米蚩酮对酸敏片光谱增感研究

酸敏片是由偏二氯乙烯-丙烯酸甲酯共聚物(简称偏丙树脂)与酸敏指示剂组成的非银记录材料。该体系仅对253.7nm的低压汞灯敏感,用作光学信息记录材料受到限制。为了克服这一缺陷,文献(3)的作者采用米蚩酮增感,使该体系对广泛使用的高压汞灯也敏感。本文试图用吸收光谱法研究该体系中是否有基态电荷转移复.合物生成,通过测定曝光后光谱的变化和光谱响应曲线对其增感机理和实际应用提供一定根据。     

A new terpene ketone,a component of the essential oil ofElsholtzia ciliata

A new terpene ketone which has been called dehydroelsholtsia ketone has been isolated from the essential oil ofElsholtzia ciliata (Thumb.) Hyl. The structure of dehydroelsholtzia ketone as 3-methyl-2-(3-methylbut-2-enoyl)furan has been proposed on the basis of a study of its IR, PMR, mass and¹³C spectra and has been confirmed by its conversion into elsholtzia ketone.     

Catalytic ionic hydrogenations

Catalytic ionic hydrogenation of ketones occurs by proton transfer to a ketone from a cationic metal dihydride, followed by hydride transfer from a neutral metal hydride. This contrasts with traditional catalysts for ketone hydrogenation that require binding of the ketone to the metal and subsequent insertion of the ketone into a M-H bond. Ionic hydrogenation catalysts based on the inexpensive metals molybdenum and tungsten have been developed based on mechanistic understanding of the individual steps required in the catalytic reaction.     

Coulometric generation of hydrogen ions by oxidation of mercury in methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone

Mercury(II)-chloride reacts with anhydrous methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone in a precise stoichiometry ratio (1:2), and weakly ionized compounds of mercury with ketones are formed and equivalent quantity of HCl is released. The application of a mercury anode for the quantitative generation of H⁺ ions in 0.25 M sodium perchlorate in anhydrous methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone has been investigated. Current/potentials curves for the solvents, titrated bases, indicator and mercury showed that in these solvents mercury is oxidized at potentials much more negative than those for the titrated bases and other components present in the solution. The protons generated in this way have been used for the titration of some organic bases, with either visual or potentiometric end-point detection. The oxidation of mercury in methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone and the reaction of mercury ions with these solvents have been found to proceed with 100% current efficiency.     

Kinetics and mechanism of oxidation of acetone,ethyl methyl ketone and diethyl ketone with chloramine-T in hydrochloric acid medium

The kinetics of oxidation of aliphatic ketones (acetone, ethyl methyl ketone and diethyl ketone) by chloramine-T in presence of hydrochloric acid (0.1 to 0.3M) have been investigated at 30 °C. The rate of disappearance of chloramine-T has been found to be first order each with respect to oxidant, ketone and [H⁺], in the range of the acid concentrations studied. The thermodynamic and kinetic parameters have been evaluated by determining the rate constants at different temperatures. The products of the reaction have been identified as chloroketones by their NMR spectra. The solvent isotope effect has been studied in the case of the oxidation of acetone and ethyl methyl ketone. A mechanism has been proposed.     

Convergent Approaches to Saudin Intermediates

Different convergent approaches to the highly oxygenated sesquiterpene natural product saudin ( 1 ), has been investigated. Our strategy has included a Michael addition and aldol condensation reaction as key steps. During the synthetic development, we have found serious steric hindrance when an α‐Me‐substituted alkyl vinyl ketone was used. Such steric hindrance has been overcome by synthesizing the vinyl ketone 16 through an anionic fragmentation, which was carefully studied. Finally, the intermediate 18 has been synthesized in a one‐pot reaction from the vinyl ketone 16 and has been cyclized to obtain the promising tricyclic intermediate 20 .     

A new terpene ketone, a component of the essential oil ofElsholtzia ciliata

A new terpene ketone which has been called dehydroelsholtsia ketone has been isolated from the essential oil ofElsholtzia ciliata (Thumb.) Hyl. The structure of dehydroelsholtzia ketone as 3-methyl-2-(3-methylbut-2-enoyl)furan has been proposed on the basis of a study of its IR, PMR, mass and¹³C spectra and has been confirmed by its conversion into elsholtzia ketone.Institute of Chemical Sciences, Academy of Sciences of the Republic of Kazakhstan, Alma-Ata. Siberian State Medical Institute, Tomsk. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 823–824, November–December, 1993.     

Mechanism of oxidation of some aliphatic ketones by N-bromosuccinimide in acidic media

Kinetics of the oxidation of methyl n-propyl ketone and methyl isobutyl ketone by N-bromosuccinimide (NBS) have been studied in perchloric acid media in presence of mercuric acetate. A zero order dependence to N-bromosuccinimide and a first order dependence to both ketones and hydrogen ion concentrations have been observed. Sodium perchlorate, mercuric acetate and succinimide additions have negligible effect while methanol addition has a positive effect on the reaction rate. A solvent isotope effect (k₀D₂O/K₀H₂O = 2.3-2.7 and 2.4-2.8 for MeCOn.pr and MeCoi-Bu, respectively) has been observed at 35°. Kinetic investigations have revealed that the order of reactivity is methyl n-propyl ketone > methyl isobutyl ketone. Various thermodynamic parameters have been computed and corresponding 1,2-diketones were found to be the products. A suitable mechanism in conformity with the above observations has been proposed.     

A study of the reactions of the chemical modification of chymotrypsin. I

Summary The reaction of chymotrypsin with a number of modified analogs of the specific inhibitor of chymotrypsin L-1-tosylamido-2-phenylethyl chloromethyl ketone has been studied; the compounds investigated were D-1-tosylamido-2-phenethyl chloromethyl ketone, phenethyl chloromethyl ketone (PECK), and benzylethyl chloromethyl ketone (BCMK).It has been shown that D-TAPK does not possess inhibiting activity. The inhibiting capacity of PECK is considerably reduced. A simultaneous decrease in the length of the carbon chain and the elimination of the tosylamino group (BCMK) practically destroys the inhibiting action of the reagent.Khimiya Prirodnykh Soedinenii, Vol. 4, No. 2, pp. 116–120, 1968     

反应型共聚醚酮酮及其关环产物的合成与表征

自从 8 0年代初英国ＩＣＩ公司[1] 将以 4,4′ 二氟二苯酮和氢醌为单体经溶液亲核取代反应合成的聚醚醚酮 (ＰＥＥＫ)投放市场以来 ,聚芳醚酮作为一类新型耐热高分子材料备受瞩目 .由于这类材料具有优异的绝缘性、良好的机械性能、自熄性以及高的耐辐射性等 ,在微电子和航天航空等高科技领域中广泛应用 .为了克服已工业化品种因为高的结晶性带来的难溶解、难溶融、难加工的缺点 ,90年代人们将目光投向合成无定形、可溶解的新型聚芳醚酮 ,比较成功的方法有[2～ 7] :( 1 )在分子主链中引入柔性基团 ;( 2 )采用不对称单体以减小聚合物的结晶性 …     

Highly stereoselective biocatalytic reduction of alpha-halo ketones

The use of recombinant carbonyl reductase biocatalysts for the reduction of alpha-halo ketone intermediates to their corresponding alpha-halo alcohols has been investigated. The alpha-halo alcohol is obtained in good yield from the corresponding ketone in a stereoselective manner.     

Chiral fluoro ketones for catalytic asymmetric epoxidation of alkenes with oxone

Two structurally dissimilar, chiral fluoro ketones have been prepared and their potential as enantioselective catalysts for asymmetric epoxidation with Oxone has been evaluated. The tropinone-based ketone (-)-5 was easily prepared and showed excellent reactivity but only modest enantioselectivity. The biphenyl-based ketone (-)-6 was prepared in a somewhat lengthy synthesis (along with its monofluoro and geminal fluoro analogues). This ketone exhibited only modest reactivity; 30 mol % of (-)-6 was needed to bring about complete conversion in a reasonable time. The enantioselectivity of this catalyst was generally much higher, but again very substrate dependent.     

Metal free amide synthesis via carbon–carbon bond cleavage

A metal-free oxidative coupling of methyl ketones and primary amines to amides has been developed. The reaction tolerates a variety of functional groups, and is operationally simple. The reaction is proposed to go through a radical pathway to form the triiodomethyl ketone intermediate and the amide is formed by the nucleophilic attack of amine on triiodomethyl ketone carbonyl.     

卡尔曼滤波同时pH滴定法研究

本文将卡尔受滤波(KF)递推算法，用于多组分同时pH滴定。讨论了方法原理，指定pH值的选择。对四组分醇酮氧化酸试样和模拟样，进行了多次测定，获得满意结果。     

Development of Molecular Mechanics Torsion Parameters for alpha,beta-Cyclopropyl Ketones and Conformational Analysis of Bicyclo[m.1.0]alkan-2-ones

Conformations of cyclopropyl methyl ketone have been studied using ab initio methods in an effort to quantify the effects of conjugative overlap between the cyclopropane ring and an adjacent ketone carbonyl. Results were comparable with previous experimental and theoretical studies. Cyclopropyl methyl ketone exhibits a global energy minimum in the s-cis conformer and a local energy minimum near the s-trans conformer. The potential energy curve obtained was used to derive torsion parameters which were employed in molecular mechanics studies of the conformations of the set of bicyclo[m.1.0]alkan-2-ones having larger ring sizes from five- to 16-membered. Similar conformations for the cyclopropyl ketone substructure are observed for all the medium and large ring systems examined. Possible synthetic ramifications of local conformational anchoring by this functional group array are discussed.     

Synthesis of furazano-substituted 1,5-diazepines

A series of furazano-substituted 1,5-diazepines have been synthesized from the reaction of a methyl ketone and 3,4-diaminofurazan in the presence of a mild Lewis acid. The reaction was found to be regiospecific. Other ketone substrates also yielded diazepines, however, these products were found to be unstable and decomposed upon contact with air.     

Acetoxyl group directed cyclization promoted by SmI2: directing group determined stereocomplementarity

Complete reversal of diastereoselectivity was observed in the SmI(2)-promoted ketyl-olefin coupling cyclizations of the hydroxy ketone or aldehyde and its acetate. For example, the stereodivergent synthesis of the epimeric five-membered-ring alcohols 2 and 4 has been accomplished through the SmI(2)-induced ketyl-olefin coupling cyclizations of the delta-hydroxy ketone 1 and delta-acetoxy ketone 3.     

Synthesis of the 4-azatricyclo[5.2.2.0(4,8)]undecan-10-one core of daphniphyllum alkaloid calyciphylline A using a Pd-catalyzed enolate alkenylation

[reaction: see text] The ABC ring system of the natural product calyciphylline A has been synthesized. The key steps were a palladium-catalyzed intramolecular coupling of an amino-tethered vinyl bromide with a ketone using potassium phenoxide as the base to generate the C-ring and a hydroxyl-directed hydrogenation of an exocyclic double bond to give the azatricyclic ketone 1.     

Towards oleananes: Geminal dimethylation at C-4

A model of the ABC rings of the oleananes, prepared by biomimetic polyene cyclization, shows that the system is sufficiently rigid to prevent epimerization of the C-5 hydrogen with a ketone functionality in place at C-4. Such a sterically hindered ketone has been successfully transformed to a geminal dimethyl group by a three-step procedure.     

Diastereocontrolled construction of pactamycin's complex ureido triol functional array

An advanced intermediate in a projected synthesis of pactamycin has been prepared. Early installation of the C1-dimethylurea functionality allows for its participation in a diastereoselective, chelation-controlled addition of organometal nucleophiles to the C5 prochiral ketone. Four of the molecule's six stereocenters are set with a ketone functional handle provided for subsequent manipulation.