利用快速定氮装置测定氮

一般化验室普遍使用的全量蒸馏装置 [1] (直接加热吸收 ) ,具有准确、重现性好的特点 ,但操作费时。半微量蒸馏装置 [2 ] (水蒸气加热吸收 )具有快速方便的特点 ,但对高含量的含氮样品 ,测定精密度稍差。以上两种装置需用冷凝管通水冷却 ,加热蒸馏吸收和滴定均分二步进行 ,比较麻烦和费时。作者装配的加热抽气吸收测定氮的装置 ,集加热蒸馏吸收滴定于一体 ,不用冷凝管 ,测定速度较快 ,但在操作过程中需经常更换反应瓶 ,而且 Na OH浓度过大 ,容易腐蚀玻璃瓶。本文将水蒸气加热蒸馏装置和抽气吸收滴定装置结合起来 ,组成一套快速可连续测定…     

生物体系中还原裂解氮氮双键的研究进展

氮氮双键作为反应活性位点,可被广泛地应用到多种领域.通过氮氮双键的引入,可在原有体系单一功能的基础上使得多种功能有机结合.前期的研究主要集中在偶氮苯类物质光异构化性能及应用,近年来氮氮双键的还原裂解反应因其在生物体内的应用而备受关注.本文主要介绍了谷胱甘肽、连二亚硫酸钠及偶氮苯还原酶还原裂解氮氮双键的原理和特点,并阐述了其对偶氮苯类物质的还原裂解性能及其在生物领域的研究进展,并对未来的发展前景进行了展望.     

分子氮络合物及配位氮分子的反应研究新进展

分子氮络合物的研究,不仅对于络合活化氮分子,阐明催化机制,寻找新型合成氨的络合催化剂是重要的,而且分子氮络合物本身在合成上也有潜在的价值。因此,分子氮络合物的研究发展很快。但是,近年来,合成新的分子氮络合物的数量显著减少,而侧重于研究络合了氮分子的反应。有关分子氮络合物研究的进展已有综述。本文主要报导76年到77年中有关的分了氮络合物反应研究的最新进展。     

氮酸和氮酸酯的结构和稳定性的相关性

在研究了迄今已知的一百多个氮酸和氮酸酯的结构特点和稳定性的基础上 ,运用共轭体系中电子效应的平衡理论 ,结合对分子结构类型的划分 ,提出了氮酸和氮酸酯的结构和稳定性关系的经验性规则 ,并且预言稳定的氮酸和氮酸酯应具有满足电子效应匹配原则的C类型的分子结构 .     

三氯化氮中氮和氯的化合价模拟研究

采用计算化学模拟方法,在MP2/6-311+g(d),B3LYP/6-311+g(d),HF/6-311+g(d),ωB97XD/6-311+g(d)水平上考察了NC13的自然布居分析电荷(natural population analysis,NPA 电荷)、原子偶极矩校正的Hirshfeld 布居电荷(atomic...     

石灰氮肥料

一、前言石灰氮(氰氨化钙 Ca CN_2)是氮肥品种之一,它是一种硷性肥料。根据不完全的资料,1951～1953年全世界石灰氮年产量约为210万吨(不包括苏联及亚洲社会主义国家),约占全世界各种氮肥产量的8.3%。在某些水电资源丰富的国家,石灰氮的产量和比例都是较高的。例如:加拿大1952年产石灰氮95万吨;日本1957年产各种氮肥410万吨(换算成硫酸铵),其中石灰氮61万吨,占14.8%。西欧各国在农业中都广泛的施用石灰氮作为肥料,根据“欧洲经济合作协会(O.E.E.C.)的资料,参加该组织的18个国家在1948～1949和1950～1951年所使用的各种氮肥中,石灰氮分别占7.3%和8.2%。     

活性氮反应产生激发态卤化氮实验研究

A new method for producing electronically excited nitrogen monohalides NX(b) (X=F,Cl,Br) is reported. The strong emission spectra of NBr(b1Σ+→X3Σ–) are observed when alkyl bromides (CHBr3, CH2Br2, C2H5Br, and C4H9Br) are added to a stream of active nitrogen, generated by a hollow-cathode discharge of N2, in a flowing afterglow system. Some tentative experiments show that the electronically excited NBr(b) is formed by means of metastable N2(A3Σu+) Electronic-to-Electronic energy transfer to NBr(X), which is from the reaction of N(4S) with alkyl bromides. The emission spectra of NCl(b1Σ+→X3Σ–) are obtained when CCl4 or SOCl2 is admitted into a flow of active nitrogen, but neither CHCl3 nor CH2Cl2 addition results in such an emission. It has been proposed that the origin of the excited NCl(b) is an energy transfer from N2 (A) to NCl(X), generated by the reaction of N(4S) with CCl3 (or SOCl2). Similar experiments are also carried out with SF6 as reagent of active nitrogen, or as mixture with N2 in the discharge. By recording fluorescence it was found that excited NF(b) is produced only under discharge through N2/SF6 mixture. The NF(b) state presumably arises from the energy transfer from N2(A) to NF(X), and the latter is generated from the abstraction of fluorine by N(4S) from SF5.     

氮氧自由基的应用研究进展

氮氧自由基化合物是指含碳、氮、氧、氢等元素以及自旋单电子的有机化合物,因其自身的特殊性质被广泛应用于很多领域。本文结合氮氧自由基的特点,对其在生物学、磁性、有机催化和阻聚等方面的应用研究进行了总结,并对氮氧自由基化合物的发展趋势进行了展望。     

分子氮的电催化还原

对温和条件下分子氮的络合活化已有研究,但用修饰电极法电催化固氮成氨(或肼)尚未见报道,Shilov等曾发现在V(OH)_2-Mg(OH)_2的悬浮液中,V(Ⅱ)可起络合及还原作用,钒固氮酶在缺钼条件下也可活化分子氮,其活性中心可能与钼酶相似,也是通过有机硫配体而定位在蛋白质的肽链上,能否用含有机硫配体的钒表面配合物模拟钒酶,用电催化方法进行电子与能量的偶联从而固氮成氨?本文对此进行了研究。     

钨的双氮配合物与碘代三甲基硅烷的反应——从配位氮分子形成N-Si键

本文首次报道了配位氮分子与碘代三甲基硅烷反应形成新的N-Si健的结果。钨的双氮配合物cis-CW (N₂)₂ (PMe₂ph) ₄〕与Me₃SiI在500℃反应可得到[WI(N₂SiMe₃)(PMe₂ph₄],又可续一步与HI反应而转化为[WI₂(N₂HSiMe₃)(PMe₂ph)₃]。用X-射线结构分析法确定了后一种配合物的分子结构。结果表明, Me₃Si-基团结合于金属的口一位氮原子上。     

OXIDATION OF ORGANIC SULFUR COMPOUNDS WITH DINITROGEN TETROXIDE

Abstract

Symmetrical disulfides were known to be oxidized with excess N₂O₄ to the corresponding sulfonic anhydride in good yields. We have found that the oxidation of methyl phenyl disufide or an intermediate, phenyl methanethiolsulfinate undergoes via forming the unstable intermediate, i.e. the thionitrite, which are derived by the cleavage of sulfur-sulfur bond of the subsrates. The oxidation products were symmetrical disulfides, thiolsulfonates, and sulfonic acids which were undoubtedly derived from the scission of sulfur-sulfur bond.     

REVIEW: SOME CONSIDERATIONS ABOUT COORDINATION COMPOUNDS WITH END-ON DINITROGEN

Abstract

There have been several reviews on dinitrogen coordination compounds but no special attention has been paid to correlate the electron configuration of the metal ions with the main features of the ligands in order to establish an electron configuration-stability relationship. In this article we consider nearly 200 complexes with terminal dinitrogen to find common characteristics that lead to the synthesis of other stable dinitrogen compounds. This survey shows that for coordination number 6 there is a strong tendency for a d ⁶ configuration in the metals, with oxidation states between 1- and 2.

On the basis of quantum chemistry, dinitrogen as a ligand can be compared with the isoelectronic species CO, CN^?, NO⁺. The MO and orbital energy diagrams indicate that N₂ is not a good donor neither a good acceptor, but with the appropriate symmetry and in the presence of a good π-donor metal it forms an N₂← M π-bond strengthened by an N₂→ M σ-back-bonding.     

双氮桥式配体双核铑(d7—d7)络合物与氯代烃光化学氧化反应的研究

本文首次报导了双氮桥式配体双铑(d~-—d~7)络合物Rh_2L_4在可见光辐照下与氯代烃发生光化学反应。四种络合物的量子产率皆具有波长依赖性并与溶剂和轴向配体的性质有关。光化学反应产物经快速原子质谱和闪光光解法鉴定。另外, 将光化学反应产物和电解产物进行了ESR和循环伏安法的对比测定。结果表明, 标题络合物与氯代烃发生不可逆的一电子光诱导转移反应, 生成Rh_2L_4Cl。     

PREPARATION AND PROPERTIES OF DIAZENIDO,HYDRAZIDO(2-), AND HYDRIDO-HYDRAZIDO(2-) COMPLEXES OF TUNGSTEN. X-RAY PHOTOELECTRON SPECTROSCOPY OF DINITROGEN AND HYDRAZIDO(2-) COMPLEXES OF MOLYBDENUM AND TUNGSTEN

Abstract

Reactions of HBr with trans-[W(N₂)₂(dppe)PPh₂Me)₂] (1) (dppe = Ph₂CH₂CH₂PPh₂) result in protonation of coordinated N₂ but no formation of ammonia or hydrazine. The tungsten-containing product depends upon the reaction conditions: (i) in MeOH, the product formed is [WBr(NNH₂) (dppe)(PPh₂Me)₂]HBr₂ (2) which converts to the hydride, [WBr₂(H)(NNH₂(dppe)(PPh₂Me)](Br(3), with loss of phosphine in THF or CH₂Cl₂, (ii) in THF or CH₂Cl₂, the hydride (3) is formed directly. Reaction of 2 with Na₂CO₃ in MeOH results in the loss of HBr and the formation of the diazenido complex [WBr(NNH)(dppe)(PPh₂Me)₂] which reacts further with Na₂CO₃ in benzene under N₂ to lose HBr and form a mixture of 1 and trans-[W(N₂)(dppe)₂]. The reaction of 1 with aqueous HF forms [WF(NNH₂)(dppe)(PPh₂Me)₂]BF₄. The X-ray photoelectron spectra of trans-[M(N₂)₂ (dppe)₂], [MBr(NNH₂)(dppe)₂Br (M = Mo, W), [WCl(NNH₂)(dppe)₂]Cl, [WCl(N)(dppe)₂]Cl and [WCl(NH) (dppe)₂] are reported. In all of these complexes, nitrogen is in a highly reduced form.