2-(4-溴甲基苯基)丙酸合成

以甲苯为原料,经Friedel-Crafts、Willgerodt-Kindler-水解"一锅法",单甲基化和溴代反应合成了洛索洛芬的关键中间体2-(4-溴甲基苯基)丙酸。结果表明:超声波能促进Friedel-Crafts、Willgerodt-Kindler水解反应,使用复合相转移催化剂可得高收率的单基化产物。该合成路线操作简便、原料易得,总收率55.1%。     

碘催化芳基重排法合成2-(4-溴甲基苯基)丙酸

对洛索洛芬钠的关键中间体2-(4-溴甲基苯基)丙酸的合成工艺进行了改进研究。甲苯与丙酰氯经Friedel-Crafts反应生成1-(4-甲基苯基)-1-丙酮,收率87.8%;1-(4-甲基苯基)-1-丙酮与碘和原甲酸三乙酯进行芳基重排反应,生成2-(4-甲基苯基)丙酸乙酯,收率88%;2-(4-甲基苯基)丙酸乙酯在氢氧化钾-甲醇-水体系中水解生成2-(4-甲基苯基)丙酸,收率93%;2-(4-甲基苯基)丙酸在偶氮双异丁腈引发下于四氯化碳-石油醚二元溶剂体系中,用N-溴代琥珀酰亚胺溴化,收率72.9%,四步反应总收率58.6%。反应步骤少、操作简便、原料易得。     

2-(4-溴甲基苯基)丙酸合成研究

本文对以前的2-(4-溴甲基苯基)丙酸合成复杂、收率低的工艺提出了新的制备方法。提出了以氯化苄、甲醇钠、氯代丙酰氯等为原料,经酯化、酰化、缩合、重排和碱解、溴化等反应合成2-(4-溴甲基苯基)丙酸。     

2-对乙氧基苯基丙烯酸乙酯的合成研究

2-对乙氧基苯基丙烯酸乙酯是合成乙氰菊酯的重要中间体.设计了一条以苯乙醚为起始原料,经过Friedel-Crafts反应、Wittig G反应合成2-对乙氧基苯基丙烯酸乙酯的新路线.在反应中考察了溶剂、投料比(摩尔比)对反应收率的影响,得到了较佳的反应条件.在Friedel-Crafts反应中,以二氯甲烷为溶剂,苯乙醚、三氯化铝、草酰氯单乙酯的投料比(摩尔比)为1∶2.5∶1.2,反应收率达76.5%,含量在92.0%以上;在Wittig G反应中,以四氢呋喃为溶剂,甲基三苯基溴化膦与α-羰基-对乙氧基-苯乙酸乙酯的投料比(摩尔比)为1∶1,反应收率达83.0%,含量为93.8%.两步反应总收率为63.8%.此合成路线简单,反应条件温和,原料价廉易得.中间产物和产品结构经1H-NMR、MS、IR表征.     

4-异氰酸酯基苯乙酸乙酯的合成工艺研究

介绍了以对氨基苯乙酸乙酯和三光气为原料合成其异氰酸酯的研究.重点讨论了溶剂、原料配比、反应时间、反应温度和滴加顺序等对合成工艺的影响.研究表明:以1,2-二氯乙烷为溶剂,反应回流时间为4-5 h,物质的量比n二(三-氯甲基)碳酸酯(BTC):n对氨基苯乙酸乙酯=1:2,收率可达97%.     

4-(2-羟乙氧基)甲苯基苯甲酮的合成研究

以4-甲基二苯甲酮为原料,经溴化合成4-溴甲基二苯甲酮再与乙二醇单钠盐反应合成新型的光引发剂4-(2-羟乙氧基)甲苯基苯甲酮,对新化合物结构进行了IR、MS、H1NMR表征。产品纯度大于95%,合成收率大于78%(以4-溴甲基二苯甲酮计)。     

4-氟-α-(2-甲基-1-氧丙基)-γ-氧-N,β-二苯基-苯丁酰胺的合成

以苯乙酸为原料,4-氟苯基苯乙酮在HBr/H2O2作用下发生α-溴代,合成2-溴-1-(4-氟苯基)-苯乙酮,再与异丁酰乙酰苯胺在碱性条件下发生α-碳上的取代反应,得到阿托伐他汀钙的关键中间体4-氟-α-(2-甲基-1-氧丙基)-γ-氧-N,β-二苯基-苯丁酰胺,总收率57.3%。化合物结构经核磁、质谱得到确认。     

2-（3-苯甲酰基苯基）丙腈的合成

以间甲基苯甲酸甲酯为原料,经溴化、氰化、甲基化、水解和付-克反应合成了2-(3-苯甲酰基苯基)丙腈,并考察了有关反应条件对溴化反应和甲基化反应的影响,获得了最佳的反应条件。在最佳反应条件下进行合成实验,所得产品2-(3-苯甲酰基苯基)丙腈的总收率为56·7%,熔点52~54℃,含量98·6%。     

1-(2-羟基-5-甲基苯基)苯乙胺的合成

对甲基苯酚与苯乙酰氯酯化得到苯乙酸 ( 4 -甲基 )苯酯 ;然后在三氯化铝作用下重排得到苄基 ( 2 -羟基 -5 -甲基 )苯基酮 ;此酮经硫酸二甲酯甲基化得到苄基 ( 2 -甲氧基 -5 -甲基 )苯基酮 ,再和甲酸铵反应得到 1-( 2 -甲氧基 -5 -甲基苯基 )苯乙胺 ,最后经氢溴酸水解得到 1-( 2 -羟基 -5 -甲基苯基 )苯乙胺。所有中间体和最终产品的结构均由IR、元素分析、1 HNMR得到证实。     

3-(2-甲氧基-5-甲基苯基)-3-(4-卤代)-苯丙醇的合成

以对甲苯酚和4-卤代肉桂酸为原料,经脱水环合、水解甲基化、还原制得3-(2-甲氧基-5-甲基苯基)-3-(4-卤代)-苯丙醇。合成3个新型托特罗定类似物中间体,经1H NMR确证其结构,合成方法简单易行,适于工业化生产。     

Interactions between shrinkage reducing admixtures (SRA) and cement paste's pore solution

Shrinkage reducing admixtures (SRA) have been developed to combat shrinkage cracking in concrete elements. While SRA has been shown to have significant benefits in reducing the magnitude of drying and autogenous shrinkage, it has been reported that SRA may cause a negative side effect as it reduces the rate of cement hydration and strength development in concrete. To examine the influence of SRA on cement hydration, this study explores the interactions between SRA and cement paste's pore solution. It is described that SRA is mainly composed of amphiphilic (i.e., surfactant) molecules that when added to an aqueous solution, accumulate at the solution-air interface and can significantly reduce the interfacial tension. However, these surfactants can also self-aggregate in the bulk solution (i.e., micellation) and this may limit the surface tension reduction capacity of SRA. In synthetic pore solutions, SRA is observed to form an oil-water-surfactant emulsion that may or may not be stable. Specifically, at concentrations above a critical threshold, the mixture of SRA and pore fluid is unstable and can separate into two distinct phases (an SRA-rich phase and an SRA-dilute phase). Further, chemical analysis of extracted pore solutions shows that addition of SRA to the mixing water depresses the dissolution of alkalis in the pore fluid. This results in a pore fluid with lower alkalinity which causes a reduction in the rate of cement hydration. This may explain why concrete containing SRA shows a delayed setting and a slower strength development.     

Influence of bleed water reabsorption on cement paste autogenous deformation

The effects of bleed water reabsorption and subsequent early age expansion on observed autogenous deformation are investigated in this research. Bleeding was induced by varying superplasticizer and shrinkage-reducing admixture dosages and by increasing the water-to-cement ratio. This research revealed that significant early age expansion occurs with increasing chemical admixture dosages and higher water-to-cement ratios, as expected, due to increasing bleeding of those samples. When samples were rotated, negligible early age expansion was observed. Thus, bleed water reabsorption is shown to be the primary mechanism causing initial expansion in sealed autogenous deformation samples. Thermal dilation and ettringite growth appear to have a minimal influence on the observed expansion. Rotating the samples during setting eliminates the potential for bleed water reabsorption and is recommended for all autogenous deformation testing.     

La掺杂(Na_(0.5)Bi_(0.5))_(0.82)(K_(0.5)Bi_(0.5))_(0.18)TiO_3系统无铅压电陶瓷的制备工艺探讨

采用传统陶瓷工艺,研究了制备[(Na0.5Bi0.5)0.82(K0.5Bi0.5)0.18]1-xLaxTiO3(x=0.00,0.01,0.03,0.05,0.10)无铅压电陶瓷的工艺条件对陶瓷的物相组成、显微结构和压电性能的影响。利用XRD、SEM等技术分析结果表明,合成温度的提高有利于主晶相的形成,且此系统烧成温度范围较窄,故需控制在合适的烧成温度下才能得到高致密度的陶瓷。同时,研究了极化工艺条件对材料压电性能的影响,结果表明,提高极化电场强度、控制适当的极化温度有利于提高材料的压电性能。     

Chemical model for cement-based materials: Thermodynamic data assessment for phases other than C-S-H

In the context of waste confinement, concrete may be used both as a confinement and as a building material. Concerning radwaste, the heat released during radioactive decay will modify the equilibrium constants of the minerals forming the concrete. The present work aims to elucidate the temperature dependency of the thermodynamic functions related to minerals from the concrete or associated with some of its degradation products. A large set of experimental data has been collected, for the chemical systems SO₃-Al₂O₃-CaO-CO₂-Cl-H₂O and SiO₂-Al₂O₃-CaO-H₂O, including iron and magnesium bearing phases. Most of the data collected concern experiments in aqueous media but results from calorimetric studies were also included, when available. Based on selected thermodynamic properties for each phase, predominance diagrams were drawn for the chemical elements listed above. Phase relations reported into predominance diagram appear rather consistent with most of the literature results. The case of katoite has been especially discussed, because it shows inconsistencies with respect to a hydrogarnet-grossular solid solution and with respect to phase relations reported into already published works. Finally, we underline the chemical compatibility of Portland cement pastes with carbonate aggregates, compared to silicates, for long-term storage applications.     

An investigation of microstructure evolution in cement paste through setting using ultrasonic and rheological measurements

The response of hydrating cement paste through setting are monitored using rheological measurements and ultrasonic reflection measurements. Increases in the elastic modulus and yield stress of cement paste with time are obtained from the rheological measurements. Ultrasonic measurements are performed using horizontally polarized shear waves (SH) reflected off of the hydrating cement paste. Changes in the ultrasonic signal through setting are related with changes in the porosity and stiffness of an equivalent water-filled poroelastic material, which provides identical acoustic impedance. The measured changes in the shear modulus obtained from ultrasonic measurement are shown to correlate well with increase in elastic modulus obtained from rheological measurements. The increase in the shear modulus of the porous material obtained from the ultrasonic measurements is shown to correspond well with the observed increase in the yield stress of the cement paste. By combining the information from rheological and ultrasonic measurements, it is found that even in the fluid stage there is sufficient structural integrity in the arrangement of cement grains to support low-amplitude shear stress and the evolution of a continuously connected network of cement particles within the paste is coincident with a rapid increase in the shear modulus of the porous skeleton.     

Nonlinear ultrasonic evaluation of load effects on discontinuities in concrete

The presence of discontinuity surfaces in concrete structures, i.e. two or more layers in contact, may be an existing situation with evident relapses on damage formation and progression. Differences occur depending on the type of discontinuity, which could be a thin weaker layer or a pre-existing crack. The behavior of pre-existing interfaces is here studied by means of the Scaling Subtraction Method, a Nonlinear Ultrasonic Non-Destructive Technique, that revealed to be effective in describing the mechanical evolution of concrete samples with discontinuity surfaces under the effects of compressive loads.     

Assessment of the long-term stability of cementitious barriers of radioactive waste repositories by using digital-image-based microstructure generation and reactive transport modelling

Cement-based grout plays a significant role in the design and performance of nuclear waste repositories: used correctly, it can enhance their safety. However, the high water-to-binder ratios, which are required to meet the desired workability and injection ability at early age, lead to high porosity that may affect the durability of this material and undermine its long-term geochemical performance.In this paper, a new methodology is presented in order to help the process of mix design which best meets the compromise between these two conflicting requirements. It involves the combined use of the computer programs CEMHYD3D for the generation of digital-image-based microstructures and CrunchFlow, for the reactive transport calculations affecting the materials so simulated. This approach is exemplified with two grout types, namely, the so-called Standard mix 5/5, used in the upper parts of the structure, and the “low-pH” P308B, to be injected at higher depths.The results of the digital reconstruction of the mineralogical composition of the hardened paste are entirely logical, as the microstructures display high degrees of hydration, large porosities and low or nil contents of aluminium compounds.Diffusion of solutes in the pore solution was considered to be the dominant transport process. A single scenario was studied for both mix designs and their performances were compared. The reactive transport model adequately reproduces the process of decalcification of the C-S-H and the precipitation of calcite, which is corroborated by empirical observations. It was found that the evolution of the deterioration process is sensitive to the chemical composition of groundwater, its effects being more severe when grout is set under continuous exposure to poorly mineralized groundwater. Results obtained appear to indicate that a correct conceptualization of the problem was accomplished and support the assumption that, in absence of more reliable empirical data, it might constitute a useful tool to estimate the durability of cement-based structures.     

Wavelet-based analysis of ultrasonic longitudinal and transverse pulses in cement-based materials

Ultrasonic pulse velocity has been used for decades to detect localized damage and to estimate concrete properties. More recent applications aim at diffuse damage characterization, such as environmental and mechanical damage. In most applications the methodology to calculate pulse speed is a very important issue. This work, applying continuous wavelet transform (CWT) to construct time-frequency signal representations, calculates frequency-dependent velocity of longitudinal and transverse ultrasonic pulses using wavelet scales. The method is applied to a total of 14 specimens of 5 different mixes and frequency-dependent velocities are calculated using four wavelet families. The CWT capability to decompose the inquiring pulse spectrum and analyze phase velocities is discussed with regard to wavelet, pulse type, and mixture. Frequency-dependent velocity of longitudinal pulses at lower frequencies (from 100 kHz up to 250 kHz) was proven to be much more sensitive to mix proportions than transverse pulses.     

La掺杂(Na0.5Bi0.5)0.82(K0.5Bi0.5)0.18TiO3系统无铅压电陶瓷的制备工艺探讨

采用传统陶瓷工艺，研究了制备[（Na0.5Bi0.5）0.82（K0.5Bi0.5）0.18]1-xLaxTiO3（x=0．00，0．01，0．03，0．05，0．10）无铅压电陶瓷的工艺条件对陶瓷的物相组成、显微结构和压电性能的影响。利用XRD、SEM等技术分析结果表明，合成温度的提高有利于主晶相的形成，且此系统烧成温度范围较窄，故需控制在合适的烧成温度下才能得到高致密度的陶瓷。同时，研究了极化工艺条件对材料压电性能的影响，结果表明，提高极化电场强度、控制适当的极化温度有利于提高材料的压电性能。