scholarly journals Decoding the Reaction Mechanism of the Cyclocondensation of Ethyl acetate 2-oxo-2-(4-oxo-4H-pyrido [1.2-a] pyrimidin-3-yl) polyazaheterocycle and Ethylenediamine using Bond Evolution Theory

2021 ◽  
Author(s):  
Mbah Maraf ◽  
Abel Idrice ADJIEUFACK ◽  
Pelagie MANWAL A MEKOUNG ◽  
Auguste ABOUEM A ZINTCHEM ◽  
. GOUET BEBGA ◽  
...  
Keyword(s):  
Ethyl Acetate ◽  
Main Product ◽  
Lone Pair ◽  
Reaction Pathways ◽  
Second Step ◽  
Evolution Theory ◽  
Single Bond ◽  
Thermodynamic Control ◽  
Bet Analysis ◽  
Chemical Events

The bonding evolution theory has been used to investigate the flow of electron density along the reaction pathways of ethyl acetate 2-oxo-2-(4-oxo-4H-pyrido [1.2-a] pyrimidin-3-yl) polyazaheterocycle (1) and ethylenediamine (2). This reaction has three channels (1-3) and each one takes place via three or four steps. DFT results reveal that channel 2, which goes through imine intermediate is by far the most favorable one, and the main product 3 is more stable than 4 and 5, showing that this reaction is under kinetic and thermodynamic control, in clear agreement with the experimental outcomes. The BET analysis allows identifying unambiguously the main chemical events happening along channel 2. For this reaction channel, the mechanism along the first step (TS2-a) is described by a series of four structural stability domains (SSDs), while five SSDs are required for the second (TS2-b) and the third (TS2-c) one. The first step can be summarized as follow, the appearance of V(N1,C6) basin illustrating the formation of N1-C6 bond (SSD-II), the splitting of N1-H1 bond, followed by the restoration of the nitrogen N1 lone pair (SSD-III), and finally, the formation of the last O1-H1 bond (SSD-IV). For the second step, the formation of hydroxide ion is noted, consequent of the disappearance of V(C6,O7) basin, the transformation of C6-N1 single bond into double one (SSD-IV). Finally, the appearance of V(O7,H2) basin leading to the elimination of water molecule within the last domain. Overall, for the three reaction steps, the formation of the N-C bond appears always before the O-H one.

THEORETICAL STUDIES ON THE REACTION MECHANISM OF HNCS WITH CH2CH RADICAL

2007 ◽  
Vol 06 (01) ◽  
pp. 1-12 ◽  
Author(s):  
JIAN-HUA XU ◽  
LAI-CAI LI ◽  
YAN ZHENG ◽  
JUN-LING LIU ◽  
XIN WANG
Keyword(s):  
Density Functional Theory ◽  
Reaction Mechanism ◽  
Reaction Mechanisms ◽  
Density Functional ◽  
Hydrogen Transfer ◽  
Main Product ◽  
Reaction Pathways ◽  
Theoretical Studies ◽  
Functional Theory ◽  
Ch Radical

The reaction mechanisms of HNCS with CH 2 CH radical have been investigated by density functional theory (DFT). The geometries and harmonic frequencies of the reactants, intermediates, transition states and products have been calculated at the B3LYP/6-311++G(d,p) level. The results show that the reaction is very complicated. Nine possible reaction pathways were identified. The results show that the most feasible reaction channel is the hydrogen-transfer pathway CH 2 CH + HNCS → IMA1 → TSA1 → CH 2 CHH + NCS . The pathway VIC C-S addition channel ( CH 2 CH + HNCS → TSD5 → IMD4 → TSD9 → CH 2 CHS + CNH ) can also occur easily. Ethene and radical NCS is the main product of the studied reaction, and product P8 ( CH 2 CHS and CNH ) may also be observed. Compared with our previous study on the reaction HNCS + CH 2 CH , the present reaction is easier to proceed.

Syntheses of azapolycyclic compounds by aminium radical routes: trapping of the radical intermediates

1978 ◽  
Vol 56 (22) ◽  
pp. 2906-2913 ◽  
Author(s):  
Richard A. Perry ◽  
Robert W. Lockhart ◽  
Masayuki Kitadani ◽  
Yuan L. Chow
Keyword(s):  
Nitrous Acid ◽  
Lone Pair ◽  
Reaction Pathways ◽  
Cleavage Reaction ◽  
Nitrate Esters ◽  
Radical Intermediates ◽  
Radical Trapping ◽  
Primary Products ◽  
Nucleophilic Displacement ◽  
Aziridinium Ion

Photolysis of three alkenyl nitrosamines in the presence of oxygen or bromotrichloromethane resulted in the interception of the intermediate C-radicals by these radical trapping agents and the reaction pathways were cleanly diverted leading to the formation of the nitrate esters or halides with pyrrolidine rings as the primary products. The exo-nitrates in the oxidative photolyses decomposed by secondary ionic pathways; these reactions were hydrolysis, nitrous acid elimination and a cleavage reaction (promoted by a β-amino group), among others. The efficiency of the cleavage reaction is controlled by a stereoelectronic factor that requires the participating bonds and the lone-pair nitrogen orbital be oriented in an antiperiplanar conformation. When such a conformation exists in a rigid or semiflexible framework, cleavage occurs extensively. However, in freely rotating acyclic systems, cleavage does not occur even when the required conformation can be attained. Only halides resistant to intramolecular nucleophilic displacement to form the aziridinium intermediates were isolated in the bromotrichloromethane trapping experiments. Other exo-halides underwent solvolysis via aziridinium ion intermediates.

scholarly journals Computational conformational antimicrobial analysis developing mechanomolecular theory for polymer biomaterials in materials science and engineering

2014 ◽  
Vol 03 (01) ◽  
pp. 1450003 ◽  
Author(s):  
Richard C. Petersen
Keyword(s):  
Materials Science ◽  
Three Dimensional ◽  
Lone Pair ◽  
Maximum Energy ◽  
Single Bond ◽  
Secondary Bonds ◽  
Complex Interactions ◽  
Electron Distributions ◽  
Three Dimensional Models ◽  
Lone Pair Electrons

Single-bond rotations or pyramidal inversions tend to either hide or expose relative energies that exist for atoms with nonbonding lone-pair electrons. Availability of lone-pair electrons depends on overall molecular electron distributions and differences in the immediate polarity of the surrounding pico/nanoenvironment. Stereochemistry three-dimensional aspects of molecules provide insight into conformations through single-bond rotations with associated lone-pair electrons on oxygen atoms in addition to pyramidal inversions with nitrogen atoms. When electrons are protected, potential energy is sheltered toward an energy minimum value to compatibilize molecularly with nonpolar environments. When electrons are exposed, maximum energy is available toward polar environment interactions. Computational conformational analysis software calculated energy profiles that exist during specific oxygen ether single-bond rotations with easy-to-visualize three-dimensional models for the trichlorinated bisaromatic ether triclosan antimicrobial polymer additive. As shown, fluctuating alternating bond rotations can produce complex interactions between molecules to provide entanglement strength for polymer toughness or alternatively disrupt weak secondary bonds of attraction to lower resin viscosity for new additive properties with nonpolar triclosan as a hydrophobic toughening/wetting agent. Further, bond rotations involving lone-pair electrons by a molecule at a nonpolar-hydrocarbon-membrane/polar-biologic-fluid interface might become sufficiently unstable to provide free mechanomolecular energies to disrupt weaker microbial membranes, for membrane transport of molecules into cells, provide cell signaling/recognition/defense and also generate enzyme mixing to speed reactions.

Reaktive E=C (p-p)π-Systeme, XL. / Reactive E=C(p-p)π Systems, XL.

1995 ◽  
Vol 50 (1) ◽  
pp. 94-100 ◽  
Author(s):  
Thomas Albers ◽  
Joseph Grobe ◽  
Duc Le Van ◽  
Bernt Krebs ◽  
Mechtild Läge
Keyword(s):  
Molecular Structure ◽  
Main Product ◽  
Chloroform Solution ◽  
Lone Pair ◽  
Secondary Amines ◽  
Molar Ratio ◽  
Electronic Interaction ◽  
X Ray Diffraction ◽  
X Ray ◽  
New Compounds

The reaction of bis(trifluoromethyl)arsane 2 with secondary amines R2NH in a molar ratio of 1:3 at -60 °C allows the preparation of trifluoromethyl arsaalkenes of the type F3CAs=C(F)NR2 in moderate yields (15-35%) [NR2 = NMe2 (3a), NMeEt (3b), NEt2 (3c)]. The main product of the reaction of 2 with Me2NH is the 1,1-diamino compound F3CAs=C(NMe2)2 (4a). With ethyl(isopropyl)- or di(isopropyl)amine the corresponding derivatives F3CAs=C(F)NEt(iPr) (3d) and F3CAs=C(F)N(iPr)2 (3e), respectively, are formed only in traces (3d), or not at all (3 e). However, 3d and 3e can be prepared by reacting perfluoro-2-arsapropene with the corresponding secondary amines. The new compounds 3 a to 3 e can be stored at 20 °C in chloroform solution for hours without decomposition and show Z configuration without exception. The molecular structure of 1-(diethylamino)-1,3,3,3-tetrafluoro-2-arsapropene 3c, determined by an X-ray diffraction study on single crystals, indicates a strong electronic interaction of the lone pair on nitrogen with the AsC double bond. This results in a trigonal planar arrangement at the nitrogen atom, a strongly shortened sp2-CN-bond (1.312 Å), an elongated AsC distance (1.867 Å), and an almost planar skeleton of the molecule.

Synthese und Struktur- und Konformationsanalyse von Triphenylphosphonium-bis(diphenylarsino)methylid

1984 ◽  
Vol 39 (11) ◽  
pp. 1456-1462 ◽  
Author(s):  
Hubert Schmidbaur ◽  
Peter Nußstein ◽  
Gerhard Müller
Keyword(s):  
Single Crystal ◽  
Spectroscopic Data ◽  
Heavy Atom ◽  
Lone Pair ◽  
Molar Ratio ◽  
Single Bond ◽  
X Ray Diffraction ◽  
Trans Conformation ◽  
X Ray ◽  
Lone Pairs

Abstract Triphenylphosphonium -diphenylarsinomethylide (1) and -bis-(diphenylarsino)methylide (2) are easily available through transylidation processes using Ph3P = CH2 and Ph2AsCl as the starting materials in the appropriate molar ratio. Analytical and spectroscopic data are presented for both ylides. The structure of 2 was studied in detail by single-crystal X-ray diffraction. The basic PCAs2 skeleton is found to deviate strongly from planarity. The Ph2As-substituents adopt a cis/trans conformation relative to the ylidic P = C bond with the directions of the lone pairs of electrons at the arsenic atoms in the heavy atom plane as expected for a maximum compensation of the electrostatic vectors. For 1, a cis-conformation of the lone pair of electrons and a large PCAs angle are predicted on the basis of NMR analogies with the phosphorus homologues. Single bond rotational barriers appear to be much lower for 1 and 2, however, than for the corresponding phosphino-substituted ylides.

scholarly journals Participation of Phosphorylated Analogues of Nitroethene in Diels–Alder Reactions with Anthracene: A Molecular Electron Density Theory Study and Mechanistic Aspect

Organics ◽  
2020 ◽  
Vol 1 (1) ◽  
pp. 36-48
Author(s):  
Agnieszka Kącka-Zych
Keyword(s):  
Electron Density ◽  
Density Functional ◽  
Diels Alder ◽  
Single Bond ◽  
Conceptual Density Functional Theory ◽  
Molecular Electron ◽  
Bet Analysis ◽  
One Step ◽  
Molecular Electron Density Theory ◽  
Step Mechanism

The structure and the contribution of the bis(2-chloroethyl) 2-nitro 1a and 2-bromo-2-nitroethenylphosphonates 1b with anthracene 2 in the Diels–Alder (DA) reactions have been studied within the Molecular Electron Density Theory (MEDT) at the B3LYP functional together with 6-31G(d), 6-31+G(d) and 6-31+G(d,p) basic sets. Analysis of the Conceptual Density Functional Theory (CDFT) reactivity indices indicates that 1a and 1b can be classified as a strong electrophile and marginal nucleophile, while 2 is classified as a strong electrophile and strong nucleophile. The studied DA reactions take place through a one-step mechanism. A Bonding Evolution Theory (BET) of the one path associated with the DA reaction of 1a with 2 indicates that it is associated with non-concerted two-stage one-step mechanism. BET analysis shows that the first C2-C3 single bond is formed in Phase VI, while the second C1-C6 single bond is formed in the Phase VIII. The formation of both single bonds occurs through the merging of two C2 and C3, C1 and C6 pseudoradical centers, respectively.

Reaction kinetics measurements and analysis of reaction pathways for conversions of acetic acid, ethanol, and ethyl acetate over silica-supported Pt

2001 ◽  
Vol 222 (1-2) ◽  
pp. 369-392 ◽  
Author(s):  
Kamalkumar I. Gursahani ◽  
Rafael Alcalá ◽  
Randy D. Cortright ◽  
James A. Dumesic
Keyword(s):  
Acetic Acid ◽  
Ethyl Acetate ◽  
Reaction Kinetics ◽  
Reaction Pathways

Unprecedented Coordination Environment in Poly-{μ-bis(methylthienyltellane)( chlorido)(thienyl)platinum(II)}

2004 ◽  
Vol 59 (5) ◽  
pp. 614-616 ◽  
Author(s):  
Raija Oilunkaniemi ◽  
Risto S. Laitinen ◽  
Markku Ahlgrén
Keyword(s):  
Main Product ◽  
Lone Pair ◽  
Polymer Chains ◽  
Octahedral Coordination ◽  
Tetrahedral Coordination ◽  
Coordination Environment ◽  
Bridging Ligand ◽  
Distorted Tetrahedral Coordination

Abstract The reaction of methylthienyltellane TeMeTh (Th = thienyl, C4H3S) and [PtCl2(NCPh)2] affords in addition to the main product [PtCl2(TeMeTh)2], also small amounts of yellow crystalline [PtCl(Th)(TeMeTh)2]n that exhibits unprecedented quasi-octahedral coordination environment around platinum(II). There are four weak Pt-Te bonds of 2.898(1) and 3.419(1) Å forming an approximate squareplane the quasi-octahedral coordination being completed by a Pt-Cl bond of 2.400(2) Å and a Pt-C bond of 1.998(8) Å of a discrete thienyl ring. The TeMeTh acts as a bridging ligand. Tellurium shows a distorted tetrahedral coordination and the weak Pt-Te bonds can be rationalized in terms of sharing one tellurium electron lone-pair by two adjacent platinum centers. The closest contacts between the polymer chains involve thienyl rings.

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