4-羟基-3-硝基吡啶的热分析

4-羟基-3-硝基吡啶(HNP)是合成4位有取代基的3-硝基吡啶的重要中间体。文献对HNP的受热行为鲜有报道。为了解其在受热时的行为,用TG-DSC法研究了HNP在加热速度为1.0~15.0℃/min,从室温到300℃的受热行为。发现在氮气氛、敞口容器中,HNP在200℃明显地失重。热分析数据证明在228~288℃之间存在几个重叠的过程。经过对比和讨论并通过升华制备的方法,证明在低于200℃时的失重是由于HNP的升华而不是分解,升华产物中HNP纯度可提高到99.9%、且为不含无机盐的高纯化合物。     

4-羟基吡啶盐酸盐的表征

在合成4-羟基-3-硝基吡啶(HNP)的过程中发现市场上供应的一种4-羟基吡啶(C)仅含78%4-羟基吡啶(HP),含氯量14.4%。在遇到浓硫酸时放出氯化氢气体,怀疑(C)是HP的盐酸盐。为了证实,制备了HP的两种盐酸盐HP.HCl(A)和(HP)2.HCl.H2O(B),分析了它们的组成,用X-射线粉末衍射谱,熔点和水溶液的pH值作为参数进行表征。据此,证实了(C)就是(B)。在此基础上修改了HNP的合成工艺得到了高于文献报道的纯度和收率。     

一浴两步法制备4-羟基-3-硝基-吡啶

已知化合物结构中的苯环经用吡啶环替代后可能成为具有更高的活性或更低毒性的药物成分,因而该类化合物是开发新农药、医药的有潜力的重要中间体。目标化合物(HNP)是制备某些在4位有取代基团的3-硝基吡啶的理想原料。使用市场上供应的仅含77%的4-羟基吡啶(HP)(含氯14.4%)作原料,用一浴两步的硝化工艺,严格控制酸碱度也可制得高质量的HNP。     

4-羟基吡啶合成研究

以4-氨基吡啶为原料,在适量的35%(质量分数)浓硫酸的溶液中,通过滴加亚硝酸正丁酯,在20～40℃左右进行重氮化反应,重氮液在Ba(OH)2溶液中水解、中和后生成4-羟基吡啶,采用活性炭提纯及负压蒸馏,得到含量为99%以上的4-羟基吡啶,产物收率可达92%以上。     

铜吡啶配合物催化合成1-甲氧基-2,2,6,6-四甲基哌啶-4-醇

目前1-烷氧基-2,2,6,6-四甲基哌啶基化合物的合成主要是以醛酮法为主。醇法合成虽然醇价格便宜,但合成效率很低。为解决这一问题,本文对醇法合成工艺进行了深入探讨,并以乙醇和4-羟基-2,2,6,6-四甲基哌啶氮氧自由基（ZJ-701）为原料,30%过氧化氢为氧化剂,氯化铜和吡啶配合物为催化剂,通过氧化和自由基偶合合成了1-甲氧基-2,2,6,6-四甲基哌啶-4-醇,通过红外光谱、核磁共振谱和质谱表征了其结构。通过实验进一步优化了反应时间、温度等一系列合成条件。研究结果表明：当反应时间为12h,反应温度为78℃,n(ZJ-701)∶n(乙醇)∶n(H₂O₂)∶n(CuCl₂)∶n(吡啶)=1∶39.25∶17.01∶0.034∶0.36时,产品产率最高,为60.6%,质量分数为98.8%,熔点为87～90℃。该方法具有原料乙醇便宜易得、反应条件温和、产品提纯容易等优点。     

2-巯基-3-苄氧基吡啶的合成

报道了超高效除草剂三氟啶磺隆的中间体2-巯基-3-苄氧基吡啶的合成方法。首先以2-氯-3-羟基吡啶(2)为原料,与溴化苄(3)在丙酮中反应制备2-氯-3-苄氧基吡啶(4);化合物4再与硫脲在无水乙醇反应得到2-巯基-3-苄氧基吡啶。总收率75.61%。     

2-(咪唑并[1,2-a]吡啶-3-基)乙酸的制备

研究了一种用于治疗骨质疏松症药物的关键中间体米诺膦酸的制备方法。实验以二乙氧基膦酰乙酸乙酯和2,2-二甲氧基乙醛为起始原料,经维蒂希-霍纳反应、水解、环合、水解4步制备得到标题化合物。其熔点与1HNMR和文献报道的结果一致,总收率87.5%(以2-氨基吡啶计)。该方法克服了文献报道的工艺缺陷,与现有技术相比,后处理更简单,更适合工业化生产。     

4-(2-乙氧基-2-氧-乙氧基)-3-硝基苯甲酸甲酯的合成研究

以4-羟基-3-硝基苯甲酸甲酯(1)和2-溴乙酸乙酯(2)为原料,合成了未见文献报道的4-(2-乙氧基-2-氧-乙氧基)-3-硝基苯甲酸甲酯(3),考察了反应条件对收率的影响,确定了优惠合成工艺条件:反应温度50℃,反应时间4h,物料比n(1)∶n(2)∶n(K2CO3)=1∶1.2∶1.5,相对于原料1,溶剂二甲基甲酰胺用量为1000mL/mol。产品的收率96.9%,含量98.9%,产品结构经元素分析、红外光谱、核磁共振确证。     

6-(4-苯磺酰基-3-甲基-2-丁烯)-基-2,3-二甲氧基-5-甲基氢醌双苄醚的合成

以异戊二烯为原料,经与苯磺酰氯加成、水解乙酰化、皂化3步反应,制得末端羟基取代的异戊二烯短侧链——(E)-1-苯磺酰基-2-甲基-4-羟基-2-丁烯(简称产物A),并用乙酸乙酯-乙醚混合溶剂对产物A进行提纯精制。以还原型辅酶Q0(氢醌)为母环,杂多酸为催化剂,与产物A进行偶联反应,然后采用溴化苄对母环羟基进行保护,用乙醚-异丙醚的混合溶剂进行提纯精制,选择性结晶得到了侧链延长法合成辅酶Q10的关键中间体辅酶Q1前体,即6-(4-苯磺酰基-3-甲基-2-丁烯)-基-2,3-二甲氧基-5-甲基氢醌双苄醚(简称产物B)。探讨了各主要影响因素对合成反应过程及结果的影响,目标产物B收率达75%(以产物A为基准)。产物A与目标产物B经测熔点、1H NMR分析和FTIR分析鉴定,确证其为(E)-异构体。     

4-羟基吡啶合成研究

以4-氨基吡啶为原料,在适量的15%(质量分数)硫酸溶液中,采用过量的10%(质量分数)的亚硝酸钠为重氮化剂,在30～50°C左右进行重氮化反应,重氮液在NaOH溶液中水解后合成4-羟基吡啶,采用连续逆流萃取得到提纯产物,产物的收率可达93%左右。     

Thermal properties of poly(tetramethyl-p-silphenylene siloxane) and (tetramethyl-p-silphenylene siloxane-dimethyl siloxane) copolymers

Some physical properties of poly(tetramethyl-p-silphenylene siloxane) homopolymer and random block copolymers of tetramethyl-p-silphenylene siloxane-dimethyl siloxane have been determined and correlated with polymer structure. Differential scanning calorimetry (d.s.c.), differential thermal analysis (d.t.a.), density gradient column measurements and optical hot stage melting point determination and diluent techniques were used. The thermodynamic melting temperature of the homopolymer was estimated to be 160°C and its heat of fusion, ΔH_u, found to be 54.4 J/g (13 cal/g or 2710 cal/mol of monomer repeat units). Its limiting glass transition temperature, T_g, was ?20°C. T_g of the copolymer was found to vary almost monotonically with increasing dimethyl siloxane (DMS) content ranging from ?20° (0% DMS) to just above ?123°C, for pure DMS polymer. The copolymer melting temperature was found to increase as the fraction of the crystalline (hard) TMPS constituent was increased. Based upon copolymer theory and extrapolated melting point data, it was estimated that the block size of soft DMS component in the copolymer most probably consists of twelve monomer units distributed amongst TMPS sequences of varying length.     

复合添加剂对石蜡性能影响的研究

以聚乙烯蜡和硬脂酸为添加剂,采用水浴加热混合蜡测量滴熔点和粘度,在聚乙烯蜡质量百分含量为0％ ～ 15％、硬脂酸质量百分含量为0％ ～ 60％范围内,对石蜡的使用性能进行改性研究.实验结果表明,聚乙烯蜡和硬脂酸均对石蜡滴熔点和运动粘度有一定的影响.在聚乙烯蜡添加量为0％ ～ 15％的范围内,改性石蜡的性能得到明显改善,其中改性石蜡的滴熔点呈缓慢增高趋势,后保持稳定;当其添加量在3％～5％的范围内,改性石蜡的熔点快速升高.在聚乙烯蜡加入量为3％时加入质量分数为5％～60％硬脂酸进行对比试验.硬脂酸在添加量为5％～25％时,改性石蜡滴熔点呈下降趋势;硬脂酸添加量为25％～60％时,改性石蜡滴熔点上升,但上升效果不明显.     

Laundry Detergency of Solid Nonparticulate Soil or Waxy Solids: Part II. Effect of the Surfactant Type

In this work, methyl palmitate with a melting point around 30°C was used as a model of waxy soil. Its detergency was evaluated with a hydrophilic surface (cotton) or a hydrophobic surface (polyester) using different surfactants: alcohol ethoxylate (EO9), sodium dodecyl sulfate (SDS), methyl ester sulfonate (MES), methyl ester ethoxylate (MEE), and two extended surfactants (C_12,14-10PO-2EO-SO₄Na and C_12,14-16PO-2EO-SO₄Na). The detergency efficiency at a 0.2 wt.% surfactant and 5 wt.% NaCl gradually increased while redeposition gradually decreased with increasing washing temperature in most studied surfactant solutions; this was observed both above and below the melting point of methyl palmitate on both studied fabrics. If the methyl palmitate was heated above the melting point when deposited on the fabric, it was better able to penetrate into the fabric matrix as compared to deposition below the melting point, resulting in poorer detergency for heated deposition, particularly for washing temperatures lower than the melting point. Among the surfactants studied, the nonionic surfactant (EO9) showed the highest detergency efficiency (73–94%) at any washing temperature especially on the polyester fabric. For washing temperatures below the melting point, detergency performance correlated well with the contact angle of surfactant solution on the solid methyl palmitate surface for all studied surfactants when salinity was varied. In this work, conditions resulting in the highest detergency below the melting point corresponded to the highest detergency above the melting point, suggesting this as a systematic approach to formulating below the melting point of the soil. Charge of particles or fabric was not observed to be important to the detergency mechanism, but steric factors resulting from surfactant adsorption were observed to be important mechanistic factors in waxy solid detergency.     

差示扫描量热熔点分析法的应用性分析

选择不同温度段熔融的5个代表性品种、国内外不同来源的13个法定熔点标准物质作为研究对象,进行差示扫描量热法和毛细管法两种熔点分析方法的关联性研究,并进一步开展差示扫描量热熔点分析法关键参数的应用性分析。研究表明,毛细管法的熔点分析结果一般延后1~2℃;差示扫描量热熔点分析法的准确性和精密度更好,并且推荐采用10℃/min的升温速率参数,而升温起点、气体流量等方法参数影响较小。质量分析还证实,我国药典熔点标准物质已经具备国际竞争力。     

Involvement of HNP‐1 in different oxidation mechanisms in human endothelial cells

The objective of this study was to elucidate the different mechanisms of low‐density lipoprotein (LDL) oxidation by human endothelial cells. High level of LDL stimulated human alpha‐defensin 1 (HNP‐1) expression strongly, activated myeloperoxidase (MPO), and accumulated malondialdehyde (MDA). In addition, lipopolysaccharides (LPS) had similar effect, however the cell response occurred even earlier. After 12 h of LDL co‐culture, the cells were washed and fresh LDL was added again. MPO activity and MDA generation were increased. Adding fresh LDL after the LPS co‐culture for 3 h, a similar trend, however weaker effect was observed. Culturing cells with LDL and adding various kinds of calcium antagonists at the same time did not make obvious changes to the expression of HNP‐1. In contrast, culturing cells with LPS, calcium antagonists increased HNP‐1 expression. Adding the anti‐radical drug sodium ferulate had no significant effect on oxidative function activated by LDL, but the oxidation activated by LPS was suppressed significantly and the HNP‐1 expression was not changed significantly. The endogenous irritant LDL and the exogenous irritant LPS activated human endothelial cells in different manners and HNP‐1 expression changes were involved.     

Melting behavior of polyacrylonitrile copolymers

Summary The melting behavior of acrylonitrile copolymers, ter- and tetrapolymers was studied in the dry state and in the presence of water. The melting point depression caused by the incorporation of a specific comonomer into the polyacrylonitrile chain was shown to be dependent on the molecular structure of the comonomer. Not all comonomers gave equivalent melting point depressions on a molar basis. The Eby theory of comonomer melting was used to model the melting behavior. This theory assumes that the non-crystallizing (non-AN) comonomers enter the crystal lattice as point defects rather than being relegated to the amorphous phase. An equation was developed for predicting the melting point of copolymers, terpolymers and higher order polymers as a function of the polymer composition and the specific melting point depression constant for each comonomer. The latter constants are derived from the copolymer melting point curves. The equation is applicable to both dry and wet polymers and excellent agreement between the observed and calculated melting points for wet terpolymers and tetrapolymers was observed.     

Positive-temperature-coefficient effect of electrical resistivity below melting point of poly(vinylidene fluoride) (PVDF) in Ni particle-dispersed PVDF composites

This paper discusses the positive-temperature-coefficient effects of resistivity in Ni particle-dispersed poly(vinylidene fluoride) (PVDF) composites based on experiment results from SEM, DSC, and pressure-volume-temperature (PVT) measurements. The melting points of composites with Ni content of 20, 30, 40, and 50vol.% were equal to that of pure PVDF. The PTC effects in composites with Ni content of 40 and 50vol.% occurred at temperatures near the melting point of the PVDF matrix, whereas those in composites with Ni content of 20 and 30vol.% occurred at temperatures below the melting point of the PVDF matrix. We found that the PTC effect occurs even without melting of the matrix polymer. Moreover, we determined that a slight increase in specific volume at temperatures below the melting point of the matrix polymer acts fully as a driving force for forming a gap between fillers. This suggestion was backed up by theoretical analyses using percolation theory and a thermal-fluctuation-induced tunneling model.