氧化法合成六硝基六氮杂异伍兹烷

研究了用氧化方法合成六硝基六氮杂异伍兹烷的无氢解合成路线。采用70％的HNO3／AN体系水解硝化六苄基六氮杂异伍兹烷的中间氧化产物,以21％的收率得到六硝基六氮杂异伍兹烷,讨论了六氮杂异伍兹烷母体环上苯甲酰基的硝解机理。     

制备六硝基六氮杂异伍兹烷的硝解工艺近期进展

六硝基六氮杂异伍兹烷(HN研)是当今已工业化生产的能量水平最高的炸药，HNIW的制备包括基本母体的合成、母体的氢解、氢解产物(硝解底物)的硝解(即生成HN研)及HNIW的转晶4步。综述了近几年来制备HNIW的硝解工艺的进展(包括作者的若干研究成果)，详细报道了硝解3种底物([四乙酰基二苄基六氮杂异伍兹烷(TADBIW)、四乙酰基二甲酰基六氮杂杂异伍兹烷(TADFIW)及四乙酰基六氮杂异伍兹烷(TAIW]）以制备HNIW的工艺条件，并评价了各自的优、缺点。     

六苄基六氮杂异伍兹烷氧化产物的亚硝解反应

采用65％硝酸／亚硝酸钠体系对六苄基六氮杂异伍兹烷氧化产物四苯甲酰基二苄基六氮杂异伍兹烷(1)和五苯甲酰基-苄基六氮杂异伍兹烷(2)进行亚硝解，脱去了剩余的苄基，将苄基转换为亚硝基，得到了四苯甲酰基二亚硝基六氮杂异伍兹烷(3)和五苯甲酰基-亚硝基六氮杂异伍兹烷(4)。     

四乙酰基二氯乙酰基六氮杂异伍兹烷的硝解研究

研究了几种硝解剂及硝解条件对四乙酰基二氯乙酰基六氮杂异伍兹烷（TADCIW）硝解产物的纯度和得率的影响。讨论了有关的机理,用发烟硝酸-浓硫酸或碱金属硝酸盐-浓硫酸硝解TADCIW,可得到纯度很高的四硝基二氢乙酰基六氮杂异伍兹烷（TNDCIW）,得率达到94%-98%,硝解时间短,硝硫混酸可以再利用;但用发烟硝酸-五氧化二磷或浓硝酸-浓硫酸硝解TADCIW的得率很低。     

六苄基六氮杂异伍兹烷氧化产物的亚硝化

采用硝酸（65％）／亚硝酸钠体系对六苄基六氮杂异伍兹烷氧化物－乙酰基三苯甲酰基二苄基六氮杂异伍兹烷（3）、二乙酰基二苯甲酰基二苄基六氮杂异伍兹烷（4）和三乙酰基一苯甲酰基二苄基六氮杂异伍兹烷（5）进行亚硝解，成功脱去了上述三种化合物上剩余的两个苄基，将苄基转换为亚硝基，得到了一乙酰基三苯甲酰基二亚硝基六氮杂异伍兹烷（6）、二乙酰基二苯甲基二亚硝基六氮杂异伍兹烷（7）和三乙基酰基一苯甲酰基二亚硝基六氮杂异伍兹烷（8）。     

由四乙酰基二苄基六氮杂异伍兹烷合成六硝基六氮杂异伍兹烷

以四乙酰基二苄基六氮杂异伍兹烷为基质,经亚硝解脱苄合成了四乙酰基二亚硝基六氮杂异伍兹烷(TADNSIW);用纯硝酸氧化TADNSIW制备四乙酰基二硝基六氮杂异伍兹烷(TADNIW),收率93.0%,以上两步反应均在室温下完成。在85℃条件下,TADNIW经硝硫混酸硝解合成了六硝基六氮杂异伍兹烷(HNIW),反应时间50 m in,收率95.1%,质量分数98.80%。用硝硫混酸对TADNSIW进行硝解合成了HNIW,并优化了反应条件,反应温度90℃,反应时间60 m in,硝解剂必须大于14 mL(底物TADNSIW 1.2 g),收率为96.1%,质量分数98.87%。分别用FTIR,1HNMR和元素分析对目标化合物进行了表征。前体TADNSIW和TADNIW分子中只有乙酰基和亚硝基,它们的硝解反应体系较简单,反应时间短、反应条件温和,母液中只含有乙酸和硝解剂,产物易分离。     

四乙酰基二氯乙酰基六氮杂异伍兹烷硝解产物中副产物的分离和鉴定

硝解四乙酰基二氯乙酰基六氮杂异伍兹烷 (TADCIW)制备四硝基二氯乙酰基六氮杂异伍兹烷 (TNDCIW)时 ,所得产物经薄层色谱 (TL C)检测发现含有少量副产物。采用柱色谱分离出了该副产物 ,经 FTIR、1H- NMR、MS(CI)及元素分析对副产物的结构进行鉴定 ,确定它为五硝基一氯乙酰基六氮杂异伍兹烷 (PNMCIW) ,这为改进 TADCIW的硝解条件提供了依据。     

超酸硝化法合成六硝基六氮杂异伍兹烷

分别采用硝酸-硝酸钾、发烟硫酸-硝酸钾、发烟硫酸-硝酸钠和发烟硫酸-硝酸铵4种超酸体系对六乙酰基六氮杂异伍兹烷(HAIW)进行硝化，合成了六硝基六氮杂异伍兹烷(HNIW)，属首次用超酸硝化方法合成HNIW。通过实验得到最佳硝化反应条件，以发烟硫酸一硝酸钾超酸体系为硝化剂，当温度为70℃，反应时间为3．5h，目标产物的最高得率为83．1％，质量分数达到98％以上(达到应用的纯度)。同时对超酸硝化N双取代的酰胺类化合物HAIW的反应机理进行了探讨，超酸体系中含有高浓度的硝酰正离子(NO2^ )，在该反应中NO2^ 是进攻酰胺氮原子的有效基团。     

一乙酰基五硝基六氮杂异伍兹烷NMR谱归属

利用ＮＭＲ技术对ＣＬ－２０制备中伴生的少量副产物－乙酰基五硝基六氮杂异伍兹烷（ＭＰＩＷ）的＾１Ｈ、＾１３ＮＭＲ谱进行了完全的归属。     

高能量密度化合物——六硝基六氮杂异伍兹烷合成研究最新进展

１９８７年由美国Ａ．Ｔ．Ｎｉｅｌｓｅｎ首次合成的六硝基六氮杂异伍兹烷（ＨＮＩＷ）,是当前密度和能量水平最高的高能量密度化合物（ＨＥＤＣ）,被誉为明天的高能炸药,并受到世界各国的普遍关注。本文综述近３年ＨＮＩＷ合成研究的最新进展,包括六苄基六氮杂异伍兹烷（ＨＢＩＷ）的合成、ＨＢＩＷ的脱苄、ＨＮＩＷ的合成及ＨＮＩＷ的转晶等几方面。目前制造ＨＮＩＷ的工艺已日趋成熟,且多有创新,ＨＮＩＷ的生产成本已大幅度下降。     

Quantification of Phospholipids Classes in Human Milk

Phospholipids are integral constituents of the milk fat globule membranes and they play a central role in infants’ immune and inflammatory responses. A methodology employing liquid chromatography coupled with evaporative light scattering detector has been optimized and validated to quantify the major phospholipids classes in human milk. Phospholipids were extracted using chloroform and methanol and separated on C18 column. Repeatability, intermediate reproducibility, and recovery values were calculated and a large sample set of human milk analyzed. In human milk, phospholipid classes were quantified at concentrations of 0.6 mg/100 g for phosphatidylinositol; 4.2 mg/100 g for phosphatidylethanolamine, 0.4 mg/100 g for phosphatidylserine, 2.8 mg/100 g for phosphatidylcholine, and 4.6 mg/100 g for sphingomyelin. Their relative standard deviation of repeatability and intermediate reproducibility values ranging between 0.8 and 13.4 % and between 2.4 and 25.7 %, respectively. The recovery values ranged between 67 and 112 %. Finally, the validated method was used to quantify phospholipid classes in human milk collected from 50 volunteers 4 weeks postpartum providing absolute content of these lipids in a relatively large cohort. The average content of total phospholipids was 23.8 mg/100 g that corresponds to an estimated mean intake of 140 mg phospholipids/day in a 4-week old infant when exclusively breast-fed.     

The hydration of reactive cement-in-polymer dispersions studied by nuclear magnetic resonance

The behaviour of two novel cement-in-polymer (c/p) dispersions, namely cement-in-poly(vinyl acetate) and cement-in-poly(vinyl alcohol) upon exposure to water at room temperature was investigated by a combination of various NMR methods. The swelling, cracking, and the water ingress were monitored non-destructively using ¹H single point imaging. The hydration of the cement matrix was investigated using ²⁹Si NMR whilst ¹³C CPMAS NMR spectra allowed the quantification of the kinetics of the hydrolysis reaction of poly(vinyl acetate) into poly(vinyl alcohol). The polymer controls the rate of water ingress and swelling which in turn determines the behaviour of the c/p dispersions upon exposure to water. For the cement-in-poly(vinyl alcohol), the rates of water ingress and swelling are much faster than the hydration of the clinker whilst for the cement-in-poly(vinyl acetate) the slow rates of the two processes allow the formation of a cementious matrix which assures the stability of the sample.     

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.     

Design and function of novel superplasticizers for more durable high performance concrete (superplast project)

In this article we shall describe our quest and ultimate success in furthering our understanding of the action of superplasticizers on the rheology of cement and concrete. By specifically producing superplasticizers with varied architectures, we have been able to show the important structural features of the macromolecules that lead to a successful superplasticizer or water reducing agent. Both polycarboxylate and lignosulfonate polymers have been investigated. Using both non-reactive model MgO powders, three different types of cement blends, the adsorption behaviour and the effect on the rheological properties of these two important superplasticizer families have been used to further develop a conceptual model for superplasticizer — cement behaviour. This paper will deal mainly with the conceptual model, the materials and methods used to asses the polymer adsorption behaviour and rheological properties of the systems studied. We shall briefly describe the adsorption of the polymers onto the different surfaces and their influence on surface charge and rheology and the influence of the various ionic species found in cement pore solutions that may influence polymer-cement affinity. The key factors are shown to be the effective adsorbed polymer thickness and the induced surface charge which can be influenced by the polymer architecture, the pore solution composition and the initial particle surface charge.     

Study of the hydration of CaO powder by gas–solid reaction

Hydration of CaO powders by reaction with water vapor has been studied in isothermal and isobaric conditions. Experimental tests were performed within the temperature range of 70 °C–420 °C and with a water vapor pressure from 5 to 160 hPa by means of a thermogravimetric device. Two powders, exhibiting slight differences in their physical properties, were studied. However, for one of the powders and under some temperature and pressure conditions, the reaction is not complete. The difference of behavior between both CaO powders was interpreted by considering the effect of the morphological properties on the mechanism of growth of Ca(OH)₂.     

The influence of water removal techniques on the composition and microstructure of hardened cement pastes

The removal of water from hardened cement paste for analysis or to arrest ongoing hydration has been reported to affect the composition of hydrated phases and microstructure. The effect that arresting the hydration of hardened cement paste by replacing the pore water with acetone before drying, and by removing the water by freeze, vacuum and oven drying has on the hardened cement paste has been investigated. Two pastes were studied, a cemented iron hydroxide floc where a high proportion of ordinary Portland cement (OPC) had been replaced by pulverised fuel ash, and a pure hydrated OPC. The results showed that none of the water removal techniques caused any major deterioration in the composition and microstructure of the hardened cement pastes studied, but the pores appeared better preserved after arresting hydration using acetone quenching. Freeze drying appeared to cause more cracking of the microstructure than the other water removal techniques.     

2-(2'-咪唑偶氮)萘酚-4-磺酸的合成及其分析性质的研究

合成了新显色剂咪唑偶氮－２－萘酚－４－磺酸（ＩＡＮ－４Ｓ）,研究了试剂的离解常数及其与金属离子的显色反应。     

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.     

Comparison between surface and bulk hydrophobic treatment against corrosion of galvanized reinforcing steel in concrete

The effectiveness of bulk hydrophobic treatment against corrosion of galvanized steel reinforcement in concrete specimens with w/c = 0.45 and w/c = 0.75 was compared with that of surface treatment, even in the presence of cracks 0.5 and 1 mm wide in the concrete cover. In this case surface hydrophobic treatments were applied both before and after cracking as a preventive and a restorative method against reinforced concrete deterioration, respectively. The obtained results in terms of water absorption, electrochemical measurements, chlorides penetration, and visual observations carried out on reinforced concrete specimens during the exposure to wet–dry cycles in 10% NaCl solution showed that bulk hydrophobization is the most effective treatment in improving the corrosion resistance of galvanized steel reinforcements in concrete also in the presence of cracks. Surface hydrophobization is very effective just in the first few exposure cycles to the aggressive environment and when used as a restorative method which is able to cancel the deleterious effect of cracks only 0.5 mm wide.     

Effect of plasma treatment of polymeric tape carriers on wetting behaviour of aqueous ceramic tape casting slurry

Due to environmental and health aspects, aqueous ceramic slurries are preferred to traditional organic solvent systems in tape casting. An important obstacle associated with the high surface energy of water is poor wetting of aqueous ceramic slurries on polymeric tape carriers. Therefore, we measured the contact angles of an aqueous epoxy-based ceramic slurry on polyethylene terephtalate (PET), polypropylene (PP), polymethyl methacrylate (PMMA), and aluminium-coated polyethylene terephtalate (PET-Al) films and investigated approaches to improving their wetting. We evaluated the effect of plasma treatment of the tape carrier surface on the wetting behaviour and compared it with the effect of adding non-ionic amphiphilic surfactants to the ceramic slurry. The treatment of the tape carrier surface by low-temperature plasma substantially improved the wetting behaviour of aqueous ceramic slurry. The lowest contact angle of 31° was obtained on the PET film. Although the addition of non-ionic surfactants improved both the wetting behaviour of the slurry and the detachment of the polymeric carrier from the ceramic tape even better than the plasma treatment of the carrier surface did, the plasma-treated carriers still present a useful alternative to the surfactants. In the case of the plasma-treated PET carrier the surfactants could be fully eliminated and potential drawbacks related to the use of surfactants could be prevented.