氯苯甲酸在水-DMF混合溶剂中的电离热力学

结构上彼此相关的取代苯甲酸在非水溶剂中电离热力学性质研究一直受到广泛的重视［‘一句，但是这类酸在水一DMF混合溶剂中的电离热力学性质的研究少见报导．DMF（N，N一二甲基甲酸胺）由于其独特性质，在许多化学、化工领域中已得到广泛的应用．本文对苯甲酸和。、。一、p氯苯甲酸在水一DMF混合溶剂中的电离热力学性质进行研究，以此深入地了解溶剂和取代基对弱酸电离的影响．1实验1．11热仪器用LKB－2277BioActivityMonitor问的流动混合测量系统部分，测量精度为0．2％（300Pw量程）1．2试剂苯甲酸为分析纯试剂，含量＞99．5％质…     

荷移分光光度法测定扑尔敏

1引言扑尔敏又称马来酸氯苯那敏,为抗组织胺药,对各种过敏性疾病有良好的疗效。本文首次利用扑尔敏与氯冉酸在丙酮介质中发生的荷移反应,建立简便的分光光度法,对扑尔敏制剂中的有效成分进行含量测定。测定波长是536nm,表观摩尔吸光系数是1．38×103L·mol－1·cm－1,线性范围是20－280mg／L,回收率在98％以上。用本方法和药典方法对制剂进行含量测定,结果相符。2实验部分2．1主要仪器与试剂721分光光度计（上海第三分析仪器厂）。1g／L扑尔敏（药物纯）丙酮溶液;3×10－3mol／L氯冉酸（分析纯）丙酮溶液;所用其它试剂均为分析…     

间接电感耦合等离子体原子发射光谱法测定煤中氯

1引言煤中氯的存在会引起煤炭或煤炭产品加工和处理设备的腐蚀。氯的测定方法多为化学法，但用于煤中氧的测定都有不同程度的局限性。间接原子吸收法测氯已有报道。本工作以爱斯卡试剂分解煤样，溶液中加入过量的银溶液．以ICP－AES测定未与CI反应的银而间接测定氯，获得满意的结果，煤中氧的测定范围宽。2实验部分2．1仪器和试剂Atomscan16顺序扫描型电感耦合等离子发射光谱仪（美国TJA公司）；以硝酸银和细化钠（均为高纯试剂）分别配制成银和氛1．0g／L贮备液。硝酸为优级纯。爱斯卡试剂（自备）。水为去高于水。2．2标准曲线的绘…     

双波长一元线性回归光度法同时测定健脑合剂中苯甲酸钠与咖啡因的含量

1 引言 健脑合剂是临床常用治疗神经衰弱的复方制剂,由多组份药物组成,苯甲酸钠与咖啡因为其主要成份。本文将双波长一元线性回归法用于多组份分析。提出了健脑合剂中苯甲酸钠与咖啡因同时测定的方法原理和数学模型,根据其原理,采用多组标准混合溶液的吸收值,经计算机处理,找出最佳测定波长对和混合溶液中系数K及工作曲线斜率k,建立工作曲线方程,并对合成样品中苯甲酸钠与咖啡因进行含量测定,得到满意结果。 2 主要仪器与试剂 瑞士UVIKON930紫外可见分光光度计。AST-386型计算机。各药物纯组份贮备溶液,准确配制。 3 最佳实验条件选择 按正交实验设计,取适量各纯组份贮备溶液于50ml容量瓶中,加水稀释至刻度,摇匀。共配制25份浓度比例不同的标准混合溶液,以水为空白,从220～320nm,间隔0.5nm,测定各波长处的吸收值,经计算机处理得,最佳测定波长对:苯甲酸钠λ_1 242nm,λ_2 254nm,;咖啡因λ_1 296nm,λ_2 306nm。工作曲线方程:苯甲酸钠y=1.044×10~(-2)x+0.6416,r=0.9987;咖啡因y=2.980×10~(-3)x+1.7828,r=0.9962。 其中y=A_1/A_2,x=LC_i/A_2,A_1、A_2表示混合溶液在测定波长λ_1及参比波长λ_2的吸收度,L为光路长,C_i为组份i的浓度。     

饮料中糖精钠、苯甲酸、山梨酸的高效液相色谱快速测定

我国食品卫生标准规定,饮料中糖精钠的含量不得超过0.15g/kg, 苯甲酸、山梨酸不得超过0.2g/kg。采用高效液相色谱法,饮料经过滤,用10～12分钟能同时测定这三种成分。本法回收率为97～110％,标准偏差0.29,变异系数0.038.含量在0.1～20μg范围内,线性关系良好。 1.仪器与试剂:美国Waters246型高效液相色谱仪,441型紫外检测器,检测波长254mm。甲醇:分析纯,重蒸;0.02M醋酸铵溶液;0.1mg/ml糖精钠,苯甲酸,山梨酸混合标准液0.1mg/ml糖精钠,苯甲酸和0.05mg/ml山梨酸混合标准液。以上溶液均用重蒸水配制。 2.实验条件:Mbondapak C~T_84×300mm不锈钢色谱柱,流动相,甲醇/0.02M醋酸铵(35/65),1ml/min,纸速0.5m/min。 3.方法与结果: (1)标准曲线法:首先分别测出糖精钠,苯     

RbCl在H2O-DMF混合溶剂中活度系数的测定

应用Corning-价阳离子选择电极（M~＋－ISE）和Orion氯离子选择电极组成可逆电池，CI~－－ISE|RbCl（m），H2O（1－x），DMF（x）M~ －ISE．测量该电池标准电动势E_m，运用扩展的Debye－Hckel公式，计算RbCl在283．15至318．15K七个温度下由H2O至H2O－DMF混和溶剂的标准迁移自由能ΔG和在不同组成（H2O－DMF）混合溶剂中平均离子活度系数γ±，并对迁移自由能及活度系数随混合溶剂有机物组份的摩尔分数的变化进行了讨论。     

以浓硫酸为催化剂乙酰化法测定伯、仲醇

1　主要试剂乙酰化试剂 :将 2 .2 m L的乙酸酐 (分析纯 )溶解在 50 m L的乙酸乙酯 (分析纯 )中 ,加入 0 .35m L浓硫酸 (分析纯 ) ,临用时摇动片刻 ;无水乙酸乙酯 (自制 ) :按文献 [4 ]所提供方法 ,用分析纯乙酸乙酯经脱水制得 ;样品 :正丁醇 (分析纯 ,天津市化学试剂二厂 ,标示含量为≥ 98% ) ;其它试剂及配制方法均见文献 [1 ]。2　实验方法准确称取浓度为 1 mmol的正丁醇样品于 1 0 0m L磨口锥形瓶中 ,加入 5.0 0 m L乙酰化试剂使之混合均匀并溶解 ,于室温下静置 1 0 min使反应完全。然后加入 5m L 水和 5m L 吡啶 ,摇匀 ,静置1 0 min…     

介质对配合物稳定性的影响 Ⅳ.Cu(SCN)~ -NaNO_3-tert-Butyl Alcohol-H_2O体系,25℃

本文用分光光度法确定了２５℃下配阳离子Ｃｕ（ＳＣＮ）＋在ＮａＮＯ３－叔丁醇－水介质中的稳定常数。混合溶剂中叔丁醇组成为０，５，１０，１５，２０和２５ｗｔ％，离子强度范围为０．２～３．０ｍｏｌｅ·ｄｍ－３，溶液的ｐＨ＝１．５～１．６。基于Ｐｉｔｚｅｒ理论用最小二乘多项式逼近法，确定了混合溶剂中配合物热力学稳定常数。讨论了配位反应的一级介质效应。     

聚L-谷氨酸乙酯手性固定相的制备及色谱评价

合成了聚L-谷氨酸乙酯,并将其三氯甲烷溶液涂敷在3-氨丙基三乙氧基硅胶上,合成和表征了聚L-谷氨酸乙酯涂敷手性固定相,以不同比例的正己烷-异丙醇、正己烷-无水乙醇为流动相,探究了在正相液相色谱条件下聚L-谷氨酸乙酯涂敷手性固定相对部分手性化合物和位置异构体的拆分能力。实验结果表明:有4种手性化合物对映体(联糠醛、奥美拉唑、萘普生、四咪唑)和9种位置异构体(o,m,p-碘苯胺、o,m,p-氯苯胺、o,m,p-溴苯胺、o,m,p-硝基苯胺、o,m,p-甲苯胺、o,m,p-氯酚、o,m,p-二硝基苯、o,m,p-苯二酚、o,m,p-氨基苯酚)得到不同程度的拆分,表明聚L-谷氨酸乙酯涂敷手性固定相能对手性药品进行一定的拆分,对位置异构体有较好的分离能力。     

四苯硼钾从水到水—乙醇混合溶剂中的标准迁移自由能

在２９８．在５Ｋ，对四苯硼钾在不同比例的水－乙醇混合溶剂顺的活度积及从水到混合溶剂中的标准迁移自由 能进行了研究，并对四苯硼钾在水－乙醇混合溶液中的介质效应进行了分析讨论 。     

Volumetric Properties of Sodium Chlorobenzoate in N,N Dimethylformamide/water Mixtures at 298.15 K

ＩｎｔｒｏｄｕｃｔｉｏｎＴｈｅｒｅｈａｓｂｅｅｎａｎｉｎｃｒｅａｓｅｄｉｎｔｅｒｅｓｔｉｎｔｈｅｔｈｅｒｍｏｄｙｎａｍｉｃｂｅｈａｖｉｏｒｏｆｔｅｒｎａｒｙｍｉｘｔｕｒｅｓ（ｗａｔｅｒ＋ｎｏｎａｑｕｅｏｕｓｓｏｌｖｅｎｔ＋ｅｌｅｃｔｒｏｌｙｔｅ）［１］．Ｈｏｗｅｖｅｒ,ｔｈｅｒｅｈａｓｂｅｅｎａｓｈｏｒｔａｇｅｏｆｉｎｖｅｓｔｉｇａｔｉｏｎｓｏｎｓｕｃｈｍｉｘｔｕｒｅｓ,ｅｓｐｅｃｉａｌｌｙｏｎａｒｏｍａｔｉｃｓｏｌｕｔｅｓｔｈａｔｃｏｎｔａｉｎｔｈｅｓｕｂｓｔｉｔｕｅｎｔ．Ｌｉｔｔｌｅｉｓｋｎ…     

Apparent Molar Volumes of Sodium Methylbenzoates in N, N-Dimethyl Formamide–Water Mixtures at 298.15 K

Densities of sodium methylbenzoate (o-, m-, p-) have been measured in dimethyl formamide (DMF)–water mixtures at 298.15 K with an oscillating-tube densimeter. From these densities, apparent molar volumes of sodium methylbenzoates in DMF–H₂O mixtures have been calculated and partial molar volumes at infinite dilution have been evaluated. Substituent and solvent effects on the transfer volumes of each isomer from water to DMF–H₂O mixed solvents have also been obtained. The results are explained in terms of solvent–solvent and solute–solvent interactions.     

Volumetric Properties of Sodium Nitrobenzoate in <Emphasis Type="Italic">N</Emphasis>, <Emphasis Type="Italic">N</Emphasis>-Dimethylformamide–Water Mixtures at 298.15 K

Densities of sodium nitrobenzoate (o-, m-, p-) have been measured in dimethylformamide (DMF)–water mixtures at 298.15 K with an oscillating-tube densimeter. From these densities, apparent molar volumes of sodium nitrobenzoate in DMF–H₂O-mixtures have been calculated and partial molar volumes at infinite dilution have been evaluated. Substituent and solvent effects on the transfer volumes of each isomer from water to DMF–H₂O-mixed solvents have also been obtained. The results are explained in terms of solvent–solvent and solute–solvent interactions.     

D2O–H2O solvent isotope effects on the volumetric properties of aqueous 1,3-dimethyl-2-imidazolidinone between (278.15 and 318.15) K

Densities of dilute solutions of 1,3-dimethyl-2-imiazolidinone in H₂O and D₂O, with the solute mole-fractions ranging up to 0.01, have been measured with an error of 1.5 · 10⁻⁵ g · cm⁻³ at (278.15, 288.15, 298.15, 308.15, 313.15, and 318.15) K and atmospheric pressure using a vibrating-tube densimeter. The partial molar volumes of the dissolved DMI (down to the infinite dilution) and solvent (H₂O or D₂O) as well as the excess molar volumes of the isotopically distinguishable solutions have been calculated. The effects of the solvent isotope substitution, solute concentration and temperature on the volume changes caused by DMI hydration have been considered. The obvious relationship between the D₂O–H₂O solvent isotope effects on the partial molar volume and enthalpy of solution of DMI has been discovered.     

Influences of solution property and charge density on the self-assembly behavior of water-insoluble polyelectrolyte sulfonated poly(sulphone) sodium salts

Two sulfonated poly(sulphone) sodium salts (SPSF) with different molecular weights and ionic exchange capacities in a N,N-dimethyl formamide/water (DMF-H2O) mixed solvent with various DMF contents were selected as a model system for investigating the influences of solvent composition, solution properties, and charge density of polyelectrolytes on the layer-by-layer (LbL) self-assembly of water-insoluble polyelectrolytes. Poly(dimethyldiallylammonium chloride) (PDDA) in aqueous solution was used as the counterpart. The PDDA/SPSF multilayer films grew nearly linearly with the layer numbers regardless of the volume fraction of DMF, phiDMF, in the SPSF solutions. The total absorption amount of the PDDA/SPSF multilayer films was strongly dependent on the charge density of the SPSF molecules and the phiDMF value of the SPSF solutions. Minimum values of absorption amount were observed at phiDMF = 0.6 to approximately 0.7. The surface hydrophobicity and roughness of the multilayer films can be tuned by varying phiDMF. These observations were rationalized in terms of the chain dimension and the ionization degree of the SPSF molecules as a function of phiDMF, which was characterized by the intrinsic viscosity ([eta]SPSF) and conductivity (LSPSF) of the SPSF solutions. The results indicate that the molecular structures of the DMF-H2O mixed solvent strongly affect the solution properties of SPSF, which in turn determine the growth behavior and physical properties of the PDDA/SPSF multilayer films.     

含(4,4′-二氟苯)甲酮肟醚官能团的1,2,3-三氮唑衍生物的合成及抗菌活性研究

以(4,4′-二氟苯)甲酮、盐酸羟胺、苄溴及溴丙炔为原料,应用5 mol%的CuI为催化剂,DMF-H 2O(1∶1)为溶剂,在70℃反应4h以23~81%的收率制得了9个含有(4,4′-二氟苯)甲酮肟醚官能团的1,2,3-三氮唑衍生物5(a~i)。合成的9个目标化合物通过熔点测定和质谱、红外光谱、核磁共振氢谱分析对其结构进行确证。经体外抗菌活性测试表明有4个化合物对时对所测试的大肠杆菌具有明显的抑制活性,其MIC为32ug·mL^-1。     

288.15, 298.15和308.15 K温度条件下甘氨酰甘氨酸在蔗糖-水混合溶剂中的体积性质研究

利用Anton Paar DMA55精密数字密度计测定了288.15, 298.15和308.15 K甘氨酰甘氨酸在蔗糖-水混合溶剂中的密度, 计算了甘氨酰甘氨酸的表观摩尔体积VΦ和极限偏摩尔体积 , 得到了其由纯水溶剂转移至混合溶剂中的迁移偏摩尔体积Δtrs 和理论水化数Nh．根据共球交盖模型, 讨论了迁移偏摩尔体积和水化数的变化规律．结果表明, 甘氨酰甘氨酸带电中心与蔗糖之间的结构相互作用对其迁移体积有正贡献, 且占主导地位．甘氨酰甘氨酸的迁移偏摩尔体积为正值, 且随着蔗糖浓度的增大而增大; 理论水化数随温度升高、蔗糖浓度的增大而减小; 温度升高, 极限偏摩尔体积增大, 迁移偏摩尔体积变化很小．     

Apparent molar volumes and compressibilities of selected electrolytes in dimethylsulfoxide

Densities at T = (293.15, 298.15, 303.15, 313.15, 323.15, and 333.15) K and sound velocities at T = 298.15 K of tetraphenylphosphonium bromide, sodium tetraphenylborate, sodium bromide, and sodium perchlorate in dimethylsulfoxide have been measured over the composition range from (0 to 0.3) mol · kg⁻¹. From these data, apparent molar volumes and apparent molar isentropic compressibilities at infinite dilution as well as the expansibilities have been evaluated. The results have been discussed in terms of employing tetraphenylphosphonium tetraphenylborate as a reference electrolyte in splitting the limiting apparent molar volumes and apparent molar isentropic compressibilities into ionic contributions.     

Volumetric Properties of Nucleic Acid Bases and Nucleosides in Aqueous Ethanol, 1,2-Ethanediol, 2-Propanol, and 2-Methyl-2-Propanol at 25°C

Partial molar volumes of cytosine, uracil, thymine, cytidine, uridine, thymidine, and adenosine have been measured in different concentrations of aqueous ethanol, 1,2-ethanediol, 2-propanol, and 2-methyl-2-propanol at 25°C using densimetry. These data are utilized in conjunction with the partial molar volumes of these nucleic acid bases and nucleosides in water reported earlier to deduce the partial molar volumes of transfer from water to aqueous alcohol or diol. The results are explained in terms of likely solute–solvent interactions; the role of solvent in these interactions is discussed. The partial molar volume data are also used to calculate the contribution of –CH₂- groups in the nucleic acid base or solvent and of ribose in the nucleoside to the partial molar volume of transfer. The validity of group additivity in these systems is discussed.     

Solvent effects on spectrophotometric titrations and vibrational spectroscopy of 5,10,15-triphenyl-20-(4-hydroxyphenyl)porphyrin in aqueous DMF

The spectrophotometric titration by sodium hydroxide of 5,10,15-triphenyl-20-(4-hydroxyphenyl)porphyrin ((OH)(1)PH(2)) is studied as a function of solvent composition of DMF-H(2)O binary solvent mixture ([OH(-)]=0.04 M). Combining the structure changes of the porphyrin and the "four orbital" model of Gouterman, many features of the optical spectra of this deprotonated para-hydroxy-substituted tetraphenylporphyrin in different composition of binary solvent mixtures can be rationalized. In highly aqueous solvents, the changes of the titration curves are shown to be mainly due to hydrogen-bonding of the oxygen of the phenoxide anion group by the hydroxylic solvent, Which decreases the energy of the phenoxide anion pi orbital. Thus the phenoxide anion pi orbital cannot cross over the porphyrin pi orbital being a different HOMO. However, its energy is close to that of the porphyrin pi orbitals. As a result, in the visible region, no charge-transfer band is observed, while in the visible-near region, the Soret peak split into two components. In nonaqueous solvents, the changes are mainly attributed to further deprotonation of pyrrolic-Hs of (OH)(1)PH(2) by NaOH and coordination with two sodium ions to form the sodium complex of (OH)(1)PH(2), which turns hyperporphyrin spectra of deprotonated of phenolic-H of (OH)(1)PH(2) into three-banded spectra of regular metalloporphyrin.