端叠氮基聚乙二醇的合成与表征

叠氮化物不仅具有重要的生理活性,如叠氮核苷(ＡＺＴ),是目前治疗爱滋病(ＡＩＤＳ)的首选药物[1、2],而且也具有广泛的反应活性[3],如可还原成氨基;与炔烃可发生1,3偶极环加成反应;发生Ｃｕｒｔｉｕｓ反应等.通过端叠氮基还原所获得的端氮基聚合物作为高分子载体在多肽液相合成中起着重要的作用[4,5].然而,目前在由醇类作为起始原料制备叠氮化物的过程中,仍大都采用对甲苯磺酸酯化或卤化,进而再叠氮化的反应[3].硝酸酯基是一种远未被人们充分认识的离去能力较强的基团,硝酸酯基化合物具有合成反应时间短、产率高、后处理容易等优点,因此,通…     

碲化物在选择性合成反应中的应用

本文评述了近期碲化物在高选择性合成反应中的应用。     

压力溶弹溶样石墨炉原子吸收法测定硫磺中的砷、硒、碲

建立了硝酸压力溶弹溶样、石墨炉原子吸收法测定硫磺中砷、硒、碲元素的方法。通过正交试验确定样品的溶解条件，选择适当的基体改进剂和最佳的石墨炉升温程序，一次溶样即可实现砷、硒、碲三种元素的检测。该法的回收率为90．0％～110．0％，测定结果的相对标准偏差为2．5％～4．8％。     

THIOPHENES CONDENSED WITH TELLURIUM HETEROCYCLES

Abstract

Tellurochromone B is obtained by intramolecular cyclisation of 1-(o-bromo tellurobenzoyl) 2-dimethylaminoethylene A, by means of hypophosphorous acid.     

REACTIONS OF SULFUR DIOXIDE WITH AMINOPHOSPHINES

Abstract

The reactions of SO₂ with tris-dimethylaminophosphine, bis-dimethylaminofluorophosphine, bis-dimethylaminochlorophosphine, dimethylaminodifluorophosphine, dimethylaminodichlorophosphine, 1,3-dimethyl-2-fluoro-1,3,2-diazaphospholidine and 1,3-dimethyl-2-chloro-1,3,2-diazaphospholidine have been investigated. The complex reactions are dominated by facile oxidation of the respective phosphine to phosphoryl and thiophosphoryl derivatives. The new heterocyclic phosphines CH₃ NCH₂CH₂N(CH₃)P(O)F and CH₃ NCH₂CH₂N(CH₃)P(S)F have been isolated and characterized by NMR, infrared, and mass spectrometry.     

REACTIONS OF XENON DIFLUORIDE WITH ORGANO-SULPHUR MOLECULES

Abstract

Xenon difluoride readily reacts with various organo-sulphur compounds. In general, three types of products were isolated, the course of the reactions depending on the structure of the organo-sulphur substrate. Alkyl-phenyl substituted sulphides, 3,3-dibromothiochroman-4-one and thiochroman-4-ol reacted to form α-fluoro substituted products, 2,5-diphenyltetrahydrothiopyran-4-one, thiochroman-4-one and 3-bromothiochroman-4-one formed dehydrogenated products, while diphenyl-sulphide, dibenzothiophene and 10-thioxanthenone reacted to form sulphoxide and sulphone. The reaction mechanism and the reaction pathways, which are shown on the Scheme, will be discussed.     

REACTIONS OF DITHIOLETHIONES WITH N,N-DICHLOROAMIDES

Abstract

Dependent on the starting materials and the reaction conditions N,N-dichloroamides Cl₂N-X (X = COaryl, CO₂alkyl, SO₂aryl, SO₂N(alkyl)₂) react with dithiolethiones 1 and 5 to N-(dithiolyliden)amides 2, 6, S-(dithiolylidene)sulfimides 3, thionoxides 7 and dithiolones 4, 8. The mechanisms have been studied.     

REACTIONS OF CHLOROTHIOLFORMATE ESTERS WITH DIMETHYL SULFOXIDE

Abstract

The reaction of an alkyl chloroformate with dimethyl sulfoxide gives the corresponding alkoxysulfonium chloride (I; X = 0) and carbon dioxide. However, the corresponding reactions with chlorothiolformate esters do not yield the salts (I; X = S). Phenyl chlorothiolformate reacts with dimethyl sulfoxide according to equation [1].     

REACTIONS OF 1,3-DIOXACYCLANES WITH SULPHURY COMPOUNDS

Abstract

Saturated 1,3-dioxacyclanes under acid catalysis conditions react with thiods forming thioacetals and glycols. The effect of the type of catalysts, structure of reagents and regime parameters on the direaction and selectivity of the process was studies.     

硅胶支载聚乙二醇相转移催化作用的研究

冠醚、鏻盐可支载于硅胶而形成有效的相转移催化剂.Sawiki报道,平均分子量为400的聚乙二醇(PEG)支载于硅胶对KOAc与n-C_4H_9Br的反应有明显的催化作用.本文报道硅胶支载不同链长PEG的催化剂在酯化反应和一些亲核取代反应中的催化效能,及PEG链长、催化剂用量、溶剂极性等对催化效能的影响.     

CHEMILUMINESCENCE OF SOME REACTIONS WITH MOLECULAR OXYGEN

Abstract— Many inorganic oxidation reactions involving a variety of oxidizing agents show chemiluminescence in the spectral region of 400–600 mp. Excited O₂O₂-associates are assumed to be the emitting molecules formed by bimolecular recombination of HO _x O₂-radicals. Oxidation of sodium sulfite with molecular oxygen in the presence of Cu- and Fe-basic oxides shows chemiluminescence which originates from the reactions of the heavy metal complexes of OH- and O, H-radicals with O₂. The simplest way of producing a radical from O₂ is by the uptake of one electron. Suitable electron donors, such as hydro-quinones and semiquinones, emit light if treated with oxygen. In certain organic solvents OH- can also act as electron donor. Its presence causes the formation of semiquinones from quinones in the absence of oxygen. The chemiluminescence which is observable upon treatment of alkaline dimethylsulfoxide, dioxane, pyridine-water and alcohol-water mixtures with oxygen is also attributable to electron transfer from OH- to O₂.     

1,1,1-三羟基丙烷为核的三臂星型聚乙二醇合成及表征

以1,1,1-三羟甲基丙烷与过量癸二酸二乙酸酐反应,制得了端羧基的三官能度小分子核三癸二酸三羟甲基丙烷酯(TMP-SK3).在辛酸亚锡催化下,以二苯醚为共沸脱水剂,将三官能度小分子TMP-SK3作为偶联剂,进一步与不同分子量的端羟基聚乙二醇(PEG)和聚乙二醇单甲醚(PEGm)缩合,减压下共沸脱水,制备了以TMP-SK3为核,PEG或PEGm为臂的三臂星形大分子.通过1H-NMR,DSC,GPC,XRD等手段对所得聚合物进行了表征.DSC测试结果表明,与线型聚乙二醇相比,三臂星型聚乙二醇由于TMP-SK3核的存在,不仅影响聚乙二醇的结晶速度,同时也影响结晶的完善程度,导致其结晶温度和结晶熔融温度发生变化.     

STUDIES ON CYCLOADDITION REACTIONS OF VINYLPHOSPHONATES WITH NITRONES

Cycloaddition reactions of vinylphosphonates with nitrones were studied. A series of 4-phosphonyl-3-aryl-N-arylisoxazolidines were synthesized by the reaction of vinylphosphonates with nitrones. The structure of 3a was confirmed by X-ray single-crystal diffraction.     

STEREOSELECTIVE REACTIONS OF CHIRAL AMINES WITH RACEMIC CHLOROPHOSPHINES

Racemic chlorophosphines react stereoselectively with chiral l-phenylethylamines or amino acid esters to give diastereomerically enriched aminophosphines 3, which were isolated as diastereomerically pure crystalline borane complexes. Oxidation, thionation, the reaction with methyl iodide provide optically active derivatives of aminophosphines. (R,S)- and (S,S)-stereomers of phosphinic acid amides were separated by crystallization and a flash-chromatography. The stereochemical properties of phosphorus acid amides were investigated. The mechanism of asymmetric induction at the trivalent phosphorus atom was rationalized.     

金属镓促进的巴豆基溴与醛的反应

α－甲基烯丙基醇是合成一些大环内酯（ｍａｃｒｏｌｉｄｅ），聚醚抗生素（ｐｏｌｙｅｔｈｅｒａｎｔｉｂｉｏｔｉｃｓ）和信息素的重要中间体［１］。立体选择性地合成α－甲基烯丙基醇是当今最富挑战性的课题之一。正是因为这类化合物具有广泛的合成价值，以致于有三十...     

REACTIONS OF OXIDIZED THIOUREAS WITH AMINE NUCLEOPHILES1

Abstract

A route for the convenient, cost effective synthesis of di- and tri-substituted guanidines from thioureas has been developed. The key transformation involves activation of the sulfur through S-oxidation followed by displacement of the activated sulfur by an amine nucleophile (oxidation/displacement). This preparation is experimentally facile and results in good isolated yields of desired guanidines. No noxious substances or sensitive intermediates are generated. The reaction time is short and overall yield of desired guanidine from thiourea is good.     

REACTIONS OF THE SUBSTITUTED THIOUREAS WITH PLATINUM COMPOUNDS

Abstract

Thiourea and its derivatives easily form the complexes with compounds of Cu^II, Fe^III, Pt^IV etc. By the formation of complexes as a rule redoxprocess proceeds to give an appropriate thiourea disulphide. It has been shown, that redoxprocess goes on prejudice on the derivatives of thiourea in that case when the thion-thiol tautomerism is possible.