1,2-二芳基取代-1,1''-二氟乙烷的合成

1,2 二芳取代 1,1’ 二氟乙烷主要用作混合液晶添加剂以达到降低粘度增加响应速度的作用,同时也可以增加混晶的工作温度范围和抗紫外辐照的能力,并且能够实现低压驱动,文献报道的4种合成方法(硫缩醛的氟化、炔的氟化加成、酮的氟化以及腙的氟化[1,2])或反应条件苛刻,或转化率低,作者参考文献[3,4,5]对反应改进后发现,当在80℃、DAST(二乙胺基三氟化硫络合物)与乙二醇二甲醚的混合溶剂(体积比为3∶1)中进行酮的氟化反应时可达到95%的转化率。合成路线如下。1　实验部分1 1　仪器与试剂美国Nicolet60XR型红外光谱仪,日本JEOL公司FX …     

NMR spectra of 1,2-difluoroethane in nematic solvents

In 1,2-difluoroethane, the gauche conformation predominates strongly. This circumstance allows the determination of its relative geometry by NMR in liquid crystals, though certain assumptions have still to be made, e.g. neglect of intermediate conformations. The principal result of the structure determination is the value of 69–70° for the dihedral angle ∠FCCF, which is quite insensitive to variations of the other internal coordinates. The value is, within the limits of error, equal to that obtained by microwave spectroscopy, but deviates from results of electron diffraction measurements.It is impossible to describe the average orientation of 1,2-difluoroethane using less than three orientation parameters. This indicates that the interconversion of the two gauche rotamers is slow compared with the reorientational motion.In an attempt to explain the lower energy of the gauche conformation relative to the trans conformation, and the high value of the dihedral angle, ∠FCCF, some explorative empirical calculations were carried out. These could not, however, reproduce the experimental data.     

Conformational analysis of 1,2-difluoroethane, an ab-initio investigation

Contrary to expectation, the gauche conformer of 1,2-difluoroethane is more stable than the trans conformer in the gas phase. In order to understand the underlying causes of the “gauche effect”, a complete geometry relaxation was performed for the gauche and trans conformers of 1,2-difluoroethane with the 4-21G, 4-31G and 4-31G** basis sets. The 4-31G** optimized geometry of the gauche conformer compares well with the experimental values obtained from a number of electron-diffraction studies. A correction for the correlation energy, calculated by means of second-order Møller—Plesset perturbation theory with the 6-31G** basis set, proves to be essential to obtain a correct estimate of the energy difference between the gauche and trans conformers 1,2-difluoroethane.     

Competition between HF And HCl molecular elimination in IRMPD of 1,2-dichloro-1,2-difluoroethane

The infrared multiple-photon decomposition of 1,2-dichloro-1,2-difluoroethane has been studied using time-resolved infrared emission. Vibrationally excited parent molecules dissociate competitively via two channels to form vibrationally excited HCl and HF, depending strongly on CO₂ laser fluence. The yield of HF elimination increases with fluence, while that of HCl elimination reaches a plateau and then decreases.     

An electron diffraction study of the molecular structure of 1,2-difluoroethane

The molecular structure of 1,2-difluoroethane in the gas phase has been determined by electron diffraction at room temperature. Only the gauche conformation was found, the dihedral angle F-C-C-F is 74.5°. The bond lengths r_g(1) are: r(C-C) = 1.535 Å, r(C-F) = 1.394 Å, r(C-H) = 1.13 Å. The valency angles are: α(C-C-F) = 108.3, α(C-C-H) = 108.3. The dihedral angle between the C-C-F and C-C-H planes is 113.6°.     

Reactions of allenylphosphonates with 1,2-diaminoethane

The reactions of dialkyl 3-methylbuta-1,2-dien-1-ylphosphonates with 1,2-diaminoethane lead to the formation of symmetrical N,N′-bis(1-dialkoxyphosphoryl-3-methylbut-1-en-2-yl)-1,2-diaminoethanes.     

Nitration of 1,1-dichlorodifluoroethylene with nitrogen dioxide. The infrared spectra of difluoronitroacetyl chloride and 1,1-dichlorodifluoro-1,2-dinitroethane

Gas-phase nitration of CF₂CCl₂ with NO₂ at 323–353 K gave difluoronitroacetyl chloride, O₂NCF₂C(O)Cl, and 1,1-dichlorodifluoro-1,2-dinitroethane, O₂NCF₂CCl₂NO₂, which were isolated by fractional condensation and characterized by molecular weight determinations and infrared spectra. [O₂NCF₂C(O)Cl]/[O₂NCF₂CCl₂NO₂] = [k′ ([CF₂CCl₂] + γ_NO2[NO₂] + γ_P[P] + γ_X[X])]⁻¹, where k′ = 3.3±0.7x10⁻² torr⁻¹, P is the sum of the products, X = C₂F₅Cl, CCl₃F, CF₄ or N₂ and γ are the relative collisional efficiency coefficients of each gas.     

Lewis Acid Catalyzed Reactions of Thioketones with 1,2-Epoxycyclohexane and 1,2-Epoxycyclopentane

Non-enolizable thioketones and 1,2-epoxycycloalkanes undergo a Lewis acid catalyzed addition reaction to give 1,3-oxathiolanes. Appropriate reaction conditions are CH₂Cl₂ as the solvent, BF₃⋅Et₂O as the Lewis acid, and a temperature between −78° and r.t. Under the reaction conditions, the 1,3-oxathiolanes are only moderately stable. They decompose to yield the corresponding epithiocycloalkane and ketone. In general, 1,3-dithiolanes are isolated as minor products or, after prolonged reaction, as the main product. These secondary products are formed via the Lewis acid catalyzed reaction of the intermediate epithiocycloalkane and a second molecule of the thioketone. In the reaction of thiobenzophenone and 1,2-epoxycyclohexane, trans-8,8-diphenyl-7,9-dioxabicyclo[4.3.0]nonane is formed in small amounts as an additional side product (Scheme 12). In all cases, the newly formed heterocycle and the carbocycle are trans-fused. This result is consistent with a nucleophilic ring-opening of the complexed oxirane by the thioketone via inversion of the configuration and subsequent formation of the O(1)−C(2) bond of the 1,3-oxathiolane (Scheme 13). The surprising formation of the fused 1,4-oxathiepan derivative 23 (Scheme 9) is in accordance with an ionic reaction mechanism (cf. Scheme 15).     

Reactions of buta-1,2-dienylphosphonate with thiols

Addition of propane-1-thiol and ethane-1,2-dithiol to 3,3-dimethylallenylphosphonate occurs at the 1,2-double bond of the cumulene system.     

Reactions of 1,2-dihaloethanes with chalcogenide anions

Reactions of 1,2-dihaloethanes with chalcogenide anions generated from elemental chalcogens and dimethylchalcogens were performed in the hydrazine hydrate-KOH system. The use of anions Se _x ^2? and Te _x ^2? (x = 1?4) resulted in ethylene evolution and chalcogen regeneration (or in increased x value in an anion). Oligomers of Thiokol type formed only in the reaction of the 1,2-dichloroethane with a mixture of potassium disulfide and diselenide. The reductive cleavage of oligomers obtained in the hydrazine hydrate-KOH system followed by methylation led to the formation of 1,2-bis(methylthio)ethane, 1-methylseleno-2-methylthioethane, and 1,2-bis(methylseleno)ethane. The features of substitution with chalcogenide anions in vicinal dihalides are discussed. Mass spectra of compounds obtained were measured and analyzed.     

Reactions of 2-polyfluoroacylcyclohexanones with 1,2-diaminoarenes

Reactions of 2-polyfluoroacylcyclohexanones with 1,2-diaminoarenes yield, depending on the reaction conditions, various 2-polyfluoroalkyl-substituted benzimidazoles. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 562–565, March, 1999.     

Reactions of 1,2-dihydroquinolines

The addition of benzene to 2,2,4-trimethyl-1,2-dihydroquinoline (I) in the presence of AlCl₃ requires prior protonation or acylation of the amino group. Electron-donor substituents in the benzene ring of I hinder the reaction. The addition of halobenzenes proceeds under more severe conditions to give only para-substituted 4-aryl-2,2,4-trimethyl-1,2,3,4-tetrahydroquinolines.See [1,2] for communications I and II.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 795–797, June, 1971.     

Reactions of 1,2-dihydroquinolines

2,2,4-Trimethyl-1,2-dihydroquinolines readily add alkylbenzenes under the influence of aluminum chloride to form 2,2,4-trimethyl-4-(p-alkylphenyl)-1,2,3,4-tetrahydroquinolines.See [1] for Communication I.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1512–1514, November, 1970.     

Reactions of 1,2-dihydroquinolines

Under the Influence of anhydrous aluminum chloride, cyclohexane converts 2,2,4-trimethyl-1,2-dihydroquinoline to the tetrahydro derivative and alkylates it at the 7-position with simultaneous reduction of the ³-bond.See [1] for communication III.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 977–980, July, 1971.     

Effect of bond orbital interactions on the conformational stabilities of 1,2-difluoroethane and 2,3-difluorobutanes

Several hypotheses have been proposed to explain the origin of the conformational stabilities of 1,2-difluoroalkanes, for which bond orbital interactions are an important factor. However, there is a limit to the effectiveness of the traditional approach focusing on only the antiperiplanar interactions between bonding and antibonding orbitals such as σ_C–H/σ_C–F*, σ_C–C/σ_C–F*, and σ_C–F/σ_C–F*, which cannot actually explain the conformational stabilities of 2,3-difuluorobutanes. In this study, to elucidate the effect of bond orbital interactions on the conformational stabilities of 1,2-difluoroethane, erythro-2,3-difluorobutane, and threo-2,3-difluorobutane, we extended the range of interactions considered to beyond these conventional interactions. The results showed that for 1,2-difluoroethane, the conformational stability can be understood by considering all antiperiplanar bond orbital interactions around the C1–C2 bond, and for 2,3-difluorobutanes, by considering all antiperiplanar bond orbital interactions around the C2–C3 bond in addition to bond orbital interactions between the methyl groups.     

1,2-联烯亚砜和1,2-联烯砜的反应

1,2-联烯亚砜和1,2-联烯砜是重要的含硫联烯化合物.综述了1,2-联烯亚砜和1,2-联烯砜的亲核加成、亲电加成、Diels-Alder反应、1,3-偶极加成、[2+2]环加成等反应以及在天然产物中的应用.     

Gauche effect in 1,2-difluoroethane. Hyperconjugation, bent bonds, steric repulsion

Natural bond orbital deletion calculations show that whereas the gauche preference arises from vicinal hyperconjugative interaction between anti C-H bonds and C-F* antibonds, the cis C-H/C-F* interactions are substantial (approximately 25% of the anti interaction). The established significantly >60 degrees FCCF dihedral angle for the equilibrium conformer can then be rationalized in terms of the hyperconjugation model alone by taking into account both anti interactions that maximize near 60 degrees and the smaller cis interactions that maximize at a much larger dihedral angle. This explanation does not invoke repulsive forces to rationalize the 72 degrees equilibrium conformer angle. The relative minimum energy for the trans conformer is the consequence of a balance between decreasing hyperconjugative stabilization and decreasing steric destabilization as the FCCF torsional angle approaches 180 degrees . The torsional coordinate is predicted to be strongly contaminated by CCF bending, with the result that approximately half of the trans --> gauche stabilization energy stems from mode coupling.     

Reactions of 1-ethyl-1,2-diphosphole with acetylenes

Russian Chemical Bulletin - The cycloaddition of 1-ethyl-3,4,5-triphenyl-1,2-diphosphacyclopenta-2,4-diene to acetylenes R1C≡CR2 (R1 = R2 = CO2Me; R1 = Ph, R2 = H) gives phosphinine along...     

Reaction of tetrachloro-3-cyanopyridine with anilines

It was determined by ¹³C NMR spectroscopy that the reaction of tetrachloro-3-cyanopyridine with anilines occurs with the formation of isomeric 6- and 4-(arylamino)trichloro-3-cyanopyridines. It was shown that the nucleophilic properties of the anilines do not affect the ratio of the isomers that are formed in the reaction.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 200–204, February, 1991.     

Addition Reactions of Benzenesulfinic Acid with Glycals and 1,2-Dibromosugars

The addition of benzenesulfinic acid to glycals was investigated under various conditions, and optimized yields of the glycosyl phenylsulfone products were obtained in the presence of tin tetrachloride as a catalyst. Double bond shift (Ferrier rearrangement) occurred in all cases except amicetal, which lacks a substituent at the allylic carbon. Glycosylation of benzenesulfinic acid with 1,2-dibromides was carried out using silver triflate as the promoter, and gave sulfinate esters as products by reaction at oxygen rather than at sulfur. The sulfinate esters were obtained as mixtures of stereoisomers at the stereogenic sulfur atom. Trapping of the sulfinates with carboxylate nucleophiles was observed during attempted oxidation with MCPBA.