The nitration of mono‐alkylbenzenes conformational analysis and steric hindrance: Part V: Mechanistic aspects

The wavenumbers of the charge transfer band maxima in the UV spectra of a large number of 3-, 4-, 3,4-, and 3,5-alkyl-substituted nitrobenzenes have been determined in isooctane and in ethanol. Extinction coefticients E,, and oscillator strengths are reported for a number of these compounds. The differences V",.,-v",, in isooctane reveal an order of substituent effects of alkyl groups which is not entangled with differential solvation effects. Methyl groups in the y-position of 4-alkyl groups are very effective in stabilising the excitation. There is no constant ratio between the substituent effects of the alkyl groups from the 3-and the 4-position. The substituent effects are approximately additive in the 3,4-and 3,S-aialkyl-substituted nitrobenzenes. Both 3-and 4-alkyl groups bulkier than methyl exert a steric hindrance of the solvation in ethanol; this hindrance has been quantified for the 4-alkyl groups.

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Conformational analysis of some alkyl groups on benzene: PMR spectra of 4‐alkyl‐2‐nitroacetanilides

Baas

1972

Recl. Trav. Chim. Pays‐Bas

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The PMR spectra of 2‐nitroacetanilide and often 4‐alkyl substituted derivatives have been measured. Two about equally stable conformers have been detected for the derivatives with the groups ‐CHPriBut, ‐CHBut2, and ‐C(OH)But2. The conformational isomerism is caused by a hindered rotation about the bond between the alkyl groups and the benzene ring; rotational barriers have been determined of approximately 12, 22, and 21 kcal/mole, respectively. The preferred conformations and the rotational barriers are discussed for the alkyl groups ‐CH2But, ‐CHMeBut, and ‐CHPri2.

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The nitration of mono‐alkylbenzenes conformational analysis and steric hindrance: Part V: Mechanistic aspects

Cited by 6 publications

References 11 publications

ChemInform Abstract: NITRIERUNG VON MONOALKYLBENZOLEN, KONFORM.‐ANALYSE UND STERISCHE HINDERUNG 5. MITT. MECHANISTISCHE ASPEKTE

ChemInform Abstract: NITRIERUNG VON MONOALKYLBENZOLEN, KONFORM.‐ANALYSE UND STERISCHE HINDERUNG 5. MITT. MECHANISTISCHE ASPEKTE

Substituent effects of meta and para alkyl groups on the charge transfer band in the UV spectrum of nitrobenzene

Conformational analysis of some alkyl groups on benzene: PMR spectra of 4‐alkyl‐2‐nitroacetanilides

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