Crystals of the N-(α-glutarimido)-derivative of phthalimide (Thalidomide), C13H10N2O4, are monoclinic, space group P21/n, with a= 8·233 (1), b= 10·070(2), c= 14·865(2)A, β= 102·53(2)°, and Z= 4. The structure has been determined by direct methods using diffractometer data; full-matrix least-squares refinement has reduced R to 0·053 for 1855 observed reflections, which were corrected for absorption. The phthalimide residue is significantly non-planar, while the glutarimido-moiety approximates a half-chair conformation; the central N–C bond is equatorial. The angle between the mean phthalimide and glutarimido-planes is 81°. Pairs of centrosymmetrically related molecules form hydrogen-bonded dimers through N–H ⋯ O contacts of 2·928 A between glutarimido-residues.
{"title":"Crystal and molecular structure of thalidomide, N-(α-glutarimido)-phthalimide","authors":"F. Allen, J. Trotter","doi":"10.1039/J29710001073","DOIUrl":"https://doi.org/10.1039/J29710001073","url":null,"abstract":"Crystals of the N-(α-glutarimido)-derivative of phthalimide (Thalidomide), C13H10N2O4, are monoclinic, space group P21/n, with a= 8·233 (1), b= 10·070(2), c= 14·865(2)A, β= 102·53(2)°, and Z= 4. The structure has been determined by direct methods using diffractometer data; full-matrix least-squares refinement has reduced R to 0·053 for 1855 observed reflections, which were corrected for absorption. The phthalimide residue is significantly non-planar, while the glutarimido-moiety approximates a half-chair conformation; the central N–C bond is equatorial. The angle between the mean phthalimide and glutarimido-planes is 81°. Pairs of centrosymmetrically related molecules form hydrogen-bonded dimers through N–H ⋯ O contacts of 2·928 A between glutarimido-residues.","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":"76694431","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 alkaline hydrolysis of six methyl diazinecarboxylates in methanol–water (85% w/w) at 10° are correlated with those of benzoates and pyridinecarboxylates with additivity of the effects of aza-substitution.
{"title":"Transmission of substituent effects in pyridines. Part IV. Alkaline hydrolysis of methyl diazinecarboxylates","authors":"L. Deady, D. Foskey, R. Shanks","doi":"10.1039/J29710001962","DOIUrl":"https://doi.org/10.1039/J29710001962","url":null,"abstract":"The rates of alkaline hydrolysis of six methyl diazinecarboxylates in methanol–water (85% w/w) at 10° are correlated with those of benzoates and pyridinecarboxylates with additivity of the effects of aza-substitution.","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":"76791248","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 principles underlying various reactivity and free-energy relationships are examined. A generalised relationship is derived which incorporates many of those presently accepted, e.g., the Hammett, Yukawa Tsuno, and Taft equations. Three new semi-empirical relationships are derived with differing numbers of constraints. The four factors commonly given independent recognition are represented as, the substituent S, the position of the substituent relative to the position of the reaction P, the reagent–solvent system R, and a factor characteristic of the type of reaction and its corresponding free-energy requirement T. In the first equation the rate or equilibrium of a particular reaction is related to an arbitrary reaction by log k/k0=A+ρ(FX+MY) where F=p(ST), M=r(ST)X=p(P), Y=r(P), ρ=pR=rR, superscripts p and r referring to polar and resonance effects respectively.The second equation log k/k0=A+BFX+CMY corresponds to the first equation with the constraint pR=rR removed, B corresponding to pR and C to rR. In the third equation, log k/k0=A+BpTFX+CrTMY, only the ratio pT to pR can in practice be derived, and then only under the assumption that B=C. Substituent effect data for the naphthalene and fluoranthene systems are considered. For transmission coefficients of delocalisation effects in electrophilic substitution qw values are slightly better than atom–atom polarisabilities. As a measure of the direct field effect of a substituent both 1/d and (cos θ)/d give in most cases equally good results. There is indication that with an improved model separation of the reaction parameter into a type parameter T and a reagent–solvent parameter R may well be viable.
考察了各种反应性和自由能关系的基本原理。一个广义的关系被推导出来，它包含了许多目前被接受的，例如，Hammett, Yukawa Tsuno和Taft方程。在不同数量的约束条件下，导出了三个新的半经验关系。通常给予独立识别的四个因素表示为:取代基S，取代基相对于反应P位置的位置，试剂-溶剂体系R，以及反应类型特征因素及其相应的自由能需求t。在第一个方程中，特定反应的速率或平衡与任意反应的关系为log k/k0= a +ρ(FX+MY)，其中F= P (ST)， M= R (ST)X= P (P)， Y= R (P)， ρ=pR=rR，上标p和r分别表示极性效应和共振效应。第二个方程log k/k0=A+BFX+CMY对应于去掉约束pR=rR的第一个方程，B对应于pR, C对应于rR。在第三个方程中，log k/k0=A+BpTFX+CrTMY，实际上只能推导出pT与pR的比值，并且只能在B=C的假设下。考虑了萘和氟蒽体系的取代基效应数据。对于亲电取代中离域效应的透射系数，量子w值略好于原子-原子极化。作为取代基直接场效应的量度，1/d和(cos θ)/d在大多数情况下都能得到同样好的结果。有迹象表明，通过改进的模型，将反应参数分离为类型参数T和试剂-溶剂参数R是可行的。
{"title":"Reactivity parameters and aromatic systems. Part III. Reactivity relationships, and their application to substituent effects in aromatic systems","authors":"K. Bancroft, G. R. Howe","doi":"10.1039/J29710001221","DOIUrl":"https://doi.org/10.1039/J29710001221","url":null,"abstract":"The principles underlying various reactivity and free-energy relationships are examined. A generalised relationship is derived which incorporates many of those presently accepted, e.g., the Hammett, Yukawa Tsuno, and Taft equations. Three new semi-empirical relationships are derived with differing numbers of constraints. The four factors commonly given independent recognition are represented as, the substituent S, the position of the substituent relative to the position of the reaction P, the reagent–solvent system R, and a factor characteristic of the type of reaction and its corresponding free-energy requirement T. In the first equation the rate or equilibrium of a particular reaction is related to an arbitrary reaction by log k/k0=A+ρ(FX+MY) where F=p(ST), M=r(ST)X=p(P), Y=r(P), ρ=pR=rR, superscripts p and r referring to polar and resonance effects respectively.The second equation log k/k0=A+BFX+CMY corresponds to the first equation with the constraint pR=rR removed, B corresponding to pR and C to rR. In the third equation, log k/k0=A+BpTFX+CrTMY, only the ratio pT to pR can in practice be derived, and then only under the assumption that B=C. Substituent effect data for the naphthalene and fluoranthene systems are considered. For transmission coefficients of delocalisation effects in electrophilic substitution qw values are slightly better than atom–atom polarisabilities. As a measure of the direct field effect of a substituent both 1/d and (cos θ)/d give in most cases equally good results. There is indication that with an improved model separation of the reaction parameter into a type parameter T and a reagent–solvent parameter R may well be viable.","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":"82133234","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}
Schiff bases have been synthesized from [15N]ammonia and 1-hydroxy-2-acetonaphthone, 2-hydroxy-1-naphthaldehyde, 5-methyl- and 4,5-dimethyl-acetophenones, 2-hydroxybenzophenone, benzoylacetone and 2-acetyl-5,5-dimethylcyclohexane-1,3-dione. The 1H n.m.r. and u.v. data permit assignment of tautomeric equilibria. The results indicate that the percentage of amide form is usually greater in these ammonia adducts than in the analogous methylamine or aniline derivatives. Proton–proton spin-coupling measurements provide important information concerning the electronic delocalization in the aromatic rings.
{"title":"Spectroscopic studies of keto–enol equilibria. Part XIII. 15N-substituted imines","authors":"G. Dudek, E. Dudek","doi":"10.1039/J29710001356","DOIUrl":"https://doi.org/10.1039/J29710001356","url":null,"abstract":"Schiff bases have been synthesized from [15N]ammonia and 1-hydroxy-2-acetonaphthone, 2-hydroxy-1-naphthaldehyde, 5-methyl- and 4,5-dimethyl-acetophenones, 2-hydroxybenzophenone, benzoylacetone and 2-acetyl-5,5-dimethylcyclohexane-1,3-dione. The 1H n.m.r. and u.v. data permit assignment of tautomeric equilibria. The results indicate that the percentage of amide form is usually greater in these ammonia adducts than in the analogous methylamine or aniline derivatives. Proton–proton spin-coupling measurements provide important information concerning the electronic delocalization in the aromatic rings.","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":"82165300","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 the C form of stearic acid has been determined from X-ray powder diffraction patterns, The crystals are monoclinic, space group P21/a, with unit-cell dimensions: a= 9·36, b= 4·95, c= 50·7 A. β= 128 °15′ and Z= 4. The crystal structure has been determined by trial-and-error methods to R 0·086. The structural parameters are compared with those of similar compounds, in particular the same acid in the polymorphous B form.
{"title":"Crystal structure of the C form of stearic acid","authors":"V. Malta, G. Celotti, R. Zannetti, A. F. Martelli","doi":"10.1039/J29710000548","DOIUrl":"https://doi.org/10.1039/J29710000548","url":null,"abstract":"The crystal structure of the C form of stearic acid has been determined from X-ray powder diffraction patterns, The crystals are monoclinic, space group P21/a, with unit-cell dimensions: a= 9·36, b= 4·95, c= 50·7 A. β= 128 °15′ and Z= 4. The crystal structure has been determined by trial-and-error methods to R 0·086. The structural parameters are compared with those of similar compounds, in particular the same acid in the polymorphous B form.","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":"81258121","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}
60 Co γ-Radiation has been used to initiate the free-radical reduction reaction (i) and the mechanism is shown to be as in reactions (ii)—(iv), where reactions (ii) and (iii) are the propagating steps and reaction (iv) the terminating ArN2++ CH3OH → ArH + N2+ CH2O + H+(i), Ar˙+ CH3OH → ArH +·CH2OH (ii), ArN2++·CH2OH → Ar˙+ CH2O + H++ N2(iii), Ar˙+ ArN2+→ products (iv) step. Pulse radiolysis shows reaction (ii) to be rate-determining. The photochemically induced reaction to yield the same products is shown to occur with quantum yields greater than unity. The products and importance of reaction (iv) with respect to some recent e.s.r. flow studies of Norman et al. is discussed.
{"title":"Free-radical reductions of arenediazonium ions in aqueous solution. Part I. Toluene-p-diazonium ions reduced with methanol","authors":"J. Packer, D. House, E. J. Rasburn","doi":"10.1039/J29710001574","DOIUrl":"https://doi.org/10.1039/J29710001574","url":null,"abstract":"60 Co γ-Radiation has been used to initiate the free-radical reduction reaction (i) and the mechanism is shown to be as in reactions (ii)—(iv), where reactions (ii) and (iii) are the propagating steps and reaction (iv) the terminating ArN2++ CH3OH → ArH + N2+ CH2O + H+(i), Ar˙+ CH3OH → ArH +·CH2OH (ii), ArN2++·CH2OH → Ar˙+ CH2O + H++ N2(iii), Ar˙+ ArN2+→ products (iv) step. Pulse radiolysis shows reaction (ii) to be rate-determining. The photochemically induced reaction to yield the same products is shown to occur with quantum yields greater than unity. The products and importance of reaction (iv) with respect to some recent e.s.r. flow studies of Norman et al. 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":"81646494","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 benzene-induced solvent shifts of some 1-substituted 3,5-dimethylbenzenes (I) and monosubstituted mesitylenes (II) were determined at high concentrations of solute for which the number of moles of the solute is comparable with that of the solvent. It was shown that the conventional 1 : 1 complex model can account for the observed shifts when the substituent is not a halogen. The possible origin of the anomaly observed for halogen derivatives is discussed.
{"title":"Substituent effects in aromatic proton nuclear magnetic resonance spectra. Part VII. [2H6]Benzene-induced solvent shifts at high solute concentration","authors":"Y. Takeuchi","doi":"10.1039/J29710001884","DOIUrl":"https://doi.org/10.1039/J29710001884","url":null,"abstract":"The benzene-induced solvent shifts of some 1-substituted 3,5-dimethylbenzenes (I) and monosubstituted mesitylenes (II) were determined at high concentrations of solute for which the number of moles of the solute is comparable with that of the solvent. It was shown that the conventional 1 : 1 complex model can account for the observed shifts when the substituent is not a halogen. The possible origin of the anomaly observed for halogen derivatives 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":"76315048","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}
Crystals of (+)-3-bromocamphor, C10H15OBr, are monoclinic, space group P21, with a= 7·36 (1), b= 7·59 (1), c= 9·12 (1)A, β= 94·1 (2)°, and Z= 2. The crystal structure has been accurately redetermined by use of three-dimensional X-ray diffraction data (R= 0·071 for 836 visually-estimated reflection intensities), in order to establish unambiguously the absolute configuration of the key monoterpene (+)-camphor. This determination has confirmed earlier, non-rigorous assignments using both chemical and X-ray techniques. The importance of this configurational assignment in the stereochemical correlation of the monoterpenes is discussed. The geometry of the norbornane skeleton is compared with data from other X-ray studies.
{"title":"X-ray studies of terpenoids. Part III. A redetermination of the crystal structure of (+)-3-bromocamphor: the absolute configuration of (+)-camphor","authors":"F. Allen, D. Rogers","doi":"10.1039/J29710000632","DOIUrl":"https://doi.org/10.1039/J29710000632","url":null,"abstract":"Crystals of (+)-3-bromocamphor, C10H15OBr, are monoclinic, space group P21, with a= 7·36 (1), b= 7·59 (1), c= 9·12 (1)A, β= 94·1 (2)°, and Z= 2. The crystal structure has been accurately redetermined by use of three-dimensional X-ray diffraction data (R= 0·071 for 836 visually-estimated reflection intensities), in order to establish unambiguously the absolute configuration of the key monoterpene (+)-camphor. This determination has confirmed earlier, non-rigorous assignments using both chemical and X-ray techniques. The importance of this configurational assignment in the stereochemical correlation of the monoterpenes is discussed. The geometry of the norbornane skeleton is compared with data from other X-ray studies.","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":"76353469","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}
p-Nitrobenzonitrile oxide reacts readily with alkyl hydrogen alkylphosphonates (I; R1= Me, R2= Me, Et, Pr, Pri, ButCH2, or ButCHMe) and (I; R1= Et, But, or Ph; R2= Et), diethyl hydrogen phosphate, and hydrogen diethylphosphinate to give the corresponding 1:1-adducts, alkyl α-hydroxyimino-p-nitrobenzyl alkylphosphonates (II; R1= Me; R2= Me, Et, Pr, Pri, ButCH2, or ButCHMe) and (II; R1= Et, But or Ph; R2= Et), diethyl α-hydroxyimino-p-nitrobenzyl phosphate (II; R1= EtO, R2= Et), and α-hydroxyimino-p-nitrobenzyl diethyl-phosphinate (III), respectively. Except for the last case, which is stable in acid, the adducts undergo very fast, anchimerically assisted, P–O fission at pH 2–3·5 in dilute aqueous dioxan (ca. 107 faster, as shown by a kinetic study, than corresponding hydrolysis of simple esters which undergo alkyl–oxygen fission under similar conditions). Transesterification, also very fast, proceeds similarly, while the O-methyl derivative of (II; R1= Me; R2= ButCH2) is stable at pH 2–4·5. The results point to a novel neighbouring-group acceleration involving the proton of the oxime group in (II).
对硝基苯腈氧化物很容易与烷基膦酸氢(I;R1= Me, R2= Me, Et, Pr, Pri, buch2, or buchme) and (I;R1= Et, But，或Ph;R2= Et)、磷酸氢二乙基和磷酸二乙基氢得到相应的1:1加合物烷基α-羟基亚胺-对硝基苄基烷基膦酸盐(II;R1 =我;R2= Me, Et, Pr, Pri, ButCH2, or ButCHMe) and (II;R1= Et, But或Ph;R2= Et)， α-羟基亚胺-对硝基苯基磷酸二乙基(II;R1= EtO, R2= Et)， α-羟基亚胺-对硝基苯基膦酸二乙酯(III)。除了最后一种情况，它在酸中是稳定的，加合物在pH 2-3·5的稀释二氧六水中进行化学辅助的P-O裂变非常快(动力学研究表明，比在类似条件下进行烷基氧裂变的简单酯的相应水解快107倍)。酯交换反应也非常快，过程类似，而(II;R1 =我;R2= buch2)在pH 2 ~ 4·5时稳定。结果指出了一种新的邻基加速，涉及(II)中肟基的质子。
{"title":"The reactivity of organophosphorus compounds. Part XXVII. Reactions of alkyl hydrogen alkylphosphonates with p-nitrobenzonitrile oxide: anchimerically assisted P–O fission in acidic hydrolysis of the resulting α-hydroxyimino-p-nitrobenzyl alkylphosphonates","authors":"J. Cadogan, J. A. Challis, D. Eastlick","doi":"10.1039/J29710001988","DOIUrl":"https://doi.org/10.1039/J29710001988","url":null,"abstract":"p-Nitrobenzonitrile oxide reacts readily with alkyl hydrogen alkylphosphonates (I; R1= Me, R2= Me, Et, Pr, Pri, ButCH2, or ButCHMe) and (I; R1= Et, But, or Ph; R2= Et), diethyl hydrogen phosphate, and hydrogen diethylphosphinate to give the corresponding 1:1-adducts, alkyl α-hydroxyimino-p-nitrobenzyl alkylphosphonates (II; R1= Me; R2= Me, Et, Pr, Pri, ButCH2, or ButCHMe) and (II; R1= Et, But or Ph; R2= Et), diethyl α-hydroxyimino-p-nitrobenzyl phosphate (II; R1= EtO, R2= Et), and α-hydroxyimino-p-nitrobenzyl diethyl-phosphinate (III), respectively. Except for the last case, which is stable in acid, the adducts undergo very fast, anchimerically assisted, P–O fission at pH 2–3·5 in dilute aqueous dioxan (ca. 107 faster, as shown by a kinetic study, than corresponding hydrolysis of simple esters which undergo alkyl–oxygen fission under similar conditions). Transesterification, also very fast, proceeds similarly, while the O-methyl derivative of (II; R1= Me; R2= ButCH2) is stable at pH 2–4·5. The results point to a novel neighbouring-group acceleration involving the proton of the oxime group in (II).","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":"76453684","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 energy barriers to rotation about the C(6)–N bond of a series of 6-p-substituted phenyl-6-dimethylamino-2-azafulvenes have been studied by n.m.r. spectroscopy and have been found to have values in the range 58·58 to 64·43 kJ/mol. The lack of a correlation between the electronic effect of the para-substituent and the rotational-energy barriers suggest a lack of coplanarity between the rings with a consequent reduction in the cross conjugation within the system.
{"title":"Pyrrole studies. Part XVI. Conformational studies of 6-aryl-6-di-methylamino-2-azafulvenes [2-aryl(dimethylamino)methylenepyrroles]","authors":"C. Candy, R. Jones","doi":"10.1039/J29710001405","DOIUrl":"https://doi.org/10.1039/J29710001405","url":null,"abstract":"The energy barriers to rotation about the C(6)–N bond of a series of 6-p-substituted phenyl-6-dimethylamino-2-azafulvenes have been studied by n.m.r. spectroscopy and have been found to have values in the range 58·58 to 64·43 kJ/mol. The lack of a correlation between the electronic effect of the para-substituent and the rotational-energy barriers suggest a lack of coplanarity between the rings with a consequent reduction in the cross conjugation within the system.","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":"87101034","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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