The isomerisation of dimethyl sulphite to methyl methanesulphonate is catalysed by the methanesulphonate ion. The reaction appears to proceed in two stages. First, dimethyl sulphite alkylates the methanesulphonate ion to form methyl methanesulphonate and methyl sulphite ion. The isomerisation is then completed by the alkylation of the methyl sulphite ion at the sulphur atom by methyl methanesulphonate.Other anions, which can accept a methyl group to give a strong alkylating agent, also catalyse the reaction.
{"title":"The mechanism of the isomerisation of dimethyl sulphite to methyl methanesulphonate","authors":"A. Brook, R. Robertson","doi":"10.1039/J29710001161","DOIUrl":"https://doi.org/10.1039/J29710001161","url":null,"abstract":"The isomerisation of dimethyl sulphite to methyl methanesulphonate is catalysed by the methanesulphonate ion. The reaction appears to proceed in two stages. First, dimethyl sulphite alkylates the methanesulphonate ion to form methyl methanesulphonate and methyl sulphite ion. The isomerisation is then completed by the alkylation of the methyl sulphite ion at the sulphur atom by methyl methanesulphonate.Other anions, which can accept a methyl group to give a strong alkylating agent, also catalyse the reaction.","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":"81648231","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 kinetics of the methanolysis of benzenesulphonyl chloride in the presence of pyridine and its methyl derivatives, and of some para-substituted benzenesulphonyl chlorides in the presence of pyridine, have been studied. The reaction as studied shows first-order kinetics, but is of the first order in sulphonyl chloride and in pyridine or alkylpyridine. From the kinetics, solvent isotope effect, and the low reactivity of 2-picoline compared with the other alkylpyridines, it is concluded that the pyridines function as nucleophilic catalysts. Structural variations in the pyridine and sulphonyl chloride follow the Bronsted and Hammett equations respectively. Comparison of the present data with those for the corresponding hydrolysis show that the reaction of pyridines with benzenesulphonyl chloride is slower in methanol than in water because of a more negative entropy of activation.
{"title":"Kinetics of the pyridine-catalysed methanolysis of aromatic sulphonyl chlorides","authors":"O. Rogne","doi":"10.1039/J29710001334","DOIUrl":"https://doi.org/10.1039/J29710001334","url":null,"abstract":"The kinetics of the methanolysis of benzenesulphonyl chloride in the presence of pyridine and its methyl derivatives, and of some para-substituted benzenesulphonyl chlorides in the presence of pyridine, have been studied. The reaction as studied shows first-order kinetics, but is of the first order in sulphonyl chloride and in pyridine or alkylpyridine. From the kinetics, solvent isotope effect, and the low reactivity of 2-picoline compared with the other alkylpyridines, it is concluded that the pyridines function as nucleophilic catalysts. Structural variations in the pyridine and sulphonyl chloride follow the Bronsted and Hammett equations respectively. Comparison of the present data with those for the corresponding hydrolysis show that the reaction of pyridines with benzenesulphonyl chloride is slower in methanol than in water because of a more negative entropy of activation.","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":"82122781","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}
During the preparation of the ditoluene-p-sulphonates of 2,3-dipentylbutane-1,4-diols and 2,4-dipentylpentane-1,5-diols, two competing reactions occurred; the ditoluene-p-sulphonylation and the formation of the appropriate cyclic ethers. Each of the meso-isomers produce a mixture of meso-ditoluene-p-sulphonyl derivative and the cis-cyclic ethers while the (±)-isomers from a mixture of the (±)-ditoluene-p-sulphonyl derivatives and the trans-cyclic ethers. As a result of a difference in the activation energy of formation, the cis- and trans-isomers of each cyclic compound are obtained in unequal amounts with the trans in majority; thus the corresponding ditoluene-p-sulphonyl products are obtained proportionally unbalanced with the (±)-form in minority. The ditoluene-p-sulphonyl derivatives are quantitatively reduced to the corresponding hydrocarbons and after chromatography, help to determine the relative retention times and volatilities of the meso-(±) and cis–trans pairs in the 3,4-dipentyltetrahydrofurans, 3,5-dipentyltetrahydropyrans, 2,3-dipentylbutanes, and 2,4-dipentylpentanes.
{"title":"Differential gas–liquid chromatographic behaviour in diastereoisomeric systems. Part II. Assignment of diastereomer configuration in 2,3-dipentylbutanes and 2,4-dipentylpentanes","authors":"B. Feibush, L. Spialter","doi":"10.1039/J29710000111","DOIUrl":"https://doi.org/10.1039/J29710000111","url":null,"abstract":"During the preparation of the ditoluene-p-sulphonates of 2,3-dipentylbutane-1,4-diols and 2,4-dipentylpentane-1,5-diols, two competing reactions occurred; the ditoluene-p-sulphonylation and the formation of the appropriate cyclic ethers. Each of the meso-isomers produce a mixture of meso-ditoluene-p-sulphonyl derivative and the cis-cyclic ethers while the (±)-isomers from a mixture of the (±)-ditoluene-p-sulphonyl derivatives and the trans-cyclic ethers. As a result of a difference in the activation energy of formation, the cis- and trans-isomers of each cyclic compound are obtained in unequal amounts with the trans in majority; thus the corresponding ditoluene-p-sulphonyl products are obtained proportionally unbalanced with the (±)-form in minority. The ditoluene-p-sulphonyl derivatives are quantitatively reduced to the corresponding hydrocarbons and after chromatography, help to determine the relative retention times and volatilities of the meso-(±) and cis–trans pairs in the 3,4-dipentyltetrahydrofurans, 3,5-dipentyltetrahydropyrans, 2,3-dipentylbutanes, and 2,4-dipentylpentanes.","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":"79445656","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}
It is shown that it is not justifiable to invoke ‘orbital steering’ to explain the variation in the rates of lactonisation of the hydroxy-acids studied by Storm and Koshland.
研究表明，用“轨道转向”来解释斯托姆和科什兰所研究的羟基酸内酯化率的变化是不合理的。
{"title":"Orbital steering: an unnecessary concept","authors":"B. Capon","doi":"10.1039/J29710001207","DOIUrl":"https://doi.org/10.1039/J29710001207","url":null,"abstract":"It is shown that it is not justifiable to invoke ‘orbital steering’ to explain the variation in the rates of lactonisation of the hydroxy-acids studied by Storm and Koshland.","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":"84505148","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}
Aromatic esters of the type Ar·CO2·CH2·CHR1R2 are found to undergo a photoelimination reaction from both singlet and triplet excited states, though the process is inefficient from states of either multiplicity. Rate constants for the primary steps are evaluated for the systems p-MeO·C6H4·CO2·CH2·CHR1R2(R1= Me; R2= H, Me). Absorption and emission data suggest that the lowest singlet and triplet states in all the esters studied are ππ* in nature.
{"title":"Type 2 photoelimination reaction of esters of aromatic carboxylic acids","authors":"J. Barltrop, J. Coyle","doi":"10.1039/J29710000251","DOIUrl":"https://doi.org/10.1039/J29710000251","url":null,"abstract":"Aromatic esters of the type Ar·CO2·CH2·CHR1R2 are found to undergo a photoelimination reaction from both singlet and triplet excited states, though the process is inefficient from states of either multiplicity. Rate constants for the primary steps are evaluated for the systems p-MeO·C6H4·CO2·CH2·CHR1R2(R1= Me; R2= H, Me). Absorption and emission data suggest that the lowest singlet and triplet states in all the esters studied are ππ* in nature.","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":"81693038","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 reactions of α-pinene and β-pinene with sulphuric acid in anhydrous acetic acid have been studied, and the results have been shown to be consistent with the addition of at least partially undissociated acid, giving an intimate ion pair in which the counter ion stabilises the carbonium ion against attack by external nucleophiles. The main mode of decomposition of the carbonium ion is thus olefin formation by loss of a proton to the counter ion. In aqueous acetic acid, the ion pair is either not formed or short lived, permitting the carbonium ion to react with external nucleophiles.
{"title":"Rearrangements of pinane derivatives. Part II. Products of acid-catalysed rearrangement of α-pinene and β-pinene in acetic acid","authors":"C. Williams, D. Whittaker","doi":"10.1039/J29710000672","DOIUrl":"https://doi.org/10.1039/J29710000672","url":null,"abstract":"The reactions of α-pinene and β-pinene with sulphuric acid in anhydrous acetic acid have been studied, and the results have been shown to be consistent with the addition of at least partially undissociated acid, giving an intimate ion pair in which the counter ion stabilises the carbonium ion against attack by external nucleophiles. The main mode of decomposition of the carbonium ion is thus olefin formation by loss of a proton to the counter ion. In aqueous acetic acid, the ion pair is either not formed or short lived, permitting the carbonium ion to react with external nucleophiles.","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":"81824129","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}
Enthalpies and entropies of activation have been determined for the acid-catalysed methanolysis of 1,2-epoxypropane, and of XCH2·[graphic omitted] (X = Ph, PhO, or OH), and for the acid-catalysed ethanolysis and propan-2-olysis of 1,2-epoxy-3-phenylpropane. Products have been analysed by g.l.c. and the results have been used to dissect the measured rate coefficients into rate coefficients for normal and abnormal attack. Entropies of activation for the methanolysis in the normal position (ca.–17 cal mol–1 K–1) have been interpreted in terms of an A2 mechanism, while those for the abnormal position (ca.–14 cal mol–1 K–1) have been interpreted in terms of a borderline A2 mechanism. The more positive values for the methanolysis of 1,2-epoxy-3-phenoxypropane apparently arise from restricted bond rotations in the initial state.The Hughes–Ingold solvation theory has been used to explain the variation of ΔS‡ and ΔH‡ with change in solvent in the acid-catalysed reactions of 1,2-epoxy-3-phenylpropane with the three alcohols.The effect of substituents has been analysed in terms of the Taft linear free-energy relationship. The negative values of the polar reaction constants and the large postive values of the steric reaction constants are in accord with the mechanisms already proposed.The effect of the solvent on the reactions is examined and certain quantitative correlations are briefly considered.
测定了1,2-环氧丙烷和XCH2·(X = Ph, PhO或OH)的酸催化甲醇解和1,2-环氧-3-苯基丙烷的酸催化乙醇解和丙烷-2水解的活化焓和活化熵。产品已通过g.l.c.进行分析，结果已用于将测量的速率系数分解为正常和异常攻击的速率系数。正常位置(ca.-17 cal mol-1 K-1)甲醇分解的激活熵用A2机制解释，而异常位置(ca.-14 cal mol-1 K-1)的激活熵用临界A2机制解释。1,2-环氧-3-苯氧丙烷甲醇分解的正值明显是由于初始状态下键旋转受限所致。Hughes-Ingold溶剂化理论被用来解释1,2-环氧-3-苯基丙烷与三种醇的酸催化反应中ΔS‡和ΔH‡随溶剂变化的变化。根据塔夫脱线性自由能关系分析了取代基的影响。极性反应常数的负值和空间反应常数的大正值与已经提出的机理一致。考察了溶剂对反应的影响，并简要讨论了某些定量关系。
{"title":"Mechanism of acid-catalysed alcoholysis of epoxides. Part III. Alcoholysis of 1,2-epoxypropane, 1,2-epoxy-3-phenoxypropane, 1,2-epoxy-3-phenylpropane, and 2,3-epoxypropan-1-ol","authors":"J. Biggs, N. Chapman, V. Wray","doi":"10.1039/J29710000066","DOIUrl":"https://doi.org/10.1039/J29710000066","url":null,"abstract":"Enthalpies and entropies of activation have been determined for the acid-catalysed methanolysis of 1,2-epoxypropane, and of XCH2·[graphic omitted] (X = Ph, PhO, or OH), and for the acid-catalysed ethanolysis and propan-2-olysis of 1,2-epoxy-3-phenylpropane. Products have been analysed by g.l.c. and the results have been used to dissect the measured rate coefficients into rate coefficients for normal and abnormal attack. Entropies of activation for the methanolysis in the normal position (ca.–17 cal mol–1 K–1) have been interpreted in terms of an A2 mechanism, while those for the abnormal position (ca.–14 cal mol–1 K–1) have been interpreted in terms of a borderline A2 mechanism. The more positive values for the methanolysis of 1,2-epoxy-3-phenoxypropane apparently arise from restricted bond rotations in the initial state.The Hughes–Ingold solvation theory has been used to explain the variation of ΔS‡ and ΔH‡ with change in solvent in the acid-catalysed reactions of 1,2-epoxy-3-phenylpropane with the three alcohols.The effect of substituents has been analysed in terms of the Taft linear free-energy relationship. The negative values of the polar reaction constants and the large postive values of the steric reaction constants are in accord with the mechanisms already proposed.The effect of the solvent on the reactions is examined and certain quantitative correlations are briefly considered.","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":"80837268","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 reaction of cyano-radicals, produced by the photolysis of cyanogen iodide, with aromatic compounds afforded aromatic nitriles. The isomer ratios and the relative reactivities were determined for a variety of monosubstituted benzenes and the results indicated that the cyano-radical preferably attacks relatively electronegative sites. The partial rate factors for the meta- and para-positions correlate with σ+ to give a slope of –0·42. It is concluded that cyano-radical possesses a slight electrophilic character.
{"title":"Photochemical production of the electrophilic cyano-radical: homolytic aromatic cyanation","authors":"P. Spagnolo, L. Testaferri, M. Tiecco","doi":"10.1039/J29710002006","DOIUrl":"https://doi.org/10.1039/J29710002006","url":null,"abstract":"The reaction of cyano-radicals, produced by the photolysis of cyanogen iodide, with aromatic compounds afforded aromatic nitriles. The isomer ratios and the relative reactivities were determined for a variety of monosubstituted benzenes and the results indicated that the cyano-radical preferably attacks relatively electronegative sites. The partial rate factors for the meta- and para-positions correlate with σ+ to give a slope of –0·42. It is concluded that cyano-radical possesses a slight electrophilic character.","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":"80637177","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 temperature range 317·5–391·3 °C methylspiro[2,2]pentane decomposes via five competing homogeneous unimolecular pathways yielding ethylidenecyclobutane (k1), 2-methyl(methylene)cyclobutane (k2), 3-methyl-(methylene)cyclobutane (k3), ethylene + buta-1,2-diene (k4), and allene + propene (k5). 3-Methyl(methylene)-k1/s–1= 1014·14 ∓ 0·15 exp [–(53 816 ∓ 415)/1·987T], k2/s–1= 1014·52 ∓ 0·14 exp [–(53,817 ∓ 412)/1·987T], k3/s–1= 1014·38 ∓ 0·15 exp [–(53,817 ∓ 416)/1·987T], k4/s–1= 1015·48 ∓ 0·42 exp [–(59,616 ∓ 1208)/1·987T], k5/s–1= 1015·32 ∓ 0·59 exp [–(59,795 ∓ 1672)/1·987T], k12/s–1= 1014·16 ∓ 1·15 exp [–(52,910 ∓ 3300)/1·987T] cyclobutane in the same temperature range isomerizes homogeneously to 2-methylpenta-1,4-diene (k12). The mechanisms of the various reactions are discussed in terms of the formation of diradical intermediates.
{"title":"Kinetics of the thermal gas phase reactions of methylspiro[2,2]pentane","authors":"M. C. Flowers, A. R. Gibbons","doi":"10.1039/J29710000612","DOIUrl":"https://doi.org/10.1039/J29710000612","url":null,"abstract":"In the temperature range 317·5–391·3 °C methylspiro[2,2]pentane decomposes via five competing homogeneous unimolecular pathways yielding ethylidenecyclobutane (k1), 2-methyl(methylene)cyclobutane (k2), 3-methyl-(methylene)cyclobutane (k3), ethylene + buta-1,2-diene (k4), and allene + propene (k5). 3-Methyl(methylene)-k1/s–1= 1014·14 ∓ 0·15 exp [–(53 816 ∓ 415)/1·987T], k2/s–1= 1014·52 ∓ 0·14 exp [–(53,817 ∓ 412)/1·987T], k3/s–1= 1014·38 ∓ 0·15 exp [–(53,817 ∓ 416)/1·987T], k4/s–1= 1015·48 ∓ 0·42 exp [–(59,616 ∓ 1208)/1·987T], k5/s–1= 1015·32 ∓ 0·59 exp [–(59,795 ∓ 1672)/1·987T], k12/s–1= 1014·16 ∓ 1·15 exp [–(52,910 ∓ 3300)/1·987T] cyclobutane in the same temperature range isomerizes homogeneously to 2-methylpenta-1,4-diene (k12). The mechanisms of the various reactions are discussed in terms of the formation of diradical intermediates.","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":"83069843","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}
M. Murray, R. Schmutzler, E. Gründemann, H. Teichmann
1 H and 31P N.m.r. data of a series of alkoxyphosphonium hexachloroantimonates are presented and compared with similar data for the corresponding phosphoryl compounds. The 31P chemical shifts cannot be explained by the theoretical treatment of Letcher and Van Wazer, and alternative empirical correlations are suggested.
{"title":"Nuclear magnetic resonance studies of alkoxyphosphonium hexachloroantimonates","authors":"M. Murray, R. Schmutzler, E. Gründemann, H. Teichmann","doi":"10.1039/J29710001714","DOIUrl":"https://doi.org/10.1039/J29710001714","url":null,"abstract":"1 H and 31P N.m.r. data of a series of alkoxyphosphonium hexachloroantimonates are presented and compared with similar data for the corresponding phosphoryl compounds. The 31P chemical shifts cannot be explained by the theoretical treatment of Letcher and Van Wazer, and alternative empirical correlations are suggested.","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":"77804407","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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