(S)-2-(ethyl propionate)-(O-ethyl xanthate)- and (S)-2-(Ethyl isobutyrate)-(O-ethyl xanthate)-mediated RAFT polymerization of vinyl acetate

(S)-2-(Ethyl propionate)-(O-ethyl xanthate) (X1) and (S)-2-(Ethyl isobutyrate)-(O-ethyl xanthate) (X2) were used as the reversible addition-fragmentation chain transfer (RAFT) agents for the radical polymerization of vinyl acetate (VAc). The former showed the better chain transfer ability in the polymerization at 60°C. Kinetic study with both RAFT agents showed pseudo-first order kinetics up to around 85% monomer conversion. Molecular weight of the resulting polymer increased linearly with increase in the monomer conversion up to around 85%. The observed molecular weights calculated from ¹H-NMR spectrum [M_n(NMR)] are close to the corresponding theoretical molecular weights [M_n(theor)]. The corresponding polydispersity index (PDI) of the resulting polymers remained almost constant at around 1.2 up to ∼ 65% monomer conversion and then increased gradually with the further increase in the monomer conversion. Chain-end analysis of the resulting polymers by ¹H-NMR showed clearly that polymerization started with the radical forming out of the xanthate mediator. The negligible homo-chain extension and the hetero-chain extension involving synthesis of poly(VAc)-b-poly(NVP) diblock copolymer were occurred. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Synthesis of fluorescence poly(N-vinylpyrrolidone) via click chemistry using azide-terminated xanthate mediator (S)-2-(4-azidobutyl propionate)-(O-ethyl xanthate)

Azide-terminated xanthate RAFT agent (S)-2-(4-azidobutyl propionate)-(O-ethyl xanthate) has been synthesized and used for the controlled radical polymerization of N-vinylpyrrolidone (NVP). Kinetics study showed the pesudo first-order kinetics along with gradual increase in molecular weight (M_n) of the resulted polymer up to 69% conversion. Chain-end analysis of the resulted polymer by ¹H NMR showed the presence of the fragments of xanthate mediator at both chain ends. Successful chain extension has also been performed via the click reaction of alkyne-terminated PNVP with azide-terminated PNVP. Moreover, fluorescence pyrene-tagged PNVP has successfully been made via the click reaction of alkyne-functionalized pyrene with azide-terminated PNVP.     

O-乙基黄原酸丙酸乙酯的工艺优化

对O-乙基黄原酸丙酸乙酯的合成工艺进行改进,以氢氧化钾、二硫化碳、2-溴丙酸乙酯为原料,以无水乙醇为溶剂,经两步反应,成功制备了黄原酸酯链转移剂O-乙基黄原酸丙酸乙酯。对第2步合成利用正交实验探究了反应时间、反应温度、反应物料摩尔比(乙基黄原酸钾与2-溴丙酸乙酯的摩尔比)对反应收率的影响。结果表明,O-乙基黄原酸丙酸乙酯的产率的优化条件是乙基黄原酸钾与2-溴丙酸乙酯的摩尔比1.1∶1,反应时间为12 h,反应温度为55℃。各因素对合成O-乙基黄原酸丙酸乙酯的产率的影响按大小排列分别为:温度反应物摩尔比反应时间。两步总收率可达62.2%,远高于文献报道的47.0%。     

O-乙基黄原酸丙酸乙酯的工艺优化

对O-乙基黄原酸丙酸乙酯的合成工艺进行改进,以氢氧化钾、二硫化碳、2-溴丙酸乙酯为原料,以无水乙醇为溶剂,经两步反应,成功制备了黄原酸酯链转移剂O-乙基黄原酸丙酸乙酯。对第2步合成利用正交实验探究了反应时间、反应温度、反应物料摩尔比(乙基黄原酸钾与2-溴丙酸乙酯的摩尔比)对反应收率的影响。结果表明,O-乙基黄原酸丙酸乙酯的产率的优化条件是乙基黄原酸钾与2-溴丙酸乙酯的摩尔比1.1∶1,反应时间为12 h,反应温度为55℃。各因素对合成O-乙基黄原酸丙酸乙酯的产率的影响按大小排列分别为:温度>反应物摩尔比>反应时间。两步总收率可达62.2%,远高于文献报道的47.0%。     

链转移剂O-乙基黄原酸丙酸乙酯的合成

以KOH、CS2和2-溴代丙酸乙酯为原料在无水乙醇中反应合成了一种新型的RAFT聚合链转移剂O-乙基黄原酸丙酸乙酯,通过红外光谱和核磁共振氢谱对其结构进行了表征和分析,确证所制备最终产物为目标产物。     

Synthesis and pH-dependent micellization of 2-(diisopropylamino)ethyl methacrylate based amphiphilic diblock copolymers via RAFT polymerization

The polymerization of 2-(diisopropylamino)ethyl methacrylate (DPA) by RAFT mechanism in the presence of 4-cyanopentanoic acid dithiobenzoate in 1,4-dioxane was studied. The DPA homopolymer was employed as a macro chain transfer agent to synthesize pH-sensitive amphiphilic block copolymers using poly(ethylene glycol) methyl ether methacrylate (PEGMA) as the hydrophilic block. ¹H NMR and GPC measurements confirmed the successful synthesis of these copolymers. Potentiometric titrations and fluorescence experiments proved that the copolymers underwent a sharp transition from unimers to micelles at a pH of ∼6.7 in phosphate buffered saline solutions. It was found that the hydrophilic/hydrophobic balance of these block copolymers had no apparent effect on their pH-induced micellization behaviors. The DLS investigation revealed that the micelles have a mean hydrodynamic diameter below 60 nm with a narrow size distribution.     

The direct polymerization of 2-methacryloxyethyl glucoside via aqueous reversible addition-fragmentation chain transfer (RAFT) polymerization

A preliminary study on the direct controlled radical polymerization of a glycomonomer, namely 2-methacryloxyethyl glucoside (MAGlu), under reversible addition-fragmentation chain transfer (RAFT) polymerization conditions in aqueous media has been conducted. This represents the first example detailing the direct polymerization of a sugar monomer via RAFT and, significantly, has been conducted without protecting group chemistry. 4-Cyano-4-methyl-4-thiobenzoylsulfanyl butyric acid (CTP) was employed as the RAFT chain transfer agent (CTA) due to its inherent water-solubility and its applicability for methacrylic monomers. The homopolymerization displays all the characteristics of a controlled/‘living’ polymerization—linear increase in M_n with conversion, pseudo-first order kinetics, the final polymers have narrow molecular distributions and novel block copolymers can be prepared.     

二甘醇单丁醚醋酸酯的合成及应用

本法以二甘醇单丁醚和醋酐为原料,在Fe_2(SO_4)_3·10H_2O的催化下合成二甘醇单丁醚醋酸酯。并给出了几个应用实例。     

2—（2—氨基噻唑—4—基）—2—甲氧基亚氨基乙酸乙酯的合成

以乙酰乙酸乙酯为起始原料,经肟化、甲基化、溴化和缩合四步反应合成2-(2-氨基噻唑-4-基)-2-甲氧基亚氨基乙酸乙酯,总收率63.14％,高于文献报道。     

一种有效制备2-(2-羟基苯基)-2-氧乙酸乙酯的方法

以环己酮和乙醛酸乙酯为原料,首先经酸性催化的Aldol缩合得中间体2-羟基-2-(2'-氧环己基)乙酸乙酯(Ⅶ),接着Ⅶ在碘酸-二甲基亚砜(HIO3-DMSO)体系下氧化、芳构化制得2-(2-羟基苯基)-2-氧乙酸乙酯(Ⅰ)。得到的最佳工艺条件为:以三氟乙酸为催化剂,n(乙醛酸乙酯)∶n(环己酮)=1∶10时,Ⅶ的收率为65.4%;氧化、芳构化反应中,n(HIO3)/n(Ⅶ)=2.0时,产物Ⅰ的收率为60.0%;对Ⅰ的结构进行了1HNMR,13CNMR和MS表征。     

R(+)对羟基苯氧基乳酸甲酯的合成

报道了一种合成高效除草剂精吡氟氯禾灵的中间体R( )对羟基苯氧基乳酸甲酯的方法。以L-乳酸为原料,控制温度为58％,反应时间为5h,得到的产物经HPLC分析纯度达到98．4％,总收率达到73.4％。     

α-甲基-缩二乙醇酸二乙酯的合成

采用重氮乙酸乙酯(EDA)与乳酸乙酯在无水硫酸铜催化下进行O-H插入反应合成α-甲基-缩二乙醇酸二乙酯。讨论了反应时间,催化剂用量,反应温度和物料比例对插入反应收率的影响,在优化反应条件下产率为58.8%。产品纯度大于98%。     

生物催化不对称还原方法生产S-4-氯-3-羟基丁酸乙酯

通过筛选得到不对称还原4-氯乙酰乙酸乙酯(COBE)合成(S)-4-氯-3-羟基丁酸乙酯(S-CHBE)对映选择性好的微生物菌株出芽短梗霉菌(Aureobasidium pullulans)SW0202. 对其还原反应条件进行优化,得到最佳转化条件为：初始细胞浓度0.32 g/mL(以湿菌体计),底物浓度20 g/L,pH 7.0,温度30℃. 在此优化条件下,产物浓度达20.32 g/L,摩尔转化率为79.6%,产物对映体过量值e.e.为97.8%. 分批添加底物可显著减小底物的抑制作用.     

2-(4-苯氧基苯基)乳酸乙酯的合成研究

以二苯醚与丙酮酸乙酯为原料,经傅克酰基化一步合成恶唑菌酮关键中间体2-(4-苯氧基苯基)乳酸乙酯,考察了溶剂、投料比、AlCl3用量、缚酸剂、温度对收率的影响。-25℃,CH2Cl2为溶剂,NaHCO3为缚酸剂,n(二苯醚)∶n(丙酮酸乙酯)∶n(AlCl3)=1.4∶1.0∶1.2,2-(4-苯氧基苯基)乳酸乙酯收率86.2%,目标产物结构经IR、1 H NMR确证。     

Synthesis and polymerization of 2-(β-N-ethylenediphenylamine)-2-oxazoline

Summary The synthesis of 2-(-N-ethylenediphenylamine)-2-oxazoline and its living cationic polymerization in the presence of methyltosylate are described. This 2-substituted 2-oxazoline was used for the synthesis of a ABA triblock copolymer with poly(N--(N-diphenylamine)propionylethylenimine) as A block and poly(ethyleneglycoladipate) as B block.     

(Z)-2-(2-氨基-4-噻唑)-2-羟亚胺基乙酸乙酯的合成工艺改进

以乙酰乙酸乙酯为原料 ,经亚硝化、溴化、环合连续反应制得 (Z) 2 (2 氨基 4 噻唑 ) 2 羟亚氨基乙酸乙酯 ,总收率为 76 73% ,含量为 98 5 %。对合成工艺进行了改进 ,简化了操作 ,提高了反应收率。     

Synthesis of polyvinyl alcohol stereoblock copolymer via the combination of living cationic polymerization and RAFT/MADIX polymerization using xanthate with vinyl ether moiety

Different types of novel xanthates containing a vinyl ether moiety, S-benzyl O-2-(vinyloxy)ethyl carbonodithioate (Xanthate 1) and S-1-(ethoxycarbonyl)ethyl O-2-(vinyloxy)ethyl carbonodithioate (Xanthate 2) were synthesized. In particular, the Xanthate 2 enabled to design polyvinyl alcohol (PVA) stereoblock copolymer via the combination of living cationic vinyl polymerization and RAFT/MADIX polymerization. For cationic polymerization of isobutyl vinyl ether (IBVE) and tert-butyl vinyl ether (TBVE), the polymerizations were conducted under Xanthate 1-HCl adduct/SnCl₄ and Xanthate 1 or 2-CF₃COOH adduct/EtAlCl₂ initiating system in the presence of ethyl acetate. Both systems proceeded in living polymerization fashion because the calculated M_n of both poly(IBVE) and poly(TBVE) matches with the M_n polymerized assuming that one polymer chain is formed per one molecule of the Xanthate 1 or 2. The resulting poly(TBVE) had a high number average α-end functionality as determined by MALDI-TOF-MS spectrometry. Xanthate 2 is more efficient for the following RAFT/MADIX polymerization of vinyl acetate (VAc). The RAFT/MADIX polymerization of vinyl acetate (VAc) using azobis(isobutyronitrile) (AIBN) at 60 °C was conducted using either poly(IBVE) or poly(TBVE) macro-CTA. The poly(TBVE) macro-CTAs synthesized from the Xanthate 2 were able to polymerize VAc smoothly via RAFT/MADIX polymerization, to prepare well-defined diblock copolymer, poly(TBVE)-b-poly(VAc). The resulting block copolymer was then hydrolyzed using KOH in methanol and followed by acid hydrolysis using HBr gas bubbling. The resulting polymer is inherently stereoblock like copolymer, isotactic rich PVA-b-atactic PVA (iPVA-b-aPVA). From the DSC measurement, the iPVA-b-aPVA has one glass transition at 69.5 °C and two melting points according to iPVA and aPVA at 237.9 and 198.1 °C, respectively. Thus, it can be suggested that the obtained PVA has two different geometries by the combination of living cationic polymerization and RAFT/MADIX polymerization.     

(2S,4E)-5-氯-2-异丙基-4-戊烯酸乙酯的简易合成

以异戊酸乙酯与(E)-1,3-二氯丙烯为原料,通过烷基化反应得到(±)-(4E)-5-氯-2-异丙基-4-戊烯酸乙酯,经猪肝酯酶催化(进行动力学拆分)得到纯阿利克仑(Aliskiren)中间体(2S,4E)-5-氯-2-异丙基-4-戊烯酸乙酯。通过回收拆分母液以88%的收率得到(2R,4E)-5-氯-2-异丙基-4-戊烯酸。该方法绿色环保,操作简洁易行,具有工业化应用前景。     

(S)-(+)-2-(2-萘)-2-N-甲基氨乙醇的合成与表征

以β-萘乙烯为原料,通过烯烃的Sharpless不对称双羟化、环化、开环、催化氢化、甲酰化、还原等6步反应,生成标题化合物,总产率以β-萘乙烯计为39.7%,e.e.值高达97%~99%。对产物进行了质谱、红外光谱、1HNMR和13CNMR表征。