New enantioselective method for hydration of alkenes using cyclodextrins as phase transfer catalyst

A new enantioselective/inverse phase transfer catalysis (IPTC) reaction for the Markovnikov hydration of double bounds by an oxymercuration-demercuration reaction with cyclodextrins as catalysts was disclosed. Moderate ee (up to 32%) and yields (14-60%) were obtained for allylic amines and protected allylic alcohols as starting materials.     

预处理条件对用于CO_2加氢的超细CuO－ZnO－SiO_2催化剂性能的影响

采用ＸＲＤ、ＢＥＴ、ＴＰＲ手段，研究了焙烧和还原温度对超细ＣｕＯ－ＺｎＯ－ＳｉＯ２催化剂的性质及其ＣＯ２加氢反应催化活性的影响．胶体在５７３－７７３Ｋ范围内焙烧生成ＣｕＯ、Ｃｕ２Ｏ、ＺｎＯ晶相，随着焙烧温度继续升高，ＣｕＯ和ＺｎＯ晶粒逐渐变大，但催化剂的比表面积和孔容变化很小．在９７３Ｋ焙烧后出现Ｚｎ２ＳｉＯ４晶相，使催化剂比表积和孔容变小，导致催化剂活性降低．焙烧温度对催化剂活性的影响大于对ＣＯ２加氢产物分布的影响．在５４８－６４８Ｋ范围内，催化剂还原温度对其催化活性影响不大．７０３Ｋ高温还原后，可能由于Ｃｕ０晶粒的出现，使得催化剂的活性下降．ＴＰＲ研究结果进一步表明，焙烧温度影响ＣｕＯ同ＺｎＯ、ＳｉＯ２之间的相互作用和催化剂的还原行为．     

Application of organolithium and related reagents in synthesis XVI: Synthetic strategies based on aromatic metallation. A concise regiospecific conversion of chlorobenzoic acids into their benzylated derivatives

Summary The reaction of benzyl bromide withbis-(N- and C-ortho)-lithiated chloroanilides4,5, and6 has been examined. It has been found that in the case where the lithiated compound was derived frommeta-methoxyanilides, pre-addition of LiBr orTMEDA was required to achieve C-benzylation. These results were accounted for by the conversion of the usually formed dimer into a mixed dimer with the LiBr orTMEDA complex in which the C-lithium bond appears to be more accessible towards electrophiles. The practical synthesis of -benzylchlorobenzoic acids10,11, and12 was accomplishedvia ionic reductive cleavage (Et₃SiH/TiCl₄) of the corresponding phthalides18,19, and20. The acids10,11b, and11c afforded the corresponding anthrones, upon treatment with trifluoroacetic anhydride which were oxidized by chromium trioxide to the new chloroantraquinones21,22, and23.

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Anwendung von Organolithium und verwandten Reagenzien in organischen Synthesen, 16. Mitt.: Synthesen mittels aromatischer Metallierung. Eine bequeme regiospezifische Umwandlung von Chlorbenzoesäuren in ihre Benzylderivate

Zusammenfassung Die Reaktion von Benzylbromid mit denbis-(N- und C-ortho)-lithiierten Chloraniliden4,5 und6 wurde untersucht. Im Falle lithiierter Verbindungen ausmeta-Methoxyaniliden ist die Zugabe von LiBr oderTMEDA während des Lithiierungsprozesses für die C-Benzylierung erforderlich. Diese Ergebnisse werden durch Umwandlung des gewöhnlich enstehenden Dimers in ein gemischtes Dimer mit dem LiBr- oderTMEDA-Komplex erklärt, in welchem die C-Li-Bindung für Elektrophile leichter zugänglich ist. Diese praktische Synthese dero-Benzylchlorbenzoesäuren10,11 und12 wird durch reduktive Spaltung der entsprechenden Phthalide18,19 und20 mit Et₃SiH/TiCl₄ ergänzt. Bei der Reaktion der Säuren10,11b und11c mit Trifluoressigsäureanhydrid entstehen die erwarteten Anthrone, die durch Oxidation mit Chromtrioxid in die neuen Chloranthrachinone21,22 und23 umgewandelt wurden.

     

还原荧光法测定水和废水中的对硝基酚

本文用乙酸丁酯萃取水和废水中的对硝基酚,用氢氧化钠溶液反萃取,然后用硼氢化钾还原对硝基酚为对氨基酚,用荧光法进行分析测定。荧光激发波长和发射波长分别为274nm和372nm。检测限为3.0μg/L。样品加标回收率为89％～96％。     

On the Reduction of Copper Oxide

The reduction of CuO with hydrogen has been studied with a temperature programmed reduction technique. According to a proposed reduction mechanism, the reduction was initiated with a interaction between hydrogen and active sites of copper oxide, the rate of the reduction was limited by the diffusion of water from the crystalline. The activation energy of this diffusion is found to be 13Kcal/mol. Reoxidation of copper powder may cause redispersion of the crystalline. The chemical interaction between copper oxide and Cabosil is found very weak.     

Microwave mediated facile one-pot synthesis of polyarylpyrroles from but-2-ene- and but-2-yne-1,4-diones

Several pyrrole derivates with multiple aryl substituents were prepared conveniently in a one pot-reaction from but-2-ene-1,4-diones and but-2-yne-1,4-diones via hydrogenation of the carbon-carbon double bond/triple bond followed by amination-cyclization. The reaction could be performed with ammonium formate or alkyl/arylammonium formates under Pd/C in polyethylene glycol-200 (PEG-200) under microwave irradiation. Using this procedure, different aryl-substituted pyrroles were prepared. Furthermore, studies on microwave vs thermal conditions indicate faster heating under microwave conditions was responsible for rate enhancement.     

Reduction of alkyl and vinyl sulfonates using the CuCl2·2H2O-Li-DTBB(cat.) system

The reduction of a series of alkyl mesylates, dimesylates and triflates to the corresponding hydrocarbons was efficiently performed using a reducing system composed of CuCl₂·2H₂O, an excess of lithium sand and a catalytic amount (5 mol%) of 4,4′-di-tert-butylbiphenyl (DTBB), in tetrahydrofuran at room temperature. The process was also applied to enol and dienol triflates affording alkenes and dienes, respectively. The use of the deuterated copper salt CuCl₂·2D₂O allowed the simple preparation of the corresponding deuterated products.     

Comparison of fast scan voltammetry with microelectrode voltammetry of reduction of 1,4-benzoquinone

The reduction of 1,4-benzoquinone (BQ) in acetonitrile was blocked in steady-state microelectrode voltammetry although it has been believed to be a sluggish electron transfer reaction. Ferrocene was added to the BQ solution with equi-concentration in order to confirm the diffusion-control step and to evaluate accurately the kinetic effect from potential differences. Fast scan voltammograms showed the negative potential shifts both of the cathodic and the anodic peaks with an increase in the scan rate. In contrast, microelectrode voltammetry showed that the ratio of the steady-state limiting current for BQ to that for ferrocene decreased with a decrease in the electrode radii. The halfwave potential of the reduction of BQ did not vary with the radii within error. These features are largely deviated from the Butler–Volmer kinetic behavior. The electrode surface after the long term electro-reduction was coated with a precipitate. The proposed reaction mechanism is formation of films by follow-up chemical reactions of BQ associated with slight potential shift. The film blocks diffusion of BQ. This model was theoretically formulated and elucidated the experimental results.     

A general and efficient reduction of acyl chlorides to aldehydes by Sm(0)/Bu3P

A facile and efficient reduction of aromatic and aliphatic acyl chlorides to their corresponding aldehydes in the presence of Sm(0)/Bu₃P has been developed with broad scope. This method prevents over reduction of products, that is, the over-reduction of aldehydes to alcohols.     

Low‐Valent Ruthenium Induced Simultaneous Reduction of Nitro Group and C‐C Double Bond in Nitroolefin 1‐Phenyl‐2‐Nitropropene‐1

The reduction of 1‐phenyl‐2‐nitropropene‐1 ( 1 ) on using ruthenium complexes was studied in detail in order to correlate this method with those previously recorded in the literature for the hydrogenation of nitroolefins. A variety of products was isolated by varying the reaction temperature and solvent. Among them was 1‐phenyl‐2‐propylamine ( 4 ), completely reduced from the selective both double bond and nitro group. 1‐Phenyl‐2‐propanol ( 5 ) was observed due to reduction of phenylacetone at 125 °C in the presence of ruthenium catalyst. When reaction temperature was lower than 125 °C, by employing RuCl₂(PPh₃)₃ complex, 1‐phenyl‐2‐nitropropane ( 2 ) and phenylacetone ( 3 ) were obtained, respectively. Ru‐BINAP complexes were attempted to produce chiral amine from starting material 1‐phenyl‐2‐nitropropene‐1 ( 1 ).