The ?-electronic structure and chemical reactivity of 2- and 4-hydroxyquinolines in aromatic substitution reactions

1972 ◽  
Vol 6 (2) ◽  
pp. 205-208
Author(s):  
V. P. Zvolinskii ◽  
M. E. Perel'son ◽  
Yu. N. Sheinker
Keyword(s):  
Electronic Structure ◽  
Chemical Reactivity ◽  
Aromatic Substitution ◽  
Substitution Reactions

scholarly journals Fast and Accurate Prediction of the Regioselectivity of Electrophilic Aromatic Substitution Reactions

2017 ◽  
Author(s):  
Jimmy Kromann ◽  
Jan Jensen ◽  
Monika Kruszyk ◽  
Mikkel Jessing ◽  
Morten Jørgensen
Keyword(s):  
Expert Knowledge ◽  
Chemical Reactivity ◽  
Computational Cost ◽  
Semiempirical Method ◽  
Computational Prediction ◽  
Electrophilic Aromatic Substitution ◽  
Aromatic Substitution ◽  
Free Energies ◽  
Substitution Reactions ◽  
Computational Resources

While computational prediction of chemical reactivity is possible it usually requires expert knowledge and there are relatively few computational tools that can be used by a bench chemist to help guide synthesis. The RegioSQM method for predicting the regioselectivity of electrophilic aromatic substitution reactions of heteroaromatic systems is presented in this paper. RegioSQM protonates all aromatic C-H carbon atoms and identifies those with the lowest free energies in chloroform using the PM3 semiempirical method as the most nucleophilic center. These positions are found to correlate qualitatively with the regiochemical outcome in a retrospective analysis of 96% of more than 525 literature examples of electrophilic aromatic halogenation reactions. The method is automated and requires only a SMILES string of the molecule of interest, which can easily be generated using chemical drawing programs such as ChemDraw. The computational cost is 1-10 minutes per molecule depending on size, using relatively modest computational resources and the method is freely available via a web server at regiosqm.org. RegioSQM should therefore be of practical use in the planning of organic synthesis.

Carbodithioato derivatives of weak nitrogenous nucleophiles. I. Electronic structure and ground state properties of Ni(II) amide N-carbodithioates

1989 ◽  
Vol 67 (5) ◽  
pp. 902-909 ◽  
Author(s):  
C. C. Hadjikostas ◽  
G. A. Katsoulos ◽  
M. P. Sigalas ◽  
C. A. Tsipis
Keyword(s):  
Electronic Structure ◽  
Molecular Orbital ◽  
Metal Ion ◽  
Chemical Reactivity ◽  
Frontier Molecular Orbital ◽  
The Novel ◽  
Substitution Reactions ◽  
Square Planar ◽  
Elemental Analyses ◽  
Derivatives Of

Nickel(II) complexes of the general type [Ni(S2CN(COR′)R)2] have been synthesized by the reaction of the appropriate Ni(II) N-alkyldithiocarbamate with acetic anhydride or benzoyl chloride in the presence of triethylamine. The complexes obtained were identified and characterized by elemental analyses, conductivity measurements, and ir and electronic spectra. It was concluded that the bonding mode of the dithiocarbamato ligands to the metal ion is not altered by the acylation reaction, the chromophore remaining square-planar NiS4. Moreover, EHMO-SCCC calculations have been used in the analysis of electronic structure, and related properties of the novel compounds. From the calculated molecular orbital description of the complexes and the frontier molecular orbital approach of chemical reactivity, plausible mechanisms of their formation reactions have been deduced. Keywords: Ni(II) amide N-carbodithioates, N-alkyldithiocarbamates, dithiocarbimates, electrophilic substitution reactions, EHMO-SCCC calculations.

Electrophilic Addition of Brominated Poly(Isobutylene-co-4-Methylstyrene) to Olefins Catalyzed by Zinc Salts: A Model Study

1993 ◽  
Vol 66 (1) ◽  
pp. 98-108 ◽  
Author(s):  
J. M. J. Fréchet ◽  
R. Bielski ◽  
H-C. Wang ◽  
J. V. Fusco ◽  
K. W. Powers
Keyword(s):  
Induction Period ◽  
Chemical Reactivity ◽  
Zinc Stearate ◽  
Gas Chromatography Mass Spectrometry ◽  
Electrophilic Aromatic Substitution ◽  
Aromatic Substitution ◽  
Substitution Reactions ◽  
Model Study ◽  
Zinc Salts ◽  
Electrophilic Additions

Abstract The chemical reactivity of a new elastomer based on brominated poly(isobutylene-co-4-methylstyrene) in electrophilic additions to olefins has been investigated using model compounds as well as appropriate polymers. The reactions catalyzed by zinc salts are influenced by the solubility as well as the composition of the catalyst. While the reactivity of zinc bromide is limited by its low solubility in nonpolar medium, zinc oxide and zinc stearate can afford excellent results once an induction period has elapsed. The induction period likely corresponds to the formation of more reactive zinc based moieties through interchange reactions with the benzylic bromide groups. The mechanism of the addition process involves initial formation of carbocationic complexes with the zinc salts, followed by addition to the double bonds of the olefins. The products resulting from these additions have been characterized by NMR as well as gas chromatography-mass spectrometry. A comparison of potential crosslinking processes involving olefin addition or electrophilic aromatic substitution reactions shows that the former process is preferred. The findings of this study are directly applicable to the co-curing of elastomers based on brominated poly-(isobutylene-co-4-methylstyrene) with polyolefins.

scholarly journals Fast and Accurate Prediction of the Regioselectivity of Electrophilic Aromatic Substitution Reactions

2017 ◽  
Author(s):  
Jimmy Kromann ◽  
Jan Jensen ◽  
Monika Kruszyk ◽  
Mikkel Jessing ◽  
Morten Jørgensen
Keyword(s):  
Expert Knowledge ◽  
Chemical Reactivity ◽  
Computational Cost ◽  
Semiempirical Method ◽  
Computational Prediction ◽  
Electrophilic Aromatic Substitution ◽  
Aromatic Substitution ◽  
Free Energies ◽  
Substitution Reactions ◽  
Computational Resources

While computational prediction of chemical reactivity is possible it usually requires expert knowledge and there are relatively few computational tools that can be used by a bench chemist to help guide synthesis. The RegioSQM method for predicting the regioselectivity of electrophilic aromatic substitution reactions of heteroaromatic systems is presented in this paper. RegioSQM protonates all aromatic C-H carbon atoms and identifies those with the lowest free energies in chloroform using the PM3 semiempirical method as the most nucleophilic center. These positions are found to correlate qualitatively with the regiochemical outcome in a retrospective analysis of 96% of more than 525 literature examples of electrophilic aromatic halogenation reactions. The method is automated and requires only a SMILES string of the molecule of interest, which can easily be generated using chemical drawing programs such as ChemDraw. The computational cost is 1-10 minutes per molecule depending on size, using relatively modest computational resources and the method is freely available via a web server at regiosqm.org. RegioSQM should therefore be of practical use in the planning of organic synthesis.

scholarly journals Xylochemical Synthesis and Biological Evaluation of Shancigusin C and Bletistrin G

Molecules ◽  
2021 ◽  
Vol 26 (11) ◽  
pp. 3224
Author(s):  
Leander Geske ◽  
Ulrich Kauhl ◽  
Mohamed E. M. Saeed ◽  
Anja Schüffler ◽  
Eckhard Thines ◽  
...  
Keyword(s):  
Total Synthesis ◽  
Biological Activities ◽  
Biological Evaluation ◽  
Aromatic Substitution ◽  
Substitution Reactions ◽  
Total Syntheses ◽  
Wittig Olefination ◽  
Starting Point ◽  
Perkin Reaction ◽  
Synthesis And Biological Evaluation

The biological activities of shancigusin C (1) and bletistrin G (2), natural products isolated from orchids, are reported along with their first total syntheses. The total synthesis of shancigusin C (1) was conducted by employing the Perkin reaction to forge the central stilbene core, whereas the synthesis of bletistrin G (2) was achieved by the Wittig olefination followed by several regioselective aromatic substitution reactions. Both syntheses were completed by applying only renewable starting materials according to the principles of xylochemistry. The cytotoxic properties of shancigusin C (1) and bletistrin G (2) against tumor cells suggest suitability as a starting point for further structural variation.

scholarly journals The use of bisphthalonitriles in the synthesis of side-strapped 1,11,15,25-tetrasubstituted phthalocyanines

1996 ◽  
Vol 74 (3) ◽  
pp. 307-318 ◽  
Author(s):  
Clifford C. Leznoff ◽  
David M. Drew
Keyword(s):  
Key Words ◽  
Nucleophilic Aromatic Substitution ◽  
Aromatic Substitution ◽  
Substitution Reactions ◽  
Pure Compounds

Nucleophilic aromatic substitution reactions of 3-nitrophthalonitrile yield 3-hydroxyphthalonitrile and 3-neopentoxyphthalonitrile, the latter of which condensed to 1,8,15,22-tetraneopentoxyphthalocyanine as a mixture of isomers. Bisphthalonitriles such as 1,3-bis(2′,3′-dicyanophenoxy)-2,2-dipentylpropane, 1,3-bis(2′,3′-dicyanophenoxy)-2,2-diethylpropane, 1,3-bis(2′,3′-dicyanophenoxy)-2,2-dioctylpropane, and 1,3-bis(2′,3′-dicyanophenoxy)-2-methyl-2-trityloxymethylpropane all gave bis-crown-like 1,11,15,25-tetrasubstituted phthalocyanines as pure compounds when treated with lithium octoxide in 1-octanol at 196 °C. A host of nine other bisphthalonitriles including 1,5-bis(2′,3′-dicyanophenoxy)-3-oxapentane, 1,1-bis(2′,3′-dicyanophenoxymethyl)cyclohexane, 1,2-bis(2′,3′-dicyanophenoxymethyl)benzene, and 2,5-bis(2′,3′-dicyanophenoxymethyl)furan did not dimerize to mononuclear phthalocynaines. The "gem dimethyl" effect was suggested as a reason for the successful macrocyclizations. Key words: nucleophilic aromatic substitution, phthalonitriles, bisphthalonitriles, 1,11,15,25-tetrasubstituted phthalocyanines.

Sign in / Sign up

Export Citation Format

Share Document