冠醚化合物的合成（ⅩⅪⅠ）．内酯型冠醚的合成

合成了１０个内酯型冠醚化合物，其中７个冠醚是新化合物，其结构均由元素分析，及红外、核磁、质谱分析证实。     

The emulsion polymerisation of vinyl acetate by redox initiation

Redox initiation enables polymerisation to be carried out at relatively low temperatures, and has been extensively studied in relation to styrene-butadiene and acrylic esters. In the case of vinyl acetate, the hydrogen peroxide-iron initiator system has been examined in detail, but is normally satisfactory only at higher temperatures of polymerisation (70 to 80 °C). The low temperature redox polymerisation of vinyl acetate appears to have received little attention. In the present work, the emulsion polymerisation of vinyl acetate using ammonium persulphate with a reducing agent and a metal ion has been studied at 50 ° C. It is shown that to achieve maximum conversion of monomer to polymer the selection of both the reducing agent and the metal ion is important, and that the pH profile during the process is critical. These results are related to the availability of the metal ion at the locus of polymerisation.     

Tracer diffusion of crown ethers in cyclohexane

Tracer diffusion coefficients in cyclohexane of s-trioxane, 12-crown-4, 15-crown-5, 18-crown-6, dicyclohexano-18-crown-6, and dicyclohexano-24-crown-8 have been measured with the Taylor dispersion technique from 298 to 358K. It is demonstrated that the deviation from the Stokes-Einstein relationship is explicable with a microfriction factor which accounts for the solute-solvent size discrepancy; the non-spherical nature of crown ethers is averaged out by rapid molecular rotation. As a result, the measured diffusivities are successfully interpreted with a rough-hard-sphere theory of molecular diffusion. The Arrhenius equation and Hildebrand's free-volume model are also capable of correlating quite well the experimental results reported here.     

Synthesis and fluorescence of crown ethers containing coumarin

The syntheses and fluorescence properties of a series of novel crown ethers containing coumarin group are presented. 2-(Benzocourmarin-3-acyloxymethyl) crown ethers were synthesized by reacting the acyl chloride of benzocourmarin-3-carboxylic acid with 2-hydroxymethyl crown ethers, while 4′-(benzocourmarin-3-carboxamido) benzo crown ethers were secured by reacting the acyl chloride of benzocourmarin-3-carboxylic acid with 4′-aminobenzo crown ethers. Only the ester-type crown ethers were fluorescent. As the polarity of the solvent increased, the emission maximum λ_em showed a slight red shift. DMSO was used as the fluorescence quenching solvent. Increased fluorescence was observed upon the addition of alkali and alkaline earth metal ions.     

Silver complexes with large crown ethers in propylene carbonate

The complex formation between large crown ethers – e.g. dibenzo-30-crown-10 – and Ag⁺ in propylene carbonate has been studied using potentiometric and calorimetric titrations. The values of the reaction enthalpies with larger crown ethers than 18-crown-6 especially with dibenzo-30-crown-10 indicate that more than six donor atoms are taking part in the interaction with the complexed cation. The values of the reaction entropies of the largest crown ethers examined indicate the high sterical requirements of the complex formation. Obviously large crown ethers are able to encapsulate the complexed cation. The effectiveness of the encapsulation however depends upon the ring size and flexibility of the crown ethers.     

Electroinitiated emulsion polymerisation of vinyl acetate. I. The mechanism of initiation

Vinyl acetate has been shown to polymerise during the electrolysis of its aqueous acidified emulsion. The stabilisation of the emulsion is difficult and sodium salts of ethoxylated fatty alcohols have been used as emulsifier. Polymerisation occurs only within a narrow, low pH range. Percentage conversion and molecular weight show a maximum at about pH = 1. Below this value, acid hydrolysis of monomer interferes with the polymerisation whilst at higher values a change in the electrode process may occur. Polymerisation is considered to occur through the presence of hydrogen radicals adsorbed on the mercury cathode.     

Schiff碱型羧酸开链冠醚溶解性及酸离解常数的测定

研究了端基为羧基的Schiff碱型开链冠醚在水中的溶解性及酸解常数。结果表明：当开链冠醚具有CH＝N－X－N＝CH，其中，X＝－CH2CH2－，R－CO2H（H2L^1）或R＝－OCH2CO2H（H2L^3）结构时，在水中易溶；而x＝R＝CO2H（H2L^3）或R＝OCH2CO2H（H2L^4）时，在水中难溶。     

基于冠醚的离子识别响应型智能材料研究新进展

金属离子对生物体的生命活动起着核心的作用,而一些重金属离子(如Pb²⁺、Hg²⁺)在很低浓度时就对生物具有极强的毒性;因此,研究具有金属离子识别特性的智能材料具有重要的理论价值和实用意义。冠醚具有选择性地络合金属离子的能力,研究者们将冠醚的离子识别特性与聚(N-异丙基丙烯酰胺)的相变行为特性相结合制备了一系列离子识别响应型智能材料。综述了近年来基于18-冠-6和15-冠-5两种冠醚分子的离子识别响应型智能材料的研究新进展。目前,基于冠醚的离子识别响应型智能材料仍多处于基础研究阶段,还需要进一步系统深入研究和开发完善。     

Biomedical potentials of crown ethers: prospective antitumor agents

Crown ethers are of enormous interest and importance in chemistry, biochemistry, materials science, catalysis, separation, transport and encapsulated processes, as well as in the design and synthesis of various synthetic systems with specific properties, diverse capabilities, and programmable functions. Classical crown ethers are macrocyclic polyethers that contain 3-20 oxygen atoms separated from each other by two or more carbon atoms. They are exceptionally versatile in selectively binding a range of metal ions and a variety of organic neutral and ionic species. Crown ethers are currently being studied and used in a variety of applications beyond their traditional place in chemistry. This review presents additional applications and the ever-increasing biomedical potentials of these intriguing compounds, with particular emphasis on the prospects of their relevance as anticancer agents. We believe that further research in this direction should be encouraged, as crown compounds could either induce toxicities that are different from those of conventional antitumor drugs, or complement drugs in current use, thereby providing a valuable adjunct to therapy.     

Synthesis of resins with crown ethers units as anchor groups

Summary Polymers containing benzo-13-crown-4 (1) and benzo-9-crown-3 (2) units (1) were crosslinked with formaldehyde, phenol/formaldehyde, and resorcin/formaldehyde (2,3). Resins (3–8) were contacted with aqueous solutions of lithium and aqueous solutions of sodium chloride at pH=7 and pH=11. Finally, re-extraction analysis were carried out by two systems, in methanol and in water. The extraction and re-extraction results were analyzed by atomic absorption.     

The use of 2,6-Di-tert-butyl-4-methylpyridine to distinguish between different modes of initiation in cationic polymerisation

Summary 2,6-Di-tert-butyl-4-methylpyridine (DBMP) effectively discriminates between the two major initiation mechanisms encountered in cationic polymerisation. Whenever a protonic acid is involved in the formation of chain carriers, directly or through cocatalysis, addition of equivalent amounts of DBMP inhibits the process. If however direct electrophilic addition of a Lewis acid to the monomer is the source of active species, the hindered base cannot intervene to alter its course. When both pathways are operative DBMP only quenches the former and provides a means of assessing the relative importance of each. Examples are given of the three situations. The simplicity of the method is emphasised.We wish to thank the Direction des Recherches, Etudes et Techniques for financial support.     

Tracer diffusion of crown ethers in chlorobenzene from 301 to 373 K

Tracer diffusivities are reported for s-trioxane, 12-crown-4, 15-crown-5, and 18-crown-6 in chlorobenzene from 301 to 373 K. The results are discussed in terms of Arrhenius equation for diffusion, Stokes' law, and Hildebrand's free-volume model. An extension of Dymond's hard sphere self-diffusion equation to tracer diffusion has been found to successfully correlate the data reported here.     

The synthesis and complexation study of some novel 3-methoxyphenyl chromenone crown ethers using conductometry

7,8-Dihydroxy-3-(3,4-dimethoxyphenyl)-2H-chromenones, 7,8-dihydroxy-3-(3,5-dimethoxyphenyl)-2H-chromenones and 7,8-dihydroxy-3-(3,4,5-trimethoxyphenyl)-2H-chromenones, o-dihydroxy-3-methoxyphenylcoumarins, were prepared from 2,3,4-trihydroxybenzaldehyde and corresponding methoxyphenylacetic acid in NaOAc/Ac₂O, respectively. 3-Methoxyphenyl-7,8-dihydroxy-2H-chromenone reacted with the polyethylene glycol ditosylate or dichloride in CH₃CN/alkali carbonate to afford [12]crown-4, [15]crown-5 and [18]crown-6-chromonones.The chromatographically purified novel chromenone crown ethers were identified with IR, ¹H NMR, ¹³C NMR and low and high resolution mass spectroscopy and elemental analysis.Stability constants for the 1:1 complexes of Na⁺ and K⁺ with different substituted methoxyphenyl derivatives of coumarino[12]crown-4, coumarino[15]crown-5 and coumarino[18]crown-6 (5a–5i) have been determined by conductometry at 25 °C in a binary solvent, dioxane/water. For all the coumarino crown ether derivatives, the stability constant decreases for K⁺ ion compared to Na⁺ ion.The selectivity sequence of these crown ethers in dioxane/water has showed an irregular order with respect to their cavity size.     

Synthesis and solution properties of phthalocyanines substituted with four crown ethers

Metal-free and metal phthalocyanines (M = Ni, Zn, Co) substituted with four benzo-15-crown-5 units through oxy-bridges have been synthesized from a new phthalonitrile derivative, 1-{[(benzo-15-crown-5)-4′-yl]oxy}phthalonitrile (3). The newly prepared compounds have been characterized by elemental analyses, IR, ¹H NMR, MS and UV–Vis spectroscopy. Alkali metal interactions of the crown ethers on the zinc phthalocyaninato (6) are shown to form intermolecular adduct. The electrochemical properties of ZnPc were investigated by using cyclic voltammetry and controlled potential coulometry.     

Investigations into the AIBN initiation steps in the free radical polymerisation of acrylonitrile by the aminoxyl trapping technique

Summary A modification of the radical trapping technique employing the stable nitroxide 1,1,3,3-tetramethyl-2,3-dihydro-1 H-isoindol-2-yloxyl, has been used to study the reaction of cyanoisopropyl radicals with acrylonitrile. By keeping the concentration of the aminoxyl radical very low (strategically added via a syringe pump), the addition of acrylonitrile to cyanoisopropyl radicals becomes competitive with radical trapping. Thus, sufficient quantities of alkoxyamines produced by the trapping of second generation carboncentred radicals (cyanoisopropyl plus one monomer unit), and even third generation carbon-centred radicals were obtained for identification by HPLC/MS techniques. Trapping by traces of adventitious oxygen was also competitive and the various peroxy radicals thus formed, underwent addition to acrylonitrile followed by further reaction or trapping by the aminoxyl. *** DIRECT SUPPORT *** AEB03077 00003     

Stilbene and Azobenzene Diazonium Compounds as dye reagents for crown ethers

The change of light absorption of six coloured diazonium compounds ( 1 , 2a , 2b , 3 , 4 , 5 ) on complexation with five 18-crown-6 derivatives ( 6 – 10 ) in 1,2-dichloroethane was investigated. In the benzene, stilbene and azobenzene series complexation produces only hypsochromic shifts of the intramolecular ct-band of the diazonium ions up to 140 nm. The extend of the shift is effected by ion pairing. The ct-transition energy of the complexes diazonium ion is independent on the present anion in contrast to the uncomplexed compounds. The colour changes are not caused by host to guest charge transfer or E/Z-isomerisation of the stilbene and azobenzene derivatives. A quantitative explanation of the colour changes is given basing on an electrostatic interaction model.     

新型冠醚及其超分子配合物研究的新进展

介绍了冠醚化学的产生、发展及应用,详细介绍了：几种新型臂式冠醚及其超分子金属配合物的合成;取代冠醚及其金属配合物的合成及应用;新型氮杂冠醚及其金属配合物的合成及应用。并对冠醚化学的发展进行了展望。     

Oxidative desulfurization of diesel fuels in the presence of crown ethers and transition metal peroxo complexes

The catalytic activity of crown ethers and their complexes with transition metal cations in diesel fuel desulfurization has been investigated. With dibenzo-18-crown-6 in combination with NbCl₅, the total sulfur content of the fuel can be reduced by a factor of 2 or larger. The effects of the reaction temperature, nature of metal and crown ether, and sorbent acidity on the residual sulfur content are reported. Methods of separation of oxidized compounds, namely adsorption chromatography and extraction are compared in terms of desulfurization efficiency. The latter method is demonstrated to be preferable.     

含二苯并-18-冠-6单元的酰胺型双臂冠醚化合物的合成

合成了２个含二苯并－１８－冠－６单元的酰胺型双臂冠醚化合物,其结构经ＩＲ、＾１ＨＮＭＲ、ＭＳ和元素分析确证,该２个化合物都不具有液晶性,探讨了冠醚结构与液晶性的关系。     

Chloroform as solvent for the complex formation of alkaline salts with crown ethers and cryptands

The complex formation between different crown ethers and the cryptand (2 2 2) with the ammonium and alkali ions was studied in chloroform as solvent using calorimetric titrations. From the reaction enthalpies for the complex formation with 18-crown-6 and the cryptand (2 2 2) as well as from competitive reactions between both ligands no influence of ion pairs can be detected within the experimental error. Stability constants of the complexes formed could only be obtained in case of the complex formation of Na⁺ with benzo-18-crown-6 and of Cs⁺ with most of the ligands.