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采用高能球磨法制备了3NaBH4/ErF3复合储氢材料, 并研究了其相结构和储氢性能. X射线衍射(XRD)显示, NaBH4和ErF3在球磨过程中未发生反应; 同步热分析(TG-DSC)测试结果表明, 3NaBH4/ErF3体系在420℃开始放氢, 比相同测试条件下纯NaBH4的放氢温度降低了约100℃, 放氢量为3.06%(质量分数). 压力-成分-温度(Pressure-Composition-Temperature, PCT)性能测试结果显示, 3NaBH4/ErF3复合储氢材料在较低的温度(355~413℃)及平台氢压(<1 MPa)下即拥有良好的可逆吸放氢性能, 最高可逆吸氢量可达到2.78%(质量分数), 吸氢后体系重新生成了NaBH4相. 计算得吸氢焓变仅为-36.8 kJ/mol H2; 而放氢焓变为-180.8 kJ/mol H2. NaBH4在ErF3的作用下提高了热动力学性能, 并实现了可逆吸放氢. 相似文献
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通过测试线性扫描伏安曲线研究了MmNi3.2Al0.2Mn0.6Co1.0(Mm为混合稀土)经KOH处理和MnO2掺杂对催化NaBH4电氧化性能的影响.发现NaBH4在经KOH处理后的合金上峰电流达到50mA/cm2.若再进行MnO2掺杂,其电催化活性会进一步提高,当掺杂MnO2的质量分数为10%时,MmNi3.2Al0.2Mn0.6Co1.0对NaBH4电氧化的峰电位和峰电流密度分别为-0.45V和126mA/cm2,峰电流密度为只经过KOH处理的合金的2.5倍,是未经过任何处理的合金的9倍. 相似文献
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本文首次将一系列α-芳香族酮酸通过与钛酸醇酯[Ti(OR^1)~4]的交换反应制备成钛羧酸盐, 随后将它与锂试剂反应。在此体系中锂试剂发生了一个未见报道的新反应: 将α-芳香族酮酸还原为相应的α-羟基羧酸。进一步研究表明: 锂试剂同时可以发生加成反应, 且因Ti(OR^1)~4, 酮酸和锂试剂的不同, 加成与还原的比例也随之不同。 相似文献
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本文首次将一系列α-芳香族酮酸通过与钛酸醉酯[Ti(OR~1)_4]的交换反应制备成钛羧酸盐,随后将它与锂试剂反应.在此体系中锂试剂发生了一个未见报道的新反应:将α-芳香族酮酸还原为相应的α-羟基羧酸.进一步研究表明,锂试剂同时可以发生加成反应,且因Ti(OR~1)_4,酮酸和锂试剂的不同,加成与还原的比例也随之不同. 相似文献
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tert-Alkyl amino hydroxy carboxylic acids are abundantly present within the structure of many biologically active natural products. We describe herein the synthesis of these substrates using an oxazolone-mediated ene-type reaction with enol ethers followed by NaBH4 reduction of the intermediate oxazolone. 相似文献
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(R,R)-Salen-based chiral polymer P-1 was synthesized by the polymerization of 5,5'-((2,5-dibutoxy-1,4-phenylene)bis(ethyne-2,1-diyl))bis(2-hydroxy-3-(piperidin-1-ylmethyl) benzaldehyde (M-1) with (1R,2R)-cyclohexane-1,2-diamine (M-2) via nucleophilic addition- elimination reaction, and (R,R)-salan-based polymer P-2 could be obtained by the reduction reaction of P-1 with NaBH(4). (R,R)-Salen-based chiral polymer P-1 can exhibit greater fluorescence enhancement response toward (l)-α-hydroxyl carboxylic acids, and the value of enantiomeric fluorescence difference ratio (ef) can reach as high as 8.41 for mandelic acid and 6.55 for lactic acid. On the contrary, (R,R)-salan-based chiral polymer P-2 shows obvious fluorescence quenching response toward α-hydroxyl carboxylic acids. Most importantly, (R,R)-salen-based polymer P-1 can display bright blue fluorescence color change in the presence of (l)-α-hydroxyl carboxylic acids under a commercially available UV lamp, which can be clearly observed by the naked eyes. 相似文献
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Du Chen Liangxuan Xu Yi Yu Qinliang Mo Xiaotian Qi Prof. Dr. Chao Liu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2023,135(2):e202215168
Building up new and efficient methods for the controlled conversion of carboxylic acids to aldehydes is important. Herein, we report a rapid, modular and scalable method for the conversion of carboxylic acids to aldehydes using pinacolborane at ambient temperature, in which a triflylpyridinium reagent is used. The conversion of carboxylic acid to intermediate acylpyridinium by triflylpyridinium is new. A binary pyridine-coordinated boronium complex is generated after reduction. The unprecedented reduction of the acylpyridinium by HBpin opens up a practically direct synthesis of aldehydes from carboxylic acids. Theoretical studies indicate that the reduction of acylpyridinium requires a lower activation free energy than that of the product aldehyde. The synthetic advantage of this protocol is further highlighted by the scalable synthesis of aldehyde via continuous flow process. Configuration retention for chiral acids are presented in those syntheses. 相似文献
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The Mitsunobu reaction is a widely used and versatile method for the dehydrative oxidation–reduction condensation of an acid/pronucleophile usually with a primary or secondary alcohol that requires the combination of a reducing phosphine reagent together with an oxidizing azo reagent. The utility of this reaction stems from the fact that it is generally highly stereoselective and occurs with inversion of the stereochemical configuration of the alcohol starting material. Furthermore, as carboxylic acids, phenols, imides, sulfonamides, and other compounds can be used as the acid/pronucleophile, this reaction is useful for the preparation of a wide variety of functional groups. This Focus Review of the Mitsunobu reaction summarizes its origins, the current understanding of its mechanism, and recent improvements and applications. 相似文献
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1 Introduction
Nowadays, green chemistry has received increased attention. The use of water and scCO2 as a solvent or reagent is an important field for organic reactions and green chemistry both in laboratory and industry. 相似文献
Nowadays, green chemistry has received increased attention. The use of water and scCO2 as a solvent or reagent is an important field for organic reactions and green chemistry both in laboratory and industry. 相似文献
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2-Thiazolines are synthesized from carboxylic acids and 1,2-aminoalcohols in the presence of Lawesson's reagent under solventless conditions. The developed method is valid for either substituted or unsubstituted aminoalcohols and a wide variety of aromatic, heteroaromatic and aliphatic carboxylic acids; thus it constitutes a general synthetic method for these kinds of compounds. The role of Lawesson's reagent is dual: to transform the 1,2-aminoalcohol into 1,2-aminothiol and to activate its reaction with the carboxylic acid leading to the formation of a thiazoline ring, all in one pot. 相似文献
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A variety of optically active carboxylic esters are produced by the kinetic resolution of racemic secondary benzylic alcohols using free carboxylic acids with benzoic anhydride and tetramisole derivatives. 4-Methoxybenzoic anhydride (PMBA) is the best reagent to use in producing the corresponding esters in high ee when the reaction is catalyzed by (+)-benzotetramisole (BTM); by contrast, when non-substituted benzoic anhydride is used as a coupling reagent, the resulting optically active alcohols are obtained with high selectivities. This protocol directly produces chiral carboxylic esters from free carboxylic acids and racemic secondary alcohols by utilizing the trans-acylation process to generate mixed anhydrides from acid components and benzoic anhydride derivatives under the influence of chiral catalysts. 相似文献
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A novel fluorescent derivatization reagent for carboxylic acids, 6-oxy-(acetyl ethylenediamine) fluorescein (AEF), was well designed, synthesized, and applied to HPLC. The derivatization reaction with 12 fatty acids, including n-valeric acid (C5), n-hexanoic acid (C6), n-heptanoic acid (C7), n-octanoic acid (C8), n-nonanoic acid (C9), n-decanoic acid (C10), lauric acid (C12), myristic acid (C14), palmitic acid (C16), stearic acid (C18), oleic acid (C18:1), and linoleic acid (C18:2), was completed at 55 degrees C within 40 min. The derivatives of fatty acids were separated on a C18 RP column and detected by fluorescence detection. The LODs attained were 0.4-1.2 nM (S/N of 3). It has been demonstrated that AEF is a prominent derivatization reagent for carboxylic acids which is suitable for HPLC. 相似文献
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Tomohiro Kuwabara Takahiro Takayama Kenichiro Todoroki Koichi Inoue Jun Zhe Min Toshimasa Toyo’oka 《Analytical and bioanalytical chemistry》2014,406(11):2641-2649
Mass spectrometry has become a popular analytical tool because of its high sensitivity and specificity. The use of a chiral derivatization reagent for the mass spectrometry (MS) detection seems to be efficient for the enantiomeric separation of racemates. However, the number of chiral reagents for the liquid chromatography (LC)–MS/MS analysis is very limited. According to these observations, we are currently in the process of developing novel labeling reagents for chiral molecules in MS/MS analysis. The derivatization reagent that is effective for enhancing not only the electrospray ionization–MS/MS sensitivity but also the reversed-phase LC resolution of carboxylic acid enantiomers should have a highly proton-affinitive moiety and an asymmetric structure near the reactive functional group. Furthermore, the resulting derivative has to provide a characteristic product ion suitable for the selected reaction monitoring. Based upon these considerations, a series of prolylamidepyridines ((S)-N-pyrrolidine-2-carboxylic acid N-(pyridine-2-yl)amide (PCP2), (S)-N-pyrrolidine-2-carboxylic acid N-(pyridine-3-yl)amide, and (S)-N-pyrrolidine-2-carboxylic acid N-(pyridine-4-yl)amide) was synthesized as ideal labeling reagents for the enantioseparation of chiral carboxylic acids and evaluated in terms of separation efficiency and detection sensitivity by ultra-performance LC (UPLC)–MS/MS. Among the synthesized reagents, PCP2 was the most efficient chiral derivatization reagent for the enantioseparation of carboxylic acid. The Rs values and the detection limits of the derivatives of non-steroidal anti-inflammatory drugs, which were selected as the representative carboxylic acids, were in the range of 2.52–6.07 and 49–260 amol, respectively. The sensitive detection of biological carboxylic acids (detection limits, 32–520 amol) was also carried out by the proposed method using PCP2 and UPLC–MS/MS. The PCP2 was applied to the determination of carboxylic acids in human saliva. Several biological carboxylic acids, such as lactic acid (LA), 3-hydroxybutylic acid, maric acid, succinic acid, α-ketoglutalic acid, and citric acid, were clearly identified in the saliva of healthy persons and diabetic patients. Furthermore, the ratio of d-LA in diabetic patients was higher than that in normal subjects. Judging from these results, PCP2 seems to be a useful chiral derivatization reagent for the determination not only of chiral, but also achiral, carboxylic acids in real samples. Figure
Labeling reagent for carboxylic acids in chiral metabolomics study 相似文献