The stabilities of Meisenheimer complexes. Part 42. Kinetic studies of the reactions of methyl 3,5-dinitrobenzoate and of methyl 4-chloro-3,5-dinitrobenzoate with hydroxide ions in dimethyl sulphoxide–water mixtures. Competitive nucleophilic attack at aryl and carbonyl carbon atoms

1986 ◽  
pp. 873-878 ◽  
Author(s):  
Michael R. Crampton ◽  
Colin Greenhalgh
Keyword(s):  
Kinetic Studies ◽  
Dimethyl Sulphoxide ◽  
Nucleophilic Attack ◽  
Carbonyl Carbon ◽  
Meisenheimer Complexes

scholarly journals Understanding the reaction mechanism of the regioselective piperidinolysis of aryl 1-(2,4-dinitronaphthyl) ethers in DMSO: Kinetic and DFT studies

2021 ◽  
Vol 46 ◽  
pp. 146867832110274
Author(s):  
Yasmen M Moghazy ◽  
Nagwa MM Hamada ◽  
Magda F Fathalla ◽  
Yasser R Elmarassi ◽  
Ezzat A Hamed ◽  
...  
Keyword(s):  
Carbon Atom ◽  
Density Functional ◽  
Function Analysis ◽  
Density Functional Theory Method ◽  
Activation Parameters ◽  
Kinetic Studies ◽  
Nucleophilic Attack ◽  
Common Mechanism ◽  
Slow Step ◽  
Rate Determining Step

Reactions of aryl 1-(2,4-dinitronaphthyl) ethers with piperidine in dimethyl sulfoxide at 25oC resulted in substitution of the aryloxy group at the ipso carbon atom. The reaction was measured spectrophotochemically and the kinetic studies suggested that the titled reaction is accurately third order. The mechanism is began by fast nucleophilic attack of piperidine on C1 to form zwitterion intermediate (I) followed by deprotonation of zwitterion intermediate (I) to the Meisenheimer ion (II) in a slow step, that is, SB catalysis. The regular variation of activation parameters suggested that the reaction proceeded through a common mechanism. The Hammett equation using reaction constant σo values and Brønsted coefficient value showed that the reaction is poorly dependent on aryloxy substituent and the reaction was significantly associative and Meisenheimer intermediate-like. The mechanism of piperidinolysis has been theoretically investigated using density functional theory method using B3LYP/6-311G(d,p) computational level. The combination between experimental and computational studies predicts what mechanism is followed either through uncatalyzed or catalyzed reaction pathways, that is, SB and SB-GA. The global parameters of the reactants, the proposed activated complexes, and the local Fukui function analysis explained that C1 carbon atom is the most electrophilic center of ether. Also, kinetics and theoretical calculation of activation energies indicated that the mechanism of the piperidinolysis passed through a two-step mechanism and the proton transfer process was the rate determining step.

What happens to formamide during C—N bond rotation? Atomic and molecular energetics and molecular reactivity as a function of internal rotation

1993 ◽  
Vol 71 (6) ◽  
pp. 872-879 ◽  
Author(s):  
Keith E. Laidig ◽  
Lynn M. Cameron
Keyword(s):  
Electric Fields ◽  
Molecular Level ◽  
Enzymatic Catalysis ◽  
Nucleophilic Attack ◽  
Torsional Angle ◽  
Carbonyl Carbon ◽  
Electrophilic Attack ◽  
Bond Rotation ◽  
Planar Conformation ◽  
Molecular Reactivity

We investigate the energetics of rotation about the C—N bond in formamide at the molecular and atomic levels using the HF/6-31G**//HF/6-31G** level of theory. At the molecular level, the barrier to rotation results from a decrease in overall attractive energies upon rotation away from the planar conformation, primarily due to the lengthening of the C—N bond. At the atomic level, the barrier is due to the loss in interatomic attraction between the nitrogen and its bonded neighbors. We investigate the susceptibility of formamide to electrophilic attack at nitrogen and oxygen as well as nucleophilic attack at carbonyl carbon as a function of C—N bond rotation using the Laplacian model of reactivity. The model predicts the susceptibility to nucleophilic attack at carbonyl carbon to reach a maximum with a O—C—N—H torsional angle of 60°. As a mimic of solvent fields, we investigate the effect of solvation upon these predictions with the application of homogeneous electric fields. This geometry–reactivity relationship is related to proposed models of activation in the enzymatic catalysis of peptides.

scholarly journals Facile Formation and Dissociation Behaviour of C–C Bond Resulted from the Nucleophilic Attack of Carbanions on a Carbonyl Carbon in [Pt(hfac)2]

2000 ◽  
Vol 29 (10) ◽  
pp. 1130-1131 ◽  
Author(s):  
Seichi Okeya ◽  
Masato Hashimoto ◽  
Fumiko Nakamura ◽  
Yoshiaki Kusuyama ◽  
Mako Kobayashi ◽  
...  
Keyword(s):  
Nucleophilic Attack ◽  
Carbonyl Carbon
Sign in / Sign up

Export Citation Format

Share Document