Substitution of Hydroxyl Groups by Deuterium in the Electrochemical Reduction of Methanesulfonates

Abstract

The electrochemical reduction of dodecyl methanesulfonate (ROMs; R = n-C₁₂H₂₅ ^?, Ms = CH₃SO₂ ^?) as model compound was studied in deuterated media. This reaction could be of potential use in syntheses of partially deuterated compounds by conversion of C?OH-groups into C?D-bonds in the presence of other reactive groups. In order to obtain detailed information about the origin of the introduced hydrogen all individual components (solvent, supporting electrolyte, substrate) of the reaction system were deuterium labelled in the model reaction. The experiments indicate, that this reduction does not proceed along a uniform pathway. Dodecyl anions play the dominating role in the reaction mechanism. Deuterium is transferred into the product dodecane-d ₁ from all components of the reaction mixture in the order of their relative proton acidities Ms-d ₃ > Bu₄N⁺-d ₃₆ > DMF-d ₇ > R-1,1-d ₂-OMs.

In the presence of D²O a hydrogen isotope exchange was found with the methyl group of MsO^?, catalyzed by electrogenerated bases.     

Resolution limits in Fourier Transform Spectrometry

It is shown by mathematical analysis, and by close inspection of experimentally determined spectra, that the frequently quoted result Δv̄= 0.5/D, where D is the maximum path difference introduced, for the resolution in unapodized Fourier transform spectrometry is over optimistic. Even when the two lines are of equal strength the resolution is found to be Δv̄ =0.7/D whilst if they differ markedly in strength the resolution is even worse (∼ 0.8/D). The loss in resolution in going to apodized spectrometry is not as severe as has previously been thought with Δv̄ = 0.9/D for equal strength components and Δv̄ = 1/D for the components having an intensity ratio of 2:1.     

红外光谱结合X射线荧光光谱分析鉴定合成橡胶粒子

利用超声波萃取技术,对合成橡胶粒子中的高聚物和其他成分进行分离,然后利用红外光谱和X射线荧光光谱对分离后的组分进行分析鉴定,获得了较好的结果。本方法具有简便、快速、准确的特点,适用于橡胶及其制品的快速鉴定。     

FTIR光谱遥测红外药剂的燃烧温度

本文利用遥感FTIR光谱，对红外药剂的燃烧特性进行了研究。在分辨率为4cm^-1时，收集4700－740cm^-1波段的光谱。从HF等燃烧产物发射的分子振转基带精细结构的谱线强度分布，可以对燃烧温度进行遥感测定，并给出了燃烧温度随时间的变化关系，实验结果表明燃烧表面附近温度梯度很大，存在着急剧的变化温度场，同时也说明，在不干扰火焰温度场的情况下，利用遥感FTIR光谱对剧烈的、非稳态快速燃烧的火焰温度进行连续实时的遥感测量，是一种快速、准确、灵敏度高的测温方法，显示了它在燃烧温度测量、产物浓度测试以及燃烧机理研究等方面的应用前景。     

不同产地双色牛肝菌FTIR光谱鉴别研究

同一种蕈菌子实体,由于外观形貌相似,凭传统外观形貌特征难以鉴别产地来源。应用傅里叶变换红外光谱(FTIR)法测定了云南省5个不同地区58个野生双色牛肝菌子实体样品的红外光谱。借助于红外光谱具有的指纹特性,利用SPSS 13.0统计软件对1 350~750 cm-1范围光谱数据进行主成分分析(PCA),根据前三个主成分累积贡献率已达到88.87%以及主成分载荷分析,表明前三个主成分能够反映样品在该段光谱的主要信息。对前三个主成分作投影显示并进行比较,发现以主成分1和主成分2作二维线形投影,对不同产地的双色牛肝菌有较好的聚类和鉴别作用,所有样品被划分为5个区域,98.3%的样品被正确归类。研究结果提示,傅里叶变换红外光谱结合主成分分析方法可以快速、方便地对不同产地的同一种野生双色牛肝菌进行鉴别分类。     

Factors Affecting Polymer Translocation Through a Nanopore in a Membrane

采用Monte Carlo方法研究了高分子链穿越"trans"侧具有吸附作用的膜上纳米孔的过程. 当体系的温度TTc时,τ随着温度的升高而增大. 穿孔时间与膜的吸附势强度μ0 之间存在非单调依赖关系,τ首先随着μ0的增大而增大,最后τ随着μ0 的增大而减小. 研究穿孔时间与溶剂性质的关系时发现,当εAB<εc时,τ随着εAB 的增加而增加,当εAB>εc时,τ 随着"AB 的增加而减小. 高分子链穿孔时间与链长N之间存在着标度关系：当吸附势强度μ0>μc时,τ∝N^1.602,当μ0相似文献   

Determination of Deuterium Content in Low Concentration Water Samples by Infra-Red Spectrometry

The deuterium content could be estimated in the low range by the infra-red method with an accuracy of ± 0.0005 mole% by using the suitable absorption band at 3·98 μ and a quartz cell of ≈0·3 mm thickness. The reproducibility of this method is tested by mass spectrometry and it is found that data of both methods are comparable.     

Spectral Investigation of Phosphorus Compounds in Spinacia Oleracea Using Fourier Transform Infrared Method

The study uses the Fourier transform infrared spectroscopy method to evaluate the influence of phosphogypsum from the soil on the growth and accumulation of nutrients in Spinacia oleracea. Attenuated total reflectance spectra of Spinacia oleracea roots and stems originated from plants cultivated on 28% to 52% phosphogypsum enriched soil have been studied in the 4000–600 cm^?1 area. The structure of the infrared absorption bands for spinach roots and stems and for the soil where plants were grown was analyzed. Thus, it was observed that phosphorus–oxygen bonds contribution can be identified both in roots and stems absorption spectra. The significance of the research is the possibility to use the infrared investigation as rapid technique, particularly useful for agriculture, to study the extraction and assimilation process of the compounds containing phosphorus and nitrogen from the soil in which the spinach seedlings grew. In the case of this study, it was observed that the absorption of phosphorus in the spinach roots and stems has not the same effect. The analysis of obtained data indicated that the assimilation of phosphorus from phosphogypsum enriched soil induces changes in spinach roots structure that are most likely due to an increase synthesis of proteins, rather than to a decrease in carbohydrates quantity.     

Structural Investigation of Biomacromolecules Using Ultrahigh-Resolution Mass Spectrometry and Isotope Exchange

We present a new analysis methodology for arbitrary complex molecular systems using ultrahigh-resolution mass spectrometry and isotope exchange. The kinetics of the hydrogen–deuterium exchange reaction is described for large biomacromolecules. The possible applications of the proposed methodology for the analysis of linear oligosaccharides, proteins, and molecular ensemble of humic acids are discussed.     

IR Spectroscopy of Bidistilled and Deuterium Water under Conditions of Geometric Limitation in Glass Nanopores

Optics and Spectroscopy - A study of IR spectra of H2O and D2O in nanoporous glass (PG) matrices with pores of different sizes has been carried out under geometric confinement. It has been...     

红外光谱法对聚丙烯腈共聚物的结构表征

用红外分析的方法表征了聚丙烯腈共聚物的结构.实验结果表明,实验用聚丙烯腈共聚物为三元共聚物,不同厂家纺丝后的聚丙烯腈共聚物纤维除有些样品含有部分DMF溶剂外,在官能团结构上与纺丝前的聚丙烯腈共聚物粉末基本一致.测定结果为合理选择纺丝方法,生产更加有利于人体健康的纺织品提供了参考意见和科学依据.     

Study of birefringence in porous silicon layers by IR Fourier spectroscopy

Birefringence in porous silicon layers prepared with different etching currents on a (110) substrate is studied by IR Fourier spectroscopy. The spectra exhibit beats in the intensity of transmitted and reflected radiation due to the summation of the intensities of the ordinary and extraordinary waves interfering in the porous layer. An analysis of the spectra shows the layers to exhibit properties of a negative uniaxial crystal with the optical axis lying in the layer plane. The difference between the refractive indices of the ordinary and extraordinary waves for a layer with a porosity of 80% reaches 18%. The experimental data are in agreement with the calculations based on the effective-medium approximation, which takes into account the anisotropy of silicon nanocrystal arrangement in a porous layer.     

An Investigation of the Reciprocity Principle of Light Exposures Using Microfading Spectrometry

It is frequently assumed that sensitive museum materials follow the reciprocity principle of light exposures. Thus, equivalent exposure doses obtained by using either high-illuminance levels for short periods of time or lower illumination for longer exhibition periods are believed to cause similar degrees of damage to an object. Microfading spectrometry permitted the investigation of this phenomenon by evaluation of light-induced changes in a series of samples. The effects of equivalent exposure doses on materials such as Blue Wool 1, LightCheck Ultra, and various dyed silks from a reference collection were compared. The results indicate that reciprocity is obeyed by the most stable colorants, while materials with lower stability to light may experience deviations that are proportional to the intensity of illumination. This study confirms that reciprocity failure is associated with the use of high-intensity lamps during accelerated-aging trials. Therefore only those tests conducted at low-illumination intensity ranges where reciprocity holds should be employed when one estimates the extent of damage occurring in a museum environment.     

Fourier IR Spectroscopy Study of the Effects of Unsteadiness on the Process of Swelling of Polymeric Membranes

Optics and Spectroscopy - The process of swelling of a Nafion polymer membrane in water poured into a cell with a characteristic size of the same order of magnitude as the membrane thickness itself...     

探索氘/固体系统中的异常核现象

本文介绍了世界有关研究机构在冷聚变这一有重大争议领域的研究动态.许多实验室相继报导了在处于非平衡态的氘/固体系统中,观察到超常热、质子、氚和中子等异常核现象.在金属氢化物的性能、电解过程中的尖端效应和聚能过程、随机中子和低产率中子的测量技术、集团束冲击核聚变等方面的探索取得了许多令人瞩目的成果.提出了热等离子体模型、多体屏蔽效应、量子玻色等离子体理论、相干核反应机制、钯核的中子俘获效应、表面定域理论等许多理论模型. A brief introduction of recent investigation about the cold nuclear fusion by numerouslaboratories throughout the world has been given experimentally and theoretically in this paper.Undernon—equilibrium conditions of deuterium/solid system,the production of excess heat,protons,tritium,neutrons,and gamma rays have been reported.Scientists have gained the quite salutary effects to learnthe behavior of metal hydrides in this brief span of time than in the past 100 years,to improve ...     

用傅里叶谱位相方法对运动目标定位

介绍一种利用运动目标图象傅里叶谱位相信息实现对目标定位的新方法，该方法具有较高定位精度，且不受运动目标姿态发迹的影响。文中介绍原理，给出计算机仿真和实验测量结果，并讨论实际应用的可行性。     

β-环糊精交联聚合物的合成及红外光谱研究

以环氧氯丙烷作为交联剂合成了β-环糊精的交联聚合物，并对产物进行了热分析及红外光谱测定。