The mass spectra of 18 variously substituted 1,2-naphthaquinones are reported and discussed. It is shown that the majority of the ortho-naphthaquinones studied are reduced by water vapour present in the mass spectrometer and that this reaction provides a mass spectral method for distinguishing between 1,2- and 1,4-naphthaquinones. No simple relationship is found to exist between the solution redox potentials and the ease of reduction of the 1,2-naphthaquinones in the spectrometer. Finally, fragmentation patterns for the individual quinones studied are suggested and these are correlated with the type and position of the substituent in the quinone nucleus.
{"title":"Mass spectrometry of quinones. Part II. A study of the distinguishing features found in the mass spectra of 1,2- and 1,4-naphthaquinones","authors":"R. Oliver, R. Rashman","doi":"10.1039/J29710000341","DOIUrl":"https://doi.org/10.1039/J29710000341","url":null,"abstract":"The mass spectra of 18 variously substituted 1,2-naphthaquinones are reported and discussed. It is shown that the majority of the ortho-naphthaquinones studied are reduced by water vapour present in the mass spectrometer and that this reaction provides a mass spectral method for distinguishing between 1,2- and 1,4-naphthaquinones. No simple relationship is found to exist between the solution redox potentials and the ease of reduction of the 1,2-naphthaquinones in the spectrometer. Finally, fragmentation patterns for the individual quinones studied are suggested and these are correlated with the type and position of the substituent in the quinone nucleus.","PeriodicalId":17268,"journal":{"name":"Journal of The Chemical Society B: Physical Organic","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1971-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83810943","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The crystal and molecular structure of 1,1-di-(p-nitrophenyl)ethylene has been determined as part of a study on diarylhalogenoethylenes and related compounds. Crystals are monoclinic, space group P21/c, with Z= 4, in a unit cell of dimensions a= 7·978(1), b= 19·386(1), c= 8·304(1)A, and β= 97·12(1)°. The crystal structure was solved by direct methods and has been refined to R= 0·079 for 1590 reflections. Conformational analysis was also carried out by semi-theoretical methods and gave good agreement with the experimental results.
{"title":"Crystal and molecular structure of 1,1-di-(p-nitrophenyl)ethylene","authors":"G. Casalone, M. Simonetta","doi":"10.1039/J29710001180","DOIUrl":"https://doi.org/10.1039/J29710001180","url":null,"abstract":"The crystal and molecular structure of 1,1-di-(p-nitrophenyl)ethylene has been determined as part of a study on diarylhalogenoethylenes and related compounds. Crystals are monoclinic, space group P21/c, with Z= 4, in a unit cell of dimensions a= 7·978(1), b= 19·386(1), c= 8·304(1)A, and β= 97·12(1)°. The crystal structure was solved by direct methods and has been refined to R= 0·079 for 1590 reflections. Conformational analysis was also carried out by semi-theoretical methods and gave good agreement with the experimental results.","PeriodicalId":17268,"journal":{"name":"Journal of The Chemical Society B: Physical Organic","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1971-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79101118","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In the presence of a large excess of diphenylhydroxylamine the title reaction gives benzoic acid and diphenyl nitroxide according to the equation 2Ph2NOH +(PhCO2)2→ 2Ph2NO·+ 2PhCO2H. The reaction is of the first order in both peroxide and hydroxylamine. Although this is one of the most clear-cut examples of molecule-induced homolysis known, no convincing evidence has been adduced in favour of any one mechanism. Substituent and isotope effects are consistent with an initial electron transfer from hydroxylamine to peroxide.
{"title":"The oxidation of diphenylhydroxylamine by benzoyl peroxide","authors":"G. R. Chalfont, M. Perkins","doi":"10.1039/J29710000245","DOIUrl":"https://doi.org/10.1039/J29710000245","url":null,"abstract":"In the presence of a large excess of diphenylhydroxylamine the title reaction gives benzoic acid and diphenyl nitroxide according to the equation 2Ph2NOH +(PhCO2)2→ 2Ph2NO·+ 2PhCO2H. The reaction is of the first order in both peroxide and hydroxylamine. Although this is one of the most clear-cut examples of molecule-induced homolysis known, no convincing evidence has been adduced in favour of any one mechanism. Substituent and isotope effects are consistent with an initial electron transfer from hydroxylamine to peroxide.","PeriodicalId":17268,"journal":{"name":"Journal of The Chemical Society B: Physical Organic","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1971-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79630479","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Dimethylphenyl-, methyldiphenyl-, and triphenyl-silyl-lithium react very rapidly with fluorene in tetrahydrofuran. The reaction can be followed at low temperature with a stop-flow technique. The thermodynamic constants of activation at –30° for this reaction with Ph3SiLi, MePh2SiLi, and Me2PhSiLi, respectively are: ΔG‡= 14·0, 13·6, 13·6 kcal. mole–1; ΔH‡= 6·1, 6·6, 6·2 kcal. mole–1; ΔS‡=–32·5, –28·8, –30·3 cal. mole–1 deg.–1. Addition of LiBPh4 to these systems has negligible effect on the rate constants.The fact that the replacement of phenyl by methyl produces so small a change has been discussed in relation to the constancy of λmax. for R3SiLi as phenyl is replaced by methyl.For the reaction of MePh2SiLi with fluorene at –30° in dimethoxyethane the thermodynamic constants of activation are: ΔG‡= 11·7 kcal. mole–1; ΔH‡= 3·5 kcal. mole–1; ΔS‡=–33·7 cal. mole–1 deg–1.Hexamethyldisilane has been cleaved by lithium in tetrahydrofuran solution to give trimethyl-silyl-lithium, and the reaction of this with fluorene has been studied qualitatively.
{"title":"The reactions of organometallic compounds containing silicon. Part III. Reactions of trimethyl-, dimethylphenyl-, methyldiphenyl-, and triphenyl-silyl-lithium with fluorene","authors":"A. G. Evans, M. A. Hamid, N. H. Rees","doi":"10.1039/J29710001110","DOIUrl":"https://doi.org/10.1039/J29710001110","url":null,"abstract":"Dimethylphenyl-, methyldiphenyl-, and triphenyl-silyl-lithium react very rapidly with fluorene in tetrahydrofuran. The reaction can be followed at low temperature with a stop-flow technique. The thermodynamic constants of activation at –30° for this reaction with Ph3SiLi, MePh2SiLi, and Me2PhSiLi, respectively are: ΔG‡= 14·0, 13·6, 13·6 kcal. mole–1; ΔH‡= 6·1, 6·6, 6·2 kcal. mole–1; ΔS‡=–32·5, –28·8, –30·3 cal. mole–1 deg.–1. Addition of LiBPh4 to these systems has negligible effect on the rate constants.The fact that the replacement of phenyl by methyl produces so small a change has been discussed in relation to the constancy of λmax. for R3SiLi as phenyl is replaced by methyl.For the reaction of MePh2SiLi with fluorene at –30° in dimethoxyethane the thermodynamic constants of activation are: ΔG‡= 11·7 kcal. mole–1; ΔH‡= 3·5 kcal. mole–1; ΔS‡=–33·7 cal. mole–1 deg–1.Hexamethyldisilane has been cleaved by lithium in tetrahydrofuran solution to give trimethyl-silyl-lithium, and the reaction of this with fluorene has been studied qualitatively.","PeriodicalId":17268,"journal":{"name":"Journal of The Chemical Society B: Physical Organic","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1971-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89287065","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A study of the acid and alkaline hydrolysis of esters (R1CO2R2) containing unsaturated substituents in aqueous acetone confirms that where the unsaturation in R1 is conjugated with CO2R2 in the initial state, the value of the Taft steric substituent constant, Es, is considerably more negative than might be expected from normal steric interactions. When there is no conjugation, Es has values consistent with steric interactions by R1 and R2. On the other hand, the Taft polar substituent constant, σ*, has fairly large positive values regardless of the presence or absence of conjugation. This may be attributed to the electron-withdrawing power of the unsaturated substituents but the property falls off as the seat of unsaturation becomes further removed from the ester group.
{"title":"Effect of unsaturated substituents on the hydrolysis of esters","authors":"C. Evans, J. Thomas","doi":"10.1039/J29710001502","DOIUrl":"https://doi.org/10.1039/J29710001502","url":null,"abstract":"A study of the acid and alkaline hydrolysis of esters (R1CO2R2) containing unsaturated substituents in aqueous acetone confirms that where the unsaturation in R1 is conjugated with CO2R2 in the initial state, the value of the Taft steric substituent constant, Es, is considerably more negative than might be expected from normal steric interactions. When there is no conjugation, Es has values consistent with steric interactions by R1 and R2. On the other hand, the Taft polar substituent constant, σ*, has fairly large positive values regardless of the presence or absence of conjugation. This may be attributed to the electron-withdrawing power of the unsaturated substituents but the property falls off as the seat of unsaturation becomes further removed from the ester group.","PeriodicalId":17268,"journal":{"name":"Journal of The Chemical Society B: Physical Organic","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1971-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89334375","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. G. Evans, J. Evans, P. J. Emes, C. L. James, P. J. Pomery
The effect of temperature on the disproportionation equilibria of the radical anions of azobenzene, naphthalene-1-azobenzene, 1,1′-azonaphthalene, and 2,2′-azonaphthalene in tetrahydrofuran with various alkali metals as gegenions has been determined by measurement of the radical-anion concentration at different temperatures by e.s.r. Equilibrium constants, ΔH° values, and ΔS° values have been determined for these disproportionation equilibria.Well resolved e.s.r. spectra of these radical anions were obtained and analysed and the analysis was compared with the splitting constants obtained from simple Huckel and McLachlan theoretical treatment. The temperature dependence of the metal splittings were measured for azobenzene and naphthalene-1-azobenzene. In all cases except sodium, practically no temperature effect was observed. In the case of sodium, however, a marked temperature dependence of metal splitting and hyperfine splitting line widths were found which have been interpreted in terms of tight ion-pair–loose ion-pair equilibria. Equilibrium constants, ΔH° values, ΔS° values, rate constants, ΔH‡, and ΔS‡ values for these equilibria have been determined.
{"title":"Reactions of radical anions. Part X. Electron spin resonance study of the radical anions of azobenzene, naphthalene-1-azobenzene, 1,1′-azonaphthalene, and 2,2′-azonaphthalene including the measurements of tight ion-pair–loose ion-pair equilibria","authors":"A. G. Evans, J. Evans, P. J. Emes, C. L. James, P. J. Pomery","doi":"10.1039/J29710001484","DOIUrl":"https://doi.org/10.1039/J29710001484","url":null,"abstract":"The effect of temperature on the disproportionation equilibria of the radical anions of azobenzene, naphthalene-1-azobenzene, 1,1′-azonaphthalene, and 2,2′-azonaphthalene in tetrahydrofuran with various alkali metals as gegenions has been determined by measurement of the radical-anion concentration at different temperatures by e.s.r. Equilibrium constants, ΔH° values, and ΔS° values have been determined for these disproportionation equilibria.Well resolved e.s.r. spectra of these radical anions were obtained and analysed and the analysis was compared with the splitting constants obtained from simple Huckel and McLachlan theoretical treatment. The temperature dependence of the metal splittings were measured for azobenzene and naphthalene-1-azobenzene. In all cases except sodium, practically no temperature effect was observed. In the case of sodium, however, a marked temperature dependence of metal splitting and hyperfine splitting line widths were found which have been interpreted in terms of tight ion-pair–loose ion-pair equilibria. Equilibrium constants, ΔH° values, ΔS° values, rate constants, ΔH‡, and ΔS‡ values for these equilibria have been determined.","PeriodicalId":17268,"journal":{"name":"Journal of The Chemical Society B: Physical Organic","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1971-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87299104","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
When xanthen, thioxanthen, and anthrone were reduced electrolytically in dimethylformamide the radical anions of the corresponding ketones were found to be formed. When anthrone was reduced with lithium and sodium metals under vacuum in tetrahydrofuran, an e.s.r. spectrum was obtained consistent with the formation of a mixture of the radical anions of anthrone and anthranol. This spectrum decayed and could not be regenerated, but further reactions were found to occur giving two further spectra, one of which was found to be due to the anthracene radical anion.
{"title":"Electron spin resonance study of some radical anion intermediates from xanthen and related compounds","authors":"B. J. Tabner, J. R. Zdysiewicz","doi":"10.1039/J29710001659","DOIUrl":"https://doi.org/10.1039/J29710001659","url":null,"abstract":"When xanthen, thioxanthen, and anthrone were reduced electrolytically in dimethylformamide the radical anions of the corresponding ketones were found to be formed. When anthrone was reduced with lithium and sodium metals under vacuum in tetrahydrofuran, an e.s.r. spectrum was obtained consistent with the formation of a mixture of the radical anions of anthrone and anthranol. This spectrum decayed and could not be regenerated, but further reactions were found to occur giving two further spectra, one of which was found to be due to the anthracene radical anion.","PeriodicalId":17268,"journal":{"name":"Journal of The Chemical Society B: Physical Organic","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1971-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86959813","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Hydrogen bromide catalyses the thermal decomposition of cyclohexanecarboxylic acid into essentially cyclohexene, carbon monoxide, and water in the temperature range 642–703 K in a seasoned Pyrex reaction vessel. The first-order rate constants are proportional to the hydrogen bromide concentration. The reaction is homogeneous and predominantly molecular. The Arrhenius equation is k2/cm3 mol–1 s–1= 1013·562 exp (–34,480/RT).
{"title":"The catalysed thermal decomposition of organic acids. Part I. The catalysed decomposition of cyclohexanecarboxylic acid by hydrogen bromide","authors":"S. I. Ahonkhai, E. Emovon","doi":"10.1039/J29710002031","DOIUrl":"https://doi.org/10.1039/J29710002031","url":null,"abstract":"Hydrogen bromide catalyses the thermal decomposition of cyclohexanecarboxylic acid into essentially cyclohexene, carbon monoxide, and water in the temperature range 642–703 K in a seasoned Pyrex reaction vessel. The first-order rate constants are proportional to the hydrogen bromide concentration. The reaction is homogeneous and predominantly molecular. The Arrhenius equation is k2/cm3 mol–1 s–1= 1013·562 exp (–34,480/RT).","PeriodicalId":17268,"journal":{"name":"Journal of The Chemical Society B: Physical Organic","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1971-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86571114","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The title compounds are shown to exist predominantly as the structures named in aqueous solution. Their tautomeric equilibria with the relevant hydroxy, imino, and zwitterionic forms are investigated by u.v. spectroscopy and basicity measurements as are the structures of the mono- and di-cationic species. The quantitative tautomeric equilibrium constants are compared with those for the pyridazine and quinoline series.
{"title":"Tautomeric azines. Part V. Cinnolin-3(2H)-one and 3- and 4-aminocinnoline","authors":"A. Boulton, I. Fletcher, A. Katritzky","doi":"10.1039/J29710002344","DOIUrl":"https://doi.org/10.1039/J29710002344","url":null,"abstract":"The title compounds are shown to exist predominantly as the structures named in aqueous solution. Their tautomeric equilibria with the relevant hydroxy, imino, and zwitterionic forms are investigated by u.v. spectroscopy and basicity measurements as are the structures of the mono- and di-cationic species. The quantitative tautomeric equilibrium constants are compared with those for the pyridazine and quinoline series.","PeriodicalId":17268,"journal":{"name":"Journal of The Chemical Society B: Physical Organic","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1971-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91118439","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
By the theoretical model described in Part III the additivity principle for substituent effects should fail in aromatic electrophilic substitutions. The non-additivity is predicted to arise because the charge-transfer effect of each substituent depends on the inductive power of all the substituents. Here the non-additivity is calculated for several series of polyhomosubstituted benzenes and heterodisubstituted benzenes. The results indicate that, although it should provide a good approximation when applied to polyalkylbenzenes, the additivity principle should lead to considerable errors when applied in the general case. From the calculations a number of predictions are made concerning the pattern of non-additivity. The outcome of empirical checks on the theoretical predictions gives confidence that the FCT theory of non-additivity may provide a much better theoretical tool than the additivity principle.
{"title":"Field and charge-transfer theory for the quantitative correlation of substituent effects in aromatic molecules. Part IV. Non-additivity in electrophilic substitution reactions","authors":"M. Godfrey","doi":"10.1039/J29710001545","DOIUrl":"https://doi.org/10.1039/J29710001545","url":null,"abstract":"By the theoretical model described in Part III the additivity principle for substituent effects should fail in aromatic electrophilic substitutions. The non-additivity is predicted to arise because the charge-transfer effect of each substituent depends on the inductive power of all the substituents. Here the non-additivity is calculated for several series of polyhomosubstituted benzenes and heterodisubstituted benzenes. The results indicate that, although it should provide a good approximation when applied to polyalkylbenzenes, the additivity principle should lead to considerable errors when applied in the general case. From the calculations a number of predictions are made concerning the pattern of non-additivity. The outcome of empirical checks on the theoretical predictions gives confidence that the FCT theory of non-additivity may provide a much better theoretical tool than the additivity principle.","PeriodicalId":17268,"journal":{"name":"Journal of The Chemical Society B: Physical Organic","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1971-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91137486","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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