Aromatic nucleophilic substitution (s n ar) reactions of halo‐substituted dinitrobenzene in liposome reaction media: Effect of reaction medium and role of halogen leaving group

Sulphur/nitrogen reactivity ratios in a series of aromatic nucleophilic substitution reactions of ambident thiocyanate ion have been determined. There are profound differences from the pattern found in SN2 reactions at a saturated carbon atom. Abnormal transition states, involving interactions between entering and leaving group, are likely in the bond-breaking step of the intermediate complex in reactions of thiocyanate ion with 1-fluoro-2,4-dinitrobenzene and with 2,4- dinitrophenyl 4-toluenesulphonate. The nitro-substituted aryl thiocyanates are shown to be tri-functional electrophiles, with reactive centres at aromatic carbon, at cyanide carbon, and at sulphur. Aryl 4-toluenesulphonates are bifunctional electrophiles with reactive centres at aryl carbon and sulphonyl sulphur. The site of attack by nucleophiles depends on the nature of the nucleophile. The sulphur/nitrogen reactivity ratio of ambident SCN-, and the electrophilic reactivity of tri- and bi-functional substrates, are in most instances consistent with the Hard and Soft Acids and Bases principle. Exceptions to the principle in some instances reveal differences between the SNAr and SN2 mechanisms, and in others indicate abnormal transition states.

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Carbon leaving group in aromatic nucleophilic substitution. Quantitative comparison with a common leaving group

The Journal of Organic Chemistry ◽

10.1021/jo00240a030 ◽

1988 ◽

Vol 53 (5) ◽

pp. 1087-1088 ◽

Cited By ~ 5

Author(s):

Mario Mattioli ◽

Paolo Mencarelli ◽

Franco Stegel

Keyword(s):

Nucleophilic Substitution ◽

Quantitative Comparison ◽

Aromatic Nucleophilic Substitution ◽

Leaving Group

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Imidazole as leaving group in aromatic nucleophilic substitution reactions

Tetrahedron Letters ◽

10.1016/s0040-4039(00)85618-x ◽

1982 ◽

Vol 23 (43) ◽

pp. 4423-4426 ◽

Cited By ~ 11

Author(s):

Elba B. de Vargas ◽

Rita H. de Rossi

Keyword(s):

Nucleophilic Substitution ◽

Substitution Reactions ◽

Aromatic Nucleophilic Substitution ◽

Nucleophilic Substitution Reactions ◽

Leaving Group

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4,6-Dichloro-5-Nitrobenzofuroxan: Different Polymorphisms and DFT Investigation of Its Reactivity with Nucleophiles

International Journal of Molecular Sciences ◽

10.3390/ijms222413460 ◽

2021 ◽

Vol 22 (24) ◽

pp. 13460

Author(s):

Elena Chugunova ◽

Nurgali Akylbekov ◽

Alexey Dobrynin ◽

Alexander Burilov ◽

Carla Boga ◽

...

Keyword(s):

Dft Calculations ◽

Nucleophilic Substitution ◽

Nitro Group ◽

Kinetic Data ◽

Aromatic Nucleophilic Substitution ◽

X Ray ◽

Nucleophilic Reactivity ◽

Amino Derivatives ◽

Torsional Angles

This research focuses on the X-ray structure of 4,6-dichloro-5-nitrobenzofuroxan 1 and of some of its amino derivatives (4a, 4e, 4g, and 4l) and on DFT calculations concerning the nucleophilic reactivity of 1. We have found that by changing the solvent used for crystallization, it is possible to obtain 4,6-dichloro-5-nitrobenzofuroxan (1) in different polymorphic structures. Moreover, the different torsional angles observed for the nitro group in 1 and in its amino derivatives (4a, 4e, 4g, and 4l) are strictly dependent on the steric hindrance of the substituent at C-4. DFT calculations on the course of the nucleophilic substitution confirm the role of the condensed furoxan ring in altering the aromaticity of the carbocyclic frame, while chlorine atoms strongly influence the dihedral angle and the rotational barrier of the nitro group. These results corroborate previous observations based on experimental kinetic data and give a deep picture of the reaction with amines, which proceeds via a “non-aromatic” nucleophilic substitution.

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