Stereocontrolled synthesis of propionate motifs froml-lactic andl-alanine aldehydes. A DFT study of the hydrogen transfer under endocyclic control

2014 ◽  
Vol 1 (8) ◽  
pp. 974-982 ◽  
Author(s):  
François Godin ◽  
Martin Duplessis ◽  
Cindy Buonomano ◽  
Thao Trinh ◽  
Karine Houde ◽  
...  
Keyword(s):  
Hydrogen Transfer ◽  
Dft Study ◽  
Stereocontrolled Synthesis

scholarly journals A DFT Study of the Hexene Hydrogenation Catalysed by the Complex RuH(CO)(Cl)(PCy3): Monophosphine vs Diphosphine Paths

2019 ◽  
Author(s):  
Zied Hosni ◽  
Bahoueddine Tangour ◽  
Sofiene Achour
Keyword(s):  
Hydrogen Transfer ◽  
Direct Consequence ◽  
Dft Study ◽  
Energy Profile ◽  
Enthalpy Of Activation ◽  
Model Complex ◽  
The One ◽  
Phosphine Complex ◽  
H2 Molecule ◽  
Catalyst Model

A DFT study of hexene hydrogenation catalysed by the RuH(CO)(Cl)(PCy3)2 complex is presented. The investigation explores the feasibility of two different mechanisms: the first exploits a single phosphine complex and the second uses a two phosphines complex. The energy barriers involving a hydrogen transfer have a ten kcal.mol-1 higher than the one obtained through the single-phosphine mechanism. These results confirm the experimental hypothesis claiming that the departure of a phosphine is favourable at the beginning of the reaction which is the substitution of the catalyst model RuHCl(CO)(PMe3)2 by the real catalyst RuHCl(CO)(PCy3)2 shows no significant influence on the energetic barriers of hexene hydrogenation mechanism. The most important step of the mechanism is the kinetically determining step. The heterolytic cleavage of ruthenium-complexed H2 molecule leads to the generation of two Ru-H bonds and the oxidation of the ruthenium from Ru(II) to Ru(IV). The energy profile of this step is not relative to an elementary reaction because a shouldering is observed after the transition state. This results in an unusual gradient norm profile with five extrema. This is a direct consequence of the asynchronous nature of the different processes taking place during this step. In the case of the model complex RuHCl(CO)(IMes)(PMe3) with IMes = ( N , N '-bis( mesityl)imidazol-2-ylidene), an increase of the free enthalpy of activation is observed during the kinetically determining step, which is in agreement with the experimental work.

A DFT Study of the Hexene Hydrogenation Catalysed by the Complex RuH(CO)(Cl)(PCy3): Monophosphine vs Diphosphine Paths

2019 ◽  
Author(s):  
Zied Hosni ◽  
Bahoueddine Tangour ◽  
Sofiene Achour
Keyword(s):  
Hydrogen Transfer ◽  
Direct Consequence ◽  
Dft Study ◽  
Energy Profile ◽  
Enthalpy Of Activation ◽  
Model Complex ◽  
The One ◽  
Phosphine Complex ◽  
H2 Molecule ◽  
Catalyst Model

A DFT study of hexene hydrogenation catalysed by the RuH(CO)(Cl)(PCy3)2 complex is presented. The investigation explores the feasibility of two different mechanisms: the first exploits a single phosphine complex and the second uses a two phosphines complex. The energy barriers involving a hydrogen transfer have a ten kcal.mol-1 higher than the one obtained through the single-phosphine mechanism. These results confirm the experimental hypothesis claiming that the departure of a phosphine is favourable at the beginning of the reaction which is the substitution of the catalyst model RuHCl(CO)(PMe3)2 by the real catalyst RuHCl(CO)(PCy3)2 shows no significant influence on the energetic barriers of hexene hydrogenation mechanism. The most important step of the mechanism is the kinetically determining step. The heterolytic cleavage of ruthenium-complexed H2 molecule leads to the generation of two Ru-H bonds and the oxidation of the ruthenium from Ru(II) to Ru(IV). The energy profile of this step is not relative to an elementary reaction because a shouldering is observed after the transition state. This results in an unusual gradient norm profile with five extrema. This is a direct consequence of the asynchronous nature of the different processes taking place during this step. In the case of the model complex RuHCl(CO)(IMes)(PMe3) with IMes = ( N , N '-bis( mesityl)imidazol-2-ylidene), an increase of the free enthalpy of activation is observed during the kinetically determining step, which is in agreement with the experimental work.

Diastereoselective Hydrogen-Transfer Reactions: An Experimental and DFT Study

2013 ◽  
Vol 19 (28) ◽  
pp. 9308-9318 ◽  
Author(s):  
François Godin ◽  
Michel Prévost ◽  
Serge I. Gorelsky ◽  
Philippe Mochirian ◽  
Maud Nguyen ◽  
...  
Keyword(s):  
Hydrogen Transfer ◽  
Dft Study ◽  
Transfer Reactions ◽  
Hydrogen Transfer Reactions

How Does Methanol Assist the Hydrogen Transfer in Pd-catalyzed Cyclocarbonylation of Allylic Alcohols? Insights from a DFT Study

2012 ◽  
Vol 41 (7) ◽  
pp. 693-695 ◽  
Author(s):  
Mawia Hassan ◽  
Xin Zhang ◽  
Wenchao Zhang ◽  
Xiaojia Guo ◽  
Biaohua Chen ◽  
...  
Keyword(s):  
Hydrogen Transfer ◽  
Dft Study ◽  
Allylic Alcohols

Effect of Niacin on Mitochondria of Allium Cepa Root Cells

1967 ◽  
Vol 25 ◽  
pp. 78-79
Author(s):  
M. Arif Hayat
Keyword(s):  
Nicotinamide Adenine Dinucleotide ◽  
Hydrogen Transfer ◽  
Nicotinamide Adenine Dinucleotide Phosphate ◽  
Nicotinamide Adenine ◽  
Root Tips ◽  
Root Cells ◽  
Transfer Processes ◽  
Standard Procedures ◽  
A Cell ◽  
Critical Interest

Although it is recognized that niacin (pyridine-3-carboxylic acid), incorporated as the amide in nicotinamide adenine dinucleotide (NAD) or in nicotinamide adenine dinucleotide phosphate (NADP), is a cofactor in hydrogen transfer in numerous enzyme reactions in all organisms studied, virtually no information is available on the effect of this vitamin on a cell at the submicroscopic level. Since mitochondria act as sites for many hydrogen transfer processes, the possible response of mitochondria to niacin treatment is, therefore, of critical interest.Onion bulbs were placed on vials filled with double distilled water in the dark at 25°C. After two days the bulbs and newly developed root system were transferred to vials containing 0.1% niacin. Root tips were collected at ¼, ½, 1, 2, 4, and 8 hr. intervals after treatment. The tissues were fixed in glutaraldehyde-OsO4 as well as in 2% KMnO4 according to standard procedures. In both cases, the tissues were dehydrated in an acetone series and embedded in Reynolds' lead citrate for 3-10 minutes.

DFT study of the effect of hidrocarbonated chains on the electronic properties of some oligothiophene derivatives

2009 ◽  
Author(s):  
Manuel Fernández-Gómez ◽  
Amparo Navarro ◽  
MªPaz Fernández-Liencres ◽  
Mónica Moral ◽  
José Manuel Granadino-Roldán ◽  
...  
Keyword(s):  
Electronic Properties ◽  
Dft Study
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