分光光度法测定对羟基苯甲酸乙酯的含量

对羟基苯甲酸乙酯是药剂和食品常用的防腐剂。对其含量的测定,中国药典采用剩余滴定法。本文利用对羟基苯甲酸乙酯在256nm 波长处有最大吸收,拟定了分光光度法测定对羟基苯甲酸乙酯的含量,对定量条件进行了考察.

L-四氢噻唑-2-硫酮-4-羧酸乙酯的合成

在硫酸铁水合物催化下由L-四氢噻唑-2-硫酮-4-羧酸与乙醇反应得到L-四氢噻唑-2-硫酮-4-羧酸乙酯.

钠代草酰乙酸乙酯的合成及与苯肼的反应

以乙酸乙酯和草酸二乙酯为原料 ,经交叉Claisen酯缩合反应合成钠代草酰乙酸乙酯 .讨论反应时间、碱的浓度、原料配比对反应的影响 .得出较佳工艺条件为∶n(乙醇钠 )∶n(乙酸乙酯 )∶n(草酸二乙酯 ) =1 .0 2∶1 .0 2∶1 .0 0 ,乙醇钠浓度为 1 9.5 % ,反应时间为 4h ,产率为 76% .用此盐与苯肼在酸性条件下进行加成缩合反应可制得 1 苯基 3 羧酸乙酯 5 吡唑啉酮 .产物的结构经红外光谱分析确认 .

氮磷反应型阻燃剂的合成及其阻燃聚氨酯的性能

以多聚甲醛、二异丙醇胺和亚磷酸二乙酯为原料,通过两步反应合成了反应型阻燃剂N,N-二(2-羟异丙基)氨甲基膦酸二乙酯(HPAPE),采用单因素法得到了合成中间体5-甲基-3-(2-羟异丙基)-1,3-恶唑的最佳条件:反应时间为4 h,反应温度为60℃,多聚甲醛与二异丙醇胺的摩尔比为1.2∶1.0,蒸馏压力为18 kPa;利用正交试验得到了合成阻燃剂HPAPE的最佳条件:温度为50℃,时间为5.0 h,反应物料MHPZ与亚磷酸二乙酯的摩尔比为1.0∶1.1,催化剂强酸性阳离子交换树脂用量为反应物料总质量的0.3%。利用极限氧指数(LOI)、垂直燃烧法测试了HPAPE阻燃聚氨酯(PUR)的性能,采用热重分析研究了HPAPE阻燃PUR的热分解过程及成炭性能,并用Proteus Analysis软件计算了其动力学参数热分解活化能。结果发现,HPAPE质量分数为24%时,HPAPE阻燃PUR的LOI为26.2%,阻燃级别可达UL94 V–0级,说明阻燃剂HPAPE对PUR具有明显的阻燃效果。在700℃时,HPAPE阻燃PUR的质量保持率比PUR高4.91%,动力学参数热分解活化能比PUR提高了32.40 kJ/(mol·K),表明阻燃剂HPAPE对PUR的热降解具有加速成炭的功效。

Study on Synthesis and Chloramphenicol Release of Poly（2-hydroxyethylmethacrylate-co-acrylamide） Hydrogels

In this article, poly（2-hydroxyethylmethacrylate-co-acrylamide） hydrogels were synthesized by bulk free-radical copolymerization of 2-hydroxyethylmethacrylate （HEMA） and acrylamide （AAm） for soft contact lens（SCL）-based ophthalmic drug delivery system. The copolymer was characterized with FT-IR and SEM, the swelling property of the hydrogels were studied by gravimetrical method, and chloramphenicol was used as a model drug to investigate drug release profile of the hydrogels. The results showed that poly（2-hydroxyethylmethacrylateco-acrylamide） hydrogels were transparent and useful SCL biomaterial, the water content increased as AAm content increase and pH decrease, and in the same way, hydrogel composition affected chloramphenicol release process too. Migration rate of chloramphenicol increased as the AAm content in the hydrogels increased in the first stage of diffusion process, whereas there was no significant difference thereafter.

Porous alumina ceramic via gelcasting based on2-hydroxyethyl methacrylate dissolved in tert-butyl alcohol

To obtain porous alumina ceramic with high strength,a novel gelcasting system based on 2-hydroxyethyl methacrylate(HEMA)dissolved in tert-butyl alcohol(TBA)was developed.The polymerization of the HEMA-TBA gelcasting system,the thermal behavior of obtained green body,and the microstructures and mechanical properties of the sintered bodies were investigated by rheometer,TG-DSC,SEM and bending strength testing,respectively.The results show that,(1)10 mg/mL of the initiator(benzoyl peroxide)is the optimal amount for polymerization of this gelscasting system at 25 ℃;(2)The alumina suspension of the HEMA-TBA gelcasting system showing shear-thinning behavior is sufficiently low for gelcasting process;(3)The bending strength of porous alumina ceramic samples,whose porosities range from 42% to 56%,is from(8±0.5)to(91±4.5)MPa.

HZSM-35 zeolite catalyzed aldol condensation reaction to prepare acrylic acid and its ester:Effect of its acidic property

Acrylic acid(AA)and its ester,methyl acrylate(MA),were produced by a green one‐step aldol condensation reaction of dimethoxymethane and methyl acetate.The reaction was conducted over ZSM‐35 zeolites with different concentrations of Bronsted acid,which were prepared by the sodium ion‐exchange process with H‐form zeolite.The acidic property of HZSM‐35 was studied in detail through infrared experiments.About 51%of all bridging OH groups were distributed in cages,while 23%and 26%,respectively,were distributed in 10‐and 8‐ring channels.The catalytic performance was enhanced by a high concentration of Bronsted acid,indicating that Bronsted acid is an active site for the aldol condensation reaction.The ZSM‐35 zeolite possessing a concentration of Bronsted acid as high as 0.049 mmol/g demonstrated excellent performance with a MA+AA selectivity of up to 73%.

Grafting of 2-Hydroxyethyl Methacrylate onto Silk by Atom Transfer Radical Polymerization

Silk was grafted using 2-hydroxyethyl methacrylate(HEMA)by atom transfer radical polymerization(ATRP)method.The amino groups and hydroxyl groups on the side chains of the silk fibroin was reacted with 2-bromoisobutyryl bromide(BriB-Br)to obtain efficient macroinitiator for ATRP.And the macroinitiator was grafted with HEMA in water aqueous using CuBr/N,N,N',N",N"-pentamethyldiethylenetriamine(PMDETA)as catalyst system.The effects of monomer concentration,the proportion of CuBr and PMDETA,grafting temperature and time on the silk grafting were discussed,and the optimal grafting technology was obtained.FT-IR characterization of the grafted silk showed a peak corresponding to HEMA,which indicated that HEMA was grafted onto the surface of silk.ATRP method could be applied on the silk modification and this technique provided a new way for silk grafting.

One‐step aldol condensation reaction of dimethoxymethane and methyl acetate over supported Cs/ZSM‐35 zeolite catalysts

This study was performed for the development of a green and promising approach for the synthesis of methyl acrylate and acrylic acid by a one‐step aldol condensation reaction of dimethoxymethane and methyl acetate over cesium oxide‐supported on ZSM‐35 zeolite catalysts; the effect of base sites as well as acid sites on the aldol condensation reaction was studied in detail. It was found that base sites were harmful for aldol condensation due to their failure in catalyzing the decomposition of dimethoxymethane precursor into formaldehyde, whereas the acid site was indispensable for the reaction to proceed. This reaction cannot take place without an acid site. Although acid sites in H‐form of the zeolite（HZSM‐35） are indispensable for the aldol condensation reaction, not all of them tend to favor this reaction. A strong acid catalyzes methanol‐to‐olefin‐like reactions resulting in hydrocarbon byproducts, which are finally transferred to hard coke. Medium strong acids and weak acids are great candidates for the target aldol condensation reaction with high activity and selectivity. A γ‐Al2O3 sample with abundant weak‐strength Lewis acid sites, together with a few medium‐strong‐strength acid sites, performs well with a high activity and considerable stability during the synthesis of methyl acrylate and acrylic acid.

Synthesis and properties of UV curable polyurethane acrylates based on two different hydroxyethyl acrylates

Two kinds of UV curable polyurethane acrylate oligomers （PUPA and PUCA） were synthesized via the addition reaction between isophorone diisocyanate （IPDI） and polyethylene glycol monoacrylate （PEA6） or polycaprolactone modified hydroxyethyl acrylate （PCLA2）. The structures of PUPA and PUCA were characterized by Fourier transform infrared spectroscopy （FT-IR）, IH nuclear magnetic resonance （^H NMR）, gel permeation chromatography （GPC） and differential scanning calorimeter （DSC）, and the thermal stability and dynamic mechanical thermal properties of their cured films were measured by thermogravimetric analysis （TGA） and dynamic mechanical analysis （DMA）, respectively. The viscosity of the oligomers and mechanical properties of the cured films were also studied. The results show that both oligomers have narrow molecular weight distribution. The viscosity of PUPA is 2.310 Pa.s at 25 ℃, while that of PUCA is： up to 3.980 Pa-s. The UV cured PUPA and PUCA films have homogeneous phase structure, and the PUCA film shows higher glass transition temperature and storage modulus. Furthermore, the PUCA film possesses better mechanical properties than PUPA, while the latter shows better alkali resistance.

HIGH SOLIDS-CONTENT NANOSIZE POLYMER LATEXES MADE BY A MODIFIED EMULSION COPOLYMERIZATION

Polymer nanoparticles were prepared in the methyl methacrylate (MMA)/buty lmethacrylate (BA) emulsion copolymerization process by a modified microemulsion copolymerization method. 2-Hydroxyethyl methacrylate(HEMA), acrylate (AA) and methyl acrylate (MAA) were used as reactive cosurfactants. With this process high polymer: surfactant weight ratios (40:1 or greater),relatively concentrated (~30wt. %) latexes and small (~60nm) particle diameters were obtained.Properties of the latexes were characterized by TEM, DSC, dynamic light scattering, and IR spectroscopy.

Crystal Structure of O，O－Diethyl－（α－p－Hydroxyphenyl－β－Nitroethyl）phosphonate

The crystal structure of the title compound C_12H_18NO_6P has been determined by X-ray diffraction methods. It belongs to orthorhombic space group Pabc with cell parameters: a=10. 708(5), b=16.151(4), c=17. 615(2) A, V=3046. 4 A￣3, Z=8, D_c= 1. 39 g/cm￣3, F(000)=1280, μ=29. 77cm￣(-1) (CuKα), M_r= 303. 25 ,R=0. 065, R_w= 0. 055. In the molecule, the P atom is coordinated by three O and one C atoms with a distorted tetrahedral configuration.

Preparation of a pH-sensitive pantoprazole-imprinted polymer and evaluation of its drug-binding and-releasing properties

The aim of this work was to synthesize a pantoprazole-imprinted polymer(MIPs)and study its binding and release properties in an aqueous media.Methacrylic acid(MAA),methacrylamide(MAAM),hydroxyethyl methacrylate(HEMA),and 4-vinyl pyridine(4VP)were tested as functional monomers.Different solvents were also applied as polymerization media under heat or UV radiation.The optimized MIP was prepared in chloroform as a solvent,4-vinyl pyridine as a functional monomer,and ethylene glycole dimethacrylate(EGDMA)as a crosslinker monomer under UV irradiation.Binding and release properties of MIP were studied in comparison with a non-imprinted polymer(NIP)in aqueous media,at different pH values.The protective effect of polymer for drugs against acidic conditions was evaluated at pH 2.Results indicated that the MIP had superior binding properties compared to NIP for pantoprazole.The percentage of drug released from MIP was significantly less than from NIP at all pH values,which was attributed to the presence of imprinted cavities in the MIP matrix.MIP also had a stronger protective effect for pantoprazole in acidic media,in comparison with NIP.

Determination and pharmacokinetic study of p-hydroxyphenethyl anisate following intravenous and oral administration in rats by RP-HPLC method

In the present study,we developed a rapid and specific reversed-phase high-performance liquid chromatographic(RP-HPLC)method for the quantification of p-hydroxyphenethyl anisate(HPA),one of the main bioactive constituents of the roots and rhizomes of Notopterygium incisum and N.franchetii,in rat plasma after an intravenous(20 mg/kg,i.v.)and an intragastrical(200 mg/kg,i.g.)administration to rats,respectively.The method involved a plasma clear-up step using liquid-liquid extraction by EtOAc,followed by RP-HPLC separation and detection.Separation of HPA was performed on an analytical DiamonsilTM ODS C18 column with the mobile phase of MeOH-H2 O at ratios of 75:25(v/v)for i.v.and 70:30(v/v)for i.g.administration.The flow-rate was 1.0 mL/min,and UV detection was performed at 256 nm.The calibration curves were linear over the ranges of 0.05-5.0μg/mL(r2=0.9984)for i.v.and 0.5-10.0μg/mL(r2=0.9995)for i.g.administration in rat plasma.The extraction recoveries were in the range of82.01%-87.97%.The intra-and inter-day precisions were between 1.71%and 3.99%,with accuracies ranging from 91.22%to110.5%.The absolute bioavailability of an orally administered HPA in rats was about 48.17%.The developed method was suitable for the determination and pharmacokinetic study of HPA in rat plasma.

States of Water in Hydrogels Containing with Glyceryl Methacrylate

Hydrogel materials were prepared by thermopolymerization with different content of glyceryl methacrylate and hydroxyethyl methacrylate. The different states of water in swelling hydrogels were described and studied by differential scanning calorimetry(DSC). It was found that the hydrophilicity of GMA was stronger than HEMA,the water content and bound water of GMA hydrogel are higher than HEMA hydrogel.With the increase of GMA content, the content of free water in hydrogel increased. When GMA content was lower than 50%, the increase of GMA content also increased the content of bound water; but when GMA content was higher than 50%, the increase of GMA content decreased the content of bound water, which was caused by the chain hydrogen bond formed on the GMA chain with hydroxyl group each other.