气相色谱法快速定量检测丙烯腈的生物催化产物

利用微生物催化丙烯腈生产丙烯酰胺在工业上已经得到了广泛的应用. 生产中反应液同时含有底物丙烯腈、产物丙烯酰胺以及副产物丙烯酸. 为了控制产品质量, 需快速定量检测反应液中各组分. 采用毛细管柱PEG-20M (30 m×0.25 mm i.d., 2 μm), 以20 g/L的乙酰胺作为内标物对反应液进行气相色谱分析, 优化分析条件为: 进样口为SPL, 温度260 ℃;FID检测器, 温度260 ℃;柱温190 ℃;载气为氮气, 流速25 cm/min;分流进样, 进样量0.4 μL, 分流比为50:1. 在4 min内, 3个组分得到完全分离, 该方法具有良好的重现性和线性关系, 回收率分别为98.5%、 102.1%、 105.0%, 相对标准偏差分别为9.1%、 5.3%、 1.7%. 该方法分析速度快, 适合实验室与工厂生产中大量快速定量检测样品.     

乙炔和氫氰酸加成的丙烯腈中微量杂质的色谱分析

对由乙炔加氢氰酸合成的丙烯腈中十余种杂质的气相色谱分离,进行了固定液的选择.选择结果认为,聚乙二醇己二酸酯固定液适用于分析合成丙烯腈的气相组分,而聚乙二醇1500和聚乙二醇400按1:1混合的固定液,适用于分析合成丙烯腈的液体产物和纯丙烯腈中的杂质.混合固定液柱分离各种杂质的操作条件是:柱温70℃,柱长3米,载气为氮,流速60毫升/分.一次分析时间,对不含氰丁二烯的样品为15分钟,含氰丁二烯的样品为40分钟.分析准确度对杂质浓度在100ppm以上的小于5％,100—20ppm的小于8％.     

全二维气相色谱-质谱法检测天然奶油和人造奶油中的脂肪酸

建立了天然奶油和人造奶油中37种脂肪酸的全二维气相色谱-质谱检测方法。样品经甲苯提取、乙酰氯-甲醇（1∶9,v/v）溶液甲酯化衍生后,以DB-5柱（30 m×0.25 mm×0.25 μm）为一维柱、BPX-50柱（2.5 m×0.1 mm×0.25 μm）为二维柱进行分离。升温程序为50℃保持2 min,以20℃/min升温至180℃,以2.5℃/min升温至250℃,以3℃/min升温至300℃,保持5 min。在调制周期为5 s、扫描范围为m/z 40~385的条件下,奶油中37种脂肪酸得到了有效分离和准确测定。将该方法应用于实际样品的分析,检测结果比传统的气相色谱法更灵敏,脂肪酸组成也更丰富,可有效鉴别不同种类奶油的差异成分。该方法不仅为奶油中脂肪酸成分分析提供了新的技术手段,同时在保障奶油的质量安全、鉴别掺假伪劣等过程中发挥重要作用。     

上试401有机担体在丙烯氨氧化制丙烯腈过程中色谱分析的应用

采用上试401有机担体作固定相(40—60目),操作条件为:柱长2米,内径4毫米,柱温120℃,氢气作载气(32—35毫升/分),热导池作鉴定器,工作电流150毫安,能将水、氢氰酸、乙醛、乙醇、乙腈、丙烯醛、丙酮、丙烯腈等组分完全分离,所需时间小于15分钟。同时,按各组分峰高,测定了八种组分的重量相对灵敏度,既可用内部归一化法,也可用内标法计算各组分的含量。精确度及准确度均良好。实践表明此法能适应生产控制分析要求。对含量低的组分(1％)相对误差为±2.5％。此外,用绝对校正曲线法、外标法,还测定了丙烯腈成品中的微量水。进样量1—10微升,测定范围0.1 0.7％。     

顶空气相色谱法测定加巴喷丁三类残留溶剂含量

建立了顶空毛细管色谱法测定加巴喷丁原料药中4种三类残留溶剂的方法。采用气相色谱顶空进样法,以水:DMF(9:1,V/V)为溶剂,DB-624为分析柱,采用程序升温:初始柱温35℃保持3 min,以10℃/min的升温速率升至155℃,保持4 min,再以30℃/min的升温速率升至245℃,保持5 min。结果表明:4种残留溶剂色谱峰面积与浓度线性关系良好,加标回收率结果满意。本方法可用于加巴喷丁原料药中残留溶剂乙醇、丙酮、异丙醇和三乙胺的检测。     

顶空固相微萃取-气相色谱质谱法定性定量分析广藿香中的挥发性成分

采用顶空固相微萃取-气相色谱质谱法(HS-SPME/GC-MS)定性定量分析广藿香药材中的挥发性成分.以百秋里醇的峰面积为指标,确定HS-SPME最佳的实验条件为:160目药材粉末用无水 Na2SO4稀释10倍,称取30 mg于15 mL萃取瓶中,以250 r/min速度搅拌预热(80 ℃) 40 min,插入65 μm聚二甲基硅烷-二乙烯(PDMS-DVB)涂层的纤维头,在相同搅拌速度下80 ℃萃取40 min,纤维头进入GC进样口在250 ℃下解吸100 s.GC色谱条件:色谱柱为DB-5MS柱;载气流速为1 mL/min;柱温的起始温度为90 ℃,以0.8 ℃/min升至110 ℃,保持5 min;1.0 ℃/min升至134 ℃,保持5 min;最后以5.0 ℃/min升至143 ℃,保持10 min.结果:百秋里醇的平均回收率为91.8%,RSD为3.0%.运用本方法对10份不同产地广藿香中百秋里醇的含量进行测定,并以其为参比对照,测定了广藿香中其它主要挥发性成分的含量.     

顶空-毛细管气相色谱法测定印刷品中15种痕量挥发性有机物

采用顶空-气相色谱法对印刷品中的挥发性有机物(苯、甲苯、乙苯、二甲苯、乙醇等15种)进行分析,研究了不同升温程序、顶空平衡温度、平衡时间等对分析结果的影响,优化的实验参数为:进样口温度:200℃;检测器温度:250℃。升温程序:初始温度40℃,保持5 min;以20℃/min速率升温至200℃,保持3 min。以高纯氮气作为载气,流速为8.0 mL/min保持5 min,再以0.2 mL/min的速率降至5.0 mL/min(分流比5:1);顶空条件:进样瓶平衡温度为90℃,平衡时间30 min,顶空进样体积1.0 mL。本方法线性关系良好,15种挥发性有机物的相关系数均大于0.9998,高、中、低3个浓度的回收率为77.8%~100.6%;相对标准偏差均低于6.0%(n=6)。方法可用于印刷品中挥发性有机物的分析。     

毛细管气相色谱法测定工业用丙烯腈中乙腈、丙酮、丙烯醛的含量

采用气相色谱法,色谱柱为FFAP键合固定相石英弹性毛细管色谱柱(50 m×0.32 mm,0.53μm),柱温54℃,载气线速15 cm/s,测定工业用丙烯腈中乙腈、丙酮、丙烯醛的含量,回收率和RSD满足分析要求.     

丙烯齐聚反应产物的气相色谱/质谱分析

采用GC MS分析技术对丙烯催化齐聚液相产物进行了分离、定性和定量分析。毛细管色谱柱为PONA柱 (5 0m× 0 .2 5mm× 0 .2 5 μm) ,FID检测器 ,He作载气 ,初温 3 5℃ ,以 3℃ min升至 2 80℃ ,恒温 60min。质谱离子源为EI源 ,能量 70eV ,离子源温度 2 0 0℃。结果表明丙烯齐聚液相产物中各组分可得到较好地分离 ,主要组分为短支链度的异构烯烃 ,另外还含有少量烷烃和环烷烃 ;由质谱图确定了 1 0 7个组分的化学结构     

多柱串联高温HPLC系统的构建及应用

在高效液相色谱(HPLC)中,使用多柱串联能够极大地增加柱效和改善分离效果,提高温度能够明显降低色谱柱反压、加快分析速度.将色谱柱串联与提高柱温相结合构建了多柱串联高温HPLC系统,该系统常温下分析标准样品时(以芴计),绝对柱效达7.6×104塔板数;柱温升高到120℃,色谱柱反压从35.3MPa降低到15.4MPa,分析时间从78.39min缩短为19.26min.采用构建的系统分析中药六味地黄丸,常温下出峰94个,升高温度至100℃出峰80个,分离效果较常规的单柱系统有明显提高;升高温度,使主要组分的出峰时间缩短,可获得更为详尽的组成信息.     

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%.     

Synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives

Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.     

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.     

A general and convenient synthesis of 4-(tosylmethyl)semicarbazones and their use in amidoalkylation of hydrogen,heteroatom, and carbon nucleophiles

A general synthesis of previously unknown semicarbazone-based α-amidoalkylating reagents, 4-(tosylmethyl)semicarbazones, has been developed. The synthesis involved three-component condensation of semicarbazones of aliphatic or aromatic aldehydes with the same or other aldehydes and p-toluenesulfinic acid. The scope and limitations of this reaction were investigated. The compounds obtained were demonstrated to be an efficient α-(4-semicarbazono)alkylating agents. They were reacted with H- (sodium borohydride), O- (sodium methylate), S- (sodium phenylthiolate), N- (pyrrolidine, sodium succinimide), P- (trialkyl phosphites), and C-nucleophiles (sodium diethyl malonate) to give the corresponding products of the tosyl group substitution, 4-substituted semicarbazones, including analogues of nitrofurazone. Among the prepared compounds tested in vitro for antibacterial and antifungal activity, three nitrofuryl-containing semicarbazones exhibited high biological activities with minimum inhibitory concentration (MIC) values of 8–32 μg/mL.     

Synthesis of novel chiral bidentate hydroxyalkyl-N-heterocyclic carbene ligands and their application in palladium-catalyzed Mizoroki–Heck couplings and asymmetric addition of diethylzinc to benzaldehyde

A small library of new chiral bidentate hydroxyalkyl-imidazolium salts 1 is conveniently synthesized on multi-gram scale from inexpensive and commercially available chiral pool amino acids. The corresponding carbenes, generated by deprotonation of imidazolium salts 1, in combination with palladium(II) chloride were tested in the Mizoroki–Heck coupling reaction. The most significant results in terms of yields and reactivities were achieved with low catalyst loading. The catalytic activities of these imidazolium salts were also investigated in the asymmetric addition of diethylzinc to benzaldehyde. The use of MgO nanoparticles as an additive in conjunction with these ligands played a crucial role in increasing the efficiency of these reactions.     

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.     

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.