Carbonylation of Benzyl Halides Over Two-Phase Catalyst of Iron Pentacarbonyl

Carbonylation of benzyl halides to phenylacetic acid was studied in a two-phase system with iron pentacarbonyl as the catalyst precursor. The solutions consisted of a benzyl halide and iron pentacarbonyl in benzene and tetrabutylammonium hydrogen sulfate in aqueous sodium hydroxide. Stirring under carbon monoxide readily produced phenylacetic salts in aqueous phase which were then acidified and extracted with ether. The yields of phenylacetic acid from benzyl iodide and from benzyl bromide were similar at a evel of about 50percnt;, that of the latter being higher by 1%. The yield from benzyl chloride was far less, at a level of only 21%. The rate as studied with gas chromatography was found to decrease in the order benzyl iodide>benzyl bromide>benzyl chloride.     

半化学法制备Pb(Fe2/3W1/3)O3陶瓷粉体的反应机理

铅系弛豫铁电陶瓷钨铁酸铅Pb(Fe2/3W1/3)O3(PFW)是一种重要的介电材料,具有较大的介电常数(8000)和较低的烧结温度(小于900℃),适用于制备低烧高介的多层陶瓷电容器犤1～4犦。在传统氧化物法合成PFW的过程中,易生成恶化介电性能的钨酸铅(PbWO4或Pb2WO5)或焦绿石相(Pb2FeWO6)等其他相犤3,4犦。尽管通过加入过量5%的Fe2O3可以消除这些其他相,但因含较多的变价铁离子(Fe3+和Fe2+)而产生介电老化的缺点犤5犦。虽然二次合成法被广泛用于制备铅系弛豫铁电陶瓷犤6犦,但对制备PFW陶瓷的效果并不明显,仍有少量的钨酸铅PbWO4存在,并且预烧…     

Synthesis and characterisation of bis(pentafluorophenyl)antimony(V) cations, [(C6F5)2SbL3]

Pentacoordinate complex cations of the general formula [(C₆F₅)₂SbL₃]³⁺ stabilized as solid salts in combination with tetraphenylborate (BPh₄), tetrafluorobroate (BF₄) anions, where L=DMSO, Ph₃AsO, PyO, DMF, α-, β- and γ-picoline have been isolated. The newly formed complexes were characterized by elemental analysis, molar conductance measurements, solid-state IR and and NMR. From these results, a five-fold coordination around antimony was required.     

Effects of cobalt-60 γ-ray irradiation on fresh-keeping and storage of kiwifruits

The boxes contained kiwifruits were irradiated with cobalt-60 γ-rays at different dosages (0.6 , 1.8 and 3.6 KGy) and stored in a room ventilated at night, the natural ambient air being used as cool source.The results showed that the treatment which fruits irradiated with 0.6 KGy was the best after 85 days. It gave the normal-fruit rate of 95.10%, fruit flesh hardness of 4.10 Kg · cm^-2, fresh and plump fruits, good quality and less Vc loss.     

Thermal investigation of iron(III) and manganese(II,III) complexes of dianils derived from 6-formylkhellin

Manganese and iron complexes of Schiff bases derived from 6-formylkhellin were prepared and characterized. Complexes of o-phenylenediamine derivative (ligand (I)) are monomeric or dimeric whereas those of p-phenylenediamine derivative (ligand (II)) are polymeric. The complexes obtained are characterized by a lower magnetic moment values. The complexes also have different solvent of crystallization with different nature of interaction. The thermal behaviour of the ligands and their metal complexes was investigated by means of DTA, TG, IR and X-ray diffraction spectroscopy. Ligand (I) shows different thermal behaviour from that of ligands (II) and (III). The complexes of ligand (II) give abnormal oxides as a final product during their thermal decomposition. This revised version was published online in August 2006 with corrections to the Cover Date.     

The role of radicals in enzymatic processes

Research on the mechanism of action of coenzyme B12, adenosylcobalamin, as a graduate student introduced the author to the field of organic free radicals in enzymology. Twenty years later, related work on S-adenosylmethionine (SAM) as a "poor man's coenzyme B12" was initiated in a detailed analysis of the mechanism of action of lysine 2,3-aminomutase (LAM). The interconversion of L-lysine and L-beta-lysine is catalyzed by LAM, which requires SAM, pyridoxal-5'-phosphate (PLP), and a [4Fe-4S] cluster as coenzymes. The mechanism of this reaction has been delineated as a radical isomerization, in which radical formation is initiated by the [4Fe-4S]-dependent cleavage of the SAM into methionine and the 5'-deoxyadenosyl radical. The mechanism of this process is discussed, together with the role of this radical in hydrogen abstraction from lysine to initiate the substrate radical isomerization. The chemistry underlying the functions of SAM, PLP, and [4Fe-4S] in the action of LAM is novel in all respects, except for the formation of a lysine-PLP aldimine at the active site. Of the four free radicals in the mechanism, three have been characterized by EPR spectroscopy. In the suicide inactivation of adenosylcobalamin-dependent dioldehydrase (DDH) by glycolaldehyde, the formation of cob(II)alamin and 5'-deoxyadenosine is accompanied by the conversion of glycolaldehyde to cis-ethanesemidione radical at the active site. The cis-ethanesemidione radical has been characterized by EPR spectroscopy. Its exceptional stability at the active site is the basis for the inactivation of DDH by glycolaldehyde.     

Quantum chemical calculations of the isomer shift in iron(II) complexes of 1,2,4-triazoles with a 1 A 1 ⇔ 5 T 2 spin transition

DFT calculations have been performed to determine the isomer shift for a series of iron(II) clusters with nitrogen-containing ligands which serve as models of coordination units in Fe(II) complexes with 1,2,4-triazoles possessing a ¹ A ₁ ? ⁵ T ₂ spin transition. Good agreement has been found between the theoretical and experimental values of the isomer shift for both low-and high-spin phases. Our calculations confirmed the hypothesis about relationship between the experimentally observed differences in the isomer shift for the low-spin phases of the complexes and variations of the Fe-N mean bond length.     

铁催化剂在碳—氧反应中的热重研究

采用动态TG－DTG，研究了铁催化剂的制备方法、前驱化合物的 种类及 热处理对其在碳－氧反应中催化活性的影响。观察到在干混法制备催化剂时，所用铁盐分解温度越低活性越高。此外还发现，热处理可明显提高由分解温度高的含氧铁盐制备的 催化剂的活性，但对于不含氧铁盐和分解温度低的含氧铁盐无影响。     

铁系元素冠醚配合物的研究——Ⅱ. 铁系氯化物与4''-碘苯并-15-冠-5固态配合物的合成与性质

对碱金属、希土与苯并-15-冠-5冠醚配合物的研究指出,4′-取代单苯并冠醚的阳离子配合物的稳定性及其他性质,受取代基电子效应的影响,给电性取代基可增加芳醚氧原子上的电子密度,改变冠氧的极性,从而影响其配位能力,扩大希土配合物之间性质上的差别,达到分离的目的。对于铁系元素,文献报导甚少。我们继Ⅰ之后,又合成了三氯化铁水合物与4′-碘苯并-15-冠-5固态配合物,并研究了其性质。