4-硝基苄醇的合成

以4-硝基甲苯为原料,经过芐位溴代生成4-硝基芐基溴,然后与无水乙酸钠在相转移催化剂作用下生成乙酸对硝基芐酯,最后在15%NaOH溶液中水解合成4-硝基苄醇。考察了不同的溴代试剂和相转移催化剂对反应收率的影响。结果表明,当采用Br2（1.1eq）-H2O2（30%,1.1eq）-AIBN（0.05eq）为溴代试剂、四丁基溴化铵（0.05eq）为相转移催化剂时,总收率达44.6%。该合成路线操作容易,后处理简便,且反应溶剂及重结晶溶剂都可以回收重复利用,具有工业化应用前景。     

Preparation of deuterated methyl 6,9,12-octadecatrienoates and methyl 6,9,12,15-octadecatetraenoates

Methyl 6,9,12-octadecatrienoate-15,15,16,16-d ₄ was obtained by Wittig coupling between 6,6,7,7-tetradeutero-3-nonenyltriphenylphosphonium iodide, 8, and the aldehyde ester, methyl 9-oxo-6-nonenoate. Methyl 6-oxohexanoate, obtained by ozonolysis of cyclohexene, was coupled in a Wittig reaction with [2-(1,3-dioxan-2-yl)ethyl]triphenylphosphonium bromide to give methyl 8-dioxanyl-6-octenoate. This compound was transacetalized to methyl 9,9-dimethoxy-6-nonenoate, which was then hydrolyzed to the aldehyde ester. For the preparation of compound 8, the tetrahydropyranyl ether of 2-pentynol was deuterated with deuterium gas and tris-(triphenylphosphine)chlororhodium. The tetradeuterated tetrahydropyranyl ether was converted to the bromide with triphenylphosphine dibromide, and the bromide was coupled with 3-butynol by means of lithium amide in liquid ammonia to give 3-nonynol-6,6,7,7-d ₄. Hydrogenation over Lindlar's catalyst converted the deuterated alkynol to 3-nonenol-6,6,7,7-d ₄. This deuterated alkenol was converted to the bromide with triphenylphosphine dibromide, then to the iodide with sodium iodide in acetone, and finally to 8 with triphenylphosphine in acetonitrile. Methyl 6,9,12,15-octadecatetraenoate-12,13,15,16-d ₄ was obtained by Wittig coupling between methyl 9-oxo-6-nonenoate and 3,4,6,7-tetradeutero-3,6-nonadienyltriphenylphosphonium iodide, 15. For the preparation of compound 15, the bromide obtained from the reaction of 2-pentynol with triphenylphosphine dibromide was coupled with 3-butynol with lithium amide in liquid ammonia. The resulting 3,6-nonadiynol was deuterated with deuterium gas in the presence of P-2 nickel, and the resultant deuterated nonadienol was converted to 15 through the bromide and iodide. The final products were separated from isomers formed during the synthetic sequences by silver resin chromatography.     

Simultaneous accommodation of Dy3+ at the lattice site of β-Ca3(PO4)2 and t-ZrO2 mixtures: Structural stability,mechanical, optical,and magnetic features

Structurally stable β-Ca₃(PO₄)₂/t-ZrO₂ composite mixtures with the aid of Dy³⁺ stabilizer were accomplished at 1500°C. The precursors comprising Ca²⁺, P⁵⁺, Zr⁴⁺, and Dy³⁺ have been varied to obtain five different combinations. The results revealed the fact that complete phase transformation of calcium-deficient apatite to β-Ca₃(PO₄)₂ occurred only at 1300°C, whereas the evidence of t-ZrO₂ crystallization is obvious at 900°C. The dual occupancy of Dy³⁺ at β-Ca₃(PO₄)₂ and t-ZrO₂ structures was evident; however, Dy³⁺ initially prefers to occupy β-Ca₃(PO₄)₂ lattice until its saturation limit and thereafter accommodates at the lattice site of ZrO₂. The typical absorption and emission behavior of Dy³⁺ were noticed in all the systems and, moreover, the surrounding symmetry of Dy³⁺ domains has been determined from the luminescence study. All the systems ensured paramagnetic response that is generally contributed by the presence of Dy³⁺. A gradual increment in the phase content of t-ZrO₂ in the composite mixtures ensured a significant improvement in the hardness and Young's modulus of the investigated compositions.     

Preparation of methyl 11,14,17-eicosatrienoate-8,8,9,9-d 4 and methyl 8,11,14,17-eicosatetraenoate-8,9-d 2

Methyl 11,14,17-eicosatrienoate-8,8,9,9-d ₄ was obtained by Wittig coupling of 3,6-nonadienyltriphenylphosphonium iodide with methyl 11-oxoundecanoate-8,8,9,9-d ₄. For the synthesis of the phosphonium salt, 2-pentynol was converted to 1-bromo-2-pentyne with triphenylphosphine dibromide. Grignard coupling of 1-bromo-2-pentyne with 3-butynol in the presence of cuprous chloride gave 3,6-nonadiynol. The latter was hydrogenated in the presence of P-2 nickel catalyst to yield 3,6-nonadienol. The dienol was convertedvia the bromide and iodide to the phosphonium salt. The aldehyde ester was prepared starting with the coupling of 7-bromoheptanoic acid and 3-butynol with lithium amide in liquid ammonia. The hydroxyalkynoic acid obtained was converted to the methyl ester and the hydroxy group was converted to the tetrahydropyranyloxy group. Subsequent deuteration of the methyl 11-(2-tetrahydropyranyloxy)-8-undecynoate with deuterium gas andtris-(triphenylphosphine)chlorohodium gave the corresponding tetradeuterated product. The tetrahydropyranyl group was removed and the methyl 11-hydroxy-undecanoate-8,8,9,9-d ₄ was oxidized to the aldehyde ester with pyridinium chlorochromate. Methyl 8,11,14,17-eicosatetraenoate-8,9-d ₂ was obtained by a similar sequence of reactions. The methyl 11-oxo-8-undecenoate-8,9-d ₂ required for the Wittig coupling was obtained by Lindlar deuteration of the protected alkynoic ester to methyl 11-(2-tetrahydropyranyloxy)-8-undecenoate-8,9d ₂. The unsaturated hydroxy ester was oxidized to the aldehyde ester by periodinane with negligible isomerization. The allcis isomers were isolated by silver resin chromatography. The mention of firm names or trade products does not imply that they are endorsed or recommended by the U.S. Department of Agriculture over other firms or similar products not mentioned.     

Nano-CuFe2O4@SO3H Catalyzed Efficient One-Pot Cyclo-Dehydration of Dimedone and Synthesis of Chromeno[4,3-b]chromenes

Chlorosulfonic acid immobilized on CuFe₂O₄ nanoparticles (nano-CuFe₂O₄@SO₃H) was evaluated as a recoverable catalyst for the one-pot cyclo-dehydration of dimedone and synthesis of chromeno[4,3-b]chromene derivatives by reaction of arylaldehydes, dimedone or 1,3-cyclohexanedione, with 3-hydroxycoumarine or 4-hydroxycoumarine in good to excellent yield. Also, 2,2′-Arylmethylene bis(3-hydroxy-5,5-dimethyl-2-cyclohexene-1-one) was synthesized by the reaction of aromatic aldehyde and dimedone using nano-CuFe₂O₄ in ethanol at room temperature. The catalyst could be recycled several times without significant loss of its catalytic activity. Clean methodologies, easy work-up procedure, high yield and simple preparation of the catalyst are some advantages of this procedure.     

Highly (≥98 %) Selective Trisubstituted Alkene Synthesis of Wide Applicability via Fluoride-Promoted Pd-Catalyzed Cross-Coupling of Alkenylboranes

(Z)-β-bromo-1-propenyl(pinacol)borane ( 4 ), recently made available in 85 % yield as a ≥98 % isomerically pure compound via bromoboration of 1-propyne, has been converted to β-alkyl-, aryl-, and alkenyl-substituted (Z)-2-methyl-1-alkenyl(pinacol)boranes ( 2a ) in ca. 75 % yield based on propyne via Pd-catalyzed Negishi alkenylation with suitable organozinc bromide. The previously sluggish and modest-yielding Suzuki alkenylation of β,β-disubstituted alkenylboranes has been significantly promoted by fluorides, especially nBu₄NF(TBAF) or CsF, to give trisubstituted alkenes, i.e., (Z)-β-Me-substituted 3 - i – 3-xi and (E)-β-Ph-substituted 2b–i and 2b–ii . In all cases, each alkene product was formed in a ≥98 % stereoselectivity. The propyne-based protocol nicely complements the widely used Zr-catalyzed alkyne methylalumination–Pd-catalyzed alkenylation by providing a highly stereoselective(≥98 %) route to (Z)-Me-substituted alkenes.     

Kinetic studies on the condensation reaction of 2-methylol-4-t-butylphenol with 4-t-butylphenol using acid catalysts. I

The rates of the individual reactions of 2-methylol-4-t-butylphenol with 4-t-butylphenol were measured under varying mole ratios of reactants in the presence of different acid catalysts (5.0 × 10^?3 N to 2.0 × 10^?4 N) at five different temperatures (60, 65, 70, 75, and 80°C). In all the experiments, the reactions were found to obey second-order rate law. The values of the Arrhenius parameters and the entropy of activation for the overall reaction were calculated. The relative catalytic efficiencies of the acid catalysts followed the order HNO₃ > HCl > H₂SO₄.     

Effect of dietary conjugated linoleic acid (CLA) on metabolism of isotope-labeled oleic,linoleic, and CLA isomers in women

The purpose of this study was to investigate the effect of dietary CLA on accretion of 9c-18∶1, 9c, 12c-18∶2, 10t, 12c-18∶2, and 9c, 11t-18∶2 and conversion of these FA to their desaturated, elongated, and chain-shortened metabolites. The subjects were six healthy adult women who had consumed normal diets supplemented with 6 g/d of sunflower oil or 3.9 g/d of CLA for 63 d. A mixture of 10t, 12c-18∶2-d ₄, 9c, 11t-18∶2-d ₆, 9c-18∶1-d ₈, and 9c, 12c-18∶2-d ₂, as their ethyl esters, was fed to each subject, and nine blood samples were drawn over a 48-h period. The results show that dietary CLA supplementation had no effect on the metabolism of the deuterium-labeled FA. These metabolic results were consistent with the general lack of a CLA diet effect on a variety of physiological responses previously reported for these women. The ²H-CLA isomers were metabolically different. The relative percent differences between the accumulation of 9c, 11t-18∶2-d ₆ and 10t, 12c-18∶2-d ₄ in plasma lipid classes ranged from 9 to 73%. The largest differences were a fourfold higher incorporation of 10t, 12c-18∶2-d ₄ than 9c, 11t-18∶2-d ₆ in 1-acyl PC and a two- to threefold higher incorporation of 9c, 11t-18∶2-d ₆ than 10t, 12c-18∶2-d ₄ in cholesterol esters. Compared to 9c-18∶1-d ₈ and 9c, 12c-18∶2-d ₂, the 10t, 12c-18∶2-d ₄ and 9c, 11t-18∶2-d ₆ isomers were 20–25% less well absorbed. Relative to 9c-18∶1, incorporation of the CLA isomers into 2-acyl PC and cholesterol ester was 39–84% lower and incorporation of 10t, 12c-18∶2 was 50% higher in 1-acyl PC. This pattern of selective incorporation and discrimination is similar to the pattern generally observed for trans and cis 18∶1 positional isomers. Elongated and desaturated CLA metabolites were detected. The concentration of 6c, 10t, 12c-18∶3-d ₄ in plasma TG was equal to 6.8% of the 10t, 12c-18∶2-d ₄ present, and TG was the only lipid fraction that contained a CLA metabolite present at concentrations sufficient for reliable quantification. In conclusion, no effect of dietary CLA was observed, absorption of CLA was less than that of 9c-18∶1, CLA positional isomers were metabolically different, and conversion of CLA isomers to desaturated and elongated metabolites was low.     

A novel paddle-wheel shaped spirocyclic cyclotetraphosphazene from the thermolysis of a P(III) azide

The spirocyclic cyclotetraphosphazene [CH₂(6-t-Bu-4-Me-C₆H₂O)₂PN]₄ (2) is obtained as one of the products from the thermolysis of the azide CH₂(6-t-Bu-4-Me-C₆H₂O)₂PN₃ (1). An X-ray structure determination reveals that the compound has a paddle-wheel shaped structure with the phosphorus bearing only eight-membered rings [phosphazene/phosphocin]. The eight-membered phosphocin ring in 2 has a tub conformation, in contrast to the boat–chair conformation present in 1, possibly due to weak C–H…N interactions. Compound 2 could not be prepared from the traditional route of starting from octachlorocyclotetraphosphazene [N₄P₄Cl₈] and hence the azide route is the only accessible pathway for 2.     

邻硝基苄基溴的合成研究

对以邻硝基甲苯为原料,NaBrO3/NaHSO3为溴化剂,偶氮双异丁腈(AIBN)为引发剂,制备邻硝基苄基溴的工艺路线进行了研究,在优惠的工艺条件下n(邻硝基甲苯)∶n(溴酸钠)∶n(亚硫酸氢钠)=1∶4∶4,反应温度70℃,时间2h,反应收率≥73%。该工艺具有生产成本低、操作简便和易于工业化生产等特点。     

Low-Pressure Carbonylation of Benzyl Bromide with Palladium Complexes Modified with PNS (PNS = Ph2PCH2CH2C(O)NHC(CH3)2CH2SO3Li) or P(OPh)3. Structural Identification of Palladium-Catalyst Intermediate

The catalytic activities of two palladium complexes with water soluble phosphine PNS (PNS = Ph₂PCH₂CH₂C(O)NHC(CH₃)₂CH₂SO₃Li) (I) and phosphite P(OPh)₃ (II) were tested in the carbonylation of benzyl bromide in methanol at 40–50°C and 1 atm of CO. The first catalyst, (I), was formed in situ from PdCl₂(cod) and PNS, the second one, (II), was based on the PdCl₂(P(OPh)₃)₂ complex. At the ratio of [NEt₃]:[PhCH₂Br] equal to 2.5 the yields of phenylacetic acid methyl ester were 83–86% in the carbonylation with PNS and 100% in the carbonylation with P(OPh)₃. The palladium catalyst with P(OPh)₃ produced under the same conditions 70% of phenylacetic acid methyl ester in the carbonylation of benzyl chloride and 60% of 2-methylphenylacetic acid methyl ester in the carbonylation of 1-bromoethylbenzene. The lower rate of carbonylation of 1-bromoethylbenzyl bromide in comparison to that of benzyl bromide was explained by the lower rate of the substrate oxidative addition step leading to palladium benzyl complexes. Two palladium benzyl complexes, cis-PdBr(PhCH₂)(P(OPh)₃)₂ and trans-PdBr(PhCH(Me))(P(OPh)₃)₂ have been isolated and characterized (X-ray, ³¹P and ¹H NMR).     

The Di-t-butylation of p-cresol with t-butanol in Supercritical CO2 over Tungstophosphoric Acid Supported on Ordered Mesoporous Silica

Tungstophosphoric acid (HPW) supported on MCM-41 was an excellent catalyst for the t-butylation of p-cresol to 2,6-di-t-butyl-4-methylphenol (2,6-DTBPC) in supercritical CO₂; however, zeolites, H-Y and H-Beta, only gave 2-t-butyl-4-methylphenol (2-TBPC) because of their limitation in pore size. The yield of 2,6-DTBPC was maximized at 110 °C, and further increase in temperature rather decreased the yield. The yield of 2,6-DTBPC was maximized at 10–11 MPa CO₂ pressure, and further increase of the pressure decreased in the conversion of phenol and the yield of 2,4-DTBC. The thermogravimetric analysis of used catalysts showed that the coke-formation was minimized in supercritical CO₂ compared to the other reaction media such as in liquid phase and in N₂ atmosphere.     

Syntheses of poly[N-(2,2 dimethoxyethyl)-N-methyl acrylamide] for the immobilization of oligonucleotides

Radical-initiated polymerization of N-(2,2 dimethoxyethyl)-N-methylacrylamide has been carried out either in chloroform or methanol using 2,2′-azobisisobutyronitrile as an initiator, allowing us to prepare acetal containing water-soluble polymers. A kinetic study in both solvents showed that this monomer fairly homopolymerized (k_p · k_t^−1/2 = 1 mol^−1/2 L^1/2 s^−1/2). Static light scattering was used to characterize the molecular weight of these polymers. In addition, the Mark–Houwink–Sakurada relationship was established based on viscosity measurements performed at 25°C in water. Recovery of the aldehyde moieties on the polymer was achieved under mild conditions using a diluted inorganic solution. The analysis of the formation of aldehyde groups was performed by ¹H- and ¹³C-NMR. The covalent binding of oligodeoxyribonucleotides was carried out in water/acetonitrile mixtures with subsequent NaBH₄ reduction of the imine bonds so as to stabilize the polymer/oligodeoxynucleotide conjugates. © 1996 John Wiley & Sons, Inc.     

Study of the SN2 Substitution Reactions Between Methyl Naphtalene-2-Sulfonate and Methyl 4-Nitrobenzene Sulfonate and Bromide Ions in Dodecyl Dibromide Dimeric Micellar Solutions in the Absence and Presence of Alcohols

The S_N2 substitution reactions between methyl naphthalene-2-sulfonate and methyl 4-nitrobenzenesulfonate with bromide ions were studied in alkanediyl-α,ω-bis(dimethyldodecylammonium) bromide, 12-s-12,2Br⁻ (s = 3, 4, 6), micellar solutions in the absence and in the presence of alcohols. The observed rate constant for the two processes was found to be sensitive to changes in micellar characteristics caused by the presence of alcohols. At high surfactant concentrations, kinetic data made evident the sphere-to-rod transition accompanying the increase in the dimeric surfactant concentration in all the micellar reaction media investigated. Kinetic results were quantitatively rationalized within the whole surfactant concentration range, below and above the second CMC, by using a new treatment based on the pseudophase kinetic model.     

四正丁基溴化铵催化合成香豆素的研究

以水杨醛和醋酸酐为原料,无水碳酸钾为催化剂来合成香豆素。研究了四正丁基溴化铵的活化作用、四正丁基溴化铵的用量、反应温度以及反应时间对香豆素产率的影响。结果表明：用四正丁基溴化铵作活化剂,香豆素的产率由原来的61.3%提高到84.3%。最佳反应条件：n（水杨醛）∶n（四正丁基溴化铵）=1∶0.04,反应温度160℃,反应时间4h,香豆素的产率可达85.1%。     

The effect of zinc–bromine interactions on electrophilic bromination in concentrated ZnBr2 solutions

Facile bromination can be carried out in concentrated solutions of zinc bromide (60–80% w/w ZnBr₂ in water) [A. Ewenson, D. Itzhak, M. Freiberg-Bergstein, A. Shushan, B. Croitoru, D. Beneish, N. Faza, WO patent 99/19275, Bromine Compounds Ltd., Israel, 1999]. These brine solutions offer an alternative to expensive and harmful organic solvents. A correlation between the reactivity and the molecular ratio H₂O:Zn has been found and quantified using UV-Vis spectroscopy [J.A. Duffy, G.L. Wood, J. Chem. Soc., Dalton Trans. (1987) 1485; E. Eyal, A. Treinin, J. Am. Chem. Soc. 86 (1964) 4287–4290; D. Meyerstein, A. Treinin, Trans. Faraday Soc. 59 (1963) 1114–1120]. Based on spectrophotometric and NMR results, it is proposed that these concentrated aqueous solutions, which behave similarly to anhydrous media, enhance the reactivity of molecular bromine by polarizing the Br–Br bond. Furthermore they affect the electron density distribution in the organic substrates.     

Thermo-responsive block copolymer micelle-supported (S)-α,α-diphenylprolinol trimethylsilyl ether for asymmetric Michael addition of nitroalkenes and aldehydes in water

An amphiphilic block copolymer PNIPAM₅₃-b-(PS₃₀-co-P4AMS₁₀) was facilely prepared by reversible addition-fragmentation chain transfer (RAFT) polymerization. The immobilization of (S)-α,α-diphenylprolinol trimethylsilyl ether onto the block copolymers was then performed through using copper-catalyzed alkyne-azide cycloaddition (CuAAC), and the generating amphiphilic diblock copolymer supported chiral catalyst PNIPAM₅₃-b-(PS₃₀-co-P4AMS₁₀)/proTMS was self-assembled into micelles with regular diameters about 50 nm in aqueous solution. The micellar catalyst was further used for the asymmetric Michael reaction between propanal and trans-β-nitrostyrene in water. Using only 1 mol% micellar catalyst, the corresponding Michael addition products could be obtained in good yields and high enantioselectivities as well as good diastereoselectivities. In addition, this micellar catalyst could be reused at least for four times. Moreover, the micellar catalyst could be applied for the asymmetric addition reaction of 4-chlorocinnamyl aldehyde and nitromethane, and thus constructing the baclofen pharmaceutical intermediate.     

3,5-二甲氧基苄溴的合成

报道了3,5-二甲氧基苯甲酸经NaBH4/I2还原体系还原得到3,5-二甲氧基苄醇,再由氢溴酸溴化得到3,5-二甲氧基苄溴,总收率70%。     

Synthesis and characterization of CeO2/Bi2O3/gC3N4 ternary Z-scheme nanocomposite

An effective and facile phytogenic method was used to prepare CeO₂/Bi₂O₃ and CeO₂/Bi₂O₃/gC₃N₄ composites using Eichhornia crassipes phytoextract. The synthesized catalysts were characterized using techniques such as XRD, FTIR, UV-DRS, PL, SEM-EDAX, XPS, zeta potential, and TGA. These catalysts showed diverse photocatalytic and optical properties due to the alteration in the bandgap. The synthesized composites exhibited good photocatalytic activity by degrading Malachite green (MG) dye. The increase in the photocatalytic activity could be attributed to the p-n heterojunction of the catalysts with efficient charge separation and strong oxidative ability. The modified photocatalysts showed excellent catalytic activity and reusability under visible light. The superior efficiency and its applications in environmental remediation make these catalysts a potential candidate for photocatalysis.     

A synthesis of 4-hydroxy-2-trans-nonenal and 4-(3H) 4-hydroxy-2-trans-nonenal

4-Hydroxy-2-trans-nonenal, the most abundant and toxic unsaturated aldehyde generated during membrane lipid peroxidation, was synthesized starting from fumaraldehyde dimethyl acetal. In the first step of the synthesis, the fumaraldehyde dimethyl acetal was partially hydrolyzed using amberlyst catalyst to obtain the monoacetal. The 4-hydroxy-2-trans-nonenal was synthesized by the Grignard reaction of the fumaraldehyde monoacetal with 1-bromopentane. 4-Hydroxy-2-trans-nonenal, obtained as its dimethylacetal, was oxidized to its corresponding 4-keto derivative using pyridinium chlorochromate buffered with sodium acetate as the oxidizing agent. 4-(³H) 4-Hydroxy-2-trans-nonenal was obtained in one step by the sodium borotriteride reduction of the 4-keto derivative.