Primary and Secondary Isotope Effects in the Photooxidation of 2,5-Dimethyl-2,4-hexadiene. Elucidation of the Reaction Energy Profile

1998 ◽  
Vol 63 (18) ◽  
pp. 6390-6393 ◽  
Author(s):  
Georgios Vassilikogiannakis ◽  
Manolis Stratakis ◽  
Michael Orfanopoulos
Keyword(s):  
Isotope Effects ◽  
Energy Profile ◽  
Reaction Energy

A reaction energy profile and fragment attributed molecular system energy change (FAMSEC)-based protocol designed to uncover reaction mechanisms: a case study of the proline-catalysed aldol reaction

2019 ◽  
Vol 21 (30) ◽  
pp. 16694-16705 ◽  
Author(s):  
Ignacy Cukrowski ◽  
George Dhimba ◽  
Darren L. Riley
Keyword(s):  
Reaction Mechanism ◽  
Reaction Mechanisms ◽  
Molecular System ◽  
Chemical Change ◽  
Aldol Reaction ◽  
Energy Profile ◽  
Molecular Fragments ◽  
Reaction Energy ◽  
System Energy

Molecular fragments and their atoms involved in the strongest inter-molecular diatomic and atom–fragment interactions drive a chemical change (explain the reaction mechanism).

scholarly journals Mechanism and Origin of Remote Stereocontrol in the Organocatalytic C(sp2)-H Alkylation using Nitroalkanes as Alkylating Agents

2021 ◽  
Author(s):  
Sharath Chandra Mallojjala ◽  
Rahul Sakar ◽  
Rachael W. Karugu ◽  
Madhu Sudan Manna ◽  
Santanu Mukherjee ◽  
...  
Keyword(s):  
Alkylating Agent ◽  
Isotope Effects ◽  
Alkylating Agents ◽  
Bond Formation ◽  
Strong Support ◽  
Kinetic Isotope Effects ◽  
Energy Profile ◽  
Bond Forming ◽  
Kinetic Isotope ◽  
Carbon Carbon Bond

ABSTRACT: Experimental 13C kinetic isotope effects (KIEs) and DFT calculations are used to evaluate the mecha-nism and the origin of enantioselectivity in the C(sp2)‒H alkylative desymmetrization of cyclopentene-1,3-diones using nitroalkanes as the alkylating agent. An unusual combination of an inverse (~0.980) and a normal (~1.030) KIE is observed on the bond-forming carbon atoms of the cyclopentene-1,3-dione and nitroalkane, respectively. These data provide strong support for a mechanism involving reversible carbon-carbon bond-formation followed by rate- and enantioselectivity-determining nitro-group elimination. The theoretical free energy profile and predicted KIEs indicate that this elimination event occurs via an E1cB pathway. The origin of remote stereocontrol is evaluated by distortion-interaction and SAPT0 analyses of the enantiomeric E1cB transition states.

scholarly journals Mekanisme Teoritis Pembentukan Senyawa Siklik Hidrokarbon dari Reaksi C4H5 dan C4H2

2020 ◽  
Vol 7 (2) ◽  
pp. 101-106
Author(s):  
Antonius Indarto ◽  
Lienda Handojo
Keyword(s):  
Molecular Structure ◽  
High Temperature ◽  
Aromatic Hydrocarbons ◽  
Reaction Mechanisms ◽  
Room Temperature ◽  
Energy Requirements ◽  
Computational Studies ◽  
Energy Profile ◽  
Reaction Energy ◽  
Polycyclic Aromatic

Acetylene and polyyne are intermediates in the formation of Polycyclic Aromatic Hydrocarbons (PAHs) and soot in combustion or pyrolysis. PAH formation from acetylene is known as the most adopted pathway because it has a low reaction energy. Another mechanism for the formation of PAH is a mechanism that involves polyyne or known as a radical pathway, proposed by Krestinin. This pathway involves the reaction of alkyne + alkenes which results in the addition of radical sites to the molecular structure. In this study, the two reaction mechanisms will be compared. Electronic features and energy requirements of the reaction process will be evaluated using molecular computational studies based on electron density (DFT). In combustion conditions (high temperature), the formation of radical sites requires relatively little energy, with a range of 2-5 kcal/mol. This is very different when compared to the energy profile for the same reaction at room temperature. From this study, it can be concluded that the mechanism of radical growth has the potential to occur in combustion reactions.Polycyclic aromatic hydrocarbons, radical growth, combustion, polyyne.

On the relation between isotope effects on vapour pressure and molecular structure

1963 ◽  
Vol 60 ◽  
pp. 52-55
Author(s):  
István Kiss ◽  
Lajos Matus ◽  
István Opauszky
Keyword(s):  
Molecular Structure ◽  
Vapour Pressure ◽  
Isotope Effects
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