Novel Products in the CO2-Laser Induced Reaction of Trichloroethylene

1995 ◽  
Vol 60 (1) ◽  
pp. 104-114 ◽  
Author(s):  
Boyd L. Earl ◽  
Richard L. Titus
Keyword(s):  
Irradiation Time ◽  
Product Distribution ◽  
Incident Power ◽  
Cell Geometry ◽  
Reaction Conditions ◽  
Peak Areas ◽  
Induced Decomposition ◽  
Nmr Methods ◽  
Induced Reaction ◽  
Novel Products

Previous reports on the thermal or CO2-laser induced decomposition of trichloroethylene have identified only one condensible product, hexachlorobenzene (in addition to HCl and mono- and dichloroacetylene). We have found that trichloroethylene vapor exposed to cw irradiation on the P(24) line of the (001 - 100) band of the CO2 laser at incident power levels from 8 - 17 W produces numerous products, of which the 13 major ones have been identified using IR, GC/MS, GC/FTIR, and NMR methods. All of these products have 4, 6, or 8 carbons, are highly unsaturated, and are completely chlorinated or contain a single hydrogen. C4HCl5 and C6Cl6 isomers (three of each) account for S 55% to 85% of total products (based on peak areas in the total ion chromatograms in GC/MS runs), depending on reaction conditions. In addition to characterizing the products, we discuss the dependence of the product distribution on laser power, irradiation time, and cell geometry, and we outline a possible mechanism.

A review of lignin hydrogen peroxide oxidation chemistry with emphasis on aromatic aldehydes and acids

Holzforschung ◽  
2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Ajinkya More ◽  
Thomas Elder ◽  
Zhihua Jiang
Keyword(s):  
Hydrogen Peroxide ◽  
Oxidative Degradation ◽  
Reaction Medium ◽  
Dicarboxylic Acids ◽  
Aromatic Aldehydes ◽  
Product Distribution ◽  
Reaction Conditions ◽  
Alkaline Conditions ◽  
The Stability ◽  
Oxidation Chemistry

Abstract This review discusses the main factors that govern the oxidation processes of lignins into aromatic aldehydes and acids using hydrogen peroxide. Aromatic aldehydes and acids are produced in the oxidative degradation of lignin whereas mono and dicarboxylic acids are the main products. The stability of hydrogen peroxide under the reaction conditions is an important factor that needs to be addressed for selectively improving the yield of aromatic aldehydes. Hydrogen peroxide in the presence of heavy metal ions readily decomposes, leading to minor degradation of lignin. This degradation results in quinones which are highly reactive towards peroxide. Under these reaction conditions, the pH of the reaction medium defines the reaction mechanism and the product distribution. Under acidic conditions, hydrogen peroxide reacts electrophilically with electron rich aromatic and olefinic structures at comparatively higher temperatures. In contrast, under alkaline conditions it reacts nucleophilically with electron deficient carbonyl and conjugated carbonyl structures in lignin. The reaction pattern in the oxidation of lignin usually involves cleavage of the aromatic ring, the aliphatic side chain or other linkages which will be discussed in this review.

Optimization of biodiesel synthesis under simultaneous ultrasound-microwave irradiation using response surface methodology (RSM)

2015 ◽  
Vol 4 (4) ◽  
Author(s):  
Seyed Mohammad Safieddin Ardebili ◽  
Teymor Tavakoli Hashjin ◽  
Barat Ghobadian ◽  
Gholamhasan Najafi ◽  
Stefano Mantegna ◽  
...  
Keyword(s):  
Response Surface Methodology ◽  
Microwave Irradiation ◽  
Response Surface ◽  
Palm Oil ◽  
Catalyst Concentration ◽  
Irradiation Time ◽  
Operating Conditions ◽  
Molar Ratio ◽  
Reaction Conditions ◽  
Biodiesel Synthesis

AbstractThis work investigates the effect of simultaneous ultrasound-microwave irradiation on palm oil transesterification and uncovers optimal operating conditions. Response surface methodology (RSM) has been used to analyze the influence of reaction conditions, including methanol/palm oil molar ratio, catalyst concentration, reaction temperature and irradiation time on biodiesel yield. RSM analyses indicate 136 s and 129 s as the optimal sonication and microwave irradiation times, respectively. Optimized parameters for full conversion (97.53%) are 1.09% catalyst concentration and a 7:3.1 methanol/oil molar ratio at 58.4°C. Simultaneous ultrasound-microwave irradiation dramatically accelerates the palm oil transesterification reaction. Pure biodiesel was obtained after only 2.2 min while the conventional method requires about 1 h.

Halogenation of Butyl Rubber—A Model Compound Approach

1984 ◽  
Vol 57 (2) ◽  
pp. 275-283 ◽  
Author(s):  
R. Vukov
Keyword(s):  
Model Compound ◽  
Product Distribution ◽  
Butyl Rubber ◽  
Methyl Groups ◽  
Reaction Site ◽  
Model Compounds ◽  
Reaction Conditions ◽  
Basic Study ◽  
Rubber Model ◽  
Trisubstituted Alkenes

Abstract The study of the halogenation behavior of butyl rubber model compounds has brought about a better understanding of the behavior of these systems. It has been established that the presence of methyl groups, in a position B to the reaction site in the butyl rubber model compound, profoundly influences the course of halogenation. Due to the steric hindrance imposed by these groups, both the products of chlorination and bromination deviate from patterns typical of other trisubstituted alkenes. In the case of chlorination, this deviation is demonstrated by the absence of addition products of chlorine across the double bond. In the case of bromination reactions, the change in product distribution is even more dramatic. Thus, substitution products normally not observed in bromination reactions of other trisubstituted alkenes become predominant products found in yields of between 70–90% depending on the precise reaction conditions. The behavior of the butyl model compound appears to be entirely consistent with the behavior of butyl rubber itself; the model compound approach is therefore a valuable tool for use in the basic study of this type of system.

scholarly journals A mass spectrometric study of secondary organic aerosols formed from the photooxidation of anthropogenic and biogenic precursors in a reaction chamber

2006 ◽  
Vol 6 (12) ◽  
pp. 5279-5293 ◽  
Author(s):  
M. R. Alfarra ◽  
D. Paulsen ◽  
M. Gysel ◽  
A. A. Garforth ◽  
J. Dommen ◽  
...  
Keyword(s):  
Irradiation Time ◽  
Organic Aerosols ◽  
Mass Spectrometric Study ◽  
Product Distribution ◽  
Reaction Chamber ◽  
Oxidation Products ◽  
Effective Density ◽  
Mass Spectral ◽  
Fragmentation Patterns ◽  
The Right

Abstract. An Aerodyne Aerosol Mass Spectrometer (AMS) has been utilised to provide on-line measurements of the mass spectral signatures and mass size distributions of the oxidation products resulting from irradiating 1,3,5-trimethylbenzene (1,3,5-TMB) and α-pinene, separately, in the presence of nitrogen oxide, nitrogen dioxide and propene in a reaction chamber. Mass spectral results indicate that both precursors produce SOA with broadly similar chemical functionality of a highly oxidised nature. However, significant differences occur in the minor mass spectral fragments for the SOA in the two reaction systems, indicating that they have different molecular composition. Nitrogen-containing organic compounds have been observed in the photooxidation products of both precursors, and their formation appeared to be controlled by the temporal variability of NOx. Although the overall fragmentation patterns of the photooxidation products in both systems did not change substantially over the duration of each experiment, the contribution of some individual mass fragments to total mass appeared to be influenced by the irradiation time. The effective densities of the 1,3,5-TMB and α-pinene SOA particles were determined for various particle sizes using the relationship between mobility and vacuum aerodynamic diameters. The effective density for the 1,3,5-TMB SOA ranged from 1.35–1.40 g/cm3, while that for α-pinene SOA ranged from 1.29–1.32 g/cm3. The determined effective densities did not show dependence on irradiation time. Results suggest that further chemical processing of SOA takes place in the real atmosphere, as neither the α-pinene nor the 1,3,5-TMB experimental results reproduce the right relative product distribution between carbonyl-containing and multifunctional carboxylic acid species measured at ambient locations influenced by aged continental organic aerosols.

Nanostructured Co3O4 Oxide for Low Temperature Ethanol Oxidation

2014 ◽  
Vol 798-799 ◽  
pp. 205-210
Author(s):  
Jairo Alberto Gomez-Cuaspud ◽  
Martin Schmal
Keyword(s):  
Ethanol Oxidation ◽  
Physicochemical Characterization ◽  
Fluorescence Analysis ◽  
Product Distribution ◽  
X Ray Diffraction ◽  
Ethanol Oxidation Reaction ◽  
Reaction Conditions ◽  
X Ray ◽  
Temperature Programmed ◽  
Combustion Technique

We investigated the synthesis of nanosized Co3O4 oxide by the polymerization-combustion technique, with different concentrations (3, 12 and 25% w/w) in the ethanol oxidation reaction. Characterization was done by X-ray fluorescence analysis, X-ray diffraction, temperature programmed reduction, scanning and transmission electronic microscopy and CO and H2 chemisorption. Principal results from physicochemical characterization show that the concentration of the metal oxide influence the product distribution and selectivity under isothermal conditions at 420 °C showed the formation of intermediate etoxi-species and preferential dehydrogenation reaction on stream of material. Specific concentrations result in high conversions and H2 selectivity under present reaction conditions.

scholarly journals Flow-mode biodiesel production from palm oil using a pressurized microwave reactor

2019 ◽  
Vol 8 (1) ◽  
pp. 8-14 ◽  
Author(s):  
Seyed Mohammad Safieddin Ardebili ◽  
Xinyu Ge ◽  
Giancarlo Cravotto
Keyword(s):  
Palm Oil ◽  
Irradiation Time ◽  
Biodiesel Production ◽  
Molar Ratio ◽  
Flow Mode ◽  
Reaction Conditions ◽  
Surface Method ◽  
Optimized Conditions ◽  
Reactor Pressure ◽  
Palm Oil Biodiesel

Abstract The factors that influence microwave-assisted biodiesel production reactions have been analyzed in this investigation. The studied parameters included microwave (MW) power, irradiation time, and reactor pressure. The response surface method was used to optimize the reaction conditions. The conversion for the 6:1 methanol/oil molar ratio and 1% catalyst ranged from 68.4% to 96.71%. The optimized conditions were found to be 138 s of MW irradiation at 780 W and 7 bar pressure. The conversion at this point was 97.82%. Biodiesel yield increased at higher radiation times (90–130 s) and pressures (5–7 bar). Results show that MW power and irradiation time have significant effects at the 1% level, whereas pressure had significant effects at the 5% level on biodiesel production in this range. The major properties of the palm oil biodiesel produced herein have met the requirements of the EN 14214 methyl ester standard.

scholarly journals Deoxydehydration of vicinal diols by homogeneous catalysts: a mechanistic overview

2019 ◽  
Vol 6 (11) ◽  
pp. 191165 ◽  
Author(s):  
Kayla A. DeNike ◽  
Stefan M. Kilyanek
Keyword(s):  
Reaction Mechanism ◽  
Product Distribution ◽  
Catalytic Cycle ◽  
Reaction Conditions ◽  
Homogeneous Catalysts ◽  
Commodity Chemicals ◽  
Reduction Methods ◽  
Vicinal Diols ◽  
Catalyst Systems

Deoxydehydration (DODH) is an important reaction for the upconversion of biomass-derived polyols to commodity chemicals such as alkenes and dienes. DODH can be performed by a variety of early metal-oxo catalysts incorporating Re, Mo and V. The varying reduction methods used in the DODH catalytic cycle impact the product distribution, reaction mechanism and the overall yield of the reaction. This review surveys the reduction methods commonly used in homogeneous DODH catalyst systems and their impacts on yield and reaction conditions.

The Reaction of Thiols and α,ω-Dithiols With Triphenylphosphine and Diisopropyl Azodicarboxylate

1990 ◽  
Vol 43 (1) ◽  
pp. 161 ◽  
Author(s):  
D Camp ◽  
ID Jenkins
Keyword(s):  
Chain Length ◽  
Disulfide Bond ◽  
Alkyl Chain ◽  
Bond Formation ◽  
Product Distribution ◽  
Alkyl Chain Length ◽  
Disulfide Bond Formation ◽  
Reaction Conditions ◽  
Mitsunobu Reactions

α,ω-Dithiols in the presence of triphenylphosphine and diisopropyl azodicarboxylate are converted into a mixture of monomeric and polymeric disulfides. The product distribution is dependent on the alkyl chain length and the reaction conditions. In contrast to normal Mitsunobu reactions, disulfide bond formation is achieved with regeneration of triphenylphosphine. The mechanism of this reaction is discussed.

cw CO2 laser-induced and SF6-sensitized decomposition of methyl iodide-d3

1983 ◽  
Vol 48 (11) ◽  
pp. 3261-3269 ◽  
Author(s):  
Jaroslav Rejnek ◽  
Marie Jakoubková ◽  
Pavel Engst ◽  
Milan Horák
Keyword(s):  
Decomposition Rate ◽  
Total Pressure ◽  
Laser Excitation ◽  
Irradiation Time ◽  
Product Distribution ◽  
Recombination Reaction ◽  
Reaction Step ◽  
Abstraction Reaction ◽  
Excitation Line ◽  
Cw Co2 Laser

The decomposition of CD3I initiated by the irradiation of a cw CO2 laser was studied in the presence of the SF6 sensitizer. The first reaction step of the decomposition produces CD3 radical that yields either methane-d4 (the abstraction reaction of „hot" radicals), or ethane-d6 (the recombination reaction of „cold" radicals). The effect of the total pressure and the composition of the reaction mixture, that of the laser excitation line and output and that of the irradiation time upon the decomposition rate and the product distribution was examined.

scholarly journals Effect of catalyst and reaction conditions on aromatic monomer yields, product distribution, and sugar yields during lignin hydrogenolysis of silver birch wood

2020 ◽  
Vol 316 ◽  
pp. 123907
Author(s):  
Thanaphong Phongpreecha ◽  
Kendall F. Christy ◽  
Sandip K. Singh ◽  
Pengchao Hao ◽  
David B. Hodge
Keyword(s):  
Product Distribution ◽  
Silver Birch ◽  
Birch Wood ◽  
Reaction Conditions ◽  
Aromatic Monomer
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