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111.
X. Andrew Guo Allen D. Hunter Jie Chen 《Journal of polymer science. Part A, Polymer chemistry》1994,32(1):47-56
Five acrylic esters having different fluorine contents and distributions in their side-groups (i.e., CH2=CHC(O)OR, where R = ? C(CH3)2C6F4H, ? C(CH3)2C6F5, ? C(CF3)2C6F5, ? C(CF3)2C6H5, and ? C(CH3)2C6H5) have been prepared from the reactions of the lithium salts of their corresponding alcohols with acryloyl chloride. These monomers are polymerized under identical conditions by the radical initiator AIBN and five polyacrylates were prepared having the structure of ? [ ? CH2CHC(O)OR? ]n? . These addition polymers were compared and fully characterized by GPC, VPO, DSC, TGA, NMR, IR, and UV-visible spectroscopies, and they showed potential for practical applications. Significant differences in their thermal stabilities were found with respect to fluorine contents and distributions in these polyacrylates, and the highest stability arises from CF3 substitutions in the side-chains of the polymers. © 1994 John Wiley & Sons, Inc. 相似文献
112.
An operationally simple oxidative methyl esterification of primary alcohols in good yields using an iodine‐mediated poly[4‐(diacetoxyiodo)styrene] in methanol at room temperature is described. The polymeric reagent can be regenerated and reused as an environmentally benign reagent. 相似文献
113.
Summary The retention, enantionselectivity and enantiomeric elution order of racemic propranolol (PP) and its ester derivatives (O-acetyl,-propionyl,-butyrul and-valeryl PP) on an 1-acid glycoprotein (AGP)-bonded column have been investigated by changing eluent composition (eluent pH, buffer concentration, type and content of organic modifier). The retention of these cationic solutes, PP and its ester derivatives, was influenced by eluent pH, ionic strength and organic modifier content. The enantioselectivity was dependent on eluent pH and type of organic modifier. Reversal of the enantiomeric elution order of ester derivatives of PP (O-propionyl-butyryl) and-valeryl PP) occurred around eluent pH 6–7. These results suggst that chiral recognition or binding properties may be altered by the change in eluent composition, espeically eluent pH and type of organic modifier. 相似文献
114.
Guey‐Sheng Liou Sheng‐Huei Hsiao 《Journal of polymer science. Part A, Polymer chemistry》2002,40(4):459-470
Two series of phosphorus‐containing aromatic poly(ester amide)s with inherent viscosities of 0.46–3.20 dL/g were prepared by low‐temperature solution polycondensation from 1,4‐bis(3‐aminobenzoyloxy)‐2‐(6‐oxido‐6H‐dibenz〈c,e〉〈1,2〉oxaphosphorin‐6‐yl)naphthalene and 1,4‐bis(4‐aminobenzoyloxy)‐2‐(6‐oxido‐6H‐dibenz〈c,e〉〈1,2〉oxaphosphorin‐6‐yl)naphthalene with various aromatic diacid chlorides. All the poly(ester amide)s were amorphous and readily soluble in many organic solvents, such as N,N‐dimethylformamide, N,N‐dimethylacetamide (DMAc), and N‐methyl‐2‐pyrrolidone (NMP). Transparent, tough, and flexible films of these polymers were cast from DMAc and NMP solutions. Their casting films had tensile strengths of 71–214 MPa, elongations to break of 5–10%, and initial moduli of 2.3–6.0 GPa. These poly(ester amide)s had glass‐transition temperatures of 209–239 °C (m‐series) and 222–267 °C (p‐series). The degradation temperatures at 10% weight loss in nitrogen for these polymers ranged from 462 to 489 °C, and the char yields at 800 °C were 55–63%. Most of the poly(ester amide)s also showed a high char yield of 35–45%, even at 800 °C under a flow of air. The limited oxygen indices of these poly(ester amide)s were 35–46. © 2002 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 459–470, 2002; DOI 10.1002/pola.10129 相似文献
115.
116.
I. V. Ukrainets L. V. Sidorenko O. V. Gorokhova S. V. Shishkina 《Chemistry of Heterocyclic Compounds》2006,42(6):776-781
Alkaline hydrolysis of the ethyl ester of 4-(cyanoethoxycarbonylmethyl)-2-oxo-1,2-dihydroquinoline-3-carboxylic acid is accompanied
by decarboxylation with loss of two molecules of CO2 and leads to 4-methyl-2-oxo-1,2-dihydroquinoline-3-carboxylic acid.
__________
Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 887–893, June, 2006. 相似文献
117.
M. Fujiwara T. Okano T. -H. Nakashima A. A. Nakamura G. Sugihara 《Colloid and polymer science》1997,275(5):474-479
For a sodium salt of α-sulfonatomyristic acid methyl ester (14SFNa), one of the α-SFMe series surfactants, critical micellization
concentration (CMC), solubility and degree of counterion binding (β) were determined by means of electrocon-ductivity measurements
at different temperatures (at every 5 °C) ranging from 15 to 50 °C. The phase diagram of 14SFNa in pure water was constructed
from the CMC- and solubility-temperature data, in which the Krafft temperature (critical solution temperature) was found around
0 °C. The changes in the Gibbs energy, ΔG
0
m, enthalpy, ΔH
0
m, and entropy, ΔS
0
m, upon micelle formation as a function of temperature were evaluated taking βvalues into calculation.
Received: 28 August 1996 Accepted: 5 November 1996 相似文献
118.
Wang J Zhou Y Wang AF Zhang SH Ning L He PG Fang YZ 《Analytical and bioanalytical chemistry》2005,382(1):198-203
A reliable and reproducible method, capillary zone electrophoresis with amperometric detection (CZE–AD), has been developed for separation and quantification of levodopa methyl ester (LDME) and its biotransformation products levodopa (L-DOPA) and dopamine (DA) in rat serum. A carbon-disk electrode was used as working electrode. The optimum conditions for CZE detection were 50 mmol L–1 phosphate solution at pH 7.0 as running buffer, 17 kV as separation voltage, 1.0 V (vs Ag/AgCl, 3.0 mol L–1) as detection potential, and sample injection for 8 s at 17 kV. The linear ranges were from 2.4×10–2 to 2.2 g mL–1
for LDME, 2.9×10–1 to 49.5 g mL–1 for L-DOPA, and 1.4×10–2 to 1.5 g mL–1 for DA with correlation coefficients of 0.9997, 0.9994, and 0.9999, respectively. The detection limits for LDME, L-DOPA, and DA were 14.6, 98.0, and 9.7 ng mL–1, respectively. Recoveries were 80.3% for LDME, 93.5% for L-DOPA, and 86.5% for DA. This method was applied to serum samples after intravenous injection of LDME and L-DOPA to rats. 相似文献
119.
120.
Michael I. Rosenthal Anthony W. Czarnik 《Journal of inclusion phenomena and macrocyclic chemistry》1991,10(1):119-126
The ability of cyclodextrins to effect rapid transacylations of bound substrates has been well studied. One important difference between cyclodextrin and enzyme-mediated transacylation is the pH required. Because the pK
a of a cyclodextrin secondary-side hydroxyl group is about 12, transacylations are accelerated in the presence of cyclodextrin under basic conditions (pH > 10.5). In 1988, our group reported the synthesis of cyclodextrin with attached cyclen-Co(III) complexes; significant acceleration in the reaction withp-nitrophenyl acetate was observed only with the primary side derivative. Of course, metalloenzymes utilize M2+ and not M3+ catalytic centers; in addition, large rate accelerations in the transacylations of both activated and unactivated substrates have been observed previously in systems utilizing M2+ ions (e.g., Zn, Cu, Ni) as well as M3+ ions (e.g. Co, Ir, Cr). In this paper, we describe the ability of CD-cyclen-M2+ conjugates to transacylate activated esters, amides, and phosphates. In addition, the ability of the apoenzyme mimic to effect transacylations was examined. 相似文献