Direct Metal-Free Transformation of Alkynes to Nitriles: Computational Evidence for the Precise Reaction Mechanism

Density functional theory calculations elucidated the precise reaction mechanism for the conversion of diphenylacetylenes into benzonitriles involving the cleavage of the triple C≡C bond, with N-iodosuccinimide (NIS) as an oxidant and trimethylsilyl azide (TMSN3) as a nitrogen donor. The reaction requires six steps with the activation barrier ΔG‡ = 33.5 kcal mol−1 and a highly exergonic reaction free-energy ΔGR = −191.9 kcal mol−1 in MeCN. Reaction profiles agree with several experimental observations, offering evidence for the formation of molecular I2, interpreting the necessity to increase the temperature to finalize the reaction, and revealing thermodynamic aspects allowing higher yields for alkynes with para-electron-donating groups. In addition, the proposed mechanism indicates usefulness of this concept for both internal and terminal alkynes, eliminates the option to replace NIS by its Cl- or Br-analogues, and strongly promotes NaN3 as an alternative to TMSN3. Lastly, our results advise increasing the solvent polarity as another route to advance this metal-free strategy towards more efficient processes.

Download Full-text

A computational study for the reaction mechanism of metal-free cyanomethylation of aryl alkynoates with acetonitrile

RSC Advances ◽

10.1039/d1ra01649k ◽

2021 ◽

Vol 11 (30) ◽

pp. 18246-18251

Author(s):

Selçuk Eşsiz

Keyword(s):

Density Functional Theory ◽

Reaction Mechanism ◽

Density Functional ◽

Computational Study ◽

Coupled Cluster ◽

Functional Theory ◽

Metal Free ◽

Coupled Cluster Methods ◽

High Level ◽

Cluster Methods

A computational study of metal-free cyanomethylation and cyclization of aryl alkynoates with acetonitrile is carried out employing density functional theory and high-level coupled-cluster methods, such as [CCSD(T)].

Download Full-text

Catalyzed Ethanol Chemical Looping Gasification Mechanism on the Perfect and Reduced Fe2O3 Surfaces

Energies ◽

10.3390/en14061663 ◽

2021 ◽

Vol 14 (6) ◽

pp. 1663

Author(s):

Laixing Luo ◽

Xing Zheng ◽

Jianye Wang ◽

Wu Qin ◽

Xianbin Xiao ◽

...

Keyword(s):

Density Functional Theory ◽

Reaction Mechanism ◽

Density Functional ◽

Oxygen Carrier ◽

Catalytic Decomposition ◽

Density Functional Theory Calculations ◽

Chemical Looping ◽

Functional Theory ◽

Barrier Energy ◽

Gasification Technology

Biomass chemical looping gasification (CLG) is a novel gasification technology for hydrogen production, where the oxygen carrier (OC) transfers lattice oxygen to catalytically oxidize fuel into syngas. However, the OC is gradually reduced, showing different reaction activities in the CLG process. Fully understanding the CLG reaction mechanism of fuel molecules on perfect and reduced OC surfaces is necessary, for which the CLG of ethanol using Fe2O3 as the OC was introduced as the probe reaction to perform density functional theory calculations to reveal the decomposition mechanism of ethanol into the synthesis gas (including H2, CH4, ethylene, formaldehyde, acetaldehyde, and CO) on perfect and reduced Fe2O3(001) surfaces. When Fe2O3(001) is reduced to FeO0.375(001), the calculated barrier energy decreases and then increases again, suggesting that the reduction state around FeO(001) favors the catalytic decomposition of ethanol to produce hydrogen, which proves that the degree of reduction has an important effect on the CLG reaction.

Download Full-text

Theoretical studies on Rh(iii)-catalyzed regioselective C–H bond cyanation of indole and indoline

Dalton Transactions ◽

10.1039/c8dt04079f ◽

2019 ◽

Vol 48 (1) ◽

pp. 168-175 ◽

Cited By ~ 2

Author(s):

Chao Deng ◽

Yingxin Sun ◽

Yi Ren ◽

Weihua Zhang

Keyword(s):

Density Functional Theory ◽

Reaction Mechanism ◽

Density Functional ◽

Density Functional Theory Calculations ◽

Theoretical Studies ◽

Functional Theory

Density functional theory calculations were carried out to study the reaction mechanism of the Rh(iii)-catalyzed regioselective C–H cyanation of indole and indoline with N-cyano-N-phenyl-para-methylbenzenesulfonamide (NCTS).

Download Full-text

The Role of SiH3 Diffusion in Determining the Surface Smoothness of Plasma-Deposited Amorphous Si Thin Films: An Atomic-Scale Analysis

MRS Proceedings ◽

10.1557/proc-862-a3.2 ◽

2005 ◽

Vol 862 ◽

Author(s):

Mayur S. Valipa ◽

Tamas Bakos ◽

Eray S. Aydil ◽

Dimitrios Maroudas

Keyword(s):

Thin Films ◽

Density Functional ◽

Activation Barrier ◽

Density Functional Theory Calculations ◽

Atomic Scale ◽

Functional Theory ◽

Weak Adsorption ◽

Dynamics Simulations ◽

Hydrogenated Amorphous

AbstractDevice-quality hydrogenated amorphous silicon (a-Si:H) thin films grown under conditions where the SiH3 radical is the dominant deposition precursor are remarkably smooth, as the SiH3 radical is very mobile and fills surface valleys during its diffusion on the a-Si:H surface. In this paper, we analyze atomic-scale mechanisms of SiH3 diffusion on a-Si:H surfaces based on molecular-dynamics simulations of SiH3 radical impingement on surfaces of a-Si:H films. The computed average activation barrier for radical diffusion on a-Si:H is 0.16 eV. This low barrier is due to the weak adsorption of the radical onto the a-Si:H surface and its migration predominantly through overcoordination defects; this is consistent with our density functional theory calculations on crystalline Si surfaces. The diffusing SiH3 radical incorporates preferentially into valleys on the a-Si:H surface when it transfers an H atom and forms a Si-Si backbond, even in the absence of dangling bonds.

Download Full-text

Unusual effects of solvent polarity on capacitance for organic electrolytes in a nanoporous electrode

Nanoscale ◽

10.1039/c4nr00046c ◽

2014 ◽

Vol 6 (10) ◽

pp. 5545-5550 ◽

Cited By ~ 47

Author(s):

De-en Jiang ◽

Jianzhong Wu

Keyword(s):

Density Functional Theory ◽

Dipole Moment ◽

Density Functional ◽

Solvent Polarity ◽

Density Functional Theory Calculations ◽

Organic Electrolyte ◽

Functional Theory ◽

Organic Electrolytes

Classical density functional theory calculations suggest that there is an optimal dipole moment for the solvent in an organic electrolyte supercapacitor.

Download Full-text

Direct carbon-carbon coupling of furanics with acetic acid over Brønsted zeolites

Science Advances ◽

10.1126/sciadv.1601072 ◽

2016 ◽

Vol 2 (9) ◽

pp. e1601072 ◽

Cited By ~ 25

Author(s):

Abhishek Gumidyala ◽

Bin Wang ◽

Steven Crossley

Keyword(s):

Acetic Acid ◽

Density Functional ◽

Reaction Rate ◽

Activation Barrier ◽

Density Functional Theory Calculations ◽

Step Change ◽

Functional Theory ◽

Transportation Fuels ◽

Bond Forming ◽

Direct Acylation

Effective carbon-carbon coupling of acetic acid to form larger products while minimizing CO2emissions is critical to achieving a step change in efficiency for the production of transportation fuels from sustainable biomass. We report the direct acylation of methylfuran with acetic acid in the presence of water, all of which can be readily produced from biomass. This direct coupling limits unwanted polymerization of furanics while producing acetyl methylfuran. Reaction kinetics and density functional theory calculations illustrate that the calculated apparent barrier for the dehydration of the acid to form surface acyl species is similar to the experimentally measured barrier, implying that this step plays a significant role in determining the net reaction rate. Water inhibits the overall rate, but selectivity to acylated products is not affected. We show that furanic species effectively stabilize the charge of the transition state, therefore lowering the overall activation barrier. These results demonstrate a promising new route to C–C bond–forming reactions for the production of higher-value products from biomass.

Download Full-text

Reaction mechanism and free energy profile for acylation of Candida Antarctica lipase B with methylcaprylate and acetylcholine: Density functional theory calculations

Journal of Molecular Graphics and Modelling ◽

10.1016/j.jmgm.2014.10.001 ◽

2014 ◽

Vol 54 ◽

pp. 131-140 ◽

Cited By ~ 6

Author(s):

Mohammad Sadegh Sadeghi Googheri ◽

Mohammad Reza Housaindokht ◽

Hassan Sabzyan

Keyword(s):

Density Functional Theory ◽

Free Energy ◽

Reaction Mechanism ◽

Density Functional ◽

Density Functional Theory Calculations ◽

Candida Antarctica Lipase B ◽

Energy Profile ◽

Candida Antarctica Lipase ◽

Functional Theory ◽

Free Energy Profile

Download Full-text

Syntheses, Structural Studies, and Copper Iodide Complexes of Macrocycles Derived from Williamson Ether Syntheses Involving 2,9-Bis(4-hydroxyphenyl)-1,10-phenanthroline, α,ω-Dibromides, and Resorcinol or 2,7-Dihydroxynaphthalene

Australian Journal of Chemistry ◽

10.1071/ch16587 ◽

2017 ◽

Vol 70 (4) ◽

pp. 373 ◽

Cited By ~ 2

Author(s):

Zuzana Baranová ◽

Hashem Amini ◽

Madhav Neupane ◽

Sydney C. Garrett ◽

Andreas Ehnbom ◽

...

Keyword(s):

Density Functional Theory ◽

Density Functional ◽

Density Functional Theory Calculations ◽

Terminal Alkynes ◽

Structural Studies ◽

Copper Iodide ◽

Functional Theory ◽

Nitrogen Donor ◽

Void Volumes ◽

Ether Synthesis

1,3-Bis(6-bromohexyloxy)benzene, 2,7-bis(6-bromohexyloxy)naphthalene, 1,3-bis(4-bromomethylbenzyloxy)benzene, and 1,3-bis(3-bromomethylbenzyloxy)benzene were prepared via Williamson ether synthesis using resorcinol or 2,7-dihydroxynaphthalene and 1,6-dibromohexane, 1,4-bis(bromomethyl)benzene, or 1,3-bis(bromomethyl)benzene (21–47 % yield). These dibromides were condensed with 2,9-bis(4-hydroxyphenyl)-1,10-phenanthroline in the presence of K2CO3 to give the corresponding 31- to 35-membered macrocycles (3a–d, 22–63 % yield). When 3a–d were treated with CuI, mononuclear 1 : 1 complexes formed, in which the CuI chelates to the nitrogen donor atoms of the phenanthroline moiety (4a–d, 40–80 % yield). The crystal structures of 3a–c and 4a–c were determined and analyzed using density functional theory calculations and in the context of rotaxanes that could be formed by treatment of 4a–d with terminal alkynes (e.g. macrocycle dimensions, void volumes). The copper and iodide atoms in 4a–c significantly protrude from the least-squares plane of the phenanthroline moiety (0.46–0.63 Å and 1.65–2.07 Å).

Download Full-text