Pentaenyl cations from the photolysis of retinyl acetate. Solvent effects on the leaving group ability and relative nucleophilicities: an unequivocal and quantitative demonstration of the importance of hydrogen bonding

1992 ◽  
Vol 114 (7) ◽  
pp. 2419-2428 ◽  
Author(s):  
Norbert J. Pienta ◽  
Robert J. Kessler
Keyword(s):  
Hydrogen Bonding ◽  
Solvent Effects ◽  
Retinyl Acetate ◽  
Leaving Group ◽  
Leaving Group Ability

Leaving group ability in base-promoted alkene-forming 1,2-eliminations

1975 ◽  
pp. 940 ◽  
Author(s):  
Donald R. Marshall ◽  
Patsy J. Thomas ◽  
Charles J. M. Stirling
Keyword(s):  
Leaving Group ◽  
Leaving Group Ability

scholarly journals Leaving Group Ability in Nucleophilic Aromatic Amination by Sodium Hydride–Lithium Iodide Composite

Synthesis ◽  
2019 ◽  
Vol 52 (03) ◽  
pp. 393-398
Author(s):  
Jia Hao Pang ◽  
Derek Yiren Ong ◽  
Kohei Watanabe ◽  
Ryo Takita ◽  
Shunsuke Chiba
Keyword(s):  
Nucleophilic Substitution ◽  
Methoxy Group ◽  
Sodium Hydride ◽  
Lithium Iodide ◽  
Substitution Reactions ◽  
Computational Approaches ◽  
Nucleophilic Substitution Reactions ◽  
Leaving Group ◽  
Leaving Group Ability

The methoxy group is generally considered as a poor leaving group for nucleophilic substitution reactions. This work verified the superior ability of the methoxy group in nucleophilic amination of arenes mediated by the sodium hydride and lithium iodide through experimental and computational approaches.

STRUCTURAL AND SOLVENT EFFECTS ON THE n → π*(′U ← ′A) TRANSITIONS IN ALIPHATIC CARBONYL DERIVATIVES: EVIDENCE FOR HYPERCONJUGATION IN THE ELECTRONICALLY EXCITED STATES OF MOLECULES

1960 ◽  
Vol 38 (12) ◽  
pp. 2508-2513 ◽  
Author(s):  
C. N. R. Rao ◽  
G. K. Goldman ◽  
A. Balasubramanian
Keyword(s):  
Hydrogen Bonding ◽  
Carbonyl Group ◽  
Excited States ◽  
Solvent Effects ◽  
Electronically Excited States ◽  
Carbonyl Derivatives ◽  
Alkyl Groups ◽  
Electronically Excited

The n → π* transition of the carbonyl group has been studied in solvents of varying degree of polarity and hydrogen-bonding ability, in a number of aliphatic carbonyl derivatives. Evidence for hyperconjugation of the alkyl groups in the electronically excited states of molecules has been presented.

scholarly journals Solvent Effects on the Hydrogen Bonding of N-Phenylurethane

1969 ◽  
Vol 72 (11) ◽  
pp. 2430-2436 ◽  
Author(s):  
Takehide TANAKA ◽  
Tetsuo YOKOYAMA ◽  
Yukio YAMAGUCHI ◽  
Seikou NAGANUMA
Keyword(s):  
Hydrogen Bonding ◽  
Solvent Effects

Ambident Heterocyclic Reactivity: Alkylation of 4-Substituted and 2,4-Disubstituted Benzimidazoles

1994 ◽  
Vol 47 (8) ◽  
pp. 1523 ◽  
Author(s):  
MR Haque ◽  
M Rasmussen
Keyword(s):  
Hydrogen Bonding ◽  
Transition State ◽  
Electrostatic Field ◽  
Transition States ◽  
Alkyl Halides ◽  
Methyl Group ◽  
Site Selectivity ◽  
Leaving Group ◽  
Standard Set ◽  
Specific Association

The N1/N3-alkylation patterns of 4-amino-, 4-methyl- and 4-nitro-benzimidazole anions, and their 2-methyl analogues, with a standard set of primary alkyl halides (in dimethylformamide, 30°) have been determined and compared. The observed regioselectivities are dominated by proximal effects-electrostatic field, non-bonded steric and in some cases specific association (hydrogen bonding)-the interplay of which is critically dependent on the (variable) geometries of the SN2 transition states involved, in particular on the N---C distance of the developing N-alkyl bonds. The presence of a symmetrically placed 2-methyl group produces an enhanced N1/N3 site selectivity, very sensitive to the loose-tight nature of the transition state. Halide leaving group effects on butylation regioselectivities of 2-unsubstituted, 2-ethoxy-, 2-methyl- and 2-chloro-4-methylbenzimidazole anions, whilst small, are consistent with a Bell-Evans-Polanyi analysis of SN2 transition state variations, with the earlier transition states of CH3(CH2)3I leading to reduced regioselectivities.

Selective deshielding of aromatic protons in some ortho-substituted acetanilides

1968 ◽  
Vol 46 (15) ◽  
pp. 2593-2600 ◽  
Author(s):  
James R. Bartels-Keith ◽  
Ronald F. W. Cieciuch
Keyword(s):  
Hydrogen Bonding ◽  
Magnetic Resonance ◽  
Solvent Effects ◽  
Proton Magnetic Resonance ◽  
Aromatic Proton ◽  
Intramolecular Hydrogen Bonding ◽  
Low Field ◽  
Intramolecular Hydrogen

Certain ortho-substituted acetanilides exhibit proton magnetic resonance signals at unusually low field for the amido proton and the aromatic proton adjacent to the acetamido group. This effect, explicable in terms of intramolecular hydrogen-bonding, has been observed for nitro, carbonyl, sulfamoyl, and sulfonyl substituents. Solvent effects are discussed.

Basicity and solvent effects on hydrogen bonding in NR3���HCOOH (R=H, CH3) model systems

1999 ◽  
Vol 74 (4) ◽  
pp. 387-394 ◽  
Author(s):  
Patricia P�rez ◽  
Gerald Zapata-Torres ◽  
Julia Parra-Mouchet ◽  
Renato Contreras
Keyword(s):  
Hydrogen Bonding ◽  
Solvent Effects ◽  
Model Systems
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