微波场协同提取金银花黄色素的研究

研究了应用微波技术从金银花(Lonicera japonicaThunb)中提取黄色素的新工艺,并确定了最佳工艺条件:提取剂为无水乙醇,原料用量(g)与提取剂用量(mL)比为1∶60,提取时间为50 s,微波功率为560 W,提取次数为3次。最佳工艺条件下的色素提取率为83.40%,产品pH值为6。与溶剂浸提法相比,微波法提取金银花黄色素的每次提取时间由1 h减少到50 s,提取率从52.21%增加到83.40%,效果明显优于常规的溶剂浸提法。     

超声波辅助测定I3-=I-+I2平衡常数实验的微型化

“测定I3-=I-+I2平衡常数”是大学无机化学实验课的实验之一,该实验中使用了较多的碘,分散振荡时间较长,导致残留的碘挥发到空气中给环境和人体带来危害。为此对该实验进行了改进,利用超声波辅助分散减少分散时间,用微量代替常量减少试剂用量。经过多次重复实验,在超声波辅助分散5 min,降低试剂用量90%的情况下,测得平衡常数为1.54×10-3,相对误差为2.67%,证明该方法完全可以替代现有的实验方法。     

微波预处理复合酶法浸提茶皂素工艺条件研究

以油茶饼粕为原材料,采用微波预处理复合酶法,通过单因素试验研究了液固比、温度、时间、pH值和复合酶用量对油茶饼粕中茶皂素提取率的影响,采用正交试验确定最佳提取工艺条件。结果表明在时间为1.5 h、液固比为9∶1、pH值为6、浸提温度为55℃、复合酶用量为0.45%的条件下,茶皂素的提取率为13.35%,产品纯度为58.47%。     

超声波半微量提取快速测定人参总皂甙

应用超声波半微量提取法建立了人参中总皂甙的快速测定方法。与索氏提取测定法相比 ,本方法测定单一样品所用时间由 2～ 3个工作日缩短到 1～ 2h ,样品用量由 2 .0g减少到 0 .1g ,并节省大量试剂 ,工作效率提高数 1 0倍。与索氏法对照分析表明 ,本法可满足人参中总皂甙的快速测定要求。     

加热抽气吸收法测定氮

目前样品中氮的测定主要采用蒸馏法(包括常量、半微量、微量法),其次还有室温抽气吸收法(常量法)、扩散法(微量法)、仪器分析法(碳氮自动分析法、氨气敏电极法)等。作者设计制作了一套定氮装置,采用加热抽气吸收法测定氮的含量。本法具有蒸馏法和室温抽气吸收法的优点,整套装置装配简单,操作方便,测定快速,只需10min左右便可完成氮的整个蒸     

气相色谱-质谱法测定苦参中生物碱

以乙醇为溶剂用微波辐射溶剂回流提取法提取苦参中生物碱,经蒸发除去乙醇后提取物残渣用稀盐酸溶解,所得溶液用氯仿萃取除去其中的杂质,所得水相经碱化后再次用氯仿萃取使生物碱溶入氯仿中.蒸发除去萃取液中氯仿,残留物溶于一定量的甲醇中,用作气相色谱-质谱分析.应用此方法分离并测定了苦参中7种生物碱.结果表明:常规的溶剂回流提法(即不用微波辐射)相比较,微波辐射溶剂回流提取法的提取率明显提高.     

星点设计-响应面法优化麦冬总黄酮提取工艺及其抗氧化活性的研究

在单因素试验的基础上,利用星点设计-响应面法来优化酶提取法提取麦冬总黄酮的提取工艺,同时利用DPPH法和Fenton法测定总黄酮提取液清除1,1-二苯基-2-三硝基苯肼自由基和羟基自由基的能力。结果表明麦冬总黄酮酶提取法的最佳提取工艺条件:酶用量为46.61 mg,酶解时间为4.14 h,酶解温度为55.56℃,提取率为0.283%。在此条件下,麦冬总黄酮提取液对DPPH自由基和羟基自由基有较强的清除作用,随着总黄酮浓度的升高,其抗氧化能力逐渐增强,其IC_(50)分别为7.33 mg·L~(-1)和14.08 mg·L~(-1)。该工艺稳定可行,可为麦冬黄酮类化合物的开发利用提供参考。     

正交试验结合响应面法优化诃子多糖提取工艺

采用正交试验结合响应面法优化诃子多糖的提取工艺,以诃子多糖的提取率为指标,以固液比、提取温度、提取时间和提取次数为因素,正交试验初步筛选工艺参数,响应面法做进一步优化.结果表明,多糖提取的最佳工艺条件为固液比1∶28,提取温度69℃,提取时间1h,提取次数3次,各项指标相对误差均小于2%,应用响应面法可减少诃子多糖提取时间.     

“红七星”大蒜油提取工艺研究

以乙醇提取法提取温江大蒜("红七星")油,通过考察各影响因素对温江大蒜油提取率的影响,最终确定最佳提取工艺是酶解p H值为6.5、酶解温度40℃、酶解时间1.5 h、料液比1∶4、95%乙醇、在35℃下萃取1.5 h,总提取率为0.35%。通过深入研究乙醇提取法提取温江大蒜油的工艺研究,为温江大蒜的产业提升提供理论基础。     

半微量快速测定多种矿石及精矿中的钴

多种矿石微量钴的测定常用亚硝基-R盐比色法。我们试验了将常量法改为半微量法以节省试剂用量并避免分取试液等操作步骤。此外,选用了柠檬酸钠为掩蔽剂,此时,铜30、镍15、铁40毫克共存时不干扰钴(含钴50微克以下)的测定;但钴量在50—300微克范围内,存在20—40毫克铁,使钴的测定结果略有偏高。我们采用了在制备标准曲线时添加适量铁作补偿的方法以消除其影响。本法适用于含钴量为0.001—0.8％。     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.     

Facile synthesis of bicyclic 1-arylpyrazol-5-ones

In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates.     

Sulfur-directed metal-free and regiospecific methyl C(sp3)–H imidation of thioanisoles

Regiospecific and direct imidation of the methyl C(sp³)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products.