基质匹配顶空-气相色谱法测定纺织品中DMF,DMAC与NMP

建立了基质匹配顶空-气相色谱法同时测定纺织品中N,N-二甲基甲酰胺(DMF)、N,N-二甲基乙酰胺(DMAC)与N-甲基吡咯烷酮(NMP)残留。剪碎样品后,在190℃下加热30 min,使3种溶剂在气固两相间达到平衡,取顶空气体进气相色谱以氮磷检测器检测。以基体匹配校正法消除基质效应,以保留时间定性,外标法定量。DMF,DMAC,NMP在0.4~500.0μg范围内线性关系良好;3种物质的平均回收率为89.6%~96.1%;RSD(n=6)为1.6%~3.1%;DM F,DM AC与NM P方法检出限均为0.5μg/g。     

氯仿萃取分离N,N-二甲基甲酰胺工艺

针对某制药企业生产过程中产生的高浓度含N,N-二甲基甲酰胺(DMF)料液，在折流板萃取塔内进行连续萃取分离，结合精馏工艺，实现了DMF的分离与回收。对于DMF初始质量分数为38.46%的料液，以氯仿作为萃取剂，采用脉冲折流板萃取塔对料液中的DMF进行萃取，研究了不同油水相比、流量和脉冲条件下在折流板萃取塔中DMF的萃取效果。结果表明，DMF的萃取效率随着脉冲的加入、油水相比的升高和两相流速的增大而增大，在优化的条件下DMF的萃取率最高为99.94%，分离后的萃余相DMF质量分数达到0.5%以下。进一步，对于负载了DMF的氯仿溶液，分别进行了间歇精馏实验和模拟计算，结果显示通过精馏可以实现氯仿和DMF的有效分离回收。     

高效液相色谱法测定血液透析器中聚乙烯吡咯烷酮、N,N-二甲基乙酰胺和N-甲基吡咯烷酮溶出量

建立高效液相色谱法测定血液透析器中聚乙烯吡咯烷酮、N,N-二甲基乙酰胺和N-甲基吡咯烷酮三种残留物的溶出量。采用超纯水作为浸提溶剂，模拟临床使用条件，在（37±1）℃的恒温水浴中对样品循环浸提6 h。以乙腈-水（体积比为5∶95）作为流动相等度洗脱，采用高效液相色谱法分离和测定溶出物，检测波长为205 nm。聚乙烯吡咯烷酮、N,N-二甲基乙酰胺和N-甲基吡咯烷酮的质量浓度分别在5.0～100.0、0.2～20.0、0.2～20.0μg/mL范围内与色谱峰面积具有良好的线性关系，相关系数均大于0.999，方法检出限分别为1.461、0.011、0.019μg/mL。样品加标平均回收率为95.13%～103.99%，测定结果的相对标准偏差为0.08%～0.67%(n=6)。该方法制样简单，适用于血液透析器中聚乙烯吡咯烷酮、N,N-二甲基乙酰胺和N-甲基吡咯烷酮三种残留物的溶出量测定。     

N,N-二甲基甲酰胺及其降解产物分析方法研究进展

随着N,N-二甲基甲酰胺(DMF)应用行业的不断拓宽及使用量的增加导致其被动暴露人群数量大且持续增加。近年来,DMF对人体健康的潜在危害引起了相关领域广大科技工作者的广泛关注。如何有效地分离分析DMF及其降解产物是研究其迁移、转化等环境行为及生物毒性的首要问题。对近年来DMF及其降解产物的色谱、质谱分析方法研究进展及其特点进行了综述,并且分析了其发展趋势。     

流动注射化学发光法测定水体中的N,N-二甲基乙酰胺

在酸性条件下,高锰酸钾氧化硫代硫酸钠产生化学发光,N,N-二甲基乙酰胺(DMAC)对该体系的发光强度具有增强作用,基于此建立了测定水体中DMAC的流动注射化学发光法。当硫酸溶液的浓度为1.2mol·L~(-1),高锰酸钾溶液、硫代硫酸钠溶液的浓度均为5.0×10~(-4)mol·L~(-1)时,化学发光强度与DMAC的质量浓度在0.20~40.0mg·L~(-1)范围内呈线性关系,检出限(3S/N)为0.071mg·L~(-1)。方法用于水体中DMAC含量的测定,加标回收率在97.3%~104%之间,测定值的相对标准偏差(n=7)在1.2%~3.6%之间。     

高效液相法测定皮革、纺织品中的N,N-二甲基甲酰胺

建立了高效液相色谱法检测皮革、纺织品中的N,N-二甲基甲酰胺的方法。使用ODB C18(ODB C18(250 mm×4.6 mm,i.d.5μm)液相色谱柱,以乙腈和KH_2PO_4缓冲体系为流动相等度洗脱,流速为1.0 m L/min,检测波长为210 nm,柱温为30℃,进样量为10μL。在上述条件下,在DMF质量浓度为0.1~10μg·m L~(-1)范围内,其峰面积与质量浓度的线性关系良好。在不同加标水平下回收率为100%~102%。本方法最低检出限(LOD)为0.5 mg·kg-1,峰面积的相对标准偏差(RSD)为1.03%~3.63%。此方法可快速、准确地测定出皮革、纺织品中DMF的残留量。     

二氧化碳与二甲胺催化合成N,N-二甲基甲酰胺

二氧化碳(CO₂)是大气中主要温室气体之一,也是丰富、安全、可再生的碳一资源。将CO₂催化转化为高附加值化学品不仅能改善人类长期依赖化石资源的困境,还能有效减少CO₂排放,助力实现“碳达峰、碳中和”这一“双碳”目标。N,N-二甲基甲酰胺(DMF)是一种年产百万吨级的平台化合物,是优良的溶剂以及重要的化工中间体。因此,以CO₂作为羰源,通过高效催化体系的构建实现CO₂与二甲胺反应合成DMF具有重要意义。本文分别从还原剂、催化体系和反应机理等角度综述了这一领域近年来的研究进展。最后,对CO₂合成DMF催化过程中所面临的问题和未来的发展方向进行了探讨和展望。     

高效液相色谱法测定覆铜板粘结片中的N,N-二甲基乙酰胺残余量

建立高效液相色谱法检测覆铜板粘结片中N,N-二甲基乙酰胺残余量的方法。以甲醇溶液萃取覆铜板粘结片中的N,N-二甲基乙酰胺,高效液相色谱法测定N,N-二甲基乙酰胺的含量。试验并确定了最佳色谱条件。在选定条件下,N,N-二甲基乙酰胺含量在0.05~300 mg/L范围内与其色谱峰面积呈良好的线性关系,线性相关系数为0.999 95,检出限为0.6 mg/kg,加标回收率为101.0%~107.8%,测定结果的相对标准偏差小于10%(n=6)。该方法准确、快速,可用于覆铜板生产的质量控制。     

p-(N,N-二甲氨基)肉桂酸乙酯在分子聚集体中的光化学行为

本文报道了p(N,N-二甲氨基)肉桂酸乙酯(DMAC)在十二酸(LA)聚集体中的光谱和光化学性质。这种肉桂酸衍生物的吸收和发射光谱表现出典型的分子内电荷转移的特征,在十二酸存在下,观察到DMAC激基缔合物荧光,荧光强度随DMAC浓度增加而增加,与普通溶液中的反应相比,十二酸聚集体中的DMAC具有较大的光二聚反应速度。用荧光光谱跟踪反应的结果表明,DMAC激基缔合物具有较DMAC单体更高的光化学活性。     

N,N-二甲氨基磺酰氯合成工艺的优化

以磺酰氯和二甲胺盐酸盐为原料在三乙胺催化剂的作用下合成N,N-二甲氨基磺酰氯,并进行了单因素实验,在此基础上运用响应面法对N,N-二甲氨基磺酰氯合成工艺进行了优化,优化调整后的工艺条件为:反应温度9℃,二氯乙烷用量250 mL,n(二甲胺盐酸盐):n(磺酰氯)=1.0:1.2.在该工艺条件下重复实验,N,N-二甲氨基磺...     

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%.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.     

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.     

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.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

KMnO₄-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.     

Chemistry of heterocyclic compounds at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, over 50 years (Review)

The review contains a concise historical account and information on the most significant researches undertaken by the staff at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry of Heterocyclic Compounds. Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008.     

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.     

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.