高效液相色谱氮杂冠醚键合固定相的合成及性能研究

我们曾用γ－氯丙基键合硅胶（ＣＰＳ），在氢化钠（ＮａＨ）作用下合成了３－（氮杂－１８－冠－６）丙基键合固定相（ＢＣＰ）［１］．该固定相对碱基、核苷酸、硝基苯酚等有较好的分离选择性，但由于ＮａＨ对硅胶基质腐蚀作用较大，导致ＢＣＰ柱效及渗透性较低．本文采...     

2,4,6-三硝基苯酚改性锆铝复合氧化物固定相分离富勒烯的色谱性能研究

制备了用于分离C60和C70的2，4，6－三硝基苯酚改性锆铝复合氧化物高效液相色谱固定相，考察了流动相中甲苯的含量、柱温及流速对C60和C70分离的影响，同时比较了酸腐蚀前后锆铝复合氧化物基质对分离的影响，结果表明，2，4，6－三硝基苯酚改性酸腐蚀后锆铝复合氧化物填料对富勒烯表现出较强的分离能力，具有作为富勒烯制备分离的潜力。     

Spectrophotometric methods for the determination of osmium-III Reaction of osmium tetroxide with 1:5-diphenylcarbo- hydrazide in aqueous solutions followed by extraction of the complex

-A spectrophotometric method has been developed which is applicable to the determination of extremely small quantities of osmium. Osmium is oxidised to the octovalent state, then added to an acidic aqueous solution containing 1:5-diphenylcarbohydrazide (DPC). After heating the aqueous solution to 65°, the osmium-DPC complex is extracted with chloroform. A molar absorbancy index of about 150,000 is obtained. From 7 to 25 μg of osmium can be determined with a coefficient of variation of 6%. It was established that Fe^III, Cu^II, Ru^III and Au^III seriously interfere in the determination of osmium by this method, while Cr^VI, Ni^II, Mo^VI, Ir^III and chloride interfere only when present in relatively high concentrations.     

酸性化合物在十二胺-N,N-二亚甲基膦酸改性氧化锆固定相上的分离

酸性化合物在十二胺-N; N-二亚甲基膦酸改性氧化锆固定相上的分离;氧化锆;色谱固定相;十二胺-N; N-二亚甲基膦酸     

Dithiocarbamate complexes of cyclopentadienylcobalt(III), [Co(η-C5H5)(L)(S2CNR2)] (L = ligand)

The reactions of [Co(η-C₅H₅)(L)I₂] with Na[S₂CNR₂] (R = alkyl or phenyl) give [Co(η-C₅H₅)(I)(S₂CNR₂)] (I) when L = CO and [Co(η-C₅H₅)(L)(S₂CNR₂)]I (II) when L is a tertiary phosphine, phosphite or stibine, or organo-isocyanide ligand. In similar reactions [Co(η-C₅H₅)(CO)(C₃F₇)I] gives [Co(η-C₅H₅)(C₃F₇)(S₂CNMe₂)] and [Mn(η-MeC₅H₄)(CO)₂(NO)]PF₆ forms [Mn(η-MeC₅H₄)(NO)(S₂CNR₂)]. The iodide ligands in I may be displaced by L, to give II, or by other ligands such as [CN]^?, [NCS]^?, H₂O or pyridine whilst SnCl₂ converts it to SnCl₂I. The iodide counter-anion in II may be replaced by others to give [BPh₄]^?, [Co(CO)₄]^? or [NO₃]^? salts. However [CN]^? acts differently and displaces (PhO)₃P from [Co(η-C₅H₅){P(OPh)₃}(S₂CNMe)]I to give [Co(η-C₅H₅)(CN)(S₂CNMe₂)] which may be alkylated reversibly by MeI and irreversibly by MeSO₃F to [Co(η-C₅H₅)(CNMe)(S₂CNMe₂)]⁺ salts. Conductivity measurements suggest that solutions of I in donor solvents are partially ionized with the formation of [Co(η-C₅H₅)(solvent)(S₂CNR₂)]⁺ I^? species. The IR and ¹H NMR spectra of the various complexes are reported. They are consistent with pseudo-octahedral “pianostool” molecular structures in which the bidentate dithiocarbamate ligands are coordinated to the metal atoms through both sulphur atoms.     

Some binuclear complexes of iron and cobalt with isocyanide ligands

Whereas Co₂(CO)₈ and RNC (R= Me, Et, and Cy) react to give mixtures of [(RNC)₅Co] [Co(CO)₄] and the covalent, carbonyl-bridged [(RNC)_mCo₂(CO)_8?m] derivatives (m = 1–3), [(π-dienyl)Fe(CO)₂]₂ give only [(π-dienyl)₂Fe₂(CO)_4?n(CNR)_n] complexes (dienyl = C₅H₅, MeC₅H₄ and C₉H₇; n = 1–2) that exist in solution as mixtures of cis- and trans-CO- and RNC-bridged tautomers with the μ-RNC species decreasing in importance as the bulk of R increases.     

Highly Enantioselective Phenylacetylene Addition to Benzaldehyde Catalyzed by Chiral Tridentate Ligand

Development of new or improved methods for the asymmetric preparation of chiral propargylic alcohols has gained considerable significance during the past years because they are useful building blocks for the synthesis of many biologically active compounds and natural products.[1] A series of chiral tridentate ligands were conveniently synthesized from amino acids with good yields (Scheme 1).[2] A preliminary study of the enantioselective alkynylation of benzaldehyde catalyzed by this chiral tridentate ligand was carried out and up to 83% ee of chiral propargyl alcohols was obtained (Table 1 ). A further investigation of the tridentate ligand is currently underway.     

How to be sure of finding a root of a complex polynomial using Newton's method

The trouble with Newton's method for finding the roots of a complex polynomial is knowing where to start the iteration. In this paper we apply the theory of rational maps and some estimates based on distortion theorems for univalent functions to find lower bounds, depending only on the degreed, for the size of regions from which the iteration will certainly converge to a root. We can also bound the number of iterations required and we give a method that works for every polynomial and takes at most some constant timesd ²(logd)² log(d ³/) iterations to find one root to within an accuracy of .     

Studies of lambert's reaction: The formation of [Mn2(CO)8(μ-AsR2)2] complexes from tertiary arsines and [Mn2(CO)10] at high temperatures

Although very bulky ligands e.g.(o-MeC₆H₄)₃E or (μ-C₁₀H₇)₃E (E = P or As) are inert, the normal photochemical or thermal reaction of tertiary phosphines or arsines, L, with [Mn₂(CO)₁₀] is CO substitution with the formation of [Mn₂(CO)₈(L)₂] derivatives (I). At elevated temperatures some triarylarsines, R₃As, undergo Lambert's reaction with ligand fragmentation to give [Mn₂(CO)₈(μ-AsR₂)₂] complexes (II) (R = Ph, p-MeOC₆H₄, p-FC₆H₄, or p-CIC₆H₄) even though, in the absence of [Mn₂(CO)₁₀] R₃As are stable under the same conditions. Exceptional behaviour is exhibited by (p-Me₂NC₆H₄)_3- As which forms a product of type I; by some HN(C₆H₄)₂AsR which give a product of type II as a result of loss of the non-aryl groups R = PhCH₂, cyclo-C₆H₁₁, or MeO; and by Ph(α-C₁₀H₇₂P which is the only phosphine to form a product of type II, albeit in trace amounts only. The thermal decomposition of a n-butanol solution of [Mn₂(CO)₈(AsPh₃)₂] in a sealed tube gives C₆H₆ and [Mn₂(CO)₈(α-AsPh₂)₂], whilst in an open system in the presence of various tertiary phosphines, L, [Mn(H)(CO)₃(L)₂] are obtained. It is suggested that Lambert's reaction is a thermal fragmentation of [Mn(CO)₄(AsR₃]^* radicals, the first to be recognised. They lose the radical R^* which abstracts hydrogen from the solvent. The resulting [Mn(CO)₄(AsR₂)] moiety dimerises to [Mn₂(CO)_8-(α-AsR₂)₂]. the reaction is facilitated by the stability of the departing radical (e.g. PhCH₂ or MeO) and, as the crowding about As is relieved, by its size (e.g. Ph, cyclo-C₆H₁₁, o-MeC₆H₄, or α-C₁₀H₇). In general, phosphine-substituted radicals [Mn(CO)₄(PR)₃]^* do not undergo this decomposition, probably because the PC bonds are much stronger than AsC.