Reaction of Isonitriles with Dibenzoylacetylene Leading to Furan and Difuropyran Derivatives

A mixture of an isocyanide and dibenzoylacetylene in dry CH₂Cl₂ undergoes a smooth addition reaction at ambient temperature to furnish 3‐[5‐(alkylimino)‐3,4‐dibenzoyl‐2‐phenylfuran‐2(2H)‐yl]‐ 1‐phenylprop‐2‐yn‐1‐ones (1 : 2 adduct) and {2,5‐bis(alkylimino)‐4,7,8a‐triphenyl‐5H‐difuro[2,3‐b:3′,4′‐e]pyran‐3(8aH)‐yl}(phenyl)methanones (2 : 2 adduct). Single‐crystal X‐ray analyses conclusively confirmed the structures of the adducts.     

Polymerization Mechanism of Vinyl Chloride with Trialkylaluminum-Lewis Base Catalyst and Thermal Stability of Poly(vinyl Chloride)

The mechanism of vinyl chloride polymerization by the tri-ethylaluminum-Lewis base-carbon tetrachloride catalyst system and the thermal stability of the resulting polymer were investigated. When the Lewis base is multidentate, the resultant complex with triethylaluminum shows significantly high catalytic activity for radical polymerization of vinyl chloride in the presence of carbon tetrachloride to give a white powder with high molecular weight. Carbon tetrachloride accelerates the rate of polymerization and participates in an initiating process rather than in a propagating step. The thermal stability of the polymer prepared with this catalyst system is much superior to that of commercial polyvinyl chloride), although the numbers of the double bonds in a chain end and of the head-to-head linkage are similar in both samples, suggesting that the thermally unstable structures of the former react with triethylaluminum to give the thermally stable structure on the polymerization process.     

RADIATION INDUCED SOLID-STATE POLYMERIZATION OF ACETYLENEDICARBOXYLIC ACID

ABSTRACT

Radiation induced solid-state polymerization of acetylenedicarboxylic acid was carried out at room temperature in open atmosphere and under vacuum conditions. The gray colored powder polymer obtained was insoluble in most common solvents but only partially soluble in DMSO and THF. The limiting conversion to polymer was about 5%. The polymer was characterized by IR, UV, DP-MS, DSC, TGA, and XRD. The mechanism of polymerization was elucidated from the available data. Polymerization followed a free radical mechanism. However, before the addition of monomer molecules to the growing chain, at least one of the carboxylic groups of the monomer breaks away as CO or CO₂. The formation of side group cyclization takes place. At least one of the bonds in the side cyclic group is an etheric bond. The DSC, TGA, and XRD results showed that the polymer was partially crystalline and showed no melting up to 1200°C. The mechanism of polymerization and assigned chain structure was studied by the direct pyrolysis mass spectrometric method.

The crystal structure of monomer and polymer was investigated by the XRD method. Both monomer and crystalline polymer were monoclinic with similar cell parameters. Thus, the polymerization follows a topotactic mechanism. The unpolymerized monomer retains its crystal structure and, therefore, CO or CO₂ in the monomer molecule has to be eliminated before polymerization could take place.     

Synthesis of 1-vinylpyrrole-2-carbonitriles

A new highly synthetically potent series of bifunctional pyrroles, 1-vinylpyrrole-2-carbonitriles, were synthesized from readily available 1-vinylpyrrole-2-carbaldehyde oximes by two methods: (1) reaction with acetylene (KOH/DMSO, 70 °C, 10 min, yields 58-67%) and (2) reaction with acetic anhydride (90-100 °C, 5 h, yields 83-93%). Starting from 2-phenyl-1-vinylpyrrole, the one-pot synthesis of the corresponding 1-vinyl-2-carbonitrile was accomplished directly by successive treatment with a DMF/(COCl)₂ complex, NH₂OH·HCl/NaOAc, and acetic anhydride (yield 58%).     

用于乙炔氢氯化的磷酸预处理活性炭负载Pd催化剂(英文)

用磷酸溶液(H3PO4)对活性炭载体(AC)进行预处理,以此为载体,采用浸渍法制备了负载型钯(Pd)催化剂(PACT)并将其应用于乙炔氢氯化反应.结果表明,与未进行处理活性炭载体负载Pd催化剂(PAC)相比,催化剂PACT表现出较高的催化剂活性.对催化剂进行了比表面积(BET),Boehm滴定,X-射线粉末衍射(XRD),透射电镜(TEM),电子能谱(EDS)等表征.结果表明,载体表面含氧基团含量的变化,活性组分Pd含量的富集以及由H3PO4引进的PO3-4的存在是催化剂具高活性的主要原因.热重分析(TG)说明,反应过程积碳的产生使得催化剂的活性降低.     

A three-component domino reaction of 2-tetralone, hydroxylamine and acetylene: a one-pot, highly regioselective synthesis of 4,5-dihydrobenz[e]indoles

2-Tetralone, hydroxylamine and acetylene react in the system MOH/DMSO to give 4,5-dihydrobenz[e]indole and its N-vinyl derivatives in up to 41% and 75% (in the case of excess acetylene) yields, respectively. The amount of the alternative regioisomer, N-vinyl-4,9-dihydrobenz[f]indole, does not exceed 2% (GLC-MS), while the corresponding regioisomer of 4,5-dihydrobenz[e]indole is not detectable.     

SN2-Selective allylic substitution of chiral γ-aryl substituted allylic picolinates with alkynylcopper reagents

Substitution of γ-aryl secondary allylic picolinates with alkynyl copper reagents was studied. The copper reagent, prepared from TMSCCMgBr and CuBr·Me₂S in 2:1, was subjected to substitution of the picolinate derived from (E)-3-phenyl-1-methyl-2-propenyl alcohol at 0 °C for 1 h in THF to produce a mixture of α- and γ-products and the alcohol in 67:20:13, while the reagent in 3 or 4:1 ratio gave the α-product with 90-91% selectivity. On the contrary, reaction in CH₂Cl₂-THF (6-8:1) at 0 °C for 1 h furnished the α-product with 99% regioselectivity. The effect of CH₂Cl₂ was also demonstrated with eight more examples. Furthermore, 99% inversion was determined by transformation to the literature compound and by chiral HPLC.     

基于金属-配体共轭界面键的纳米粒子内电荷离域:金属d电子的影响

Intraparticle charge delocalization occurs when metal nanoparticles are functionalized with organic capping ligands through conjugated metal-ligand interfacial bonds. In this study, metal nanoparticles of 5d metals (Ir, Pt, and Au) and 4d metals (Ru, Rh, and Pd) were prepared and capped with ethynylphenylacetylene and the impacts of the number of metal d electrons on the nanoparticle optoelectronic properties were examined. Both FTIR and photoluminescence measurements indicate that intraparticle charge delocalization was enhanced with the increase of the number of d electrons in the same period with palladium being an exception.     

Density functional theory study of the near edge X-ray absorption fine structure and infrared spectroscopy of acetylene and benzene on group IV semiconductor surfaces

The near edge X-ray absorption fine structure and infrared spectroscopy of acetylene and benzene adsorbed on C(1 0 0)-2 × 1, Si(1 0 0)-2 × 1 and Ge(1 0 0)-2 × 1 surfaces is studied with density functional theory calculations. Time dependent density functional theory calculations of the near edge X-ray absorption fine structure with a modified exchange-correlation functional agree well with experiment, and show that the spectral features arise from excitation to π^∗, and orbitals, where X represents C, Si or Ge. The excitation energies are dependent on the surface, and for acetylene, the location of the π^∗ band also varies with the surface. Calculations of the vibrational modes show the CH stretching frequencies for carbon atoms bonded directly to the surface vary significantly between the three surfaces, while those for carbon atoms not bonded to the surface do not change significantly.     

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

利用双光子共振四波混频差频技术产生高分辨、可调谐的真空紫外(VUV)激光,在142.8-152.3nm波长范围内测量了超声射流冷却乙炔分子的吸收光谱. 由于射流冷却的效果和VUV激光高分辨的特性,当前的吸收光谱显示出较以往实验光谱更清晰的光谱振动峰结构,其中主要的三个振动谱峰序列对应了乙炔分子C1Ⅱu态的C-C对称伸缩振动激发(v2=0-2). 此外,148.2 nm处的肩峰则被归属为反对称弯曲振动v4的第一泛频激发,同时由于Renner-Teller效应分裂和跃迁选律的限制,当前的吸收光谱中观测到420(μ1Ⅱu)和420(к1Ⅱu)两个组分. 由此获得了各振动子带的带源位置和半高峰宽. 随着振动的激发,各振动峰逐渐加宽,能级寿命减小.