DFT studies on the mechanism of acetylene hydrochlorination over gold-based catalysts and guidance for catalyst construction

2019 ◽  
Vol 6 (10) ◽  
pp. 2944-2952 ◽  
Author(s):  
Chaoyue Zhao ◽  
Qingxin Guan ◽  
Wei Li
Keyword(s):  
Transition State ◽  
Linear Structure ◽  
Membered Ring ◽  
Dft Studies ◽  
Acetylene Hydrochlorination ◽  
Ring Transition State ◽  
Catalyst Construction

In the presence of both HCl and C2H2, the linear structure of AuCl is proposed to form a tetracoordinated five-membered ring transition state, along with the oxidation of the Au center from Au(i) into Au(iii).

An Alternate Energy-Conserved Pathway for the Morita-Baylis-Hillman (MBH) Reaction

2020 ◽  
Author(s):  
Veejendra Yadav
Keyword(s):  
Proton Transfer ◽  
Transition State ◽  
Lower Energy ◽  
Aldol Reaction ◽  
Membered Ring ◽  
Ammonium Ion ◽  
Alternate Energy ◽  
Ring Transition State ◽  
Mbh Reaction

An new overall lower energy pathway for the amine-catalysed Morita-Baylis-Hillman reaction is proposed from computations at the M06-2X/6-311++G(d,p) level. The pathway involves proton-transfer from the ammonium ion to the alkoxide formed from the aldol reaction through a seven-membered ring transition state (TS) structure followed by highly exothermic Hofmann<i> </i>elimination through a five-membered ring TS structure to form the product and also release the catalyst to carry on with the process all over again.

An Alternate Energy-Conserved Pathway for the Morita-Baylis-Hillman (MBH) Reaction

2020 ◽  
Author(s):  
Veejendra Yadav
Keyword(s):  
Proton Transfer ◽  
Transition State ◽  
Lower Energy ◽  
Aldol Reaction ◽  
Membered Ring ◽  
Ammonium Ion ◽  
Alternate Energy ◽  
Ring Transition State ◽  
Mbh Reaction

An new overall lower energy pathway for the amine-catalysed Morita-Baylis-Hillman reaction is proposed from computations at the M06-2X/6-311++G(d,p) level. The pathway involves proton-transfer from the ammonium ion to the alkoxide formed from the aldol reaction through a seven-membered ring transition state (TS) structure followed by highly exothermic Hofmann<i> </i>elimination through a five-membered ring TS structure to form the product and also release the catalyst to carry on with the process all over again.

scholarly journals Oxidation of geraniol using niobia modified with hydrogen peroxide

2019 ◽  
Author(s):  
Jairo Cubillos ◽  
José J. Martínez ◽  
Hugo Rojas ◽  
Norman Marín-Astorga
Keyword(s):  
Hydrogen Peroxide ◽  
Transition State ◽  
Kinetic Data ◽  
Room Temperature ◽  
Membered Ring ◽  
Morphological Properties ◽  
Peroxo Complex ◽  
Complex Species ◽  
Ring Transition State

Nb2O5 bulk and Nb2O5 modified with H2O2 were studied in the epoxidation of geraniol at 1 bar and room temperature. The structural and morphological properties for both catalysts were very similar, indicating that the peroxo-complex species were not formed. The order of the reaction was one respect to geraniol and close to zero respect to H2O2, these values fit well with the kinetic data obtained. The geraniol epoxidation is favored by the presence of peroxo groups, which is reached using an excess of H2O2. Moreover, the availability of the geraniol to adopt the three-membered-ring transition state was found as the best form for this type of compound.

scholarly journals An Alternate Energy-Conserved Pathway for the Morita-Baylis-Hillman (MBH) Reaction

2020 ◽  
Author(s):  
Veejendra Yadav
Keyword(s):  
Proton Transfer ◽  
Transition State ◽  
Lower Energy ◽  
Aldol Reaction ◽  
Membered Ring ◽  
Ammonium Ion ◽  
Alternate Energy ◽  
Ring Transition State ◽  
Mbh Reaction

An new overall lower energy pathway for the amine-catalysed Morita-Baylis-Hillman reaction is proposed from computations at the M06-2X/6-311++G(d,p) level. The pathway involves proton-transfer from the ammonium ion to the alkoxide formed from the aldol reaction through a seven-membered ring transition state (TS) structure followed by highly exothermic Hofmann<i> </i>elimination through a five-membered ring TS structure to form the product and also release the catalyst to carry on with the process all over again.

Why Is THCA Decarboxylation Faster than CBDA? an in Silico Perspective

2020 ◽  
Author(s):  
Weiying He ◽  
Paul J. Foth ◽  
Markus Roggen ◽  
Glenn M. Sammis ◽  
Pierre Kennepohl
Keyword(s):  
Dipole Moment ◽  
Transition State ◽  
Single Molecule ◽  
In Silico ◽  
Theoretical Calculations ◽  
Reaction Rates ◽  
Membered Ring ◽  
Organic Components ◽  
Ring Transition State ◽  
Rate Determining Steps

Tetrahydrocannabinol acid (THCA) and cannabidiol acid (CBDA), the two crucial organic components in cannabis and hemp, decarboxylate at different rates to their more active neutral forms. Theoretical calculations are used herein to analyze how the remote annulated ring or pendant substituent influences the rate determining steps of the decarboxylation processes. The uncatalyzed keto-enol tautomerization that precedes decarboxylation is found to be extremely slow in both cases albeit with a ten-fold preference for CBDA. A single molecule of methanol dramatically enhances the reaction rates by allowing for tautomerization through a more favorable six-membered ring transition state. Methanol-catalyzed tautomerization is found to be faster in THCA than in CBDA. This difference results from both the larger dipole moment of the THCA scaffold as well as its greater rigidity relative to CBDA. The greater dipole moment leads to a somewhat better binding of methanol. The lower entropic penalty in THCA towards tautomerization leads to faster decarboxylation.

Why Is THCA Decarboxylation Faster than CBDA? an in Silico Perspective

2020 ◽  
Author(s):  
Weiying He ◽  
Paul J. Foth ◽  
Markus Roggen ◽  
Glenn M. Sammis ◽  
Pierre Kennepohl
Keyword(s):  
Dipole Moment ◽  
Transition State ◽  
Single Molecule ◽  
In Silico ◽  
Theoretical Calculations ◽  
Reaction Rates ◽  
Membered Ring ◽  
Organic Components ◽  
Ring Transition State ◽  
Rate Determining Steps

Tetrahydrocannabinol acid (THCA) and cannabidiol acid (CBDA), the two crucial organic components in cannabis and hemp, decarboxylate at different rates to their more active neutral forms. Theoretical calculations are used herein to analyze how the remote annulated ring or pendant substituent influences the rate determining steps of the decarboxylation processes. The uncatalyzed keto-enol tautomerization that precedes decarboxylation is found to be extremely slow in both cases albeit with a ten-fold preference for CBDA. A single molecule of methanol dramatically enhances the reaction rates by allowing for tautomerization through a more favorable six-membered ring transition state. Methanol-catalyzed tautomerization is found to be faster in THCA than in CBDA. This difference results from both the larger dipole moment of the THCA scaffold as well as its greater rigidity relative to CBDA. The greater dipole moment leads to a somewhat better binding of methanol. The lower entropic penalty in THCA towards tautomerization leads to faster decarboxylation.

The role of synergic interaction in transition state formation for the aldol reaction on a metal oxide catalyst: a DFT investigation

2015 ◽  
Vol 17 (35) ◽  
pp. 22529-22532 ◽  
Author(s):  
Wei An
Keyword(s):  
Metal Oxide ◽  
Transition State ◽  
State Formation ◽  
Oxide Catalyst ◽  
Aldol Reaction ◽  
Membered Ring ◽  
Metal Oxide Catalyst ◽  
Ring Transition State

This contribution highlights an eight-membered ring transition state for the aldol reaction of propanal on O-terminated ZrO2(111) and CeO2(111) surfaces.

A DFT study on the mechanism of reaction between 2, 4-diisocyanatotolune and cellulose

2016 ◽  
Vol 15 (02) ◽  
pp. 1650012 ◽  
Author(s):  
Jiping Cao ◽  
Yali Liu ◽  
Aijuan Shi ◽  
Yuan Yuan ◽  
Mingliang Wang
Keyword(s):  
Reaction Mechanisms ◽  
Energy Barrier ◽  
Density Functional ◽  
Membered Ring ◽  
Functional Theory ◽  
Mechanism Of Reaction ◽  
The Density Functional Theory ◽  
Good Accordance ◽  
Experimental Activation Energy ◽  
Ring Transition State

The reaction mechanisms between 2, 4-Diisocyanatotolune (2, 4-TDI) and cellulose have been investigated using the density functional theory at the B3LYP/6-31[Formula: see text]G (d, p) level. The calculations show that the direct addition of 2, 4-TDI and cellulose possesses an unrealistically high barrier of 32–34[Formula: see text]kcal[Formula: see text]mol[Formula: see text]. With a neighboring [Formula: see text]-d-glucose serving as a proton transporter by forming a flexible six-membered ring transition state, the energy barrier of the reaction is significantly reduced to 16–18 kcal[Formula: see text]mol[Formula: see text], which is in a good accordance with the experimental activation energy of 13.9–16.7[Formula: see text]kcal[Formula: see text]mol[Formula: see text]. It is indicated that the reaction between 2, 4-TDI and cellulose is auto-catalyzed with a neighboring [Formula: see text]-d-glucose acting as a reactive catalyst.

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