2-甲基-6-异丙基萘的分子筛催化合成、分离提纯和结构表征

2,6-二烷基萘的氧化产物2,6-萘二甲酸与乙二醇反应得到的聚2,6-萘二甲酸乙二醇酯(PEN),是一种具有广阔市场前景的新一代聚酯产品,其开发的关键在于降低2,6-二烷基萘的生产成本[1~3]。利用裂解重油的2-甲基萘副产烷基化获得2,6-二烷基萘,将大大降低PEN的生产成本,同时也帮助石化     

2-乙酰基-6-甲氧基萘的多相催化氢化

乙酰基溴甲基萘;甲氧基萘基;2-乙酰基-6-甲氧基萘的多相催化氢化     

用新方法催化合成6-乙酰基-1-甲基环己烯

室温下用HY沸石取代传统催化剂通过1-甲基环己烯与乙酐的酰基化反应合成了6-乙酰基-1-甲基环己烯，考察了HY沸石的SiO2／Al2O2摩尔比、用量和活化时间以及反应时间对该酰化反应的影响．当1-甲基环己烯／乙酐／HY沸石(SiO2／Al2O3摩尔比=29)=1mmol／10mmol／0．200g、反应温度25℃、反应时间3h时，所得酰化产品的产率为60％，HY沸石能够回收和重新使用，显示出与新鲜催化剂几乎相同的催化活性．     

2-卤乙基-2-(6＇-甲氧基-2＇-萘基)-4-甲基-1,3-二氧杂环戊烷重排合成外消旋体萘普生

卤乙基甲氧基萘基甲基二氧杂环戊烷;2-卤乙基-2-(6＇-甲氧基-2＇-萘基)-4-甲基-1;3-二氧杂环戊烷重排合成外消旋体萘普生;丙二醇;卤化铜     

氯化铜对6-甲氧基-2-酰基萘选择性氯化反应

甲氧基酰基萘;甲氧基萘;氯化铜对6-甲氧基-2-酰基萘选择性氯化反应     

2-乙酰基-6-三甲基硅基苯基三氟甲磺酸酯的合成

以2-三甲基硅基苯酚为原料,经甲酰化、酯化、亲核加成和氧化反应首次合成了3-乙酰基苯炔的前体——2-乙酰基-6-三甲基硅基苯基三氟甲磺酸酯,总收率35%,其结构经1H NMR和13C NMR确证。     

5-甲氧基-2-[(E)-(6-甲基吡啶-2-亚氨基)甲基]苯酚的合成与表征

研究了以2-羟基-4-甲氧基苯甲醛和2-氨基-6-甲基吡啶为原料合成新型席夫碱化合物5-甲氧基-2-[(E)-(6-甲基吡啶-2-亚氨基)甲基]苯酚的方法。当2-羟基-4-甲氧基苯甲醛与2-氨基-6-甲基吡啶摩尔比为1∶1.6,反应时间为6 h,反应温度为75℃时,反应产率最高。采用元素分析、UV-Vis、IR、1H NMR、X-射线单晶衍射等方法进行结构表征。该化合物为单斜晶系,空间群P21/c,a=1.1886(3)nm,b=0.65948(16)nm,c=1.6897(4)nm,β=108.505(3)°,V=1.2560(5)nm3,Dc=1.281 g·cm-3,Z=4,F(000)=512,μ=0.087 mm-1,R1=0.0477,wR2=0.1342。通过π···π堆积和分子内氢键O2-H2···N1、C8-H8A···N2形成较稳定的晶体结构,并具有蓝色荧光。     

1-[(乙氧基)甲基]-6-(1-萘甲基)胸腺嘧啶的合成

HEPT是抑制HIV-1逆转录酶的潜在活性化合物。1-[(乙氧基)甲基]-6-(1-萘甲基)胸腺嘧啶是HEPT的类似物,通过增加6位取代基的位阻可提高药效。文献设计并合成了该化合物,并对关键中间体(d)的合成及脱羟基反应作了初步讨论。     

2-甲基-6-(3-甲基-2-丁烯基)对苯二醌的合成

以邻甲基苯酚为原料,与1-氯-2-甲基-2-丁烯反应生成2-甲基-6-(3-甲基-2-丁烯基)苯酚,然后催化氧化得到目标产物2-甲基-6-(3-甲基-2-丁烯基)对苯二醌。该合成路线简单,易于操作,最终收率51%。     

1-芳氨基乙酰基-4-芳乙酰基氨基硫脲的合成及结构表征

利用超声波辐射与相转移催化联用技术合成了6个1-芳氨基乙酰基-4-芳乙酰基氨基硫脲化合物,并用IR、1HNMR及元素分析进行了表征,确定了其空间结构,归属了酰氨基硫脲类化合物1HNMR谱中低场的3个NH质子的信号峰。这种合成方法具有反应条件温和、反应时间较短、产率较高等优点。     

二维NMR确定吡喃酮衍生物C_9H_（12）O_4的结构

利用Ｈ－ＨＣＯＳＹ和Ｃ－ＨＣＯＳＹ谱实现对~１Ｈ和~（１３）Ｃ谱的指认和归属；利用ＨＭ－ＢＣ谱确定分子的骨架；根据~１Ｈ－~１Ｈ标量偶合常数的大小推出相邻碳原子上质子的相对位置；并结合其它谱学数据，确定了从天然产物分离得到的吡喃酮衍生物Ｃ_９Ｈ_（１２）－Ｏ_４的化学结构并命名为２－（１’，２’－环氧丙烷基）－４－羟基－５－甲基－２－戊烯－５－酸内酯。     

Systematic studies on the computation of nuclear magnetic resonance shielding constants and chemical shifts: the density functional models

We present a systematic density functional investigation on the prediction of the 13C, 15N, 17O, and 19F NMR properties of 23 molecules with 21 density functionals. Extensive comparisons are made for both 13C magnetic shieldings and chemical shifts with respect to the gas phase experimental data and the best CCSD(T) results. We find that the OPBE and OPW91 exchange-correlation functionals perform significantly better than some popular functionals such as B3LYP and PBE1PBE, even surpassing, in many cases, the standard wavefunction-based method MP2. Further analysis has been performed to explore the individual role played by various exchange and correlation functionals. We find that the B88 and PBE exchange functionals have a too strong tendency of deshielding, leading to too deshielded magnetic shielding constants; whereas the OPTX exchange functional performs remarkably well. We claim that the main source of error arises from the exchange functional, but correlation functional also makes important contribution. We find that the correlation functionals may be grouped into two classes. class A, such as LYP and B98, leads to deshielded NMR values, deteriorating the overall performance; whereas class B, such as PW91 and PBE, generally increases the absolute shieldings, which complements the exchange functionals, leading to improved results in the calculation of NMR data.     

氘代DMSO试剂中残留~1H的检测

本文提出一种利用尿素作为内标物质,通过加入不同量的尿素测量它与氘代DMSO中溶剂残留信号峰面积比变化的方法。结果表明,尿素和DMSO溶剂峰的1H共振峰面积比与它们之间摩尔比之间有很强的线性关系,进而可以计算DMSO溶剂的氘代率。该方法简单、快速,所需试剂较少,低毒,可在实验室准确测试DMSO试剂的氘代率,也可以将此方法推广到其他氘代试剂的检测。     

Systematic investigation on the geometric dependence of the calculated nuclear magnetic shielding constants

We perform a systematic examination on the dependence of the calculated nuclear magnetic shielding constants on the chosen geometry for a selective set of density functional methods of B3LYP, PBE0, and OPBE. We find that the OPBE exchange-correlation functional performs remarkably well when either the optimized geometries or the experimental geometries are used. The popular B3LYP and PBE0 functionals have a clear tendency of deshielding, giving shieldings that are usually too low and shifts that are usually too high, at the experimental geometries. Combined with the Hartree-Fock geometries, however, much improved magnetic constants are obtained for B3LYP and PBE0, due to the compensation effect from the systematic underestimation of bond lengths by the Hartree-Fock method.     

Slc11a2第六跨膜区在十二烷基磷酰胆碱胶束中的结构

采用圆二色谱和核磁共振波谱研究了Slc11a2第六跨膜区在十二烷基磷酰胆碱(DPC)膜模拟环境中的结构和定位.结果表明,Slc11a2第六跨膜区在DPC胶束中N端和C端各形成一小段α螺旋,两段螺旋中间通过高度灵活的区域连接,整个肽插入到DPC胶束中.H267A突变使螺旋长度变长,H272A突变使螺旋长度略有变短,突变后结构的变化可能和蛋白功能缺失相关.     

Empirically predicted 13C NMR chemical shifts for 8-hydroxyflavone starting from 7,8,4'-trihydroxyflavone and from 7,8-dihydroxyflavone

8-Hydroxyflavone is not found in nature. While the (13)C chemical shifts of 8-hydroxyflavone have been reported previously, the observed (13)C chemical shifts were not assigned. A previously reported empirical predictive tool has been applied in reverse in order to deconvolute the (13)C chemical shifts for 8-hydroxyflavone from each of those of 7,8,4'-trihydroxyflavone and 7,8-dihydroxyflavone together with those of 7-hydroxyflavone, 4'-hydroxyflavone, and flavone. The two sets of calculated (13)C chemical shifts for 8-hydroxyflavone are in good agreement with each other in that the average absolute difference is 0.4 ppm. The previously reported but unassigned (13)C chemical shifts for 8-hydroxyflavone have been assigned by matching them with the averages of the two sets of calculated (13)C chemical shifts for 8-hydroxyflavone such that the minimum average absolute difference is 0.63 ppm. The assigned (13)C chemical shifts of 8-hydroxyflavone may be used, along with the (13)C chemical shifts of the remaining monohydroxyflavones, as part of a predictive tool to rapidly assess the (13)C NMR spectra of C8-hydroxylated flavonoids.     

The Synthesis and Characterization of 2-Amino-3-methylpyridinium Dihydrogenmonophosphate: (C6H9N2)H2PO4

A new crystal of 2-amino-3-methylpyridinium dihydrogenmonophosphate has been prepared and characterized by X-ray crystallography, thermal analysis, and impedance and NMR spectroscopies. This compound crystallizes in the triclinic space group P with a = 7.343(2) Å, b = 7.987(2) Å, c = 8.116(4) Å, α = 77,62(3)°, β = 77,74(3)°, γ = 87,03(2)°, V = 454.3 (3)ų, and Z = 2. The crystal structure was solved and refined to R = 0.030 with 1602 independent reflections. The atomic arrangement can be described as (H₂PO₄ ^?)_n polymeric chains anchoring the 2-amino-3-methylpyridinium cations through short hydrogen bonds. All ring atoms of the organic entity are coplanar. The exocyclic N atom is an electron receiving center, which is consistent with features of imino resonance evidenced by bond lengths and angles. Solid state ³¹P, ¹³C, and ¹⁵N CP-MAS-NMR spectroscopies are in agreement with the X-ray structure. Ab initio calculations allow the attribution of carbons and nitrogen to the independent crystallographic sites.     

“Through-Space” Relativistic Effects on NMR Chemical Shifts of Pyridinium Halide Ionic Liquids

We have investigated, using two-component relativistic density functional theory (DFT) at ZORA-SO-BP86 and ZORA-SO-PBE0 level, the occurrence of relativistic effects on the ¹H, ¹³C, and ¹⁵N NMR chemical shifts of 1-methylpyridinium halides [MP][X] and 1-butyl-3-methylpyridinium trihalides [BMP][X₃] ionic liquids (ILs) (X=Cl, Br, I) as a result of a non-covalent interaction with the heavy anions. Our results indicate a sizeable deshielding effect in ion pairs when the anion is I⁻ and I₃⁻. A smaller, though nonzero, effect is observed also with bromine while chlorine based anions do not produce an appreciable relativistic shift. The chemical shift of the carbon atoms of the aromatic ring shows an inverse halogen dependence that has been rationalized based on the little C-2s orbital contribution to the σ-type interaction between the cation and anion. This is the first detailed account and systematic theoretical investigation of a relativistic heavy atom effect on the NMR chemical shifts of light atoms in the absence of covalent bonds. Our work paves the way and suggests the direction for an experimental investigation of such elusive signatures of ion pairing in ILs.