Solvent effects on the proton magnetic resonance spectra of p-substituted phenyltin chlorides

A PMR study of solvent effects on some p-substituted phenyltin chlorides (substituents = CH₃, (CH₃)₃C, CH₃O) is reported. Co-ordination of solvent molecules to the tin atom leads to an unusual low field shift of the o-ring protons. The results for p-tolytin trichloride have been compared with those for p-tolylsilyl trichloride and discussed. In o-, m- and p-tolyltin trichlorides long range spin-spin couplings between the ring methyl protons and the tin atom have been observed. The order of magnitude is o- > p- > m-methyl protons.     

The 1H NMR spectra of p-substituted phenyl 2-chloro-2-fluoroethyl sulphides

The 60 MHz ¹H NMR spectra of p-substituted phenyl 2-chloro-2-fluoroethyl sulphides have shown characteristic patterns; in the ABC portion of an ABCX spin system (X = ¹⁹F) of the compounds, one of the subspectra shows an ABC pattern and the other apparently an AB₂ pattern. These spectral patterns have been analysed and the ¹H NMR data obtained are discussed briefly.     

Phosphomethylation of p-substituted anilines

Conclusions The phosphomethylation of p-substituted anilines in three-component systems (amine-paraformaldehyde-trialkyl phosphite, diethyl phosphite, or diethyl thiophosphite) proceeds best with trialkyl phosphites, and the yields are 55–95%.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 1, pp. 178–180, January, 1982.     

1H and 13C NMR spectra of cyclic trimers,tetramers and pentamers derived from p-substituted phenylacetylenes

The ¹H and ¹³C spectra of p-substituted 1,3,5-triarylbenzenes, 7- and p-substituted 1,3,9-triaryl-9-methyl-fluorenes and 2-, 10- and p-substituted 6,12,13a-triaryl-12-methylbenzo(6,7)cycloheptadieno[1,2,3-jk]fluorenes have been examined. p-Substituents were methoxy, methyl and fluorine groups. The ¹H spectra were recorded at 300 MHz and permitted assignments for the aromatic protons by selective proton decouplings. Partial assignment of the carbon atoms in the ¹³C spectra was also possible.     

The deuteration of p-substituted phenylalanines

The isotope exchange between substituted /p-OH, p-CH₃O, p-C₂H₅O, H, p-NO₂/ phenylalanines and deuterated water in the presence of K₂PtCl₄ as a catalyst was studied. It was found that isotope exchange is centered in the aromatic ring, in the methoxy and methyl groups. Electron donating groups accelerate the reaction and electron with-drawing groups retard it.     

Far IR spectra of dithiocarbamate complexes correlations with structure parameters

The far IR spectra (32–500cm⁻¹) of N,N-disubstituted dithiocarbamate complexes, M(R₂dtc)_n (n = 3, M Mn, Fe, Co; n = 2, M  Ni, Cu, Zn, Cd, Hg, Pb; R  Et, n-Pr, i-Pr, n-Bu, i-Bu; R₂N  pyrrol, pyrrolidyl) have been studied with the purpose of locating the modes involving displacement of the central atom. The IR bands related to changes in R(MS) and SMS have been found by comparing the IR spectra with M  const and R  variable, and those related to internal ligand modes with R  const and Mvariable. The spectral assignment thus obtained have been found to produce correlations with a number of structural parameters (v_ivs CFSE, v²_ivs R(MS) and ∡ SMS). The correlations reveal that the modes involving displacement of the central atom are coupled to a large extent.     

Effects of substituents on chain-transfer reactivities of p-substituted cumenes in radical polymerization of p-substituted styrenes

In order to study the effects of the substituents in both substrate and attacking radical on the chain-transfer reactivities of nuclear-substituted cumenes toward substituted polystyryl radicals, the polymerizations of p-substituted styrenes in the presence of p-substituted cumenes were carried out with α,α′-azobisisobutyronitrile as an initiator at 60°C, and their chain-transfer constants were determined. The relative chain transfer reactivities of p-substituted cumenes toward given p-substituted polystyryl radicals did not follow the Hammett equation, but were correlated with the modified Hammett equation, log(k/k₀) = pρ + γE_R, which was proposed by the present authors for evaluating the substituent effects in radical reactions. On the other hand, the relative reactivities of poly-(p-substituted styrene) radicals toward given p-substituted cumenes were correlated by the Hammett equation. Thus, it was concluded that the effects of the substituents in substrate cumene depended upon the contributions of both polar and resonance factors, while those in attacking polystyryl radical depended upon only a polar factor.     

Nanoscale 1,3,5,7-tetrasubstituted adamantanes and p-substituted tetraphenyl-methanes for AFM applications

[structure: see text] Tetrahedrally shaped nanoscale molecules 18-20 were synthesized from the corresponding tetraiodide by a series of Sonogashira coupling reactions. Three of the sulfur-containing termini are intended for eventual binding to a gold-coated conventional AFM tip, while the fourth terminus scans the sample. AFM images of 19 demonstrate that the molecule is sufficiently large and rigid to be imaged by a conventional AFM tip.     

HMO correlations with the electronic spectra of a large non-homogeneous series

A basic set of electronic spectra for 46 compounds of widely divergent structures have been used to form a correlation with HMO transition energies for p-bands, and β-bands. Regression equations have been used to predict the location of these bands in a varied series of 88 additional compounds. The results serve to extend the applicability of the Hückel method as a simple tool for the qualitative and approximate quantitative prediction of the basic elements of singlet transitions.     

对位取代苯基烯丙基醚的烷基化反应

烯丙基醚是一个重要的β-羰基化合物的合成等价物,已有许多应用,它的应用和反应的区域选择性有密切关系.最近,Werstiuk 曾对烯丙基化合物的反应及其在合成上的应用作了综述,并讨论了立体因素对烯丙基化合物反应区域选择性的影响.Evans 等研究了烯丙基烷基醚阴离子和亲电试剂反应中位阻和区域选择性的关系.当亲电试剂是卤代烷时,烯丙基醚中烷基体积增大,γ位烷基化的比例也增大;而亲电试剂为羰     

Acylation of dibenzofuran with p-substituted benzoyl chlorides

It is shown that benzoylation and p-chloro- and p-nitrobenzoylation of dibenzofuran in the presence of small amounts of FeCl₃, the FeCl₃ · CH₃NO₂ complex, ZnCl₂, and acetylacetonatoiron lead to the production of the corresponding 3-acyldibenzofurans in high yields.Deceased.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 895–896, July, 1977.     

Alkylation of p-substituted phenols by heteropoly acids

Liquid-phase alkylation of p-tert-butylphenol (TBP) and p-cresol by olefins and benzyl chloride in the presence of solid heteropoly acids (HPA) H₃PW₁₂O₄₀ and 25% H₃PW₁₂O₄₀/SiO₂ at 100–150°C provides high yields of mono- and disubstituted products. HPAs are more active than H₂SO₄, easily separated from the reaction mixture and can be used repeatedly. -- () - () H₃PW₁₂O₄₀ 25% H₃PW₁₂O₄₀/SiO₂ 100–150°C - - . , H₂SO₄, - - .     

Inversion of 1JCC correlations in 1,n‐ADEQUATE spectra

ADEQUATE experiments provide an alternative to the more commonly employed GHMBC experiment for the establishment of long‐range heteronuclear connectivities. The 1,1‐ADEQUATE experiment allows the unequivocal identification of both protonated and non‐protonated carbon resonances adjacent to a protonated carbon. The 1,n‐ADEQUATE experiment establishes correlations via an initial ¹J_CH heteronuclear transfer followed by an ⁿJ_CC out‐and‐back transfer, most typically, via three carbon–carbon bonds. Hence, the 1,n‐ADEQUATE experiment allows the equivalent of ⁴J_CH heteronuclear correlations to be probed when they are not observed in a GHMBC spectrum. Aside from the lower sensitivity of the 1,n‐ADEQUATE experiment relative to GHMBC experiments, the interpretation of the former is also complicated by the ‘leakage’ of ¹J_CC correlations into the spectrum that must be identified. A method for the inversion of ¹J_CC correlations to facilitate the interpretation of 1,n‐ADEQUATE spectra is presented that allows a single experiment to be performed to access ¹J_CC and ⁿJ_CC correlation information. Copyright © 2012 John Wiley & Sons, Ltd.     

Observation of potentially troublesome 2JCC correlations in 1,1‐ADEQUATE spectra

Despite the tremendous usage of HMBC to establish long‐range ¹H–¹³C and ¹H–¹⁵N heteronuclear correlations, an inherent drawback of the experiment is the indeterminate nature of the ⁿJ_XH correlations afforded by the experiment. A priori there is no reliable way of determining whether a given ⁿJ_CH correlation is, for example, via two‐, three‐, or sometimes even four‐bonds. This limitation of the HMBC experiment spurred the development of the ADEQUATE family of NMR experiments that rely on, in the case of 1,1‐ADEQUATE, an out‐and‐back transfer of magnetization via the ¹J_CC homonuclear coupling constant, which is significantly larger than ⁿJ_CC (where n = 2–4) couplings in most cases. Hence, the 1,1‐ADEQUATE experiment has generally been assumed to unequivocally provide the equivalent of ²J_CH correlations. The recent development of the 1,1‐ and 1,n‐HD‐ADEQUATE experiments that can provide homodecoupling for certain ¹J_CC and ⁿJ_CC correlations has increased the sensitivity of the ADEQUATE experiments significantly and can allow acquisition of these data in a fraction of the time required for the original iterations of this pulse sequence. With these gains in sensitivity, however, there occasionally come unanticipated consequences. We have observed that the collapse of proton multiplets, in addition to providing better s/n for the desired ¹J_CC correlations can facilitate the observation of typically weaker ²J_CC correlations across intervening carbonyl resonances in 1,1‐HD‐ADEQUATE spectra. Several examples are shown, with the results supported by the measurement of the ²J_CC coupling constants in question using J‐modulated‐HD‐ADEQUATE and DFT calculations. Copyright © 2016 John Wiley & Sons, Ltd.     

Multistep correlations via covariance processing of COSY/GCOSY spectra: opportunities and artifacts

Long-range homonuclear coupling pathways can be observed in COSY or GCOSY spectra by the acquisition of spectra with larger numbers of increments of the evolution period, t(1), than would normally be used. Alternatively, covariance processing of COSY-type spectra acquired with modest numbers of t(1) increments, allows the observation of multistage correlations. In this work results obtained from covariance-processed GCOSY spectra are fully analyzed and compared to normally processed COSY and 80 ms TOCSY spectra. Multistage or 'RCOSY-type' correlations are observed when remote protons both exhibit correlations to the same coupling partner e.g. A --> B and B --> C gives rise to an A --> C correlation. In the strict sense, RCOSY-type responses are artifacts albeit providing useful information. Nonbeneficial artifact correlations are observed when protons couple to other protons that overlap or partially overlap. The origin of artifact responses is also analyzed.     

X-Ray spectra and electronic correlations of FeSe(1-x)Te(x)

Critical issues concerning emerging Fe-based superconductors include the degree of electron correlation and the origin of the superconductivity. X-Ray absorption spectra (XAS) and resonant inelastic X-ray scattering spectra (RIXS) of FeSe(1-x)Te(x) (x = 0-1) single crystals were obtained to study their electronic properties that relate to electron correlation and superconductivity. The linewidth of Fe L(2,3)-edges XAS of FeSe(1-x)Te(x) is narrower than that of Fe-pnictides, revealing the difference between their hybridization effects and localization character and those of other Fe-pnictides. While no significant differences exist between the Fe L-edge XAS and RIXS of FeSe(1-x)Te(x) and those of Fe-pnictides, Se K-edge and Te K-edge XAS exhibit substantial edge shift, suggesting that the superconductivity in an Fe-Se superconductor is strongly associated with the ligand states. A comparison of the Se K-edge and Te K-edge spectra reveals that the charge transfer may occur between Se and Te. Given the Coulomb interaction and the bandwidth, the spectral results indicate that FeSe(1-x)Te(x) is unlikely to be a weakly correlated system unlike the Fe-pnictides of the "1111" and "122" families. The spectral results further demonstrate that superconductivity in this class of Fe-based compounds is strongly associated with the ligand 4p hole state.