Papers by Benedito S Lima-Neto
Bio-Based Plant Oil Polymers and Composites, 2016
This chapter provides an overview on new polyester materials from plant oil. In recent years, ind... more This chapter provides an overview on new polyester materials from plant oil. In recent years, industrial and academic research teams have been strongly involved in replacing conventional polyesters from petroleum-based material with biodegradable ones. The goal is to design good performance materials that, after use, could be susceptible to microbial and environmental degradation, using adequate solid waste management disposal practices without any adverse environmental impact. It is necessary to develop new routes to enhance the properties of biodegradable polymers. In fact, polyesters are considered the most competitive biodegradable polymers commercialized so far. Unsaturated polyester resins (UPRs) incorporated with plant oil are interesting materials because of their high modulus, strength, durability, and thermal and chemical resistance, which are provided by high cross-linking density.
Cinnamyl alcohol (AC) and cinnamyl acetate (ACM) were used as substrates in olefin metathesis rea... more Cinnamyl alcohol (AC) and cinnamyl acetate (ACM) were used as substrates in olefin metathesis reactions catalyzed by RuCl2(PCy3)2(=CHPh), first-generation Grubbs catalyst-G1, and RuCl2(PCy3)(H2IMes)(= CHPh), second-generation Grubbs catalyst-G2. The reactions occurred in the same reaction conditions for both substrates, 50 °C, for 24 h, in the proportions Ru:substrate of 1:1 and 1:10 mol. At the end of each experiment, the reaction mixture was evaluated by GC-MS and NMR of 13C{1H}. The results revealed different products when G1 and G2 are applied in the metathesis of AC, 1,5-diphenyl-2-pentene and stilbene, respectively. When ACM is the substrate, no product is noted with G1 and stilbene was the compound obtained with G2 as catalyst. In this study, we have presented a discussion about the electronic and steric influence of the ancillary ligands in the yield and type of product formed in the catalytic process.
Revista Virtual de Química, 2021
Chinese Journal of Experimental Traditional Medical Formulae, 2013
Objective: To establish a mouse model with kidney Yang deficiency infected by influenza virus.Met... more Objective: To establish a mouse model with kidney Yang deficiency infected by influenza virus.Method: Kidney Yang deficiency mice were established by intraperitoneal injection of estradiol benzoate(0.008 mg.g-1) as previously described.The physical signs in mice were observed,and the swimming time of mice,rectal temperature,toe temperature,autonomic mobility were examined.On the basis of above model,Mice were inoculated with mouse lung influenza virus(FM1) by the nasal cavity to establish the mice model with kidney Yang deficiency infected by influenza virus.Then physical signs,mortality,body weight and temperature changes were observed daily.The concentrations of tumor necrosis factor-α(TNF-α) and interferon-γ(IFN-γ) in mouse serum were measured,and the organ indexes of lung,spleen,kidney,adrenal and thymus were detected.Pathological changes of lung were observed.Result: The swimming time,rectal temperature,toe temperature,and autonomic activities of mice model were significantly d...
目的本研究组在参考国外先进技术的基础上历时5年研制成功了先进的放疗剂量自动化检测大型仪器.该机适用于医院放疗科和省级放射卫生检测机构对放疗设备的验收检测.对于放疗计划系统需要的大量临床物理参数可... more 目的本研究组在参考国外先进技术的基础上历时5年研制成功了先进的放疗剂量自动化检测大型仪器.该机适用于医院放疗科和省级放射卫生检测机构对放疗设备的验收检测.对于放疗计划系统需要的大量临床物理参数可以实现快速测量.方法采用2个电离室为扫描探头和检测探头,利用最新的自动化测量和控制技术,可以快速方便和准确地扫描测量各种型号医用直线加速器、X刀和60Co远距离治疗机的射线束参数.通过计算机控制多细分步进电机驱动精密机械传动系统,使该系统的扫描定位精度小于0.1mm;实现对放疗射线束的水平和垂直方向的扫描,对放射治疗射野的离轴比和百分深度等参数实现快速的测量.结果 RTS-200放疗二维自动扫描水箱系统扫描测量的加速器X射线的Profile和PDD测量曲线比较平滑,对X射线的均整度,对称性等数据的分析结果与Varian公司的测量结果吻合;从测量PDD曲线可以看出,15MV的测量的D10/Dmax的分析值与Varian公司的测量标称值接近.结论 RTS-200S放疗二维自动扫描测量水箱的性能完全可以满足测量医用加速器的射线束特性的需要.
Letters in Organic Chemistry, 2019
Methyl eugenol olefin metathesis was conducted with non-carbene Ru-complexes ([RuCl2(PPh3)2amine]... more Methyl eugenol olefin metathesis was conducted with non-carbene Ru-complexes ([RuCl2(PPh3)2amine]) in the absence and presence of SnCl2 or CuCl2 as additives. and Ttheir catalytic activities were compared with that of a commercial Grubbs catalyst 2nd Generation (G2).
Journal of Macromolecular Science, Part A, 2019
Abstract Nickel(II) complexes of Schiff base derived from cycloalkylamines (cycloalkyl = cyclopen... more Abstract Nickel(II) complexes of Schiff base derived from cycloalkylamines (cycloalkyl = cyclopentyl (cpen), cyclohexyl (chex), and cycloheptyl (chep)) were synthesized: [NiII(Lcpen)2] (1), [NiII(Lchex)2] (2), and [NiII(Lchep)2] (3). The Schiff base-NiII complexes 1-3 were characterized by FTIR, UV–Vis, elemental analysis, and computational methods. Electrodeposited films of complexes 1–3 were obtained by potential cycling CH2Cl2 on platinum electrode, and their electrochemical behavior were characterized by cyclic voltammetry. The polymerization of vinyl acetate (VAc) initiated by azobisisobutyronitrile (AIBN) at 55 °C were conducted according to an organometallic-mediated radical polymerization (OMRP) mechanism. The best conversions were obtained using a ratio of [VAc]/[AIBN]/[Ni] = 542/3.25/1, reaching 50, 69 and 85% in 12 h for 1, 2 and 3, respectively. The kinetic of polymerization mediated by complex 1 exhibited a linear dependence of ln([VAc]0/[VAc]) versus time, supporting a constant radical concentration; while for the complexes 2 and 3, the radical concentration was constant for a short period of time. The increase of molecular weights with the conversion coupled with low polydispersities indicate a certain level of control of the polymerization when using the complexes [NiII(LR)2] as controlling agents. GRAPHICAL ABSTRACT
Journal of Molecular Structure, 2019
New Journal of Chemistry, 2019
New dimethyl sulfoxide ruthenium(ii) complexes bearing aryl-substituted NHC ligands as pre-cataly... more New dimethyl sulfoxide ruthenium(ii) complexes bearing aryl-substituted NHC ligands as pre-catalysts for ROMP of norbornene.
Molecular Catalysis, 2018
Dimethyl sulfoxide ruthenium(II) complexes of N-heterocyclic carbenes derived from cycloalkylamin... more Dimethyl sulfoxide ruthenium(II) complexes of N-heterocyclic carbenes derived from cycloalkylamines (cycloalkyl = cyclopentyl (1a), cyclohexyl (1b), cycloheptyl (1c), and cyclooctyl (1d)) were synthesized: [RuCl 2 (Sdmso) 2 (IPent)] (2a), [RuCl 2 (S-dmso) 2 (IHex)] (2b), [RuCl 2 (S-dmso) 2 (IHept)] (2c), and [RuCl 2 (S-dmso) 2 (IOct)] (2d). The imidazolium salts 1a-1d were characterized by FTIR, UV-vis, and 1 H and 13 C NMR spectroscopy, while their respective dimethyl sulfoxide ruthenium(II) complexes (2a-2d) were characterized by elemental analysis, FTIR, UV-vis, 1 H and 13 C NMR, and cyclic voltammetry. The complexes 2a-2d were evaluated as catalytic precursors for ROMP of norbornene (NBE) and for ATRP of methyl methacrylate (MMA). The polynorbornene (polyNBE) syntheses via ROMP using the complexes 2a-2d as pre-catalysts were evaluated under reaction conditions of [EDA]/[Ru] = 28 (5 μL), [NBE]/[Ru] = 5000 at 50°C as a function of time. The polymerization of MMA via ATRP was conducted using the complexes 2a-2d in the presence of ethyl 2-bromoisobutyrate (EBiB) as the initiator. All tests were using the molar ratio [MMA]/[EBiB]/[Ru] = 1000/2/1 and conducted at 85°C. The linear correlation of ln([MMA] 0 /[MMA]) and time clearly indicates that the concentration of radicals remains constant during the polymerization and that the ATRP of MMA mediated by 2a-2d proceeds in a controlled manner.
Journal of Organometallic Chemistry, 2017
Olefin metathesis of ethyl linoleate (EL) was investigated under different conditions of substrat... more Olefin metathesis of ethyl linoleate (EL) was investigated under different conditions of substrate amount, temperature, and catalyst. Second-generation Grubbs catalyst (G2) was used in experiments at 20 and 50 ºC for 24 and 48h, whereas first-generation Grubbs catalyst (G1) and [RuCl2(PPh3)2perhydroazepine] (LN) were used in experiments at 50 ºC for 24h, with the latter also being investigated in the presence or absence of SnCl2 as co-catalyst. Catalytic products were analyzed for GC-MS and discussed in terms of relative percent of the metathesis products. With G2 as catalyst, GC-MS chromatograms were similar in all the amounts of EL investigated at 50 ºC for 24h, except for ethyl hexadec-9-enoate (compound K), which was obtained with different percentage as a function of EL amount (55% for 2 and 5 mL and 65% for 8 mL). An α,ω-dicarboxylic acid with m/z = 444.00 (compound L) was produced from the experiments at 50 ºC for 24h with similar percentage as...
Inorganica Chimica Acta, 2017
The catalytic activity of the five-coordinated [RuCl 2 (PPh 3)(S-dmso) 2 ] complex was investigat... more The catalytic activity of the five-coordinated [RuCl 2 (PPh 3)(S-dmso) 2 ] complex was investigated for ringopening metathesis polymerization (ROMP) of norbornene (NBE) and for atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA). Syntheses via ROMP of polyNBE were dependent on the ethyl diazoacetate (EDA) amount, used as starting carbene source, monomer concentration, temperature, and reaction time. The best polyNBE yields were obtained at 50°C for 120 min with [NBE]/[Ru] = 5000 in presence of 5 lL of EDA. MMA polymerization via ATRP was conducted as a function of time with different ethyl 2-bromoisobutyrate initiator and monomer concentrations. The kinetic data for ATRP show linear increase between MMA conversion and molecular weight. Kinetic studies with the six-coordinated [RuCl 2 (S-dmso) 3 (O-dmso)] complex also showed an increase in the molecular weight with conversion, but with a marked deviation from theoretical molecular weights. This is consistent with the better control in the polymerization supported by electronic and steric properties of the PPh 3 ligand in the title complex
Journal of Chromatography A
ABSTRACT
Journal of Molecular Catalysis A: Chemical, 2015
Abstract This investigation combines theoretical results and experimental data to elucidate the m... more Abstract This investigation combines theoretical results and experimental data to elucidate the main kinetic and mechanism for the ring opening metathesis polymerization of norbornene by means of the [RuCl2(PPh3)2(piperidine)] complex as catalyst initiator. Structural species were defined and a kinetic profile of the entire reaction is depicted. The determined mechanism showed an associative reaction between the [RuCl2(PPh3)2(piperidine)] complex initiator and ethyl diazoacetate as the first step, resulting in a metal-carbene species. This species loses one triphenylphosphine molecule (PPh3) and the global rate-determining step is associated with a removal of the second PPh3 molecule due to an electronic trans-synergism between piperidine and this PPh3 molecule. Entropic factors are crucial to the spontaneity observed for the dissociation of both PPh3 ligands. The step following the rate-determining one is associated with the binding of a norbornene molecule and a similar trans-synergism between this monomer and piperidine activates the catalysis. This electronic effect maintains the system in a very important conformation along the catalytic chain.
Journal of the Chemical Society, Dalton Transactions, 1995
New J. Chem., 2015
The ring size of cyclic amines influences the yield, Mw and PDI values of polynorbonene obtained ... more The ring size of cyclic amines influences the yield, Mw and PDI values of polynorbonene obtained via ROMP using [RuCl2(PPh3)2(amine)x] as the starting complex.
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Papers by Benedito S Lima-Neto