微乳液的热力学性质 I: 芳烃类的侧链链长对微乳液热力学函数影响

本文研究以非离子型表面活性剂-正辛醇-水-芳烃类所组成的微乳液, 探讨醇从油相转移到界面相时的自由能变化, 以及温度对自由能的影响。计算出熵和焓的变化, 发现在实验范围内, 上述热力学函数的对数值与芳烃侧链的碳原子数(n)呈线性关系。这些关系式对微乳液的构成和稳定性的讨论是重要的, 还对几种芳烃异构体所构成的微乳液的热力学函数进行了实验和讨论。     

Palladium-catalyzed aerobic oxidation of amines

Pd-Catalyzed aerobic oxidation of different amines was systematically examined for the first time. A PdCl₂/PPh₃ system was successfully developed to catalyze the aerobic oxidation of several types of amines including Ar-CH₂NHPh, Ar-CH₂NHOMe, and Ar-CH₂NHMs with high yields. Theoretical studies showed a remarkable difference in the energy barriers of β-hydride elimination between an alcohol and various amines.     

Photo-induced catalytic partial oxidation of citronellol with assistance of phthalocyanines

Attention was paid to the role of sulfonated phthalocyanines as efficient photocatalysts in the photo-induced partial oxidation of citronellol. Performance of the singlet oxygen species inducing the formation of citronellol hydroperoxides was studied in detail. The involved reactions may be of great importance in the catalytic production of rose oxide — a highly appreciated component of many synthetic fragrances.     

Oxidation of alkyl aromatics to ketones by tert-butyl hydroperoxide on manganese dioxide catalyst

The catalytic activity of the manganese oxide was investigated for the oxidative functionalization of alkylaromatics to benzylic ketones using tert-butyl hydroperoxide (TBHP) as an oxidant. Manganese oxides of different types were tested for this reaction. Of all the oxides, the nano amorphous manganese dioxide exhibited significant catalytic activity and selectivity for the reaction. The nano amorphous MnO₂/TBHP catalytic system could also be reused for six consecutive cycles with no considerable loss in catalytic activity.     

Study of alkyl nitrites oxidation with DMSO

The oxidation of nine alkyl nitrites to the corresponding carbonyl compounds in yields of 76–96% by dimethyl sulfoxide (DMSO) is described; since oxidation with DMSO is very selective this method can be used to obtain aldehydes or ketones from alcohols which include other labile functional groups such as alkene, alkyne and aldehyde.     

Selective aerobic oxidation of hydroxy compounds catalyzed by photoactivated ruthenium-salen complexes (selective catalytic aerobic oxidation)

Selective oxidation of alcohols to the corresponding carbonyl compounds is one of the most fundamental reactions in organic synthesis. Traditional methods for this transformation generally rely on stoichiometric amount of oxidants represented by Cr(VI) or DMSO reagents, though their synthetic utility is encumbered by unpleasant waste materials. From ecological and atom-economic viewpoints, catalytic aerobic oxidation is much more advantageous because molecular oxygen is ubiquitous and the byproduct is basically non-toxic water or hydrogen peroxide. On the other hand, phenol derivatives undergo oxidative coupling, forming C-C or C-O bond, through radical intermediates coupled with an electron-transfer process. Molecular oxygen is also well known to serve as electron acceptor in this reaction. Thus, a variety of transition metal complexes have so far been examined for aerobic oxidations of alcohols and phenols, and high catalytic activities have been achieved in some cases. However, stereo- and chemo-selective aerobic oxidations are still limited in number and are of current interest. Presented in this paper is our recent studies on catalytic aerobic oxidations with photoactivated nitrosyl ruthenium-salen complexes, including asymmetric oxidation of secondary alcohols to ketones (kinetic resolution), enantioselective oxidative coupling of 2-naphthols to binaphthols and oxygen-radical bicyclization of 2,2'-dihydroxystilbene, chemoselective oxidation of primary alcohols to aldehydes and diols to lactols, and asymmetric desymmetrization of meso-diols to lactols.     

Photo-induced oxidation of some organic carbonyl compounds by vanadium(V)

The oxidation of pyruvic acid, levulinic acid, acetaldehyde, isobutyraldehyde and acetylacetone by vanadium(V) in aqueous solution on illumination with visible light is described. Pyruvic acid undergoes oxidation much more rapidly than does levulinic acid ; both give acetic acid. Acetaldehyde is more rapidly oxidized than is isobutyraldehyde, the former giving formic acid, and the latter, formic acid and acetone. Acetylacetone is converted into acetic acid. The oxidations are rapid and quantitative and may be used for the estimation of these carbonyl compounds.     

Regioselective aerobic oxidation of bis-sulfides into monosulfoxides

The cobalt(II) acetylacetonate/aldehyde-promoted aerobic oxidation of three bis-sulfides of general formula R¹-SCH₂CH₂S-R², where R¹ is a heterocycle and R² is p-tolyl, provides a method to functionalise selectively the sulfur atom bonded to the p-tolyl moiety leading to the corresponding monosulfoxides. The same chemoselectivity and little diastereoisomeric excess (10%) was achieved by submitting to oxidative conditions the chiral bis-sulfide (S)-R³-SCH₂CH(CH₃)CH₂-SR⁴ (R³=benzothiazolyl, R⁴=p-tolyl).     

Methyltrioxorhenium catalyzed aerobic oxidation of organonitrogen compounds

A variety of tertiary, secondary and primary organonitrogen compounds have been efficiently and selectivity oxidized to their corresponding N-oxides, nitrones, and nitro compounds with molecular oxygen using methyltrioxorhenium as catalyst.     

Oxovanadium complex-catalyzed aerobic oxidation of propargylic alcohols

A catalytic system consisting of vanadium oxyacetylacetonate [VO(acac)(2)] and 3 A molecular sieves (MS3A) in acetonitrile works effectively for the aerobic oxidation of propargylic alcohols [R(1)CH(OH)Ctbd1;CR(2)] to the corresponding carbonyl compounds under an atmospheric pressure of molecular oxygen. Although the reactivity of alpha-acetylenic alkanols (R(1) = alkyl) is lower compared to that of the alcohols of R(1) = aryl, alkenyl, and alkynyl, the use of VO(hfac)(2) as a catalyst and the addition of hexafluoroacetylacetone improve the product yield in these cases. A catalytic cycle involving a vanadium(V) alcoholate species and beta-hydrogen elimination from it has been proposed for this oxidation.     

Na-promoted aerobic oxidation of alcohols to ketones

Aerobic oxidation of a number of diaryl and arylalkyl carbinols to ketones was promoted by Na in THF at room temperature with up to 99% yield. This new oxidation method is also selective with good efficiency for the oxidation of benzylic secondary alcohols but not for a primary alcohol or nonbenzylic secondary alcohols. Under nitrogen, a catalytic amount of Ni or transition metal halides such as CoCl₃, FeCl₃, and NiCl₃ in combination with Na was also found to conduct a dehydrogenation of a secondary alcohol to the corresponding ketone in high yield at room temperature.     

Zinc-catalyzed aerobic oxidation of benzoins and its extension to enantioselective oxidation

Zn(II)-DABCO complex is used as an efficient catalyst for the aerobic oxidation of benzoins to benzils in the presence of molecular oxygen. Usage of chiral zinc complex as catalyst resulted in enantioselective oxidative kinetic resolution of racemic benzoin to yield enantiomerically enriched benzoins.     

Advances in value-added aromatics by oxidation of lignin with transition metal complexes

Transition Metal Chemistry - Lignin is the second most abundant component in biomass, considered as the most abundant and available renewable source of aromatics in Nature. The depolymerization of...     

A comparative study of aerobic oxidation of turpentine

The catalytic activity exhibited in turpentine oxidation at elevated pressure by cobalt coordination compounds, some transition metal compounds, in particular, polyoxometallate with spherical nanoclusters (Mo₁₃₂), vanadium oxide bronze, and cobalt complexes immobilized on AN-241 anion exchanger was studied.     

Highly efficient, organocatalytic aerobic alcohol oxidation

5-Fluoro-2-azaadamantane N-oxyl (5-F-AZADO) realizes a simple, organocatalytic aerobic alcohol oxidation system that has a wide scope under mild conditions at ambient pressure and temperature and is weakly acidic and halogen- and transition-metal-free. The oxoammonium nitrate (5-F-AZADO(+)NO(3)(-)) works as a bifunctional catalyst of 5-F-AZADO and NO(x) that enables the catalytic aerobic oxidation of alcohols by itself (a metal-salt-free system).     

A highly efficient catalyst-free protocol for C-H bond activation: sulfamidation of alkyl aromatics and aldehydes

A catalyst-free protocol has been developed for amidation of alkyl aromatics and aldehydes using TsNBr(2)via a nitrene transfer process in the presence of a base in excellent yield within a short time. The reaction was found to be selective for secondary and tertiary benzylic C-H bonds and C-H bonds of aldehydic groups.     

Biomimetic aerobic oxidation of amino alcohols to lactams

The right path: N-Protected amino alcohols undergo aerobic and biomimetic oxidation to the corresponding lactams in the presence of a ruthenium catalyst and a combination of electron-transfer mediators under air. The reaction was used for the synthesis of five-, six-, and seven-, membered lactams and showed good tolerance to a number of N-protecting groups.     

泡沫铜无溶剂催化氧化苄醇的应用研究

本文报道了在模拟的鼓泡床反应器中,以1-甲基咪唑(NMI)和2,2,6,6-四甲基-1-哌啶基氧基(TEMPO)作为助催化剂,空气泵鼓入空气作为氧源,泡沫铜作为催化剂,室温、无溶剂条件下催化氧化苄醇的应用研究.具体优化条件为:以50 mmol苯甲醇为反应底物,2.5 mmol泡沫铜,0.625 mmol NMI,2.5...     

Flavin-catalyzed aerobic oxidation of sulfides in aqueous media

An aerobic, organocatalytic, and aqueous method for the oxidation of sulfides is described. Synthetic flavin, 5-ethyl-3,7,8,10-tetramethylisoalloxazinium perchlorate, acts as an efficient catalyst for the oxidation of sulfides in water under an oxygen atmosphere (1 atm) with the assistance of ascorbic acid as a reductant. This is an inexpensive, convenient, and environmentally benign method for the selective oxidative transformation of sulfides into sulfoxides.