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Y. Wolman 《Israel journal of chemistry》1967,5(5):231-236
The use of 2-nitro-4-methoxy-phenylsulfenyl-(I) as an amino protecting group which is extremely sensitive towards electrophilic attack in the synthesis of amino penicillins (amino-penicillin and DL-α-amino-benzylpenicillin) is described. Synthesis of few protected dipeptides (2-nitro-4-methoxyphenylsulfenyl-L-phenylalanyl-L-valine, 2-nitro-4-methoxyphenylsulfenyl-L-phenylalanyl-L-phenylalanine and 2-nitro-4-methoxyphenylsulfenyl-L-valyl-L-phenylalanine) demonstrates the use of the protecting group in peptide synthesis. 相似文献
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合成了稀土高氯酸盐与咪唑、DL α 丙氨酸的4种配合物晶体。经傅里叶变换红外光谱(FTIR)、元素分析和化学分析测定后确定其组成为[Ln(C3H7NO2)x(C3H4N2)(H2O)](ClO4)3(Ln=La,x=3;Ln=Pr,Nd,Sm,x=2)。用差示扫描量热法(DSC)测定了4种配合物的热分解数据,4个配合物开始熔化分解的温度分别为502 5K,532 4K,495 7K,516 7K,配合物有较高的热稳定性。 相似文献
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DL-414铝酸酯偶联剂的性质及其在天然橡胶中的应用 总被引:3,自引:0,他引:3
叙述了含有双键的DL - 41 4铝酸酯偶联剂的性质及其在天然橡胶中的应用。结果表明 :DL - 41 4能溶于多种有机溶剂 ,热稳定性高 ,降粘性能好 ,降粘幅度达 98%。经 1 %DL - 41 4改性的活性碳酸钙填充于天然橡胶中 ,与碳酸钙填充的相比 ,胶料焦烧时间、正硫化时间均缩短 ,硫化速度加快 ,体系的转矩减小 ,流动性能得到改善 ,硫化胶的拉伸强度、扯断伸长率等机械性能也得到提高。 相似文献
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Lyophilized preparations of the soil amoeba Mayorella palestinensis hydrolyzed hemoglobin. Maximum cleavage occurred near pH 3. Mercapto compounds enhanced the activity only slightly, versene and iodoacetamide had no influence. Synthetic oligopeptides were also hydrolyzed by the preparations. Maximum degree of cleavage occurred at neutral or slightly alkaline pH values. While L-leucylglycine was readily hydrolyzed, the D-isomer of this peptide was not attacked. With DL-leucylglycine 50% cleavage was obtained. Carbobenzoxy-glycyl-L-phenylalanine and DL-α-bromoisocaproyl glycylglycine were not hydrolyzed while glycyl-L-phenylalanine and DL-leucylglycylglycine were readily cleaved. Hemoglobin was very poorly hydrolyzed by the preparations at neutral or slightly alkaline pH values. However, preincubation of hemoglobin with the preparations at pH 2.7 rendered it available for further appreciable hydrolysis at pH 8. The significance of these findings for understanding the process of protein digestion in the food vacuole of protozoa is discussed. 相似文献
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以DL-丝氨酸为原料,先采用氨基酸关环法化学合成酶的作用底物———DL-5-羟甲基海因,收率93.5%。然后,该底物在酶的作用下,起始pH=9.0,培养温度38℃,转化时间42 h,经过一系列的酶解反应即得到D-丝氨酸,收率为81.7%。 相似文献
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分别采用低不饱和度聚醚多元醇DL-1000D和氧氧化钾体系聚醚多元醇DL-1000与TDI-80反应合成出聚氨酯预聚体,比较了2种不同聚醚多元醇合成预聚体的工艺性能、预聚体的稳定性和由它们合成聚氨酯弹性体制品的力学性能和耐磨性能。结果表明,二者的丁艺性能和稳定性相当,采用前者合成的聚氨酯弹性体的力学性能比后者高10%左右,耐磨性能按阿克隆磨耗测试提高17.6%。 相似文献
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Sulphochlorinated and chloromethylated polystyrene reacted with D-α-phenyl-ethylamine, D-ephedrine, D-alanine, L-alanine, L-alanine methyl ester, L-alanine benzyl ester, L-phenyl-alanine and D-α-aminophenylacetic acid yielding asymmetric polymers. These polymers were used as specific adsorbents for the chromatographic resolution of racemates. The influence of the different substituents in the asymmetric centre of the polymers and the racemates on the resolution was investigated. DL-Mandelic acid and DL-α-aminophenylacetic acid could be partially resolved, using different eluents, on the polymers, prepared from polystyrenesulphonyl chloride and optically active amino acids. Polymers prepared from polystyrenesulphonyl chloride and L-alanine esters showed stereoselective adsorption power only after the saponification of the ester groups to the free carboxyl groups. An exchange of the carboxyl group by a methyl group on the asymmetric C-atom of the polymers and also of the racemates leads to a loss of resolution activity, -respectively- separability. The replacement of the benzyl- or methyl-groups by a phenyl group showed a much greater influence on the resolution effect in the racemates than in the polymers. The presence of a (? SO2? NH? )-bridge, in comparison to a (? CH2-NH? )-bridge, between the matrix polymer and the optically active component increased the resolution activity. The difference in the firmness of the binding of the antipode over a hydrogen bridge linkage in the polymer was thought to be the reason for the partial resolution of the racemates. 相似文献
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以α,w-二羟基聚二甲基硅氧烷(WS-62M),N—B-氨乙基-1-氨丙基甲基二甲氧基硅烷(DL-602),单端环氧聚醚(X-09)为主要原料,合成了-系列聚醚改性氨基聚硅氧烷,探讨了最佳改性条件,并考查了DL-602用量【n(X-09):n(DL-602)]对聚醚改性氨基硅油乳液性能及其应用性能的影响。结果表明,以异丙醇作溶剂,偶联剂用量为11%,n(DL-602):n(X-09):1:3,80℃下反应4h为最佳反应条件;所制聚醚改性氨基硅油乳液稳定性好,用该乳液整理的织物其白度有所提高,硬挺度和悬垂系数有所下降。 相似文献
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氨基聚硅氧烷皮革手感剂的合成研究 总被引:19,自引:3,他引:16
以八甲基环四硅氧烷 (D4)、N β 氨乙基 γ 氨丙基甲基二甲氧基硅烷 (DL - 10 3)、六甲基二硅氧烷 (MM)为原料 ,KOH为催化剂 ,二甲基亚砜 (DMSO)为促进剂 ,通过本体聚合进行共聚反应 ,合成了适用于皮革手感剂的氨基聚硅氧烷 (氨值为 0 .6 ,2 5℃时黏度为 2 .4× 10 4mPa·s,外观为无色透明黏稠状液体 )。最优合成条件为 :93 .71gD4,6 .19gDL - 10 3 ,0 .10gMM ,w(KOH) =0 .12 % ,w(DMSO) =1.0 0 % (相对于D4、DL - 10 3与MM的总质量 ) ,反应温度 90℃ ,反应时间 6h ,抽真空时间 3h(在 0 .0 1MPa条件下 )。 相似文献
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不同偶联剂对苯丙乳液的改性效果 总被引:2,自引:2,他引:0
采用核壳乳液聚合法,利用前期研究已确定的核壳乳液合成配方,分别将不同种类和用量的硅烷偶联剂[γ-氨丙基三乙氧基硅烷(KH-550)、γ-(2,3-环氧丙氧)丙基三甲氧基硅烷(KH-560)以及乙烯基三乙氧基硅烷(DL-151)]引入到苯丙乳液中,制得有机硅改性苯丙乳液。利用差示扫描量热分析(DSC)法、透射电镜(TEM)法和粒度分析法等多种检测手段,研究了偶联剂的种类与用量对乳液性能(包括粒径及其分布、钙离子稳定性、黏度、玻璃化转变温度及乳胶粒的核壳结构等)和乳胶膜性能(包括成膜性、吸水率、耐水性、附着力和铅笔硬度等)的影响。结果表明:乳胶粒的平均粒径最小为115 nm;DL-151和KH-560对苯丙乳液的改性效果较好,可以考虑将两者复配后共同改性苯丙乳液,以期获得综合性能较好的改性苯丙乳液。 相似文献
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以二苯基甲烷二异氰酸酯(MDI)和甲苯二异氰酸酯(TDI)共混二异氰酸酯为原料,合成一系列聚氨酯弹性体制品,讨论了MDI/TDI摩尔比、扩链剂种类、聚醚多元醇种类等对聚氨酯弹性体制品性能的影响。结果表明,当MDI/TDI摩尔比为1∶1时,具有最高的伸长率,但拉伸强度和撕裂强度有所降低;以3,3′-二氯-4,4′-二苯基甲烷二胺(MOCA)作为扩链剂时,性能优于3,5-二甲硫基甲苯二胺(E-300)和1,4-丁二醇(BDO);采用聚醚DL-1000合成聚氨酯弹性体时,其拉伸强度和撕裂强度优于聚醚DL-2000,但伸长率降低。 相似文献
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两种硅烷偶联剂同时改性苯丙乳液的制备与性能研究 总被引:1,自引:0,他引:1
以十二烷基硫酸钠(SDS)和OP-10为乳化剂,采用种子乳液聚合法将硅烷偶联剂γ-(2,3-环氧丙氧)丙基三甲氧基硅烷(KH-560)、乙烯基三乙氧基硅烷(DL-151)引入苯丙共聚物中,制备两种硅烷偶联剂同时改性核壳型苯丙乳液。采用红外光谱(FT-IR)法、粒径分析(PSA)法和差示扫描量热(DSC)法等手段对改性乳液的结构、粒径大小及其分布等进行了表征,并对其应用性能进行了测定。结果表明:当w(KH-560+DL-151)=5%、n(KH-560)=n(DL-151)时,改性乳液及其乳胶膜的综合性能最佳;其平均粒径为146 nm,粒径多分散性指数仅为0.205,玻璃化转变温度(Tg)分别为-35.63、48.31℃,吸水率为0.55%,铅笔硬度为2H,并且其成膜性、附着力及耐水性等俱佳。 相似文献