New synthetic route to alternating copoly(aromatic ester–aliphatic amide)s

The preparation of three novel alternating copoly(aromatic ester–aliphatic amide)s containing the same ordered amide–amide–ester–ester (AAEE), the same para-disubstituted phenyl, and the different long methylene chain structure were described. 1,1′-(Adipoyl)bisbenzotriazole (AdBBT), 1,1′-(suberoyl)bisbenzotriazole (SuBBT), and 1,1′-(sebacoyl)bisbenzotriazole (SeBBT) were synthesized. These diacylbenzotriazoles were preferred to aminoethanol at the amino group because of the selective N-acylation of active acylamide of benzotriazole in excellent yield at room temperature to give diol monomers such as N,N′-bis(2-hydroxyethyl)adipic amide (HEAdA), N,N′-Bis(2-hydroxyethyl)subaric amide (HESuA), and N,N′-bis(2-hydroxyethyl)sebacic amide (HESeA). Polycondensation of 1,1′-(teraphthaloyl)bisbenzotrizole (tPBT) with HEAdA, HESuA, and HESeA gave the corresponding alternating copoly(aromatic ester–aliphatic amide)s: P(tPE–AdA), P(tPE–SuA), and P(tPE–SeA), respectively. The alternating copoly(aromatic ester–aliphatic amide)s were characterized by ¹H-NMR spectra. The resulting polymers have two different chain units; one is chain unit of poly(ethylene terephthalate) and the other is a chain unit of polyamide-2,6, polyamide-2,8, and polyamide-2,10; both are linked via a C? N bond.     

季胺基修饰的Salen配合物的合成及性质

采用季胺基取代的水杨醛(由2,4-二羟基水杨醛、1,2-二溴乙烷、高氯酸钠等为原料合成)合成了两个新型Salen配体N,N'-二{4-[[2-(三甲胺基)乙基]氧化]水杨醛}-邻苯二胺二高氯酸盐(L¹), N-(2-羟基-5-甲基二苯甲基)-N'-{4-[[2-(三甲胺基)乙基]氧化]水杨醛}-邻苯二胺高氯酸盐(L²), 并进一步合成了8个新型Salen金属配合物[ZnL¹, NiL¹, CuL¹, ZnL², NiL², CuL², MnL², CoL²]. 用¹H NMR, ¹³C NMR, FT-IR, UV-vis, MS对配体和配合物进行了表征, 测定了金属配合物的水溶性及在水中的摩尔电导率. 结果表明, 与相应母体配合物的水溶性比较, 含有季胺基修饰的Salen金属配合物的水溶性有了较大提高.     

Poly(ethylene terephthalate) reinforced by N,N′‐diphenyl biphenyl‐3,3′,4,4′‐tetracarboxydiimide moieties

Starting with 3,3′,4,4′‐biphenyltetracarboxylic dianhydride and methyl aminobenzoate, we synthesized a novel rodlike imide‐containing monomer, N,N′‐bis[p‐(methoxy carbonyl) phenyl]‐biphenyl‐3,3′,4,4′‐tetracarboxydiimide (BMBI). The polycondensation of BMBI with dimethyl terephthalate and ethylene glycol yielded a series of copoly(ester imide)s based on the BMBI‐modified poly(ethylene terephthalate) (PET) backbone. Compared with PET, these BMBI‐modified polyesters had higher glass‐transition temperatures and higher stiffness and strength. In particular, the poly(ethylene terephthalate imide) PETI‐5, which contained 5 mol % of the imide moieties, had a glass‐transition temperature of 89.9 °C (11 °C higher than the glass‐transition temperature of PET), a tensile modulus of 869.4 MPa (20.2 % higher than that of PET), and a tensile strength of 80.8 MPa (38.8 % higher than that of PET). Therefore, a significant reinforcing effect was observed in these imide‐modified polyesters, and a new approach to higher property polyesters was suggested. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 852–863, 2002; DOI 10.1002/pola.10169     

Formation of diethylene glycol as a side reaction during production of polyethylene terephthalate

Polymers of poly(ethylene terephthalate) (PET) always contain a certain amount of incorporated diethylene glycol (DEG), substituting the incorporated glycol. DEG is formed in a side reaction during the ester interchange of dimethyl terephthalate (DMT) with ethylene glycol or during direct esterification of terephthalic acid with ethylene glycol, and to a smaller extent during the polycondensation of the low-molecular material. DEG is formed via an unusual type of reaction: ester + alcohol → ether + acid. Some evidence of this type of reaction is given by the formation of dioxane in low molecular PET and of methyl Cellosolve and methyl carbitol during the ester interchange of DMT with ethylene glycol and diethylene glycol, respectively. The strongest support for this type of reaction, however, was obtained from kinetic data. Polyesters of low molecular weight with OH group contents ranging from 3 to 0.5 mole/kg were heated at 270°C in sealed tubes for 1–7 hr. The kinetic equation for the proposed reaction is: d[DEG]/dt = k[OH] [ester]. With the aid of one rate constant the formation of DEG in all esters could be described.     

Evaluation of mosquito larvicidal activity of fruit extracts of Acacia auriculiformis against the Japanese encephalitis vector Culex vishnui

The larvicidal potentiality of crude and ethyl acetate extracts of fruits of Acacia auriculiformis was investigated against all the larval instars of JE vector Culex vishnui. The crude extracts showed good results against all the larval instars with highest mortality at 0.09%. Highest mortality was found at 300 ppm of ethyl acetate extract. Lowest LC₅₀ value was obtained at 72 h for third instar larvae. Non target organisms tested, showed no to very less mortality to ethyl acetate solvent extract. Presence of N–H stretching, a C=O stretching, C=C and C–N stretching vibrations of secondary amide or amine group were confirmed from IR analysis. GC-MS analysis revealed the presence of three compounds namely Ethane 2-chloro-1,1-dimethoxy, Acetic acid, 1-methyl ether ester and [4-[1-[3,5-Dimethyl-4[(trimethylsilyl)oxy)phenyl]-1,3-dimethylbutyl)-2,6dimethylphenoxy)(trimethyl) silane, responsible for mosquito larval death.     

Semifluorinated side group poly(oxyethylene) derivatives having extremely low surface energy: Synthesis, characterization, and surface properties

Poly[oxy[[2-(perfluorooctyl)ethyl]thiomethyl]ethylene]s (H2F8TP-Xs, where X is mole% of perfluorooctyl groups in the side chain) with different levels of conversion were synthesized using polymer analogous reactions from poly[oxy(chloromethyl)ethylene] and 2-perfluorooctyl ethane thioacetate. H2F8TP-20, 41, 64, and 85 were obtained by changing the poly[oxy(chloromethyl)ethylene] to 2-perfluorooctyl ethane thioacetate mole ratio in the reaction from 0.35 to 1.50. H2F8TP-85 (85% conversion) was found to have an extremely low surface energy of 6.2 mN/m at room temperature, which was attributed to the highly ordered perfluorinated alkyl groups on the surface as a result of phase separation between the perfluorinated side chain part and the hydrogenated flexible backbone. The films of the polymers were characterized by electron spectroscopy for chemical analysis (ESCA) and near edge X-ray absorption fine structure (NEXAFS).     

2-Benzoyl-2-ethoxycarbonylvinyl-1 and 2-benzoylamino-2-methoxy-carbonylvinyl-1 as N-protecting groups in peptide synthesis. Their application in the synthesis of dehydropeptide derivatives containing N-terminal 3-heteroarylamino-2,3-dehydroalanine

Ethyl 2-benzoyl-3-dimethylaminopropenoate ( 6 ) and methyl 2-benzoylamino-3-dimethylaminopropenoate ( 46 ) were used as reagents for the protection of the amino group with 2-benzoyl-2-ethoxycarbonylvinyl-1 and 2-benzoylamino-2-methoxycarbonylvinyl groups in the peptide synthesis. Reactions of ethyl 2-benzoyl-3-dimethylaminopropenoate (6) with α-amino acids gave N-(2-benzoyl-2-ethoxycarbonylvinyl-1)-α-amino acids 13–19. These were coupled with various amino acid esters to form N-(2-benzoyl-2-ethoxycar-bonylvinyl-1)-protected dipeptide esters 20–31. The removal of 2-benzoyl-2-ethoxycarbonylvinyl-1 group, which was achieved by hydrazine monohydrochloride or hydroxylamine hydrochloride, afforded hydrochlo-rides of dipeptide esters 32–41 in high yields. Similarly, the substitution of the dimethylamino group in methyl 2-benzoylamino-3-dimethylaminopropenoate ( 46 ) by glycine gave N-(2-benzoylamino-2-methoxycar-bonylvinyl-1)glycine ( 47 ), which was coupled with glycine ethyl ester to give N-[N-(2-benzoylamino-2-methoxycarbonylvinyl-1)glycyl]glycine ethyl ester ( 48 ). Treatment of 48 with 2-arnino-4,6-dirnethylpyrimi-dine afforded N-[glycyl]glycine ethyl ester hydrochloride (34) in high yield. Amino acid esters and dipeptide esters were employed in the preparation of tri- 58-70, tetra- 71–82, and pentapeptide esters 83–85 containing N-terminal 3-heteroarylamino-2,3-dehydroalanine. 2-Chloro-4,6-dimethoxy-1,3,5-triazine was employed as a coupling reagent for the preparation of peptides 58–85.     

On the preparation of substituted 4H- 1,3,4-thiadiazolo[2,3-c]-1,2,4-triazin-4-ones and 1,2,4-triazolo[3,4-b]-1,3,4-thiadiazoles

The reaction of benzoyl isothiocyanates and methoxycarbonyl isothiocyanate with 4-amino-4,5-dihydro-3-(methylthio)-1,2,4-triazin-5-ones in acetonitrile gave several substituted 4H-1,3,4-thiadiazolo[2,3-c]-1,2,4-triazin-4-ones VIa-h instead of the expected thioureas. In addition, benzoyl isothiocyanate reacted with 4-amino-3-(methylthio)-5-(trifluoromethyl)-4H-1,2,4-triazole to give the benzoyl thiourea IX and with 4-amino-3-mercapto-5-(trifluoromethyl)-4H-1,2,4-triazole to give the bicyclic compound N-[3-(trifluoromethyl)-1,2,4-triazolo[3,4-b]-1,3,4-thiadiazol-6-yl]benzamide IX .     

Sequential analysis of polyesters by stepwise chemical degradation: Preparation of degradation products

Model reactions for the sequential analysis of polyesters, especially those of the poly(ethylene terephthalate) and poly(butylene terephthalate) type, by stepwise chemical degradation were performed. The cyclic degradation products, containing the reagent and an ethylene terephthalate or butylene terephthalate unit, terephthalic acid mono(2-{o{N-<N′-[4-(iminomethyl-) benzoyl-]> 2′-(imino)ethoxycarbonyl-}iminobenzoyl-} oxyalkyl) ester N″-lactams, were deliberately synthesized.     

Chain extension of polyesters PET and PBT with N,N′-bis (glycidyl ester) pyromellitimides. I

Three N,N′-bis (glycidyl ester imide) of pyromellitic acid (diepoxides) were prepared and were used as chain extenders for poly (ethylene terephthalate) (PET) and poly (butylene terephthalate) (PBT). The typical reaction conditions for the coupling of the polyester macromolecules were heating with the chain extender under argon atmosphere above the melting temperature (280°C for PET and 250°C for PBT) for several minutes. The Characterization of the samples, obtained at variable residence times in the reactor, was based on solution viscosity measurements and carboxyl and hydroxyl end-group determinations. Two of the diepoxides used gave satisfactory results. Starting from a PET having intrinsic viscosity [η] = 0.60 dL/g, and carboxyl content CC = 42 eq/10⁶ g, one could obtain PET with [η] = 1.15 dL/g and CC = 16 eq/10⁶ g within 30 min at 280°C. Analogous results were observed for PBT. The hydroxyl content of polyester in all cases was increased. When the quantity of the chain extender used was higher than that theoretically required for its reaction with all carboxyl end groups of the polyester, this resulted in some gel formation indicative of crosslinking. © 1995 John Wiley & Sons, Inc.     

Synthesis and characterization of hydrogen‐bonded thermotropic liquid crystalline aromatic‐aliphatic poly(ester–amide)s from amido diol

Fifteen highly regular hydrogen‐bonded, novel thermotropic, aromatic‐aliphatic poly(ester–amide)s (PEAs) were synthesized from aliphatic amido diols by melt polycondensation with dimethyl terephthalate and solution polycondensation with terephthaloyl chloride. Intermolecular hydrogen bonds more or less perpendicular to the main‐chain direction induce the formation and stabilization of liquid crystalline property for these PEAs. The structure of these polymers, even in the mesomorphic phase is dominated by hydrogen bonds between the amide–amide and amide–ester groups in adjacent chains. Aliphatic amido diols were synthesized by the aminolysis of γ‐butyrolactone, δ‐valerolactone and ε‐caprolactone with aliphatic diamines containing a number of methylene groups from two to six in isopropanol medium at room temperature. Effects of polarity of the solvent on solution polymerization and effect of catalyst on trans esterification were studied. These polymers were characterized by elemental analysis, FTIR, ¹H NMR, ¹³C NMR, solubility studies, inherent viscosity, DSC, X‐ray diffraction, polarized light microscopy, and TGA. All the melt/solution polycondensed PEAs showed multiple‐phase transitions on heating with second transitions identified as nematic/smectic/spherullitic texture. The mesomorphic properties were studied as a function of their chemical structure by changing alternatively m or n. Odd‐even effect on mesophase transition temperature, isotropization temperature, and crystallinity were studied. The effect of molecular weight and polydispersity on mesophase/isotropization temperature and thermal stability were investigated. It was observed that there exists a competition for crystallinity and liquid crystallinity in these PEAs © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 2469–2486, 2000     

Synthesis of N-arylsulfonyl-2-aryl(hetaryl)aminoacetic acids

Hydrolytic transformations of 4-[2,2,2-trichloro-1-(arylsulfonylamino)-and-(ethoxycarbonylamino)ethyl]phenyloxy(or sulfanyl)acetic acids under microwave irradiation in alkaline medium involve both trichloromethyl group and ester fragment to give N-arylsulfonyl-2-[4-carboxymethyloxy(or sulfanyl)phenyl]-2-aminoacetic acids in good yields. Hydrolysis of methyl 4-[2,2,2-trichloro-1-(arylsulfonylamino)ethyl]phenyloxy(or sulfanyl)acetates without microwave activation occurs only at the ester group with quantitative formation of 4-[2,2,2-trichloro-1-(arylsulfonylamino)ethyl]phenyloxy(or sulfanyl) acetic acids. N-[2,2,2-Trichloro-1-(1-naphthyl, 2-furyl, and 1-methylindol-3-yl)ethyl]-4-chlorobenzenesulfonamides in alkaline medium under microwave irradiation were converted in 10–15 min into the corresponding N-(4-chlorophenylsulfonyl)-2-aryl-2-aminoacetic acids in preparative yields.     

Synthesis of a novel high sensitive photo‐radical initiator with good thermal stability based on naphthalic‐1,8‐N‐alkylimide derivatives

A new high‐sensitive photo‐radical initiator, N‐[2‐(2‐acryloyloxyethoxy)ethyl]‐1,8‐naphthalimide (NI6), with good thermal stability based on naphthylimide derivative was developed. NI6 was prepared by the condensation of N‐[2‐(2‐hydroxyethoxy)ethyl]‐1,8‐naphthalimide and acryloyl chloride in the presence of 4‐dimethylaminopyridine. The film consisting of NI6 and pentaerythritol triacrylate (PETA) showed higher photosensitivity than those containing conventional photo‐radical initiators such as acrylic acid 2‐(2‐{2‐[2‐(4‐benzoyl‐phenoxy)‐ethoxy]‐ethoxy}‐ethoxy)‐ethyl ester, cyclohexylmaleimide, and the resulting film exhibited very high transmittance over 400 nm. The thermal stability of NI6 was very high and no decomposed residues were observed from the film consisting of NI 6 after heating at 250 °C for 1 h. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 5571–5580, 2005     

Synthesis and properties of poly(oxyethylene)s containing thioether,sulfoxide, or sulfone groups

Poly[oxy(ethylthiomethyl)ethylene] (ETE) was prepared from poly[oxy (chloromethyl)ethylene] (CE) by reaction with sodium ethanethiolate. Sulfoxide and sulfone analogues were synthesized by oxidation of the poly[oxy(ethylthiomethyl)ethylene]. By changing the chloromethyl/sodium ethanethiolate ratio, poly[oxy (chloromethyl)ethylene-co-oxy(ethylthiomethyl)ethylene] (CE-ETEs) were easily made. Poly[oxy(ethylsulfinylmethyl)ethylene] (ESXE), poly[oxy(chloromethyl)ethylene-co-oxy(ethylsulfinylmethyl)ethylene] (CE-ESXEs), poly[oxy(ethylsulfonylmethyl)ethylene] (ESE), and poly[oxy(chloromethyl)ethylene-co-oxy(ethylsulfonylmethyl)ethylene] (CE-ESEs) were obtained by oxidation of ETE or CE-ETEs. There was little if any chain degradation. The (co)polymer structures were confirmed by FTIR and ¹H-NMR spectroscopic studies. Their thermal properties were studied by DSC and TGA. T_gs of ETE, ESXE, and ESE were -57, 36, and 57°C, respectively, and T_d,os (initial decomposition temperature, TGA) were 331, 198, and 308°C, respectively. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 793–801, 1998     

Addition of trimethylsilyl azide and of “mixed anhydrides” to the N-C(3) σ-bond in 3-substituted-1-azabicyclo[1.1.0]butanes

Trimethylsilyl azide adds smoothly to the highly strained N-C(3) σ-bond in 3-ethyl-1-azabicyclo[1.1.0]-butane ( 1 ) to afford an adduct, 2 , that reacts in situ with a variety of electrophilic reagents (i.e., ethyl chloroformate, p-toluenesulfonyl chloride, benzoyl chloride, acetyl chloride, and oxalyl chloride) to afford the corresponding N-substituted-3-azido-3-ethylazetidines 3–7 , respectively in 62–72% yield. Similarly, 1 reacts regiospecifically with “mixed anhydrides” (i.e., p-toluenesulfonyl acetate, methanesulfonyl acetate, and benzoyl trifluoromethanesulfonate) to afford the corresponding adducts, 8–10 , respectively) in 38–68% yield. Reaction of p-toluenesulfonyl azide with 1-aza-3-phenylbicyclo[1.1.0]butane ( 12 ) produces two products: N-(p-toluenesulfonyl-3-azido-3-phenylazetidine ( 13 , 15%) and a dimeric product, N-(N'-p-toluenesulfonyl-3′-phenyl-3′-azetidinyl)-3-azido-3-phenylazetidine ( 14 , 28%). Ethyl chloroformate adds to the N-C(3) σ-bond in 1-aza-3-(bromomethyl)bicyclo[1.1.0]butane ( 15 ) to afford N-carboethoxy-3-(bromomethyl)-3-chloroazetidine ( 16 ) in 73% yield.     

Fluorescence study on dynamics of liquid-crystalline polymers

Fluorescence measurements of various main-chain liquid-crystalline (LC) polyesters, poly[oxybiphenyl-4, 4'-diyloxy(2, 5-dihexadecyloxy)-1, 4-pyromellitoyl] (B-C16), poly[(ethylene terephthalate)-co-(p-oxybenzoate)] (PET40/OBA60), poly(oxybiphenyl-4, 4'-diyloxy-1, 10-decanedioyl) (PB-10), low-molecular-weight LC bis(p-hexyloxyphenyl) terephthalate (PP6), and a lyotropic LCP, poly(sulfo-1, 4-phynelene 3'-nitroterephthalate) (PSPNT), were carried out to investigate their dynamics and intermolecular interaction changes.     

Synthesis and Mesomorphic Properties of Novel γ-Substituted β-Diketonates

The synthesis and mesomorphic properties of two series of novel γ-substituted β-diketonates have been reported. All of the compounds 2,4-dioxo-3-pentyl 4-[[4-(n-alkoxyl) cinnamoyl]oxy]cinnamatetes Ia-If (n=7-12) exhibit two monotropic phases(N and Sc) and have a wider mesophase range than the compounds 2,4-dioxo-3-pentyl 4-[[4-(n-alkoxyl) benzoyl]oxy] cinnamatetes Ⅱa-Ⅱf (n=7-12), which display one monotropic nematic phase (n=7-10) or an enantiotropic nematic phase for n=11 or two enantiotropic phases (N and Sc)for n=12.     

Folic acid analogs. III. N-(2-[2-(2,4-diarnino-6-quinazolinyl)ethyl]benzoyl)-l-glutamic acid

A trideaza analog of aminopterin, N-(4[2-(2,4-diamino-6-quinazolinyl)ethyl]benzoyl)-L-glutamic acid, was prepared by a Wittig condensation of 2,4-diaminoquinazoline-6-carboxaldehyde and [P-(N-[1,3-bis(ethoxycarbonyl)propan-1-yl]aminocarbonyl)phenylmethyl]triphenylphosphonium bromide followed by catalytic reduction and mild hydrolysis. This compound was found to have confirmed inhibitory activity against leukemia L1210 in mice.     

A new approach of characterizing the hydrolytic degradation of poly(ethylene terephthalate) by MALDI-MS

The hydrolytic degradation of technical poly(ethylene terephthalate) (PET) was investigated by means of different methods such as size-exclusion chromatography (SEC), viscometry, light-scattering, thin-layer chromatography, end-group titration, and matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). The long-term degradation was simulated by exposing PET filament yarns to aqueous neutral conditions at 90°C for up to 18 weeks. By means of MALDI-MS and thin-layer chromatography, the formation of different oligomers was obtained during polymer degradation. As expected, an ester scission process was found generating acid terminated oligomers (H-[GT]_m-OH) and T-[GT]_m-OH and ethylene glycol terminated oligomers (H-[GT]_m-G), where G is an ethylene glycol unit and T is a terephthalic acid unit. Additionally, the scission of the ester bonds during the chemical treatment led to a strong decrease in the number of cyclic oligomers ([GT]_m). The occurrence of di-acid terminated species demonstrated a high degree of degradation. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 2183–2192, 1997     

Synthesis of N,N′-bis[4-(1H-1,2,3-triazol-1-yl)furazan-3-yl]-methylenediamine derivatives

[3+2] Cycloaddition of azide groups of N,N′-bis(4-azidofurazan-3-yl)methylenediamine to 1,3-dicarbonyl compounds and malonodinitrile was shown to proceed regioselectively with the formation of the corresponding N,N′-bis[4-(1H-1,2,3-triazol-1-yl)furazan-3-yl]methylenediamine derivatives. The reactions of N,N′-bis(4-azidofurazan-3-yl)methylenediamine with cyanoacetic acid ethyl ester and amide led to the formation of the product of transformation of the azide group in the starting compound to the amino groups.