes or Thiirenes and their Open-Chain Valence Isomers

1980 ◽  
Vol 35 (8) ◽  
pp. 1040-1048 ◽  
Author(s):  
Herbert Meier ◽  
Heinz Kolshorn
Keyword(s):  
Experimental Data ◽  
Kinetic Models ◽  
Ring Opening ◽  
Product Distribution ◽  
Ring Closure ◽  
Quantitative Interpretation ◽  
Open Chain ◽  
Energy Profiles ◽  
Ring Opening Reactions ◽  
Kinetische Analyse

Abstract Ring closure and ring opening reactions possess an outstanding significance for the formation and reactivity of antiaromatic heterocycles like oxirenes and thiirenes. The valence isomerisations 2 ⇆ 1 ⇆ 2' can be controlled by the product distribution 2 → P/2' → P'. A quantitative interpretation of many experimental data, published in the last years, is given on the basis of a few kinetic models, which consider thermal and photochemical pathways. Possible energy profiles of single hypersurfaces (S0 or S1) and the transition between different hypersurfaces (S1 → S0) are the most important features of these models.

On random simplices in product distributions

1980 ◽  
Vol 17 (2) ◽  
pp. 553-558 ◽  
Author(s):  
Hiroshi Maehara
Keyword(s):  
Product Distribution ◽  
Asymptotically Normal ◽  
Product Distributions ◽  
Sample Points

It is proved that the r-dimensional volume Vn of the r-simplex spanned by r + 1 sample points taken from the n-fold product distribution of a distribution F is asymptotically normal as n →∞.

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