磷钼蓝分光光度法测定药物中异烟肼

建立了磷钼蓝分光光度法测定异烟肼的新方法。实验表明:在0.24 mol/L H2SO4介质中,PO43-与Mo7O246-反应生成磷钼杂多酸([H2PMo12O40]-),它能被异烟肼还原形成磷钼蓝,其最大吸收波长为710 nm。磷钼蓝的吸光度与异烟肼浓度呈良好线性关系,其线性范围为0.64～160 mg/L,线性回归方程为A=0.04582+0.01047ρ(mg/L),线性相关系数R=0.9996,表观摩尔吸光系数ε=1.8×103L/(mol.cm)。本法已用于药片中异烟肼含量测定。     

磷钼酸铵分光光度法测定药物中6-巯基嘌呤

建立了磷钼酸铵分光光度法测定6-巯基嘌呤(6-MP)的方法。结果表明,在一定条件下,6-MP可以定量地与磷钼酸铵反应生成磷钼蓝,通过测定磷钼蓝的吸光度,从而间接地测定6-MP的含量。显色体系最大吸收波长为710nm,6-MP质量浓度在0.004～0.06 mg/mL范围内与A呈良好的线性关系,线性回归方程为A=0.0258+10.655ρ(mg/mL),线性相关系数r=0.9986。方法用于实际药品中6-PM的含量测定,结果与药典法一致。     

赤霉素-二氯化锡混合液在钼蓝法测定水中无机磷的应用

应用赤霉素－二氯化锡混合液作为钼蓝法的新显色剂。在 1.0 mol/L HNO3介质和有机相中 ,赤霉素－二氯化锡混合物与无机磷杂多酸反应生成杂多蓝,经萃取分离测定有机相,最大吸收波长为 690 nm,表观摩尔吸光系数为 2.36× 104 L· mol－ 1· cm－ 1。质量浓度范围在 0～ 3.0 mg/L符合朗伯－比尔定律。赤霉素－二氯化锡混合还原剂还原速度快,产物稳定性好,操作简便,该法用于水中无机磷的测定,结果令人满意。     

磷钼酸铵分光光度法测定盐酸羟胺

建立了磷钼酸铵分光光度法测定盐酸羟胺的新方法,在酸性条件下,盐酸羟胺可以定量地将磷钼酸铵还原为磷钼蓝,通过测定磷钼蓝的吸光度,从而间接测定盐酸羟胺的含量。显色体系最大吸收波长为720 nm,盐酸羟胺在0.01～0.12 mg/mL浓度范围内与A呈良好的线性关系,其回归方程为A=0.0139+6.1826c(mg/mL),线性相关系数r=0.9994。方法用于实际样品中盐酸羟胺的含量测定,结果与标准方法一致。     

生铁和铸铁中磷的测定

生铁和铸铁中磷的含量在ω_90.3％以下,通常采用氟化钠—氯化亚锡还原钼蓝法及抗坏血酸还原磷钼蓝法进行测定。该两方法的缺点为钼蓝色泽不稳定和重现性差。锑磷钼蓝法灵敏度高、稳定性好,但通常采用该方法进行痕量磷的测定。本文对该方法加以改进测定生铁及铸铁中磷,经改进后方法测定范围从0.01％～0.06％扩大到0.01％～0.32％。试验结果表明,该法简便、准确,显色液稳定时间达到5h以上。 1 试验部分 1.1 主要试剂 磷标准溶液:100μg·ml~(-1),称取基准磷酸二氢钾0.4393g溶于水中并稀释到1L。使用时稀释成4μg·ml~(-1)标准工作溶液。 硝酸-盐酸混合液:硝酸和盐酸(1+2)混合     

基于磷钼蓝反应测定钴-钼催化剂浸渍液中钼离子含量

基于磷钼蓝反应测定钴-钼催化剂浸渍液中钼离子含量。建立了一个流动注射-磷钼蓝分光光度法测定高浓度钼离子的含量,优化后的条件为:1酸度调节剂为0.5mol·L-1硫酸溶液;2载流为超纯水;3反应试剂为120g·L-1磷酸二氢钾、100g·L-1抗坏血酸及0.3mol·L-1硫酸的混合液;4总流量为2.8 mL·min-1;5酸度调节盘管长度为20cm;6反应盘管长度为250cm。三氧化钼的质量浓度在10.0~300.0g·L-1范围内与峰高呈线性关系,检出限(3s/k)为2.0g·L-1。方法用于钴-钼催化剂钼浸渍液的分析,回收率在99.7%~105%之间,测定值的相对标准偏差(n=11)小于1%。     

磷钼杂多酸光度法测定水果中的维生素C

在一定条件下,PO43-与Mo(VI)形成的磷钼杂多酸H3[P(Mo3Ol0)4]被维生素C还原成磷钼蓝,其最大吸收波长为710 nm,磷钼蓝的表观摩尔吸光系数为4.8×103L/(mol.cm),维生素C在1.0～80.0μg/mL浓度范围内符合比尔定律,线性回归方程为A=-0.01747+0.02722ρ(μg/mL),相关系数为0.9992,检测限为0.23μg/mL。该方法已用于水果中维生素C含量的测定。     

磷钼杂多酸光度法测定吲哚乙酸

研究了吲哚乙酸与磷钼杂多酸在浓度为 0 .0 3 mol/L的硫酸介质中发生氧化还原反应 ,形成的还原产物 (钼蓝 )在 NH3-NH4Cl缓冲溶液 (p H8.4)中最大吸收波长为 314 nm,表观摩尔吸光系数 ε值为 3.5 4× 10 4L· mol-1·cm-1 ,吲哚乙酸含量在 5 .0× 10 -7～ 5 .0× 10 -5 mol/L范围内符合比尔定律 ,检出限为 1.0× 10 -7mol/L,对 2 .0 0× 10 -5 mol/L吲哚乙酸测定 10次的相对标准偏差为 6 .42 % ,加标回收率为 94.2 %～ 10 0 .1%     

对苯二酚—磷钼杂多酸光度法测定比色钢中的磷

研究了对苯二酚-氟化钠-氯化亚锡联合还原磷钼蓝光度法测定钢铁中的磷含量,使磷钼蓝的吸光度值能够稳定在40 min以上不变。最佳实验条件下,磷含量在0.00～0.80μg/mL范围内符合比尔定律,最大摩尔吸光系数εmax,730 nm=3.32×104L.mol-1.cm-1。对钢标样进行多次测定相对误差小于5%,回收率在99.3%～104.3%之间,适用于比色钢中磷含量的快速、准确测定。     

水解还原铜磷钼酸光度法间接测定丙酮肟

利用丙酮肟在酸性条件下经加热水解生成具有还原性的羟胺,将铜磷钼黄定量还原为铜磷钼蓝的现象,建立了光度法间接测定丙酮肟的方法。结果表明,测定的线性范围为0～24mg/L,相关系数r=0.9996,检出限为0.06mg/L,丙铜肟质量浓度为12.0mg/L时,RSD为0.37%(n=7)。已用于合成水样中丙酮肟的测定。     

氮、磷、碳化物比较研究初探

环保法规的日益严格使得研究者越来越重视新型加氢脱硫、脱氮催化剂的开发。国内外学者在对负载型Mo—Co、Mo—Ni和W—Ni等传统硫化物催化剂进行不断改进的同时,新型催化材料尤其是具有贵金属性质的过渡金属间充化合物一氮化物、碳化物和磷化物的研究也受到很大的关注。人们在探索不同的载体或者是不同的助剂对单金属间充化合物-氮化物、碳化物或磷化物催化剂活性组分的表面状态和结构以及其深度加氢脱硫脱氮性能的影响,而对同一载体负载的氮、磷、碳化物催化剂缺乏横向的比较。本研究制备了以γ-Al2O3为载体的负载型氮化钼、磷化钼和碳化钼催化剂,比较了它们的孔结构、比表面积,并初步分析了钼的质量分数为19％,氮化、磷化和碳化温度均为650℃时三类催化剂的二苯并噻吩加氢脱硫性能。     

络合物分解法制备碳氮夹杂钼基催化剂及其催化性能

通过调变六次甲基四胺与金属钼盐的摩尔比例,以络合物分解法制备了碳氮夹杂钼基催化剂,并将其负载于氧化铝载体上．采用X射线衍射（XRD）、X射线光电子能谱（XPS）、低温氮吸附、元素分析等方法对催化剂进行了表征,发现碳氮夹杂钼基催化剂实为碳化钼（β-Mo2C）与碳氮化钼（M02CxNy）的混合物．以二苯并噻吩（DBT）的加氢脱硫反应（HDS）为探针,比较了负载型碳化钼、氮化钼及碳氮夹钼基催化剂的催化活性,发现由于夹杂催化剂中含有新的活性相Mo2CxNy。而表现出高于碳化钼和氮化钼催化剂的催化活性．     

Phosphacumulene Ylides and Phosphaallene Ylides [New synthetic methods (19)]

Phosphacumulene ylides and phosphaallene ylides are nucleophilic compounds which can add reactants in a variety of ways. Cycloadditions can occur both at the polar C—P ylide bond and at the C?C double bond.     

Moco Carrier and Binding Proteins

The molybdenum cofactor (Moco) is the active site prosthetic group found in numerous vitally important enzymes (Mo-enzymes), which predominantly catalyze 2 electron transfer reactions. Moco is synthesized by an evolutionary old and highly conserved multi-step pathway, whereby the metal insertion reaction is the ultimate reaction step here. Moco and its intermediates are highly sensitive towards oxidative damage and considering this, they are believed to be permanently protein bound during synthesis and also after Moco maturation. In plants, a cellular Moco transfer and storage system was identified, which comprises proteins that are capable of Moco binding and release but do not possess a Moco-dependent enzymatic activity. The first protein described that exhibited these properties was the Moco carrier protein (MCP) from the green alga Chlamydomonas reinhardtii. However, MCPs and similar proteins have meanwhile been described in various plant species. This review will summarize the current knowledge of the cellular Moco distribution system.     

Synthesis and Thermolysis of the Homoleptic Iron(II) Complex [Fe{cyclo‐(P5tBu4)}2]

Na[cyclo‐(P₅tBu₄)] ( 1 ) reacts with [FeBr₂(CO)₄] (2:1) to give the first homoleptic iron(II) complex [Fe{cyclo‐(P₅tBu₄)}₂] ( 2 ) containing two tridentate cyclo‐(P₅tBu₄)^– ligands. Thermolysis of 2 up to 500 °C produces a new phosphorus‐rich iron phosphide, calculated as FeP₆ according to the mass change.     

Displacement Reactions of Phosphorus(V) Compounds and Their Pentacoordinate Intermediates

Reactions of phosphorus(v) compounds involving the mutual interconversion of tetra- and pentacoordinate species are discussed in a critical review emphasizing stereochemical implications of the reaction mechanism. This discussion includes the formation and decomposition of the stable oxyphosphoranes, the Michaelis-Arbusov, Perkov, and Wittig reactions, interconversions of phosphines and their oxides, and the nucleophilic displacements on phosphonium compounds. Reactions of phosphate esters and related compounds receive particular attention. All chemical arguments are derived by considering the effect of factors determining the relative stabilities of phosphorane derivatives, their rates of formation, decomposition and rearrangement by bond deformation or rupture and recombination processes, considerations which are uniformly applied on the basis of concepts developed in a preceding communication^[2]. It is shown that a comprehensive mechanistic interpretation of the foregoing reactions requires substantial addition to available conceptual foundations such that, in many cases, present concepts and mechanisms must be revised.     

Active Site Model for Phosphoryl Transfer Enzymes Via Hexacoordination

Previous work has demonstrated the ease with which phosphorus can increase its coordination geometry. The present study has more closely modeled active sites of phosphoryl transfer enzymes by the inclusion of anionic phosphorus, which allows for oxygen atom donor coordination at phosphorus in the presence of a hydrogen bonding network. The resulting increase in phosphorus-oxygen donor coordination compared to analogous systems containing neutral phosphorus compounds serves as a model applicable to proposed mechanisms at active sites of phosphoryl transfer enzymes.     

Untersuchungen zur Bildung multifunktioneller 1,2‐Bis(tritylierter) Diphosphin‐Monoxide

Studies on the Formation of Multifunctional 1,2‐Bis(tritylated) Diphosphine Monoxides The products formed in the systems Ph₃CPH(:O) X /Ph₃CP( Y )Cl/NEt₃ with X = F, H, OH and Y = Cl, H, TMG (= N,N,N′,N′‐tetramethylguanidinyl) are discussed. In the case of the systems X =F/ Y =Cl, X =F/ Y =H, and X = Y =H the diphosphine monoxides 4 a , 5 a and 13 a were formed, while in the case of X =H/ Y =Cl, instead of the expected diphosphine monoxide 14 , a mixture of 13 a and of the POP compound 16 (molar ratio ca. 2 : 1) was observed. Treatment of 4 a with N,N,N′,N′‐tetramethylguanidine (= HTMG) led to the diphosphine monoxide, 7 a whereas its tautomer 7 b was formed, when Ph₃CP(TMG)Cl 6 reacted with Ph₃CPH(:O)F 1 . The conversion of one tautomer, 7 a or 7 b , into the other was not observed. On the other hand Cl₂P–PCPh₃(:O)F 8 a , formed as an intermediate in the reaction of 4 a with PCl₅, spontaneously rearranged to give Ph₃CPClF 9 and P(:O)Cl₃ as the final products. Surprisingly, oxidation of the σ³(P)‐atom in 4 a , 5 a and 13 a was impossible with H₂O₂ · (O:)C(NH₂)₂ as the oxidizing agent. The diphosphite 19 showed no rearrangement to the tautomeric diphosphine dioxide 18 , but oxidation to 20 was possible. All the products containing two asymmetrically substituted phosphorus atoms were obtained as diastereomeric mixtures of the meso and racemic form, as proved by ³¹P NMR spectroscopy.     

The Crystal and Molecular Structure of γ‐P4S6

The crystal and molecular structure of γ‐P₄S₆ was determined from single‐crystal X‐ray diffraction. It crystallizes monoclinically in the space group P2₁/m (No. 11) with a = 6.627(3) Å, b = 10.504(7) Å, c = 6.878(3) Å, β = 90.18(4)°, V = 478.8(4) ų, and Z = 2. The structure consists of cage‐like P₄S₆ molecules with C_S symmetry arranged with the topology of a cubic close packing.