The kinetics of reactions of the penta-aquo-2-, -3-, and -4-pyridiniomethylchromium(III) ions with mercury(II) perchlorate and thallium(III) perchlorate have been studied as a function of the acidity and chloride ion concentration at constant ionic strength. As with the higher chloro-mercury(II) and -thallium(III) species studied earlier, the reaction is believed to involve the bimolecular displacement of the aquated chromium(III) cation by attack of the metallic electrophile at the saturated carbon atom. Individual rate coefficients for the reactions of the species Hg2+, Tl3+, TlOH2+, TlCl2+, and HgCl+ have been estimated. These results, together with those for the higher chloro-mercury(II) and -thallium(III) species, show that the rate of substitution at the 2-position is less than that at the 3-position by approximately the same factor, irrespective of the charge or the character of the electrophile. Any significant bond breaking prior to bond formation in the transition state can be ruled out, and the direct influence of the charge on the pyridinium ion on the incoming charged electrophile is the same for each position of substitution. The influence of ion-pairing on the rates of reaction is discussed.
{"title":"Mechanism of electrophilic substitution at a saturated carbon atom. Part XVI. Rates of reaction of metallic electrophiles with the 2-, 3-, and 4-pyridiniomethylchromium(III) ions","authors":"D. Dodd, M. D. Johnson, D. Vamplew","doi":"10.1039/J29710001841","DOIUrl":"https://doi.org/10.1039/J29710001841","url":null,"abstract":"The kinetics of reactions of the penta-aquo-2-, -3-, and -4-pyridiniomethylchromium(III) ions with mercury(II) perchlorate and thallium(III) perchlorate have been studied as a function of the acidity and chloride ion concentration at constant ionic strength. As with the higher chloro-mercury(II) and -thallium(III) species studied earlier, the reaction is believed to involve the bimolecular displacement of the aquated chromium(III) cation by attack of the metallic electrophile at the saturated carbon atom. Individual rate coefficients for the reactions of the species Hg2+, Tl3+, TlOH2+, TlCl2+, and HgCl+ have been estimated. These results, together with those for the higher chloro-mercury(II) and -thallium(III) species, show that the rate of substitution at the 2-position is less than that at the 3-position by approximately the same factor, irrespective of the charge or the character of the electrophile. Any significant bond breaking prior to bond formation in the transition state can be ruled out, and the direct influence of the charge on the pyridinium ion on the incoming charged electrophile is the same for each position of substitution. The influence of ion-pairing on the rates of reaction is discussed.","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":"89468739","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 structure of 1-bromo-2,4-epidithio-1-nitro-4-phenylbutadiene has been determined by three-dimensional counter methods. The crystals are monoclinic, space group P21/c with Z= 4 in a unit cell of dimensions a= 9·281(8), b= 12·457(9), c= 12·713(9)A, and β= 132° 7′(8′). The structure has been refined to R 0·073 for 1677 non-zero reflections measured on an automatic diffractometer. The central eight atoms of the molecule are almost planar with one of the oxygen atoms of the nitro-group being held at a distance of 2·373(7)A from S(2). The S(2)–S(4) distance is 2·074(3)A.
{"title":"Crystal and molecular structure of 1-bromo-2,4-epidithio-1-nitro-4-phenylbutadiene","authors":"K. Reid, I. Paul","doi":"10.1039/J29710000952","DOIUrl":"https://doi.org/10.1039/J29710000952","url":null,"abstract":"The crystal structure of 1-bromo-2,4-epidithio-1-nitro-4-phenylbutadiene has been determined by three-dimensional counter methods. The crystals are monoclinic, space group P21/c with Z= 4 in a unit cell of dimensions a= 9·281(8), b= 12·457(9), c= 12·713(9)A, and β= 132° 7′(8′). The structure has been refined to R 0·073 for 1677 non-zero reflections measured on an automatic diffractometer. The central eight atoms of the molecule are almost planar with one of the oxygen atoms of the nitro-group being held at a distance of 2·373(7)A from S(2). The S(2)–S(4) distance is 2·074(3)A.","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":"86772593","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}
G. Bandoli, C. Panattoni, D. A. Clemente, E. Tondello, A. Dondoni, A. Mangini
The crystal structure of 2,5-diphenyl-1,4-dithiin 1-oxide, C16H12O2S2, has been determined by a three-dimensional X-ray analysis. The crystals are orthorhombic, space group Pbca, with cell dimensions of a= 27·855, b= 12·162, and c= 8·089 A and Z= 8. The structure has been solved, by the symbolic-addition procedure, from 702 reflections collected by counter, and refined by least-squares methods to R 0·05.The heterocyclic ring is arranged in a boat structure with the sulphinyl oxygen in the axial position; the phenyl rings lie below the plane of the two CC bonds. The arrangement around the oxidized sulphur is slightly distorted pyramidal with the sulphur atom at the apex. The C–S bonds have different lengths: the two bonds to the unoxidized sulphur are significantly shorter than the C–S distance for the other two bonds to the sulphoxidic sulphur. This situation is discussed in terms of the CNDO method.
用三维x射线分析确定了2,5-二苯基-1,4-二硫胺1-氧化物C16H12O2S2的晶体结构。晶体为正交晶格，空间群为Pbca，胞元尺寸为a= 27.855, b= 12.162, c= 8.089 a, Z= 8。该结构由计数器收集的702个反射信号用符号加法法求解，并用最小二乘法将其细化为r0·05。所述杂环呈船状排列，亚砜基氧在轴向位置;苯环位于两个CC键的平面之下。氧化硫周围的排列呈轻微扭曲的金字塔状，硫原子位于顶端。C-S键有不同的长度:两个键到未氧化硫的C-S距离明显短于其他两个键到亚氧硫的C-S距离。用CNDO方法对这种情况进行了讨论。
{"title":"Crystal, molecular, and electronic structure of 2,5-diphenyl-1,4-dithiin 1-oxide","authors":"G. Bandoli, C. Panattoni, D. A. Clemente, E. Tondello, A. Dondoni, A. Mangini","doi":"10.1039/J29710001407","DOIUrl":"https://doi.org/10.1039/J29710001407","url":null,"abstract":"The crystal structure of 2,5-diphenyl-1,4-dithiin 1-oxide, C16H12O2S2, has been determined by a three-dimensional X-ray analysis. The crystals are orthorhombic, space group Pbca, with cell dimensions of a= 27·855, b= 12·162, and c= 8·089 A and Z= 8. The structure has been solved, by the symbolic-addition procedure, from 702 reflections collected by counter, and refined by least-squares methods to R 0·05.The heterocyclic ring is arranged in a boat structure with the sulphinyl oxygen in the axial position; the phenyl rings lie below the plane of the two CC bonds. The arrangement around the oxidized sulphur is slightly distorted pyramidal with the sulphur atom at the apex. The C–S bonds have different lengths: the two bonds to the unoxidized sulphur are significantly shorter than the C–S distance for the other two bonds to the sulphoxidic sulphur. This situation is discussed in terms of the CNDO method.","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":"86318858","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 rates of detritiation of some 10-X-[9-3H]phenanthrenes in anhydrous trifluoroacetic acid have been measured at several temperatures. The values of the rates, krel, at 70° relative to that for [9-3H]phenanthrene are (X =) Me, 180; F, 4·1; Cl, 0·185; Br, 0·11; I, 0·14. Change of temperature has a large effect on the activating influence of the methyl group, the values of krel being ∼420, ∼350, and 230 at 0, 25, and 50°, respectively. The relatively large activation by fluorine, and the order of deactivation by the other halogens point to a contribution from resonance effects relative to those from inductive effects which is unusually high for ortho-substituents.
{"title":"Aromatic reactivity. Part XLVII. Effects of 10-substituents on the rates of detritiation at the 9-position of phenanthrene","authors":"C. Eaborn, A. Fischer, D. Killpack","doi":"10.1039/J29710002142","DOIUrl":"https://doi.org/10.1039/J29710002142","url":null,"abstract":"The rates of detritiation of some 10-X-[9-3H]phenanthrenes in anhydrous trifluoroacetic acid have been measured at several temperatures. The values of the rates, krel, at 70° relative to that for [9-3H]phenanthrene are (X =) Me, 180; F, 4·1; Cl, 0·185; Br, 0·11; I, 0·14. Change of temperature has a large effect on the activating influence of the methyl group, the values of krel being ∼420, ∼350, and 230 at 0, 25, and 50°, respectively. The relatively large activation by fluorine, and the order of deactivation by the other halogens point to a contribution from resonance effects relative to those from inductive effects which is unusually high for ortho-substituents.","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":"88297727","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}
Aralkyl tertiary amines are oxidised slowly at room temperature by aqueous alkaline potassium hexacyanoferrate-(III). Kinetic studies using a series of para-substituted NN-dimethylbenzylamines show that the rate law for these oxidations is –d[Fe(CN)63–]/dt=k2′[Amine][Fe(CN)63–]. The second-order rate constants are correlated by use of the Hammett, Bronsted, and Taft linear free-energy relationships and give ρ=–0·989, α= 0·990, and ρ*=–4·24, respectively.The quantitative estimation of the products is complicated by the Cannizzaro disproportionation of the benzaldehydes. However, the course of the oxidation is controlled by the acidity of the α-hydrogens; thus, whether an alkyl or an aralkyl group is lost is rationalised in terms of the effect of the substituent on the relative acidities of the N-methyl and N-benzyl hydrogens, respectively.The results show that the mechanism of the oxidation of these amines by potassium hexacyanoferrate(III) is identical to that suggested previously for trialkylamines.
{"title":"Amine oxidation. Part III. The oxidation of some aralkyl tertiary amines with alkaline potassium hexacyanoferrate(III)","authors":"C. A. Audeh, J. Smith","doi":"10.1039/J29710001741","DOIUrl":"https://doi.org/10.1039/J29710001741","url":null,"abstract":"Aralkyl tertiary amines are oxidised slowly at room temperature by aqueous alkaline potassium hexacyanoferrate-(III). Kinetic studies using a series of para-substituted NN-dimethylbenzylamines show that the rate law for these oxidations is –d[Fe(CN)63–]/dt=k2′[Amine][Fe(CN)63–]. The second-order rate constants are correlated by use of the Hammett, Bronsted, and Taft linear free-energy relationships and give ρ=–0·989, α= 0·990, and ρ*=–4·24, respectively.The quantitative estimation of the products is complicated by the Cannizzaro disproportionation of the benzaldehydes. However, the course of the oxidation is controlled by the acidity of the α-hydrogens; thus, whether an alkyl or an aralkyl group is lost is rationalised in terms of the effect of the substituent on the relative acidities of the N-methyl and N-benzyl hydrogens, respectively.The results show that the mechanism of the oxidation of these amines by potassium hexacyanoferrate(III) is identical to that suggested previously for trialkylamines.","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":"88536295","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 β-keto-enol ethers acetylacetone enol methyl ether, dimedone enol methyl ether, and 2,3-dihydro-2,6-dimethyl-γ-pyrone undergo fast olefinic addition reactions with aqueous bromine. Rate measurements for the last two are correlated with published data for olefins and enols. The bromination products of the first two, but not those of the last one, undergo slow, acid-catalysed fission of the methoxy-group to give the bromo-enol.
{"title":"Reactions of β-keto-enol ethers with bromine in aqueous solution","authors":"D. R. Marshall, T. R. Roberts","doi":"10.1039/J29710000797","DOIUrl":"https://doi.org/10.1039/J29710000797","url":null,"abstract":"The β-keto-enol ethers acetylacetone enol methyl ether, dimedone enol methyl ether, and 2,3-dihydro-2,6-dimethyl-γ-pyrone undergo fast olefinic addition reactions with aqueous bromine. Rate measurements for the last two are correlated with published data for olefins and enols. The bromination products of the first two, but not those of the last one, undergo slow, acid-catalysed fission of the methoxy-group to give the bromo-enol.","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":"80080807","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}
Semi-empirical SCF (CNDO/2) theory is applied to a series of compounds containing either one or two sulphur atoms in 1,3-positions of saturated carbon rings. The u.v. spectra can only be accounted for if d-orbitals are included on the sulphur atoms. The degree to which d-orbitals participate in the ground and low-lying excited states of these molecules is discussed.
{"title":"The importance of d-orbitals in determining the ultraviolet spectra of cyclic organic sulphides","authors":"D. Williams, L. T. Kontnik","doi":"10.1039/J29710000312","DOIUrl":"https://doi.org/10.1039/J29710000312","url":null,"abstract":"Semi-empirical SCF (CNDO/2) theory is applied to a series of compounds containing either one or two sulphur atoms in 1,3-positions of saturated carbon rings. The u.v. spectra can only be accounted for if d-orbitals are included on the sulphur atoms. The degree to which d-orbitals participate in the ground and low-lying excited states of these molecules is discussed.","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":"76533945","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}
Spectroscopic and pKa value comparisons with model compounds indicate that benzimidazole 3-oxide exists predominantly in the NH-form in aqueous solution, but predominantly in the OH-form in non-polar solvents. For 2,4,5-triphenylimidazole 3-oxide, steric hindrance in the N-methyl model complicates matters, but this compound appears to exist as comparable amounts of OH- and NH-forms in aqueous solution and in the OH-form in non-polar solvents. The structures of these compounds in the solid state are discussed.
{"title":"The tautomerism of heteroaromatic compounds with five-membered rings. Part XII. The imidazole 3-oxide versus 3-hydroxy[3H]imidazole equilibrium","authors":"S. Chua, M. Cook, A. Katritzky","doi":"10.1039/J29710002350","DOIUrl":"https://doi.org/10.1039/J29710002350","url":null,"abstract":"Spectroscopic and pKa value comparisons with model compounds indicate that benzimidazole 3-oxide exists predominantly in the NH-form in aqueous solution, but predominantly in the OH-form in non-polar solvents. For 2,4,5-triphenylimidazole 3-oxide, steric hindrance in the N-methyl model complicates matters, but this compound appears to exist as comparable amounts of OH- and NH-forms in aqueous solution and in the OH-form in non-polar solvents. The structures of these compounds in the solid state are discussed.","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":"76406505","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 pKa values of a series of substituted 9-phenylfluorenes have been measured. In conjunction with earlier studies, the results enable the establishment of an H– acidity function for 25–97% aqueous dimethyl sulphoxide containing tetramethylammonium hydroxide. It is indicated that this scale does not parallel the acidity function based on the ionisation of aniline indicators in the more aqueous solutions. Substituents in the fluorene ring exert a greater influence on hydrocarbon acidity than those in the 9-phenyl nucleus. The correlation of substituent effects on hydrocarbon acidity, by use of a modified Hammett equation, suggests that the 9-phenyl ring is displaced from planarity with the fluorene nucleus by ca. 39°, close to the value predicted earlier by molecular orbital calculations.
{"title":"Acidity of hydrocarbons. Ionisation constants for some substituted 9-phenylfluorenes","authors":"A. F. Cockerill, John E. Lamper","doi":"10.1039/J29710000503","DOIUrl":"https://doi.org/10.1039/J29710000503","url":null,"abstract":"The pKa values of a series of substituted 9-phenylfluorenes have been measured. In conjunction with earlier studies, the results enable the establishment of an H– acidity function for 25–97% aqueous dimethyl sulphoxide containing tetramethylammonium hydroxide. It is indicated that this scale does not parallel the acidity function based on the ionisation of aniline indicators in the more aqueous solutions. Substituents in the fluorene ring exert a greater influence on hydrocarbon acidity than those in the 9-phenyl nucleus. The correlation of substituent effects on hydrocarbon acidity, by use of a modified Hammett equation, suggests that the 9-phenyl ring is displaced from planarity with the fluorene nucleus by ca. 39°, close to the value predicted earlier by molecular orbital calculations.","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":"83867200","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}
Methanolysis of the 2-pinanyl p-nitrobenzoates in the presence of base gives a mixture of products including both cis- and trans-methyl 2-pinanyl ethers from both esters. In contrast, other substitution products show a rigid retention of stereochemistry. It is suggested that each ester forms a delocalised ion, and that these ions can subsequently be interconverted. The results contrast with data reported from the study of the nopinol system, but both sets of results have been shown to be consistent with a mechanism of interconversion of ions in which two possible reaction paths exist, the direction of reaction being controlled by the substituent on C-2. Elimination products fit this general pattern except for a very high yield of α-pinene from the cis-ester, which may arise from elimination within an intimate ion pair, rather than from the ‘free’ ion. The trans-ester, in contrast, gives an intimate ion pair which undergoes collapse rather than elimination.
{"title":"Rearrangements of pinane derivatives. Part III. Solvolysis of the 2-pinanyl p-nitrobenzoates","authors":"J. Salmon, D. Whittaker","doi":"10.1039/J29710001249","DOIUrl":"https://doi.org/10.1039/J29710001249","url":null,"abstract":"Methanolysis of the 2-pinanyl p-nitrobenzoates in the presence of base gives a mixture of products including both cis- and trans-methyl 2-pinanyl ethers from both esters. In contrast, other substitution products show a rigid retention of stereochemistry. It is suggested that each ester forms a delocalised ion, and that these ions can subsequently be interconverted. The results contrast with data reported from the study of the nopinol system, but both sets of results have been shown to be consistent with a mechanism of interconversion of ions in which two possible reaction paths exist, the direction of reaction being controlled by the substituent on C-2. Elimination products fit this general pattern except for a very high yield of α-pinene from the cis-ester, which may arise from elimination within an intimate ion pair, rather than from the ‘free’ ion. The trans-ester, in contrast, gives an intimate ion pair which undergoes collapse rather than elimination.","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":"88339804","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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