An ab initio and matrix isolation infrared study of the 1:1 C2H2–CHCl3 adduct

The details of weak C–Hπ interactions that control several inter and intramolecular structures have been studied experimentally and theoretically for the 1:1 C₂H₂–CHCl₃ adduct. The adduct was generated by depositing acetylene and chloroform in an argon matrix and a 1:1 complex of these species was identified using infrared spectroscopy. Formation of the adduct was evidenced by shifts in the vibrational frequencies compared to C₂H₂ and CHCl₃ species. The molecular structure, vibrational frequencies and stabilization energies of the complex were predicted at the MP2/6-311+G(d,p) and B3LYP/6-311+G(d,p) levels. Both the computational and experimental data indicate that the C₂H₂–CHCl₃ complex has a weak hydrogen bond involving a C–Hπ interaction, where the C₂H₂ acts as a proton acceptor and the CHCl₃ as the proton donor. In addition, there also appears to be a secondary interaction between one of the chlorine atoms of CHCl₃ and a hydrogen in C₂H₂. The combination of the C–Hπ interaction and the secondary ClH interaction determines the structure and the energetics of the C₂H₂–CHCl₃ complex. In addition to the vibrational assignments for the C₂H₂–CHCl₃ complex we have also observed and assigned features owing to the proton accepting C₂H₂ submolecule in the acetylene dimer.     

金刚石(111)面上乙炔合成金刚石薄膜的成核机理

运用量子力学半经验分子轨道AMl方法计算乙炔作为生长基在金刚石(111)附氢表面上的吸附和成核过程,提出了两种可能的由乙炔合成金刚石薄膜的成核机理,探讨了其生长基作用.     

High-resolution Absorption Spectra of Acetylene in 142.8-152.3 nm

The absorption spectra of acetylene molecules was measured under jet-cooled conditions in the wavelength range of 142.8-152.3 nm,with a tunable and highly resolved vacuum ultraviolet (VUV) laser generated by two-photon resonant four wave difference frequency mixing processes. Due to the sufficient vibrational and rotational cooling effect of the molecular beam and the higher resolution VUV laser, the observed absorption spectra exhibit more distinct spectral features than the previous works measured at room temperature. The major three vibrational bands are assigned as a CC symmetry stretching vibrational progress (v2=0-2) of the C1Ⅱu state of acetylene.The observed shoulder peak at 148.2 nm is assigned to the first overtone band of the trans-bending mode v4 of the C1Ⅱu state of acetylene. Additionally,the two components, 420 (μ1Ⅱu) and 420(к1Ⅱu),are suggested to exhibit in the present absorption spectra,due to their Renner-Teller effect and transition selection rule.All band origins and bandwidths are obtained subsequently,and it is foundthat bandwidths are broadened and lifetimes decrease gradually with the excitation of vibration.     

Efficient degradation of sulfamethoxazole by acetylene black activated peroxydisulfate

Acetylene black (AB), as a kind of carbon material with large specific surface area, low density, strong electron transferability, is supposed to have great potential for application in advanced oxidation processes (AOPs). In this study, AB was utilized as a peroxydisulfate (PDS) activator for the catalytic degradation of sulfamethoxazole (SMX) in aqueous media. Scanning electron microscopy (SEM), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) techniques, zeta potential and Raman spectra were employed to characterize the features of AB. To verify the excellent performance of AB/PDS systems, a series of control experiments were carried out. Compared to graphite/PDS and biochar/PDS system, AB/PDS system could complete degradation of SMX within 15 min. Besides, the effects of key factors including AB dosage, PDS dosage, initial pH and SMX concentration on SMX degradation in AB/PDS system were elucidated systematically. Furthermore, through the radical quenching experiments, it was proved that singlet oxygen (¹O₂) was dominantly responsible for the degradation of SMX. Finally, based on the experiment results and comprehensive analysis, a probable reaction mechanism of AB/PDS system for SMX degradation was proposed. This work suggests that AB has a good potential for tackling the hazardous pollutants in environmental remediation.     

Effective dipole moment parameters of C2H2 for the 100, 7.7, 1.4, 1.3, 1.2 and 1.0 μm regions

Based on new line intensity measurements collected from the literature, the effective dipole moment parameters of acetylene have been found for the 100, 7.7, 1.4, 1.3, 1.2 and 1 μm spectral regions by least-squares fittings. On average, the experimental uncertainty was obtained in all fits. The new sets of the effective dipole moment parameters combined with those that were previously published allow for the calculation of the line intensities for the majority of the acetylene bands in the spectral range from 100 to 1 μm.     

Hydrochlorination of acetylene using expanded multilayered vermiculite (EML-VMT)-supported catalysts

Catalyst supports have very important effects on catalyst performance.A novel expanded multilayered vermiculite(EML-VMT) is successfully used as the catalyst support for the acetylene hydrochlorination.By mixing carbon on the surface of EML-VMT[i.e.,EML-VMT-C),the HgCl_2/EML-VMT-C achieved a high acetylene conversion of 97.3%,a vinyl chloride selectivity of 100%and a turn over frequency(TOF) value of 8.83 × 10~(-3)s~(-1) at a temperature of 140 C,an acetylene gas hourly space velocity(GHSV) of 108 h~(-1)',and a feed volume ratio V(HC1)/V(C_2H_2) of 1.15.Moreover,the HgCl_2/EML-VMT-C shows good stability.The EML-VMT also shows potential in the preparation of other EML-VMT-supported catalysts.     

Versatile Methodology to Hydrate Alkynes,in the Presence of a Wide Variety of Functional Groups,with Mercury(II) p-Toluensulfonamidate,Under Catalytic,Mild, and Neutral Conditions

A method to generate carbonylic compounds from alkynes under mild and neutral conditions, with excellent functional group compatibility and good yields, is described. Hydration takes place under catalytic conditions by using 0.1 to 0.2 equivalents of the easily available and inexpensive mercury(II) p-toluensulfonamidate in a hydroalcoholic solution. After use, the catalyst is rendered inert and/or recycled.

Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications® to view the free supplemental file.     

An Efficient Synthesis of 3,4-bis(Tri-n-butylstannyl)furan

Abstract

Palladium-catalysed addition of hexa-n-butylditin to 2-butyne-1,4-diol, followed by oxidative cyclisation and dehydration gives 3,4-bis(tri-n-butylstannyl)furan in high yield.     

Investigation of the reaction of some unsaturated dicarboxylic acid anhydrides with cyclic carbonates

This work reports attempts to extend to unsaturated anhydrides the rapid reaction of dicarboxylic acid anhydrides with ethylene carbonate to form polymer directly. The reaction of unsaturated diacid anhydrides with two cyclic carbonates, ethylene and propylene carbonate, leads to gelled products whenever the anhydride is capable of Michael addition, while an anhydride without such unsaturation gave linear polymer in- stead. The GC/MS results, along with efforts to trap radical reactions, support Michael addition as an explanation of gelation in these systems.