SYNTHESIS OF 2-(TRIMETHYLSILYL)ETHYL α-d-MANNOPYRANOSIDES REVISITED

Glycosylation of 2-(trimethylsilyl)ethanol with various ethyl 1-thioglycosides, which were activated with N-iodosuccinimide and silver triflate, was studied. The starting thioglycosides, some prepared for the first time, were obtained conventionally from the corresponding α-1-acetates. When β-1-acetates were more readily available, these were converted to the α-anomers by anomerization, prior to the glycosylation. Using ethyl 1-thioglycosides as glycosyl donors, especially those bearing a pivaloyl or a nonparticipating group at O-2, the corresponding 2-(trimethylsilyl)ethyl α-d-mannopyranosides were obtained in excellent yields.     

REACTION BETWEEN 2,2′-DITHIODIANILINE AND ETHYL 2-OXO-1-CYCLOALKANECARBOXYLATES

Abstract

A study has been carried out on the acid-catalysed reaction between 2,2′-dithiodianiline (1) and ethyl 2-oxo-1-cycloalkanecarboxylates (2a–d). While the 1,4-benzothiazines 3a, b and benzothiazoles 6a, b are obtained from the keto esters 2a, b, mixtures of the 1,4-benzothiazines 3c, d and 4c, d and benzothiazolines 5c, d are obtained from the keto esters 2c, d.

The formation of the benzothiazines 4 falls within the general pattern previously proposed for reactions between 2,2′-dithiodi(aryl- or alkylamines) and ketones.

The benzothiazines 3 arise from an acid-catalysed rearrangement of the benzothiazines 4, involving a [1, 3] sulfur migration.     

FIBRE-FORMING OF ETHYL CELLULOSE IN POLYPROPYLENE MELT

Ethyl cellulose (EC), taken as a thermotropic liquid crystalline polymer, was blended with polypropylene (PP), followed by injection molding. Fibre-forming of EC in the PP matrix is analyzed,based on the rheological data,dynamic mechanical analysis and fracture micrographs of EC/PP blends. The addition of maleated PP, for the modification of the interphasial interaction between the PP matrix and the EC fibrils, did not impair the fiber formation substantially.     

THE REACTION OF ETHYL AROYLACETATES AND o-PHENYLENEDIAMINE

Instead of 2-(aroylmethylene)benzimidazolines 3 or 2-(aroyl-methyl)benzimidazoles 4, 4-aryl-2, 3-dihydro-1H-1, 5-benzodiazepin-2-ones 5 were obtained exclusively from the reaction of o-phenylenediamine (1) and ethyl aroylacetates 2 in the presence of a catalytic amount of potassium hydroxide.     

GROUP TRANSFER POLYMERIZATION OF ETHYL ACRYLATE WITH LEWIS ACID CATALYST

This paper reports the kinetics of group transfer polymerization (GTP)of ethyl acrylate (EA)with zinc iodide catalyst in 1,2-dichloroethane using dimethyl ketene methyl trimethylsilyl acetal (MTS) as initiator at 0℃and above 0℃. The amount of catalyst used was studied. When zinc iodide catalyst used is more than 10mol% relative to monomer, the rate of polymerization is proportional to the concentration of monomer, whereas zinc iodide catalyst used is less than 10 mol% of the monomer, the rate of polymerization is independent of the monomer concentration.In the GTP of EA an induction period was observed when the zinc iodide contents are less than l0mol%. If the reaction temperature is over 0℃, living species become unstable and diminish, leading to incomplete monomer conversion. The reaction curves equations are obtained. The polymers have narrow molecular weight distributions which are not changed as decreasing zinc iodide contents. The polydispersity is about 1.2.     

CYCLOPROPANATION OF ENAMINE AND ETHYL DIAZOACETATE CATALYZED BY COPPER COMPLEX

ＣＹＣＬＯＰＲＯＰＡＮＡＴＩＯＮＯＦＥＮＡＭＩＮＥＡＮＤＥＴＨＹＬＤＩＡＺＯＡＣＥＴＡＴＥＣＡＴＡＬＹＺＥＤＢＹＣＯＰＰＥＲＣＯＭＰＬＥＸ￥ＭＩｎＷＡＮＧ，ＭｉｎｇＡｎＷＡＮＧ，ＢｉｎｇＦａｎｇＨＵ（ＤｅｐａｒｔｍｅｎｔｏｆＡｐｐｌｉｅｄＣｈａｍｉｓ...     

A NEW APPROACH TO SYNTHESIZING 2－ALKOXYCARBONYL －2－METHYL ETHYL TIN TRICHLORIDES AND THEIR COMPLEXES WITH DBSO AND HMPA

ＡＮＥＷＡＰＰＲＯＡＣＨＴＯＳＹＮＴＨＥＳＩＺＩＮＧ２－ＡＬＫＯＸＹＣＡＲＢＯＮＹＬ－２－ＭＥＴＨＹＬＥＴＨＹＬＴＩＮＴＲＩＣＨＬＯＲＩＤＥＳＡＮＤＴＨＥＩＲＣＯＭＰＬＥＸＥＳＷＩＴＨＤＢＳＯＡＮＤＨＭＰＡ￥ＬａｉＪｉｎＴＩＡＮ（Ｄｅｐａｒｔｍｅｎｔ...     

THE INTERACTION OF ETHYL BENZOATE AND TRIFLUOROACETIC ACID IN EXCITED STATE

This paper is concerned with the interaction of ethyl benzoate (EBA) and trifluoroaceticacid (TFA) molecules in the excited state by measurements of steady--state and transient fluo-rescence spectra at room and low temperatures. The results show that not only the 1:1 exci-plex but also the 2:1 triplex between EBA and TFA was formed. The formation pathway ofthe triplex is that the exciplex formed at first, then by the interaction with the EBA mole-cule it transformed into triplex. But it could not be formed by the dimer of EBA by interac-tion with TFA. The dimer of EBA is confirmed in the concentrated solution. So there arefour components in EBA/TFA--concentrated solution and their fluorescence lifetimes aremeasured respectively.     

SYNTHESIS OF ETHYL ACETATE OVER HZSM—5 CATALYST(Ⅰ)

A study on the esterification of ethanol with acetic acid on the HZSM—5 zeolite catalyst ina fixed bed reactor was reported.The influence of the kaolin level and the hydrothermal treatment ofthe catalyst,and also the effect of the reaction conditions,such as the reaction temperature,the molarratio of acid/alcohol and the liquid hour space velocity(LHSV)on the catalytic performance weredetermined.     

THE CRYSTAL STRUCTURE OF N-(TBUTOXYCARBONYL)-L-METHIONYL GLYCINE ETHYL ESTER

The crystal structure of N-(t-butoxycarbonyl)-L-methionyl-glycine ethyl ester has been determined. The crystal data are: P2_1, α=14.504(6), b=5.015(2), c=12.762(6), β=93.63(3)°, Z=2. The final R is 0.066 for 1495 reflections. The torsion angles of methionyl side chain are X~1=-177.7°. X~2=178.6°, X~3=-71.7°. The plan of the side chain is approximately vertical to the plan of the peptide. The peptide main chains are packed in a parallel β-sheet structure, the main chain torsion angles(φ,ψ) of the methionyl residue being (-118.9°,115.4°). This compound, BOC-L-Met-Gly-OEt, is very similar to certain derivatives used in the peptide transport studies which were carried out by Naider et al.     

COPOLYMER OF 1-(ACETYLSALICYLYLOXY)ETHYL METHACRYLATE AND ITS HYDROLYSIS

The copolymers of 1-(acetylsalicylyloxy)ethyl methacrylate (HEMA-ASA) with methacrylicacid (MA) have been prepared and their hydrolysis in dioxane-H_2.O either in acdic or alkaline medium,at 60℃or 37℃have been investigated. It is found that the chief product of hydrolysis is alwaysaspirin with minor amount of salicylic acid. Due to its neighbouring group effect, the hydrolysisrate of (HEMA-ASA)-MA copolymer markedly depends on its composition and the pH value ofhydrolysis medium, i.e. the hydrolysis rate increases with increasing mole fraction of MA in the copoly-mer and pH value of hydrolysis medium.     

THE MECHANISM OF THE COPOLYMERIZATION OF BF_3-COMPLEXED ETHYL ACRYLATE WITH PROPYLENE

The copolymerization of BF_2-omplexed ethyl acrylate with propylene in the presence ofAIBN at 25℃was investigated. It was found that the rate of the copolymerization was propor-tional to the square root of the initiator concentration. The chain transfer agent CCl_4 greatly af-fects the inherent viscosity of the resulting copolymer. The smaller the dielectric constant of thesolvent, the greater the rate of copolymerization is. The equal concentration of the two monomersgive the maximum copolymerization rate. The ~1H-NMR and ~(13)C-NMR analysis indicated, when[EA.BF_2]/[EA.BF_2]+[P]>0.5, the resulting copolymer was the acrylate-rich random copoly-mer. Through the kinetic experiments we suggest that copolymerization follows the mechanismof the random copolymerization of the ternary complex with binary complex. When [EA.BF_3]/[EA.BF_2]+[P]<0.5, the resulting copolymer is always strictly alternating, and the alternatingcopolymerization follows the mechanism of the ternary complex homopolymerization. Usingthe homolog of the propylene, 1-pentene, we found that BF_3-complexed ethyl acrylate can forma ternary complex with 1-pentene identified by UV spectroscopy. This is a strong evidence forthe mechanism of ternary complex homopolymerizetion.     

TEMPERATURE DEPENDENCE OF AIR SEPARATION OF LIQUID CRYSTALLINE TRIHEPTYL CELLULOSE/ETHYL CELLULOSE MEMBRANES

Triheptyl cellulose/ethyl cellulose(3/97)binary blend membranes were preparedfrom tetrahydrofuran,chloroform and dichloromethane solutions and their air separation capabit-ities were studied at different temperatures.With increasing temperature from 25 to 85℃,theflux QOEA of O_2-enriched air(OEA),O_2 permselectivity and the O_2 concentration Yo_2 in the OEA allincrease.The membranes show a unique trend in their Yo_2～QOEA relationship,that is,the airseparation capability increases simultaneously with the OEA permeation capability.The magnitudesof QOEA and Yo_2 for 17μm-thick membrane after the testg time of 36hours at 70℃ are 5×10~(-4)cm~3(STP)/s·cm~2 and 37.6%,respectively.The air separation capability depends slightly on membraneforming solvents.     

VINYL RADICAL POLYMERIZATION INITIATED WITH CERIC ION AND ETHYL N, N-DIETHYLDITHIOCARBAMYL ACETATE SYSTEM

Acrylamide polymerization initiated with a redox initiation system consisting of cericion and ethyl N, N-diethyldithiocarbamyl acetate (EDCA) has been studied. It was foundthat the polymerization rate equation is in good agrement with that of a redox initiatedpolymerization, and the overall activation energy of the polymerization was determinedto be 25.2kJ·mol~(-1). Accordingly, the system belongs to a redox initiator. The initiationmechanism was proposed based on the end group analysis using FT-IR, UV spectroscopies.Analysis results revealed that the N, N-diethyldithiocarbamyl radical produced from theredox reaction of EDCA with ceric ion can initiate acrylonitrile (AN) polymerization andform the end group on PAN. The resulting PAN was photopolymerized with butyl acrylate(BA) to form PAN-b-PBA block copolymer.     

REACTION OF ETHYL N-CYANOMETHYLBENZEHECARBOXIMIDATE WITH ALIPHATIC ALDEHYDES UNDER THE SOLID-LIQUID PHASE TRANSFER CATALYSIS

Ethyl N-cyanomethytbenzenecarboximidate reacted with aliphaticaldehydes under the solid-liquid PTC condition to gire a-ethoxyphenylmethylene-aminoacrylonitrile derivatives and oxazoline derivatives.It is a convenientand new method for synthesis of β,β'-dihyroxy-a-amino acids by hydrolysis ofthe oxazoline derivatives.     

SYNTHESES OF ETHYL PERFLUOROACETYLENIC ESTERS AND STEREOCHEMISTRY OF A NOVEL ACETYLENIC ESTER-VINYL ETHER REARRANGEMENT

The intramolecular Wittig reaction has been applied to the syntheses of ethyl trifluoro-but-2-ynoate (2a) and ethyl heptafluoro-hex-2-ynoate (2b). Treatment of 2a and 2b withaqueous sodium hydroxide, followed by acidification, affords 3-ethoxy-4,4,4-trifluoro-2-bu-tenoic acid (3a) and 3-ethoxy-4,4,5,5,6,6,6-heptafluoro-2-hexenoic acid (3b) respectively. Anovel acetylenic ester to vinyl ether rearrangement takes place as thc corresponding methylestors. Their structures are ascertained by elemental analysis and IR and NMR spectra.The stereochemistry of this novel acetylenic ester to vinyl ether rearrangement has been studied.On the basis of ~1H NMR data, we find that the reaction is highly stereoseleetive and the Z-isomer predominated to the extent of above 94% in all cases. The results of the solventeffect of benzene and NOE enhancement in NMR spectroscopy further confirm the configura-tion of the Z- and E-isomer.     

TRANSESTERIFICATION OF METHANOL WITH ETHYL ACETATE AND ETHANOL WITH METHYL FORMATE CATALYZED BY DBN

采用三步合成了１，５二氮杂环双环［４，３，０］壬烯５（ＤＢＮ）并考察了其在酯交换反应中的催化活性。结果表明，在没有环氧丙烷（ＰＯ）助剂存在时，ＤＢＮ的催化活性很低；但在有ＰＯ助催化剂存在时，ＤＢＮ对酯交换反应的催化活性极高，其催化活性随ＤＢＮ和ＰＯ浓度的增加而增大。考察了反应温度对ＤＢＮ催化剂的酯交换活性的影响，提出了酯交换反应的催化机理。     

BASIC HYDROLYSIS OF ETHYL OXAL-ACETATE AND SOME CHEMICAL CHARACTERS OF 3-ETHOXY CAEBONYL PYRUVIC ACID

The products of basic hydrolysis of ethyl oxal-acetate and the preparation of 3-ethoxy carbonyl pyruvic acid 1 are reported.Esterification reaction of 1 with unhindered alcohols could be carried out smoothly, but it was unsuccessful with hindered alcohols.     

HIGH－PERFORMANCE CAPILLARY ELECTROPHORESIS OF REDUCING OLIGOSACCHARIDES AS THEIR ETHYL P－AMINOBENZOATE DERIVATIVES

ＨＩＧＨ－ＰＥＲＦＯＲＭＡＮＣＥＣＡＰＩＬＬＡＲＹＥＬＥＣＴＲＯＰＨＯＲＥＳＩＳＯＦＲＥＤＵＣＩＮＧＯＬＩＧＯＳＡＣＣＨＡＲＩＤＥＳＡＳＴＨＥＩＲＥＴＨＹＬＰ－ＡＭＩＮＯＢＥＮＺＯＡＴＥＤＥＲＩＶＡＴＩＶＥＳ￥ＬｉＷｅｎＣＨＡＮＧ；ＱｉｎｇＧＵＯ；Ｚ...