脂肪胺类化合物的13C核磁共振波谱模拟

对脂肪胺类化合物的13C核磁共振波谱进行了模拟,所用方法为数学模型法,为此,提取了共振碳原子所处化学环境的拓扑特征,几何特征及电子特征,运用变量最优子集回归法对变量进行了选择,用多元回归法构造了数学模型,得到了比较满意的预测结果。     

Determination of the Microstructure of Some Methyl Methacrylate-Butadiene Copolymers by 220 MHz Proton Magnetic Resonance Spectroscopy

Abstract

Proton magnetic resonance (PMR) spectroscopy at 220 MHz has been used to gain information about the relative proportions of various methyl methacrylate centered triads and pentads in some methyl methacrylate (MMA)-butadiene (BU) copolymers prepared with a free-radical catalyst. The PMR peaks used are the MMA α-methyl peaks recorded using CDCL₃ as solvent, and the MMA α methyl peaks recorded using C₅D₅N as solvent. Measured triad and pentad fractions are in good agreement with those calculated from the reactivity ratios r₁ = 0.17 and r₂ = 0.60, where MMA = Monomer 1. Surprisingly, the α-methyl peaks provide information also about the ratio of cis-1,4- to trans-1, 4-butadiene units in the copolymer. Proportions of 1,2-butadiene units are obtained from the relative areas of peaks due to vinyl and vinylene protons.     

Copolymerization and Copolymers of 2,4,5-Tribromostyrene with Methyl Acrylate and Methyl Methacrylate

Abstract

2,4,5-Tribromostyrene (TBSt) was copolymerized with methyl acrylate (MA) or methyl methacrylate (MMA) in a toluene solution using 2,2′-azobisisobutyronitrile as free radical initiator. The copolymerization reactivity ratios were found to be for the system TBSt / MA r₁= 7.4 ± 1.2 (TBSt) and r₂= 0.1 ± 1.4 (MA) and for the system TBSt / MMA r₁ = 1.8 ± 0.2 (TBSt) and r₂ = 0.1 ± 0.2 (MMA). The e and Q values were also calculated. The initial rate of copolymerization, as well as molecular weight of the obtained copolymers for both system linearly increase as the content of TBSt in the monomer mixture increases. Similar behavior has also been established for the course of the copolymerization reactions to high conversions. The resulting copolymers rapidly decompose at temperatures 20–800°C above the decomposition of corresponding (metha)crylate hompolymers. However, the glass transition temperature increases markedly with increasing TBS content.     

相似分析-13 C核磁共振法鉴定(10,12,14)-十六碳共轭三烯-1-乙酸酯异构体的几何构型

报道了利用相似分析-13C核磁共振法确定(10,12,14)-十六碳共轭三烯-1-乙酸酯异构体的几何构型。该方法将共轭三烯6个烯碳的特征化学位移作为相似分析的基本参数,计算样品与每一个几何异构体间的相似指数,根据最大相似指数确定样品最可能的构型。该方法简便,结果满意。     

Alternating Copolymers of Limonene with Methyl Methacrylate: Kinetics and Mechanism

The radical copolymerization of limonene (optically active) with methyl methacrylate in xylene at 80±0.1°C for 1 hr, initiated by benzoyl peroxide (BPO) yield alternating copolymer(s), under the inert atmosphere of nitrogen, as evidenced by reactivity ratios r₁ (MMA)=0.07 and r₂ (limonene)=0.012 using the Kelen–Tüdos method. The kinetic expression is Rα[I]^0.5[MMA]^1.0[Lim.]^?1.0. The decrease in the rate of polymerization with increase in concentration of limonene is due to penultimate unit effect. The overall energy of activation is calculated as 49 kJ/mole. FTIR of the copolymer(s) shows the characteristic frequencies at 1732.40 and 2951.40 cm^?1 due to –OCH₃ of MMA and aromatic C–H stretching of limonene, respectively. ¹H NMR spectra shows peak at 3.8–4.1 δ and 5.3–5.6 δ due to –OCH₃ of MMA and trisubstituted olefinic protons [–CH=CH–CH₂–] of limonene, respectively.     

丝胶-甲基丙烯酸甲酯接枝共聚物的合成与表征

在酸性水介质中,以硝酸铈铵为引发剂合成了丝胶-甲基丙烯酸甲酯接枝共聚物,其结构经1H NMR,IR,SEM和GPC表征。用正交试验法考察了各因素对接枝共聚反应的影响,结果表明,单体浓度对接枝聚合反应的影响最大,反应时间的影响最小。     

聚甲基丙烯酸2,2,3,3-四氟丙酯及其单体与甲基丙烯酸甲酯共聚物的合成与表征

含氟甲基丙烯酸酯聚合物中的氟原子可使其折光指数n_D很低。这是光导纤维皮材的首要条件^[1]。这类材料的大分子主链与作为芯材使用的聚甲基丙烯酸甲酯(PMMA)具有相同的结构,因此其间的相容性和粘结性好,有利于光的全反射;其热稳定性也好^[2,3],可用于共挤出法制造塑料光导纤维.     

碳-13核磁共振法研究小皮伞多糖结构

采用＾１３Ｃ核磁共振法测定和确定了小皮伞多糖中的大分子葡聚糖,葡甘聚糖等３种多糖的一级结构,这些结果与组成分析和甲基化分析结果是一致的,确定了毫克级直接用＾１３Ｃ核磁共振法分析和检测多糖结构的方法。     

Acrylonitrile Copolymerizations. III. Flash Pyrolysis of Methyl Methacrylate and Styrene Copolymers

Flash pyrolysis of the copolymers acrylonitrile-methyl methacrylate and acrylonitrile-styrene has been carried out over the whole range of compositions, and yields of the monomers have been measured. In the first case, all of the methyl methacrylate is recovered as monomer except when a unit is isolated between two acrylonitrile segments. However, the yield in acrylonitrile monomer is lower; it corresponds to the units isolated between long sequences of methyl methacrylate plus the isolated acrylonitrile diads. The agreement between the calculated and experimental yields is excellent only if one takes into account the penultimate effects. In the second case, however, it is not possible to deduce a quantitative interpretation of the yields of either styrene or acrylonitrile monomers.     

Some Factors Affecting the Photosensitized Polymerization of Methyl Methacrylate

The effects of sensitizer, alcohol, and reaction temperature on the photosensitized polymerization of methyl methacrylate in cyclohexane-alcohol mixtures were investigated. A maximum conversion was indicated at a certain concentration of alcohol in the mixture for the systems sensitized with quinones such as anthraquinone, 2-tert-butylanthraquinone, and α-naphthoquinone, while it was not observed for the benzophenone-sensitized system. The concentration of alcohol corresponding to the maximum conversion increased in the order methanol < ethanol < n-propanol < n-butanol, and shifted to the lower side by raising the reaction temperature from 20 to 40°C. Based on the absorption and ESR spectra of irradiated solution of quinones, reasons for maximum conversion at an optimum concentration of alcohol are discussed.     

Effect of Cathode Potential on Electrosynthesis and Physicochemical Properties of Styrene and Methyl Methacrylate Copolymers

The voltammetry, ESR and UV spectroscopy methods and quantum chemical calculations (PPDP/2) are used to determine the nature of active centers, the anionic mechanism of electrochemical copolymerization (ECP) of styrene (St) and methyl methacrylate (M) at the cathode surface, and the radical-anion mechanism in aprotic solvents. The composition, microstructure, and dielectric properties of copolymers are determined by the cathode potential, which is due to a change in the nature of inducing species (M°^–, °M–M^–, ^–M–M^–, St^2–) and in the ratio of their concentrations during ECP.     

Synthesis and Investigation of Copolymers of Glycidyl Methacrylate and Methyl Pheophorbide a in a Solution

Russian Journal of General Chemistry - Copolymers of glycidyl methacrylate and methyl pheophorbide a of different compositions were synthesized by radical copolymerization in toluene and THF...     

梳状丙烯酸酯类共聚物凝胶电解质的传输性能与自由体积

用三种分子量大小不等的聚乙二醇单甲醚(PEGME)与甲基丙烯酸甲酯-马来酸酐共聚物[P(MMA-co-MAh)]反应,制备了三种支链长度不等的梳状共聚物(MMA/MAh-g-PEGME), 并以此为基体, 加入增塑剂碳酸丙烯酯(PC)和高氯酸锂(LiClO₄), 采用溶剂浇铸法制备了三种凝胶聚合物电解质(GPE)膜, 研究了其离子传输性能, 发现该聚合物凝胶电解质的离子传输机理符合VTF (Vogel-Tamman-Fulcher)方程, 即离子传输性能与凝胶体系自由体积的大小有关; 采用正电子湮没寿命谱仪(PALS)研究了GPE 体系的自由体积特性, 获得了各支链长度不同的共聚物凝胶电解质的自由体积分数, 分析各自由体积与离子传输性能之间的关系, 建立了共聚物结构、凝胶聚合物自由体积及其传输性能之间的关系. 发现梳状共聚物支链长度越长, 凝胶电解质的自由体积越大, 离子传输性能越高.     

13C-Nuclear Magnetic Resonance spectroscopy as a probe of enzyme environment—II: Effect of solvent and pH on 13C-chemical shifts in derivatized amino-acid models

The synthesis and characterization of side-chain derivatives of amino- and carboxy-protected lysine, serine and cysteine, and of two tripeptides is reported. Broad-band proton-decoupled ¹³C-nuclear magnetic resonance spectra have been determined and in almost all cases, each carbon resonance has been unambiguously assigned by a combination of off-resonance and specific decoupling techniques. The effect of solvent and pH on chemical shifts is discussed. The objective of these studies is to provide models relevant to the use of ¹³C-labelled electrophilic inhibitors as probes of enzyme active-site environment.     

Fullerene-C60, A New Effective Inhibitor of High-Temperature Thermooxidative Degradation of Methyl Methacrylate Copolymers

Fullerene-C₆₀ inhibits thermal and thermooxidative degradation of copolymers of methyl methacrylate with styrene, butyl acrylate, glycidyl methacrylate, and hydroxyethyl methacrylate.     

Separation Mechanism of Copolymers from Styrene and Methyl Methacrylate According to Composition by Liquid Adsorption Chromatography

Abstract

Silica gel and a mixture of chloroform and ethanol were used as the stationary and the mobile phases, respectively. At the isocratic elution mode, the copolymers tended to adsorb on the column with increasing MMA content in the copolymers, with increasing column temperature, and with decreasing ethanol content in the mobile phase. The copolymers appeared always at the position proportional to the interstitial volume in the column, otherwise they adsorbed on the column. The equilibrium distribution of the copolymers between the mobile phase and the stationary phase cannot be considered in this system. Hydrogen bonding of carbonyl groups in MMA units of the copolymers to silanol groups on the surface of silica gel was considered to be the main interaction between the copolymers and the adsorbent. The hydrogen bonding increases with increasing the number of carbonyl groups per unit surface of copolymer coil in solution and with increasing free silanol groups on the silica surface. Ethanol in the stationary phase controls the content of the free silanol groups on the surface and is controlled by the content of ethanol in the mobile phase in addition to column temperature. This phenomena can be explained by introducing the term of the adsorption energy of a copolymer segment with the silica surface. The adsorption energy is proportional to the strength of the hydrogen bonding. Above the critical adsorption energy which is defined to be equal to the dissolution energy of the copolymer to the mobile pahse, the copolymers adsorb on the surface of silica gel and the desorption of the copolymers advances when the adsorption energy approaches to the critical adsorption energy. No adsorption of the copolymers is possible when the adsorption energy is equal or below the critical adsorption energy.     

Polymerization of Methyl Methacrylate in the Presence of Boroxyl Radicals. Synthesis of Block Copolymers

The kinetics of the radical polymerization of methyl methacrylate under the action of the amine–tripropylborane–oxygen system is studied at different borane : oxygen ratios in two modes: at direct contact between the polymerization mixture and oxygen and under the postpolymerization conditions, i.e., when, after brief contact, oxygen is removed from the system by vacuum pumping. It is shown that reversible-deactivation postpolymerization becomes possible when organoborane is in a twofold excess over oxygen. There were block copolymers of methyl methacrylate with styrene and acrylonitrile characterized under these conditions.     

聚氧乙烯大单体与甲基丙烯酸甲酯的共聚合及其共聚物的研究

研究了聚氧乙烯（ＰＥＯ）大单体与甲基丙烯酸甲酯的溶液共聚合，考察了引发剂用量，单体总浓度、投料比、反应时间对共聚物组成和分子量的，ＩＲ、ＨＮＭＲ、ＧＰＣ、ＶＰＯ、ＤＳＣ航透射电等测定结果表明，经纯化的共聚物具有预期的结构，且呈现微相分离，体外人体正常抗凝血浆复钙时间测定结果显示：共聚物的抗凝血明显好于玻璃和ＰＭＭＡ均聚物，且随共聚物中ＰＥＯ含量的增加而增强，经水化处理的共聚物的抗凝血性比未经处理的     

4-叔丁基苯乙烯和甲基丙烯酸甲酯共聚物磁性吸油树脂

以4-叔丁基苯乙烯(t BS)和甲基丙烯酸甲酯(MMA)为单体,二乙烯基苯(DVB)为交联剂,与双键修饰的Fe3O4纳米粒子共聚,制备了一系列基于t BS和MMA的磁性高分子吸油树脂.用红外光谱(FTIR)、X-射线衍射(XRD)、光学显微镜(OM)、扫描电子显微镜(SEM)、接触角(CA)和比表面积测试等技术对样品进行了表征.详细考察了两单体配比、交联剂用量对树脂的吸附容量、吸附速率的影响规律.实验发现,当两单体用量分别为2 m L,交联剂为0.5 m L时,磁性吸油树脂的吸油性能达到最好.