相转移催化下4-氯苯磺酰基乙酸异丙酯的烷基化反应

在有机合成中可用芳磺酰基作暂时性活化基团。芳磺酰基乙酸酯是具有活性亚甲基的弱酸性化合物。通常要在氢化钠、醇钠存在下才能起烷基化反应。Ono等曾报道4-甲苯磺酰基乙酸甲酯在DBu存在下进行烷基化反应,但反应时间长。近年来,相转移催化在有机反应中的应用受到重视,然而用固液相转移催化法使芳磺酰基乙酸酯起烷基化反应还未见报道。我们在K₂CO₃/DMF体系中,用TEBA作催化剂,研究了4-氯苯磺酰基乙酸异丙酯与不同类型卤代烃所起的烷基化反应。合成了尚未见报道的一或二烷基化产物。     

含功能取代基的C2Mo2簇合物的合成与晶体结构测定

利用苯乙炔或丙炔醇与[Mo(CO)₂(η⁵-C₅H₄R¹)]₂[R¹＝C(O)Me,C(O)OEt,C(O)Ph]的反应合成了6个新的炔烃配位的双钼化合物[Mo(CO)₂(η⁵-C₅H₄R¹)]₂(μ-η²,η²-(CH=CR²)[R¹＝C(O)Me,R²＝Ph,1;R¹＝C(O)OEt,R²＝Ph,2;R¹＝C(O)Ph,R²＝Ph,3;R¹＝C(O)Me,R²＝CH₂OH,4;R¹＝C(O)OEt,R²＝CH₂OH,5;R¹＝C(O)Ph,R²＝CH₂OH,6],并对这些化合物进行了C/H元素分析,IR,¹HNMR等表征.晶体X射线衍射分析结果表明,化合物1属单斜晶系,P2₁(＃4)空间群,晶胞参数a＝0.7671(2)um,b＝0.8365(2)nm,c＝1.8308(3)nm,β＝98.34(1)°,V＝1.1623(5)um³,Z＝2,D_c＝1.772g·cm^-3,F(000)＝616,R＝0.041,R_w＝0.045.     

Preparation, spectroscopic properties and thermal stabilities of organomercury compounds containing the bulky ligand (Me3Si)3C or (PhMe2Si)3C

Mercury compounds of the types HgR¹R (R¹ = C(SiMe₃)₃; R = Me, ⁱPr, Bu, ^tBu or Ph) and HgR²R(R² = C(SiMe₂Ph)₃; R = Me, Bu, CH₂Ph or Ph) have been prepared. Those containing R¹ were made by reactions of the bromides HgR¹Br with the Grignard reagents MgRX, and those containing R² by reaction of HgR²Cl with LiR or, for R = CH₂Ph, with Mg(CH₂Ph)Cl. Replacement of one R group in HgR₂ by the bulky R¹ or R² group leads to a large increase in thermal stability, a marked shift in the ¹⁹⁹Hg resonance to lower frequency and an increase in the coupling constant ¹J(¹³C---¹⁹⁹Hg) for the Hg---R bond. The compound HgR²Cl does not react further with LiR² in tetrahydrofuran, but with LiR¹ gives HgR¹R²; the arrangement of the SiMe₂Ph groups in the latter in solution in CH₂C12 at low temperature appears to be different from that in the solid.     

Primary radicals in the photo-oxidation of aromatics — reactions of xylenols with OH, N3 and H radicals and formation and characterization of dimethylphenoxyl, dihydroxydimethylcyclohexadienyl and hydroxydimethylcyclohexadienyl radicals by pulse radiolysis

Photo-oxidations of environmental organics in illuminated TiO₂ dispersions have implicated surface-bound ^•OH radicals and/or valence band holes. To explore the implications of the former oxidizing entity, six isomeric xylenols (dimethylphenols) were examined by pulsed (nanoseconds to milliseconds) radiolysis methods. The spectral and kinetic characteristics of formation and decay of the transients formed by the reaction of N₃^•, ^•OH and H^• radicals with these xylenols were assessed in buffered (pH 4, 10⁻³ M phosphate) aqueous media, where the xylenols exist in their protonated form (pK ≈ 10.19–10.65). The products from the reaction of N₃^• with 2,6- and 3,4-xylenol were exclusively the corresponding dimethylphenoxyl radicals, formed via electron transfer followed by deprotonation. In contrast, except with 3,4-xylenol, the principal radical intermediates formed initially upon reaction with ^•OH were the corresponding ^•OH adducts, the dihydroxydimethylcyclohexadienyl radicals. 3,4-Xylenol was examined in the pH range 4–10. At pH 8 the initial ^•OH adduct (dihydroxy-3,4-dimethylcyclohexadienyl radical) was subsequently transformed (about 20%–40%) via water elimination into the dimethylphenoxyl radical. In contrast, at pH 9 and 10 the ^•OH adduct and the dimethylphenoxyl radical were formed concurrently (about 60% ^•OH adduct and about 40% dimethylphenoxyl species), the latter through an inner-sphere electron transfer pathway. The switch in behaviour from pH 8 to pH 9 suggests that the pK_a of the dihydroxy-3,4-dimethylcyclohexadienyl radical is about 8–9, about 2 pK units below the pK_a of the parent substrate (10.4). A mechanism for the conversion of the ^•OH adduct to the dimethylphenoxyl radical is proposed. Reaction of 2,6-xylenol with H^• radicals gave exclusively the H^• adduct (hydroxycyclohexadienyl radical), whose spectral characteristics are similar to those of the related ^•OH adduct.     

Hydroxyl radical formation upon dark oxidation of reduced iron minerals: Effects of iron species and environmental factors

Dark oxidation of reduced iron minerals can produce hydroxyl radical under ambient conditions.     

Reaction of octafluorotoluene, 3,5-dichlorotrifluoropyridine, 3-chlorotetrafluoro-yridine and tetrafluoropyrimidine with alkali-metal oximates

Treatment of octafluorotoluene (2) with approximately one-molar equivalents of the oximates R¹R²C = NO~ M⁺ (R¹ = R²=Me;R¹ = R² = Ph; R¹ = Me, R² = Ph;M = Na) (6a-c) in diethyl ether gives 4-(R¹R²C = NO)C₆F₄CF₃ (7a-c) as the only isolated products. Corresponding reaction of 3,5-dichlorotrifluoropyridine (3) with the oximates 6a-c affords 4-and 2-(R¹R²C = NO)C5F₂C12N (8a-c) and (9a-c), respectively (4-/2ratios at −35 °C: 65:35; 30:70; 12:88) ; the lithium oximates (R¹ = R² =Ph ; R¹ = Me, R² = Ph; M = Li) (6d) and (6e) give comparable results. With 3-chlorotetrafluoropyridine (4), treatment with sodium oximate 6c gives 4-(PhCMe = NO)-3-ClC₅F₃N (10) and 2-(PhCMe = NO)-5ClC₅F₃N (11) (ratio 44:56 at −35 °C). Such competition between S_NAr attack of these alkali-metal oximates at the C-4 and C-2 positions of chlorofluoropyridines 3 and 4 can be rationalized by invoking chelation of an alkali-metal cation with ring nitrogen in the transition state leading to formation of an orthio-quinonoidal σ-complex. Exclusive initial attack at the C-4 ring site appears to occur in the reaction of tetrafluoropyrimidine (5) with oximates 6a and 6c to afford 4-(MeC = NO)C₄F₃N₂ (12a) and 4-(PhCMe=NO)C₄F₃NN₂ (12b), respectively; Some further attack on product 12b by oximate 6c at the C-6 site takes place to give the disubstituted derivative 4,6-(PhCMe=NO)₂C₄F₂N₂ (13).     

Synthesis and characterization of planarly chiral nonbridged bis(1-R-indenyl) zirconium dichloride complexes and X-ray structure of rac-[(η-C9H6-1-C(CH3)2---o-C6H4---OCH3)2ZrCl2]·THF

Reactions of the lithium salts of 3-substituted indenes 1, 2 with ZrCl₄(THF)₂ gave two series of nonbridged bis(1-substituted)indenyl zirconocene dichloride complexes. Fractional recrystallization from THF–petroleum ether furnished the pure racemic and mesomeric isomers of [(η⁵-C₉H₆-1-C(R¹)(R²)---o-C₆H₄---OCH₃)₂ZrCl₂]·nTHF (R¹=R²=CH₃, n=1, rac-1a and meso-1b; R¹=CH₃, R²=C₂H₅; n=0.5 or 0, rac-2a and meso-2b), respectively. Complex 1a was further characterized by X-ray diffraction to have a C₂ symmetrically racemic structure, where the six-member rings of the indenyl parts are oriented laterally and two o-CH₃O---C₆H₄---C(CH₃)₂--- substituents are oriented to the open side of the metallocene (Ind: bis-lateral, anti; Substituent: bis-central, syn). The four zirconocene complexes are highly symmetrical in solution as characterized by room temperature ¹H-NMR, however ¹H–¹H NOESY of meso-1b shows that some of the NOE interactions arise from the two separated indenyl parts of the same molecule, which can only be well explained by taking into account the torsion isomers in solution.     

Half-way coordination state of a butadienyl group on ruthenium. η-Allylic bonding with η-character or vice versa

The butadienyl complexes formed by the reaction of trans-(R¹)CH=CHCCR² (R¹, R² = SiMe₃, ^tBu, Me, Et) with RuCl(CO)H(PPh₃)₃ exhibit unique structures: instead of taking the 18-electron configuration of the metal by conventional η³-coordination of the butadienyl ligand, they shift significantly to the 16-electron η¹-coordination state.     

Electric magnetic resonance and spectrophotometry evidence on the photodynamic activity of a new perylenequinonoid pigment

Di-cysteine substituted hypocrellin B (DCHB) is a new water-soluble photosensitizer with significantly enhanced red absorption at wavelengths longer than 600 nm over the parent compound hypocrellin B (HB). The photosensitizing properties (Type I and/or Type II mechanisms) of DCHB have been investigated in dimethylsulfoxide (DMSO) and aqueous solution (pH 7.4) using electron paramagnetic resonance (EPR) and spectrophotometric methods. In anaerobic DMSO solution, the semiquinone anion radical of DCHB (DCHB^•−) is predominantly photoproduced via self-electron transfer between excited- and ground-state DCHB species. The presence of an electron donor significantly promotes the formation of the reduced form of DCHB. When a deoxygenated aqueous solution of DCHB and an electron donor are irradiated with 532 nm light, the hydroquinone of DCHB (DCHBH₂) is formed via the disproportionation of the first-formed DCHB^•− and second electron transfer to DCHB^•− from the electron donor. When oxygen is present, singlet oxygen (¹O₂), superoxide anion radical (O₂^•−) and hydroxyl radical (^•OH) are produced. The quantum yield of ¹O₂ generation by DCHB photosensitization is estimated to be 0.54 using Rose Bengal as a reference, a little lower than that of HB (0.76). The superoxide anion radical is also significantly enhanced by the presence of electron donors. Moreover, (O₂^•−) upon disproportionation generated H₂O₂ and ultimately the highly reactive ^•OH via the Haber-Weiss reaction pathway. The efficiency of (O₂^•−) generation by DCHB is obviously enhanced over that of HB. These findings suggest that the photodynamic actions of DCHB may proceed via Type I and Type II mechanisms and that this new photosensitizer retains photosensitizing activity after photodynamic therapy-oriented chemical modification.     

用可解的六次势研究9-羟基苯嵌萘酮的基态能级劈裂

质子转移（PT）得到了理论和实验方面广泛的研究［1-10],9－羟基苯嵌萘酮（9－HPO）是一个典型体系．在荧光光谱中,观测到氖化的9－HPO的基态能级劈裂,结合其它光谱和X射线衍射数据,提出用四次函数V（R）=A（R4-BR2）作为势能函数［1]．迄今,这一势能函数对应的Schr dinger方程还不能精确求解,且得到的结果与实验值[4]有较大差异．本文用可解的六次势V（R,γ）＝C[R6＋2γR4+(γ2＋μ）R2] 来描述该体系质子转移时的势能面,得到这一势能对应的Schr dinger方程的解析解,再用变分法并结合得到的解析解可计算9－HPO的基态能级劈裂．     

Protein nanoparticles containing Cu(II) and DOX for efficient chemodynamic therapy via self-generation of H2O2

Chemodynamic therapy (CDT) refers to generating hydroxyl radical (^·OH) in tumor sites via hydrogen peroxide (H₂O₂) catalyzed by transition metal ions in cancer cells under acidic environment. However, H₂O₂ content is not enough for effective CDT, although H₂O₂ content in cancer cells is higher than that of normal cells. Herein, we synthesized DOX@BSA-Cu NPs (nanoparticles) for effective CDT by providing enhanced content of H₂O₂ in cancer cells. The results proved Cu²⁺ in NPs could be reduced to Cu⁺ by glutathione (GSH) and effectively converted H₂O₂ to ^·OH. Moreover, the loaded low-dose doxorubicin (DOX) in the NPs could improve the content of H₂O₂ and resulted in more efficient generation of ^·OH in cancer cells. Thus DOX@BSA-Cu NPs exhibited higher cytotoxicity to cancer cells. This research may provide new ideas for the further studies on more effective Cu(II)-based CDT nanoagents.     

Synthesis of polysilanes bearing pendant carbosilyl groups and Si-NMR probe on the tacticity using side chain silicon atoms

New functional polysilanes [R₂R¹Si(CH₂)₂SiH]_n (R=Me, R¹=H (1); R=R¹=Et (2); R=Me, R¹=Ph (3)) bearing carbosilyl side chains have been synthesized by catalytic dehydropolymerization of precursor carbosilanes R₂R¹SiCH₂CH₂SiH₃ using Cp₂TiCl₂–BuLi as a catalyst. These polymers are characterized by ¹H, ¹³C, ²⁹Si, {¹H–²⁹Si} HSQC NMR spectroscopy, GPC and TGA. Attempts to delineate the tacticity from the analysis of deconvoluted ²⁹Si{¹H}-NMR signals associated with the side chain silicon atoms reveal that the triad concentration ratio follows a Bernoullian statistical model for polymers 1 and 2 only.     

NMR conformational studies of (1,2-bis(diarylphosphino) ethane) -(diorgano sulfide) ruthenium complexes

Some (η⁵-cyclopentadienyl)(1,2-bis(diarylphosphino)ethane)(diorganosulfide)ruthenium complexes, [Ru(η⁵-C₅H₅)(Ar₂PCH₂CH₂-PAr₂)(R¹R ²S)]BF₄ (Ar = Ph, p-Tol; R¹, R² = Ph, Et) were prepared. Variable temperature NMR spectra of these complexes showed the existence of two fluxional processes; inversion at the sulfur atom and δ-λ interconversion of the chelate ring. The former process was slower, and its barriers in these complexes were calculated as ca. 7 kcal mol⁻¹. The spectral features of ethyl phenyl sulfide complexes suggested that substantiation of the new chiral center at sulfur induces a significant conformational rigidity at the chelate ring.     

Soluble Ni alkoxides based on dimethylaminoisopropoxide ligands: molecular structure of [Li(PrOH)Ni (η-OR)2Cl]2 and of cis-NiCl2(ROH)2 (R = CHMeCH2NMe2)

Various routes to Ni^II aminoalkoxides have been investigated. A nickel isopropoxide derivative 1 was prepared by anodic dissolution of the metal in the presence of LiCl as electrolyte. Alcoholysis reactions of 1 with 1-dimethylamino-2-propanol afforded the homoleptic nickel(II) aminoalkoxide 2 together with a Ni---Li species 3. 2 was also obtained by metathesis reactions between sodium alkoxide and the nickel hexammine complex whereas the reaction between the latter and the aminoalcohol led to an halide solvate, cis-NiCl₂(η²-ROH)₂, 4. The various compounds were characterized by elemental analysis, FT-IR and UV-vis spectroscopies as well as by X-ray diffraction for 3 and 4. 3 corresponds to [Li(PrⁱOH)Ni(η²-OCHMeCH₂NMe₂)Cl]₂ and the overall structure can be seen as two [Ni(η²-OCHMeCH₂NMe₂)₂Cl]⁻ moieties assembled by Li(PrⁱOH)⁺. The lithium atom is 4-coordinate due to its interaction with the oxygen atoms of the aminoalkoxide ligands. Nickel is 5-coordinate with a distorted tetragonal pyramidal stereochemistry, one nitrogen being in the apical position. The metal displays a distorted octahedral surrounding for the NiCl₂ adduct 4. The bond distances vary in the order Ni---OR < Ni---N ≈ Ni---O(H)R < Ni---Cl for 3 and 4. The various compounds (except 1) are soluble in organic media.     

11-Mercaptoundecanoic acid functionalized gold nanoclusters as fluorescent probes for the sensitive detection of Cu2+ and Fe3+ ions

Metal ions are physiologically essential,but excessive metal ions may cause severe risk to plants and animals.Here,we prepared gold nanoclusters(Au NCs) protected by 11-mercaptoundecanoic acid(11-MUA),which have excellent fluorescence properties for the detection of metal ions.The results showed that the copper ions(Cu~(2+)) and iron ions(Fe~(3+)) in the solution have obvious quenching effect on the fluorescence intensity of Au NCs.The detection range of Fe~(3+) was 0.8–4.5 mmol/L(R~2= 0.992) and 4.5–11.0 mmol/L(R~2= 0.997).And Cu~(2+) has a lower linear range(0.1–1.0 mmol/L,R2= 0.993).When EDTA was added into the reaction system,it was observed that the quenching effect of Cu~(2+) and Fe~(3+)on Au NCs showed different phenomenon.Then,the effect of metal ions on the fluorescence of Au NCs was investigated.The selective detection of Cu~(2+) was achieved by EDTA masking of Fe~(3+).In addition,we realized the metal ions detection application of Au NCs in the serum     

X-ray crystal structure analysis and atomic charges of color former and developer: 5. Colored formers

The spirocarbon C6 of colorless forms of a fluoran compound is the base of the disengagement from the bond C(sp³)–O by the accessibility of the electrophilic H⁺, the phthalide ring is cleaved and this ring becomes a benzene ring D and a carboxyl group as colored forms. The crystal and molecular structures of colored forms 2-anilino-3-methyl-6-diethylamino-9-(o-carboxyphenyl) xanthene C₃₁H₂₉N₂O₃⁺·Cl⁻ (1) and 2-methyl-3-anilino-7-dibutylamino-9-(o-carboxyphenyl) xanthene C₃₅H₃₇N₂O₃⁺·Cl⁻ (2) complexes were determined by single-crystal X-ray diffraction analysis. The xanthene ring skeletons of colored forms 1 and 2 have planar geometries, and the ring junctions between the xanthene ring and the benzene ring D make a small angle compared to the colorless forms which are almost at right angles to the xanthene ring skeletons. 1 and 2 are just different from the ethyl and butyl groups in two side chains R¹ and R², but the rigid body and internal motions in molecules differ at R¹ and R⁵ (the ring F). The charges of the root atom N1 of the two side chains are increased by π-electron densities, those from N1 to C6 atoms show distinct odd alternant system, and two oxygens (O2 and O3) of the carboxyl group are decreased. The group charges of N1 of colored forms are positive, while those of the colorless forms are negative. Colored forms make networks of X–HY contacts with an anion Cl⁻ and the anion in the nucleus of network. It is explained here that delicate positive charges of atoms N2 and O2 cause ClH(N2)–N2 and ClH(O2)–O2 contacts.     

Photoinduced reaction in the ion–molecule complex Mg–nitromethane

The intra-complex reaction in Mg⁺-nitromethane by photons in the spectral region of 240–400 nm has been studied. The product Mg⁺, Mg⁺O, Mg⁺OH, and Mg⁺NO₂ were observed. The products Mg⁺ and Mg⁺OH appeared throughout the whole wavelength range, but the product Mg⁺O emerged only in the shorter wavelength region, whereas the product Mg⁺NO₂ in the longer one. The calculated results show that there are the two isomers. The absorption spectrum of the two isomers were calculated, and the isomer, which is with Mg⁺ attached to single O atom, was in good agreement with the experimental data. On the basis of the branching fraction data, the orientation of the electronic orbital, and reaction energies, the photoreaction mechanisms were explained for the Mg⁺ insertion the chemical bonds and the state-specificity.     

二酰胺结构对其萃取Am(Ⅲ)和Eu(Ⅲ)性能的影响

二酰胺化合物（Ｒ１Ｒ２ＮＣＯ）２Ｒ３用于从乏燃料元件后处理高放废液（ＨＬＷ）中分离、回收锕系和镧系元素的工艺中有良好的前景［１～４］．以ＣＨ２ＯＣＨ２ｎ为桥撑链的二酰胺称为酰胺荚醚（Ａｍｉｄｏｐｏｄａｎｄ）．在大阴离子（如苦味酸根等）存在下对三价...     

Alkylaminomethylation d'organomagnesiens

The organomagnesium compound RMgX is converted, in two steps, into the secondary amine R---CH₂---NH---R¹(R¹=CH₃ or alkyl).     

圆环上的无规行走

研究了半径为R的圆环上的无规行走问题,给出了n步末端向量的几率分布ω(θ,n)和均方末端距2>的数学表达式,发现当R²》nl²时,2≈nl²即还原为一维直线上无规行走的结果;而当r²《nl²时,2>≈π²r²/3.还计算了平均末端距<|r|>及k阶矩k>和半径R的关系,同时作了简单的物理讨论。