Polysubstituted Benzene Derivatives Research Articles

Studies on the proton magnetic resonance spectra in aromatic systems. II. Discussions on the polysubstituted benzene derivatives.

The reliability and limitation on the simple sum rule of the shielding parameters in polysubstituted benzene series have been discussed and the ring proton chemical shifts for several systems have been estimated from the above parameters.

Ketovinylation of β-dicarbonyl compounds

The introduction of the ketovinyl group into β-dicarbonyl compounds with only one labile hydrogen proceeds normally, but the presence of two labile hydrogens results in the formation of complex mixtures. Ethyl malonate and ethyl acetoacetate have, however, been successfully ketovinylated. In the former case, α-carbethoxy-δ-keto-β,γ-unsaturated acids are produced in high yield and depending on the conditions of ketovinylation of ethyl acetoacetate either 4-alkyl salicyclic acids or polysubstituted benzene derivatives may be prepared. Further, the ketovinylation products of ethyl malonate and alkyl acetoacetates may be used for the synthesis of either (1) unsaturated aliphatic keto acids or diketones or (2) a variety of α-pyrone derivatives. A mechanism for the ketovinylation of ethyl acetoacetate is proposed and the trans configuration of the ketovinylation products established.

New Compounds. Some Polysubstituted Benzene Derivatives

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTNew Compounds. Some Polysubstituted Benzene DerivativesReynold Fuson and Joseph CorseCite this: J. Am. Chem. Soc. 1945, 67, 11, 2054–2055Publication Date (Print):November 1, 1945Publication History Published online1 May 2002Published inissue 1 November 1945https://doi.org/10.1021/ja01227a054RIGHTS & PERMISSIONSArticle Views48Altmetric-Citations1LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (274 KB) Get e-Alerts Get e-Alerts

Absorption of Polysubstituted Benzene Derivatives

The intensification, by nonchromophoric substitutions, of the forbidden, 1A1g→1B2U, transition in benzene is due, on the one hand, to the unsymmetrical distortion of the ring by the normal vibrations and, on the other hand, to the transition moment produced at the equilibrium position by the migration of charge from the substitution into the ring or vice versa. The latter effect is treated by the method of antisymmetrical molecular orbitals, all calculations being limited to the first order. The rules for combining transition moments due to the various groups in a polysubstituted benzene are calculated. It is shown that, for weak nonchromophoric substitutions, the intensity ratios (except for the less important variation in the normal vibrations) are for C6H5X:oC6H4X2:mC6H4X2:pC6H4X2:1,3,5 C6H3X3:1,2,3 C6H3X3:1,2,4 C6H3X3=1:1:1:4:0:0:3. It is further shown that if one substitutes benzene by a meta-directing group, M, and by an orthopara-directing group, P, of the same intensifying power, the ratios for the mono : ortho : meta : para-derivatives should be 1 : 3 : 3 : 0. These ratios are shown to be in good qualitative agreement with experimental data.