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531.
W. H. Binder R. H. Prenner W. Schmid 《Monatshefte für Chemie / Chemical Monthly》1994,125(6-7):763-771
Summary A simple and efficient procedure for the syntheses of all four stereoisomers of the 2,2,5-trimethyl-1,3-dioxolane-4-carbaldehydes1a–1d has been developed. Starting with readily available aldopentose diethyl dithioacetals2,6,10 and14, the title compounds were obtained by a selective protecting group strategy and subsequentRaney-nickel reduction, followed by lead tetraacetate cleavage. This procedure allows an application on a multigram scale. 相似文献
532.
Allyl diethyl phosphate (ADP) was found to function as a stoichiometric hydrogen acceptor in a catalytic oxidation reaction of alcohols with Pd(OAc)2. A variety of acyclic primary and secondary alcohols were oxidized in good yields and under mild conditions to the corresponding aldehydes and ketones, in the presence of Na2CO3 or K2CO3. Simple aliphatic primary alcohols yielded esters, exclusively. Polar ligand solvents (DMF, DMSO) were found to accelerate the reaction. Slow, but high yield reactions were encountered in THF and acetonitrile as solvents. The reactivity of several other allyl systems serving as H-acceptors, and several Pd compounds serving as catalysts, in the above oxidation reaction, was evaluated. It has been experimentally demonstrated (H-NMR) that ADP is capable of generating a π-allyl-Pd complex using a Pd(0) complex. Consequently, a catalytic cycle was proposed for the above oxidation reaction. 相似文献
533.
Manisha Sathe 《Tetrahedron letters》2006,47(18):3107-3109
Silica chloride is used as an effective heterogeneous catalyst for the rapid esterification of alkyl/aryl phosphonic/phosphoric acids to their corresponding alkyl/aryl phosphonates/phosphates under mild conditions with quantitative yields. 相似文献
534.
The effects of temperature, dissolved oxygen level, and diethyl phthalate (DEP) concentration on the rates of DEP biodegradation
have been investigated in shake flask and fermenter experiments, using aerobic and facultatively aerobic microorganisms. The
aerobic strain followed Monod growth kinetics, and was negatively affected by temperatures lower than 25 °C and dissolved
oxygen levels lower than 0.8 mg/L, whereas the specific DEP-degrading activity of the facultative strain was substrate inhibited
under anaerobic conditions, higher at 15°C than 25°C under aerobic conditions, and unaffected by the dissolved oxygen level.
Studies were also carried out in soil columns to identify additional factors that might be important for modeling DEP biodegradation. 相似文献
535.
I. García de la Fuente J. A. González J. C. Cobos C. Casanova 《Journal of solution chemistry》1995,24(8):827-835
The excess molar volumes V
m
E
at atmospheric pressure and at 25°C for binary mixtures of diethyl carbonate with n-heptane, n-decane, n-tetradecane, 2,2,4-trimethylpentane, cyclohexane, benzene, toluene, or tetrachloromethane have been obtained over the whole mole-fraction range from densities measured with a vibrating-tube densimeter. The V
m
E
are positive for all the systems investigated, except for the mixture with toluene which is negative. The results for V
m
E
together with data previously published on excess molar enthalpies H
m
E
and excess molar Gibbs energies G
m
E
, suggest interactions between carbonate and hydrocarbons which are stronger with aromatic than with aliphatic hydrocarbons.Thermodynamics of binary mixtures containing organic carbonates, Part 10. 相似文献
536.
The copolymer poly(3-(4-fluorophenyl)thiophene-co-3-methylthiophene) was successfully prepared from mixtures of 3-(4-fluorophenyl)thiophene (FPT) and 3-methylthiophene (MET) via electrochemical oxidation in boron trifluoride diethyl etherate (BFEE) and its mixed electrolytes with acetonitrile (ACN). The influence of monomer concentration ratios on the copolymerization was investigated by using linear sweep voltammetry and cyclic voltammetry. The structure and morphology of these copolymer films were elucidated by UV-Vis, infrared spectroscopy, elemental analysis, thermal analysis and scanning electron microscopy (SEM), respectively. The results showed that the molar ratio of FPT and MeT units, when copolymer was electrodeposited from feed ratio of FPT:MeT = 1:2, was about 1.08:1. In addition, the introduction of ACN into BFEE has little effect on the properties of as-formed copolymers. 相似文献
537.
The reaction of monohydrazides of 2-R-4-methylcyclohex-4-ene-1,1-dicarboxylic acids with ethoxymethylenemalonic acid diethyl ester leads to N-(2,2-diethoxycarbonylethylenyl)hydrazides of 2-R-4-methylcyclohex-4-ene-1,1-dicarboxylic acids, which are acylated by the anhydrides of trifluoroacetic and acetic acids with the formation of derivatives of 3,5-dioxopyrazolidine and 5-oxopyrazoline respectively.__________Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 216–220, February, 2005. 相似文献
538.
Zhan Shi 《Journal of solid state chemistry》2003,172(2):464-470
A novel compound, [HN(C2H4)3N][(VO)2(HPO3)2(OH)(H2O)]·H2O, was hydrothermally synthesized and characterized by single crystal X-ray diffraction. This compound crystallizes in the monoclinic system with the space group C2/c and cell parameters a=11.0753(3) Å, b=17.8265(6) Å, c=16.5229(5) Å, and β=92.362(2)°. The structure of the compound consists of vanadium phosphite layers which are built up from the infinite one-dimensional chains of [(VO)(H2O)(HPO3)2]2− of octahedral VO5(H2O) and pseudo pyramidal [HPO3], and bridging binuclear fragments of [VO(OH)]2. Thermogravimetric analysis and magnetic susceptibility data for this compound are given. 相似文献
539.
Fandong Meng Genhui Xu Zhenhua Pa DuState Key Laboratory of C Chemical Technology Tianjin University Tianjin China Luoyang Petrochemical Engineering Corporation Luoyang China 《天然气化学杂志》2002,(Z2)
The chemical reactions and kinetics of the catalytic coupling reaction of carbon monoxide to diethyl oxalate were studied in the presence of hydrogen over a supported palladium catalyst in the gaseous phase at the typical coupling reaction conditions. The experiments were performed in a continuous flow fixed-bed reactor. The results indicated that hydrogen only reacts with ethyl nitrite to form ethanol, and kinetic studies revealed that the rate-determining step is the surface reaction of adsorbed hydrogen and the ethoxy radical (EtO-). A kinetic model is proposed and a comparison of the observed and calculated conversions showed that the rate expressions are of rather high confidence. 相似文献
540.
Alkylation of β-dicarbonyl compounds with 2,3-dibromopropan-1-ol in the K2CO3-dibenzo-18-crown-6 system in toluene leads to products of C,O- or C,C-cycloalkylation.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1695–1697, September, 1997. 相似文献