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1.
系统地研究四异丙氧基酞菁的子化和脱质子化对吸收和发射光谱的影响,研究表明,三氟乙酸可对酞菁分子连续质子化,分别生成(H2Pc(O^iPr)4.H^+)^和(H2Pc(O^iPr)4.2H^+)^2+,而硫酸可使酞菁形成(H2Pc(O^iPr)4.4H^+^4+此外,NaOH/EtOH可使酞菁分子脱质子化生成(Pc(O^iPr)4)^2-反应一步完成,表明分子中的两个吡咯-NH-同步酸解,质子化可使  相似文献   

2.
和芹  周立新  章志强 《中国化学》2005,23(10):1355-1360
用量子化学从头算研究一系列平面四方金属配体作用于腺嘌呤N7位点对其质子化的影响。计算结果表明气相中,配合物质子化能力主要受长程静电效应影响,不同金属离子的影响差别甚微。综合考虑极性溶剂影响后长程静电效应影响显著降低。NBO电荷布居分析表明质子化位点电子云密度的变化直接影响该位点质子化能力。  相似文献   

3.
采用微量光度滴定法测定了两种具有不同取代基的新型咔咯化合物,三(4-氯苯基)咔咯(化合物1)和三(2,4-二氯苯基)咔咯(化合物2)在非水溶剂中的质子化和去质子化常数。结果表明:化合物1和化合物2在二氯甲烷中均可以与三氟乙酸反应得到一个质子生成正一价阳离子,其质子化常数(lgKb)分别为4.2和4.0。在甲醇溶液中,化合物1和化合物2与氢氧化钠反应时可以失去一个质子生成负一价阴离子,其去质子化常数(lgKa)分别为3.4和3.5。而在二氯甲烷中与碱反应时,化合物1和化合物2均能够一步失去两个质子生成负二价阴离子,其累积去质子化常数(lgβ2)分别为7.9和11.0。  相似文献   

4.
四苯基卟啉衍生物质子化热力学   总被引:1,自引:0,他引:1  
用光度法六种四苯基卟啉衍生物的表 观质子化常数及质子化热力学函数,并用半经验量子化学计算方法PM3计算了卟啉环中两个氮原子( =N-)的净电荷,探讨了取代基的电子效应及空间效应对质子化常数的影响。  相似文献   

5.
刘畅  于歌  黄翠英  王长生 《化学学报》2015,73(4):357-365
优化得到了碱基腺嘌呤、胸腺嘧啶、尿嘧啶、鸟嘌呤及胞嘧啶与甘氨酸二肽分子形成的28个氢键复合物的稳定结构并计算了结合能, 探讨了五种碱基与甘氨酸二肽分子间氢键作用的最佳位点. 本文研究发现: 每种碱基均可以通过不同位点与二肽分子形成氢键复合物, 腺嘌呤、胸腺嘧啶、尿嘧啶、鸟嘌呤及胞嘧啶分别最倾向使用A3、T1、U1、G3及C1位点与甘氨酸二肽分子形成氢键复合物; 碱基分子某位点的质子化反应焓变越负所形成的氢键复合物越稳定, 去质子化反应焓变越小所形成的氢键复合物越稳定; 由氢键复合物的结合能计算得到的稳定性次序与由碱基分子质子化和去质子化反应焓变推得的稳定性次序一致.  相似文献   

6.
在小型固定流化床装置上采用酸性催化剂进行了多系列不同反应深度的催化裂化实验,对大庆VGO催化裂化过程中发生的质子化裂化反应进行了初步的研究。在重质油的催化裂化过程中会出现二次质子化裂化反应。二次质子化裂化反应主要是由于汽油中烷烃重新在酸性催化剂上形成五配位正碳离子随后分解所造成,其产生的原因主要是由于反应后期催化剂对反应中间产物的选择性吸附改变所致。二次质子化裂化反应对温度不敏感。大庆VGO在500℃下反应时二次质子化裂化反应约占整个质子化裂化反应的60%。  相似文献   

7.
在25 ℃, 分别在水及乙醇-水混合溶剂中, 用电位滴定法研究了国产的含有胺亚二乙酸功能基的大孔螯合树脂D751的质子化反应. 在对树脂相中各组分的活度系数不作任何假定的前提下, 用外推法从表观质子化常数的对数值与滴定度间的关系, 求得了该树脂的三级本征质子化常数. 本文肯定了表观质子化常数对滴定度的依赖性, 合理地解释了在不同溶剂中树脂的酸碱性的变化.  相似文献   

8.
用紫外-可见吸收光谱和荧光光谱研究了CF3COOH浓度变化对CHCl3溶液中N-[p-5′-(m-10′,15′,20′-三苯基卟啉)基]-N′-正十二烷基-3,4:9,10-四羧基二酰亚胺分子阵列(TrPP-MDPTCDI)的光致激发态衰变机理的影响,发现无论激发无金属卟啉还是酰亚胺基元,分子阵列均表现出质子化无金属卟啉生色团的特征荧光发射.对电子结构的分析说明质子化使[H22+TrPP*-MDPTCDI]成为各种激发态中相对稳定的物种,因此,未质子化前占主导的从卟啉到酰亚胺基元的光致电子转移衰变途径在质子化后受到有效抑制,激发卟啉生色团(λ=439nm)直接得到[H22+TrPP-MDPTCDI*],并以辐射衰变方式回到基态;激发酰亚胺生色团(λ=491nm)得到的[H22+TrPP*-MDPTCDI]通过电荷分离态迅速弛豫到[H22+TrPP*-MDPTCDI],并辐射荧光,同时伴随少量的从酰亚胺到质子化无金属卟啉生色团的能量转移.  相似文献   

9.
用紫外-可见吸收光谱和荧光光谱研究了CF3COOH浓度变化对CHCl3溶液中N-[P-5′-(m-10′,15′,20′-三苯基卟啉)基]-N′-正十二烷基-3,4:9,10-四羧基茈二酰亚胺分子阵列(TrPP-MDPTCDI)的光致激发态衰变机理的影响,发现无论激发无金属卟啉还是苝酰亚胺基元,分子阵列均表现出质子化无金属卟啉生色团的特征荧光发射.对电子结构的分析说明质子化使[H2^2 TrPP^ -MDPTCDI]成为各种激发态中相对稳定的物种,因此,未质子化前占主导的从卟啉到茈酰亚胺基元的光致电子转移衰变途径在质子化后受到有效抑制,激发卟啉生色团(λ=439nm)直接得到[H2^2 TrPP^ -MDPTCDI],并以辐射衰变方式回到基态;激发苝酰亚胺生色团(λ=491nm)得到的[H2^2 TrPP-MDPTCDI^ ]通过电荷分离态迅速弛豫到[H2^2 TrPP^ -MDPTCDI],并辐射荧光,同时伴随少量的从茈酰亚胺到质子化无金属卟啉生色团的能量转移.  相似文献   

10.
赵泓  王东红 《分析化学》1993,21(12):1446-1448
本文报道测钪新试剂均三溴氯磺酚在水溶液中的离解与质子化作用,用电位法和光度法测得了它的逐级离解常数与质子化常数,以及热力学参数,并由分布函数获得试剂主要存在形式和pH值的关系。  相似文献   

11.
The spectral-polarization characteristics of absorption and phosphorescence of molecules of the initial form of nitro-substituted indolinospirobenzothiopyran were studied in oriented polyethylene films and in solutions with different polarity. An oscillator model of the electron transitions responsible for the formation of absorption and luminescence spectra was suggested. It was established that the principal differences in the spectral and photophysical properties of the compound studied and its oxygen-containing analog are associated with the fact that the electronegativity of the S atom is lower than that of the O atom. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1143–1146, June, 1997.  相似文献   

12.
非那雄胺能抑制5α-还原酶的活性,明显降低二氢睾酮水平,是一种治疗良性前列腺增生的有效药品。该合成工艺以甾烯酮酸为原料,将其与氯化亚砜反应,无须分离即与叔丁胺反应得17β-酰胺化合物,再氧化开环,环合,氢化,脱氢合成了非那雄胺。经元素分析、IR、1HNMR、13CNMR、MS分析表征了其结构。该法无须使用昂贵的2,2-二吡啶二硫化物和剧毒药品苯亚硒酸酐,且以乙酸铵代替氨气,降低了对设备的要求和腐蚀,更适用于工业生产。  相似文献   

13.

The heats of detonation of 20 simple high explosives and explosive mixtures were determined by means of an adiabatic detonation calorimeter designed by the authors. The results indicated that the performance of the instrument was reliable and the experimental data were very accurate. For explosive mixtures, there was a linear accumulative relationship between the heats of detonation of the explosive mixture and its components. Accordingly, the heats of detonation of explosive mixtures could be calculated directly from the heats of detonation of simple explosives and the characteristic heats of other components. The experiments showed that the gold or brass shell of the cylindrical charge could be substituted by a thick-walled porcelain shell, which had the advantage of cheapness.

  相似文献   

14.
Two vanilloids, (5E)-8-(4-hydroxy-3-methoxyphenyl)oct-5-en-4-one (1) and 4-[3-hydroxydecyl]-2-methoxyphenol (2), isolated from the dried seeds of Grains of Paradise (Aframomum melegueta), were synthesized; the latter compound was made as the S-enantiomer and the material derived from the seeds was found to be a 1:1.7 mixture of the R and S isomers. The synthetic route used should allow the preparation of analogs having extended alkyl chains and consequently different lipophilicity, and 3, a homolog of 2, was also prepared.  相似文献   

15.
针对恶臭测试的环境影响问题,提出了解决的实例方案,并对方案的要点及优缺点进行讨论,此方案在实际操作中具有较好的效果。  相似文献   

16.
翟宗玺  刘树深  夏树屏 《化学学报》1990,48(10):946-950
用氧化镁氯化镁水溶液制备了8水合氯氧化镁[nMg(OH)2·MgCl2·8H2O], 并测定了其在盐酸中的溶解热, 实验结果表明, 氯氧化镁溶解热与n值呈线性关系, 根据溶解热求出5Mg(OH)2·MgCl2·8H2O和3Mg(OH)2·MgCl2·8H2O的生成热分别为-7727.1和5888.1kJ·mol^1^-。  相似文献   

17.
In this review, the research of the author in the field of colloidal systems is summarized. The factors influencing colloidal stability are systematized and analyzed. Examples are presented to illustrate the practical utilization of the theory of stability of colloids and thin films.This review was prepared on the basis of the works of the author, which were awarded the State Premium for 1991 in the field of science and technology, chemistry section.Institute of Physical Chemistry, Russian Academy of Sciences, 117915 Moscow. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 8, pp. 1708–1717, August, 1992.  相似文献   

18.
Main hydration products of two cement pastes, i.e. CSH-gel, portlandite (P) (and specific surface S) were studied by static heating, and by SEM, TEM and XRD, as a function of cement strength (C-33 and C-43) hydration time (th) and subsequent hydration in water vapour.Total change in mass on hydration and air drying, Mo, increased with strength of cement paste and with hydration time. Content of water escaping at 110 to 220°C, defined as water bound with low energy, mainly interlayer and hydrate water, was independent on cement strength but its content increased with (th). Content of chemically bound (zeolitic) water in CSH-gel, escaping at 220-400°C, was slightly dependent on strength and increased with (th). It was possibly derived from the dehydroxylation of CSH-gel and AFm phase. Portlandite water, escaping at 400-500°C, was independent on cement strength and was higher on longer hydration. Large P crystals were formed in the weaker cement paste C-33. Smaller crystals were formed in C-43 but they increased with (th). Carbonate formated on contact with air (calcite, vaterite and aragonite), decomposed in cement at 600-700oC. It was high in pastes C-33(1 month) and C-43(1 month), i.e. 5.7 and 3.3%, respectively; it was less than 1% after 6 hydration months (low sensitivity to carbonation) in agreement with the XRD study showing carbonates in the air dry paste (1month), and its absence on prolonged hydration (6 months) and on acetone treatment. Water vapour treatment of (6 months) pastes or wetting-drying increased this sensitivity.Nanosized P-crystals, detected by TEM, could contribute to the cement strength; carbonate was observed on the rims of gel clusters.This revised version was published online in November 2005 with corrections to the Cover Date.  相似文献   

19.
袁丽秋 《化学教育》2006,27(5):8-10
面对日益枯竭的能源危机,氢能是一种洁净、最有前景的替代能源。目前在各种制氢的方法中光催化分解水制氢的研究最多,光解水过程中催化剂最关键,本文对利用太阳能光解水的途径、提高光催化反应效率以及光催化剂的开发研究进行了综述。  相似文献   

20.
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