Radical addition to ynol ethers — A convenient procedure for the stereoselective preparation of α-iodo enol ethers in neutral conditions

2008 ◽  
Vol 86 (10) ◽  
pp. 970-975 ◽  
Author(s):  
Fanny Longpré ◽  
Natalia Rusu ◽  
Maxime Larouche ◽  
Rana Hanna ◽  
Benoit Daoust
Keyword(s):  
Radical Reaction ◽  
Radical Addition ◽  
Reaction Conditions ◽  
Neutral Radical ◽  
Enol Ethers ◽  
Convenient Procedure ◽  
Different Temperatures ◽  
Ynol Ethers ◽  
Neutral Conditions ◽  
High Stereoselectivity

α-Iodo enol ethers, precursors of acyl anion equivalents, are not easily prepared. Herein we report that addition of activated iodoalkanes to ynol ethers under mild and neutral radical reaction conditions leads to α-iodo enol ethers in moderate to excellent yields with high stereoselectivity. The reaction can be carried out in various solvents at different temperatures. The methodology allows the preparation of β-alkylated and β,β-dialkylated α-iodo enol ethers. Reduction of the carbon-iodine bond of these species leads to the corresponding enol ethers with good yields.Key words: ynol ethers, enol ethers, radical addition, stereoselective.

Cleavage of C=N derivatives and Oxidation of Thiols in Water under Neutral Conditions with 1,4-dichloro-1,4-diazoniabicyclo[2,2,2]octane bischloride

2007 ◽  
Vol 2007 (8) ◽  
pp. 486-489 ◽  
Author(s):  
Mahmood Tajbakhsh ◽  
Setareh Habibzadeh
Keyword(s):  
Carbonyl Compounds ◽  
High Yield ◽  
Reaction Conditions ◽  
Neutral Conditions

1,4-Diazabicyclo[2,2,2]octane (DABCO) is easily chlorinated and gives a complex which efficiently converts aliphatic and aromatic oximes, phenylhydrazones and semicarbazones to their corresponding carbonyl compounds in water at 50°C in high yield. This reagent can also be used for conversion of thiols to their compounding disulfide under the same reaction conditions. DABCO is quantitatively recovered which can be rechlorinated and reused several times.

Radical Addition Reaction of Brominated Active Methylene Compounds to Enol Ethers Using 2,2‘-Azobis(2,4- dimethyl-4-methoxyvaleronitrile) (V-70) as an Initiator

1999 ◽  
Vol 64 (2) ◽  
pp. 675-678 ◽  
Author(s):  
Yasuyuki Kita ◽  
Atsunori Sano ◽  
Takahiro Yamaguchi ◽  
Masahisa Oka ◽  
Kentoku Gotanda ◽  
...  
Keyword(s):  
Addition Reaction ◽  
Radical Addition ◽  
Enol Ethers ◽  
Active Methylene Compounds ◽  
Active Methylene

Kinetics and Mechanism of Oxidation of Aliphatic Secondary Alcohols by Benzimidazolium Fluorochromate in Dimethyl Sulphoxide Solvent

2021 ◽  
Vol 37 (3) ◽  
pp. 626-633
Author(s):  
Bhawana Arora ◽  
Jitendra Ojha ◽  
Pallavi Mishra
Keyword(s):  
Activation Parameters ◽  
Sigmatropic Rearrangement ◽  
Dimethyl Sulphoxide ◽  
Secondary Alcohols ◽  
Hydrogen Ions ◽  
Reaction Conditions ◽  
First Order Kinetics ◽  
Aqueous Solvent ◽  
Ester Formation ◽  
Different Temperatures

Oxidation of secondary alcohols is an important part of synthetic organic chemistry. Various studies are carried out at different reaction conditions to determine the best mechanistic pathways. In our study, oxidation of different secondary alcohols was done by using Benzimidazolium Fluorochromate in Dimethyl Sulphoxide, which is a non-aqueous solvent. Oxidation resulted in the formation of ketonic compounds. The reaction showed first order kinetics both in BIFC and in the alcohols. Hydrogen ions were used to catalyze the reaction. We selected four different temperatures to carry out our study. The correlation within the activation parameters like enthalpies and entropies was in accordance with the Exnerʼs criterion. The deuterated benzhydrol (PhCDOHPh) oxidation exhibited an important primary kinetic isotopic effect (kH / kD = 5.76) at 298 K. The solvent effect was studied using the multiparametric equations of Taft and Swain. There was no effect of addition of acrylonitrile on the oxidation rate. The mechanism involved sigmatropic rearrangement with the transfer of hydrogen ion taking place from alcohol to the oxidant via a cyclic chromate ester formation.

Reaction de méthanation du gaz de synthèse: Influence de la température de calcination des catalyseurs à base de nickel

1993 ◽  
Vol 71 (1) ◽  
pp. 107-111
Author(s):  
M. Ghazi ◽  
J. Barrault
Keyword(s):  
Nickel Content ◽  
Great Part ◽  
Extreme Temperature ◽  
Nickel Catalysts ◽  
Economic Situation ◽  
Reaction Conditions ◽  
Methanation Reaction ◽  
Different Temperatures ◽  
Usual Process ◽  
Important Activity

Due to their important activity and selectivity, nickel catalysts are often used to realize the methanation reaction; however, the usual process based on these catalysts is not fitted for the present economic situation. To raise their stability, three catalysts with similar nickel content but calcinated at different temperatures have been studied for the reaction of methanation. The results obtained show that the catalyst calcinated at the highest temperature (973 K) shows the greatest promise because a great part of its activity and of its stability is preserved even when the reaction conditions are extreme (temperature of 773 K).

Preliminary Study on the Removal of Hexavalent Chromium in Wastewater with Reduction of Sulfur Dioxide

2013 ◽  
Vol 864-867 ◽  
pp. 1699-1703
Author(s):  
Ji Ming Wu ◽  
Sheng Gao Cheng
Keyword(s):  
Reaction Time ◽  
Sulfur Dioxide ◽  
Hexavalent Chromium ◽  
Reduction Reaction ◽  
High Concentration ◽  
Reaction Conditions ◽  
Ph Values ◽  
Different Temperatures ◽  
Preliminary Study ◽  
High Concentrations

The paper focused on a self-developed methodology through using sulfur dioxide to deal with high concentration of chromium-containing wastewater. It studied the effects of different pH values, different reaction time, different temperatures and different amounts of sulfur with sulfur dioxide reduction reaction on the chromium-containing wastewater. The results showed that: when the reaction conditions were controlled as follows: the pH values ranged from 2 to 4, the reaction temperature was controlled 40~60°C, the amount of sulfur in theoretical was 1.2 times and the reaction time was 40 min, the hexavalent chromium in the high concentrations of chromium-containing wastewater could be effectively removed.

Polymerization and oxidation of phenols in supercritical water

2019 ◽  
Vol 80 (4) ◽  
pp. 620-633 ◽  
Author(s):  
Huiwen Zhang ◽  
Xiaoman Zhang ◽  
Lei Ding ◽  
Miao Gong ◽  
Ying Su ◽  
...  
Keyword(s):  
Reaction Mechanism ◽  
Phenolic Compounds ◽  
Supercritical Water ◽  
Water Oxidation ◽  
Reaction Pathway ◽  
Radical Reaction ◽  
Dominant Factor ◽  
Supercritical Water Oxidation ◽  
Free Radical Reaction ◽  
Reaction Conditions

Abstract The treatment of toxic and difficult-to-degrade phenolic compounds has become a key issue in the coking, pharmaceutical, and chemical industries. Considering the polymerization and oxidation of phenolic compounds in supercritical water partial oxidation/supercritical water oxidation (SCWPO/SCWO), the present study reviewed the removal efficiency and reaction pathway of phenolic compounds and phenolic waste/wastewater under different reaction conditions. Temperature is the dominant factor affecting the SCWO reaction. When the oxidizing ability is insufficient, the organics polymerize to form phenolic compounds. The gradual increase of oxidant equivalent causes the intermediate product to gradually oxidize to CO2 and H2O completely. Finally, the free radical reaction mechanism is considered to be a typical SCWO reaction mechanism.

scholarly journals Semiconductors as sensitisers for the radical addition of tertiary amines to electron deficient alkenes

2003 ◽  
Vol 5 (3) ◽  
pp. 175-182 ◽  
Author(s):  
Siniša Marinković ◽  
Norbert Hoffmann
Keyword(s):  
Electron Transfer ◽  
Organic Synthesis ◽  
Radical Reaction ◽  
Heterogeneous Photocatalysis ◽  
Radical Addition ◽  
Point Of View ◽  
Tertiary Amines ◽  
Radical Intermediate ◽  
Radical Chain ◽  
High Yields

Using heterogeneous photocatalysis, the radical addition of tertiary amines with electron deficient alkenes can be performed in high yields (up to 98%) and high facial diastereoselectivity. The photochemical induced electron transfer process initiates the radical chain reaction and inorganic semiconductors likeTiO2and ZnS were used. According to the proposed mechanism, the reaction takes place at the surface of the semiconductor and the termination step results from an interfacial electron transfer from the conduction band to the oxoallyl radical intermediate. Frequently, semiconductors are used for the mineralisation of organic compounds in wastewater. However, in this case, they are used in organic synthesis. The process can be performed in a convenient way and is particularly interesting from the ecological and economical point of view. No previous functionalization of the tertiary amines is necessary for C − C bond formation. Further on, the amines are used both as reactant and as solvent. The excess is recycled by distillation and the inexpensive sensitiser can be easily removed by filtration. In this way, products of high interest for organic synthesis are obtained by a diastereoselective radical reaction.

Phosphonyl Radical Addition to Enol Ethers. The Stereoselective Synthesis of Cyclic Ethers.

ChemInform ◽  
2004 ◽  
Vol 35 (40) ◽  
Author(s):  
Christopher M. Jessop ◽  
Andrew F. Parsons ◽  
Anne Routledge ◽  
Derek J. Irvine
Keyword(s):  
Stereoselective Synthesis ◽  
Radical Addition ◽  
Cyclic Ethers ◽  
Enol Ethers ◽  
Phosphonyl Radical
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