New azo-decorated N-pyrrolidinylthiazoles: synthesis, properties and an unexpected remote substituent effect transmission

2016 ◽  
Vol 14 (29) ◽  
pp. 7061-7068 ◽  
Author(s):  
Carla Boga ◽  
Silvia Cino ◽  
Gabriele Micheletti ◽  
Daniele Padovan ◽  
Luca Prati ◽  
...  
Keyword(s):  
Benzene Ring ◽  
Substituent Effect ◽  
Hindered Rotation ◽  
Synthesis Properties ◽  
Remote Substituent

A series of new 5-azo substituted derivatives from 2-N-pyrrolidinylthiazole show an hindered rotation around the C2–N bond in good correlation with the sigma constants of the substituents on the ‘remote’ benzene ring.

scholarly journals Photochemical Transformation of some 3-benzyloxy-2-(benzo[b]thiophen-2-yl)-4Hchromen-4-ones: A Remote Substituent Effect

2018 ◽  
Vol 16 (1) ◽  
pp. 79-86
Author(s):  
Aarti Dalal ◽  
Radhika Khanna ◽  
Ramesh C. Kamboj
Keyword(s):  
Substituent Effect ◽  
Product Yield ◽  
Photochemical Transformation ◽  
Spectroscopic Techniques ◽  
Reaction Site ◽  
State Switching ◽  
Photochemical Transformations ◽  
Remote Substituent ◽  
Electron Donating Groups

AbstractThe effect on photochemical transformations of the substituents present remotely from the reaction site in 3-benzyloxy-2-(benzo[b]thiophen-2-yl)-4H-chromen-4-ones has been determined. The structure(s) of the substrates and photoproducts were established by spectroscopic techniques (UV, IR, and NMR). The substituents had profound effects on product yield and distribution. Electron withdrawing groups (EWGs) on the benzenoid moiety of the chromenone nucleus increased the yield of the photoproducts whereas electron donating groups (EDGs) decreased the yield. These results may be attributed to “state switching” of the substituents during excitation.

A Study of Substituent Effect on the Oxidative Strengths of N-Chloroarenesulphonamides: Kinetics of Oxidation of Leucine and Isoleucine in Aqueous Acid Medium

2004 ◽  
Vol 59 (1) ◽  
pp. 63-72 ◽  
Author(s):  
Mahesha Shetty ◽  
B. Thimme Gowda
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Ionic Strength ◽  
Acid Medium ◽  
Benzene Ring ◽  
Thermodynamic Data ◽  
Substituent Effect ◽  
Kinetics Of Oxidation ◽  
Aqueous Acid ◽  
Kinetics Of

Abstract To study the variation of oxidative strengths of N-chloro-arenesulphonamides with substitution in the benzene ring, six mono- and five di-substituted N-chloro-arenesulphonamides are employed as oxidants for studying the kinetics of oxidation of two neutral amino acids, L-leucine and Lisoleucine in aqueous acid medium. The N-chloro-arenesulphonamides studied are of the constitution: ArSO2NaNCl·H2O (where Ar = C6H5, 4-CH3C6H4, 4-C2H5C6H4, 4-FC6H4, 4-ClC6H4, 4-BrC6H4, 2,3-(CH3)2C6H3, 2,4-(CH3)2C6H3, 2-CH3-4-ClC6H3, 2,4-Cl2C6H3, and 3,4-Cl2C6H3). The reactions show second order kinetics in [oxidant], fractional order in [amino acid] and inverse dependence on [H+]. Addition of the reduced product of the oxidants or variation in ionic strength of the medium has no significant effect on the rates of oxidations. A two-pathway mechanism is considered to explain the experimental results. Effective oxidizing species of the oxidants is Cl+ in different forms. Therefore the oxidising strengths of N-chloro-arenesulphonamides depend on the ease with which Cl+ is released from them. The study reveals that the introduction of substituent in the benzene ring of the oxidant affects both the kinetic and thermodynamic data for the oxidations The electron releasing groups such as CH3 generally inhibit the rates, while electron-withdrawing groups such as Cl enhance this ability, as the electron withdrawing groups ease the release of Cl+ from the reagents and hence increase the oxidising strengths. The on Ea and logA and validity of the Hammett and isokinetic relationships for the oxidations are also analysed.

Conformational Studies by Dynamic NMR. 95.1Rotation around the Adamantyl−Alkyl Bond. Remote Substituent Effect on Conformational Equilibrium

2003 ◽  
Vol 68 (22) ◽  
pp. 8494-8499 ◽  
Author(s):  
J. Edgar Anderson ◽  
Armin de Meijere ◽  
Sergei I. Kozhushkov ◽  
Lodovico Lunazzi ◽  
Andrea Mazzanti
Keyword(s):  
Substituent Effect ◽  
Conformational Equilibrium ◽  
Dynamic Nmr ◽  
Conformational Studies ◽  
Remote Substituent

Medium-sized cyclophanes — Part 85: Benzylation by 8-(bromomethyl)[2.2]metacyclophanes. Through-space electronic interactions of [2.2]metacyclophane benzyl cations

2010 ◽  
Vol 88 (5) ◽  
pp. 458-462 ◽  
Author(s):  
Tomoe Shimizu ◽  
Kan Tanaka ◽  
Arjun Paudel ◽  
Takehiko Yamato
Keyword(s):  
Benzene Ring ◽  
Aromatic Ring ◽  
Substituent Effect ◽  
Reaction Rate ◽  
Electronic Interactions ◽  
Benzyl Cation ◽  
Internal Position ◽  
Benzylation Of Benzene

TiCl4-mediated Friedel–Crafts benzylation of benzene with 8-(bromomethyl)[2.2]metacyclophanes to afford 8-benzyl[2.2]metacyclophanes is described. Substituent effect through space on the rate of the benzylation of benzene with a bromomethyl group attached on the opposite aromatic ring was first found in this investigation. Interestingly, the introduction of the substituents at the internal position 16 tends to promote the present benzylation reaction rate 1.8–3.8 times. It was found that the benzyl cation intermediate was stabilized by the the direct through-space cation–π interaction among the opposite benzene ring in the benzylation of [2.2]metacyclophane systems.

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