共查询到20条相似文献,搜索用时 15 毫秒
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《Journal of Energy Chemistry》2015,(2)
An improved two-step process for converting carbohydrate biomass to acetic acid under hydrothermal conditions is proposed. The first step consists of the production of lactic acid from carbohydrate biomass, and the second step consists of conversion of the lactic acid obtained in the first step to acetic acid using CuO as an oxidant. The results indicated that CuO as an oxidant in the second step can significantly improve the production of high-purity acetic acid from lactic acid, and the maximum yield of acetic acid was 61%, with a purity of 90%. The yield of acetic acid obtained using the improved two-step hydrothermal process from carbohydrate biomass, such as glucose, cellulose and starch, was greater than that obtained using traditional two-step process with H2O2 orO2. In addition, a proposed pathway for the production of acetic acid from lactic acid in the second step with CuO was also discussed. The present study provides a useful two-step process for the production of acetic acid from carbohydrate biomass. 相似文献
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The potential market for lactic acid as the feedstock for biodegradable polymers, oxygenated chemicals, and specialty chemicals
is significant. L-lactic acid is often the desired enantiomer for such applications. However, stereospecific lactobacilli
do not metabolize starch efficiently. In this work, Argonne researchers have developed a process to convert starchy feedstocks
into L-lactic acid. The processing steps include starch recovery, continuous liquefaction, and simultaneous saccharification
and fermentation. Over 100 g/L of lactic acid was produced in less than 48 h. The optical purity of the product was greater
than 95%. This process has potential economical advantages over the conventional process. 相似文献
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《International Journal of Radiation Applications and Instrumentation. Part C. Radiation Physics and Chemistry》1992,39(3):243-249
Aqueous solutions of phenylacetic acid have been evaluated for possible use in γ-ray dosimetry. When aerated aqueous phenylacetic acid solutions are irradiated, photoflourescent species are formed and identified as hydroxyphenylacetic acid. When excited by ultraviolet light at 280 nm, the radiation-induced product shows an emission spectrum with a maximum at 307 nm. The intensity of the emission peak at 307 nm (as well as the area under the peak from 290 to 350 nm) is a linear function of absorbed dose from 0.5 to 25 Gy. This aqueous dosimeter is about ten times more sensitive than that of the conventional ferrous sulfate solution (Fricke) dosimeter. The differences in response at dose rates in the range 0.0055–67 Gy/min are negligible. Conversely, at higher dose rates (170 Gy/min), although the response is linear with dose up to 135 Gy and with proper calibration can be used up to 350 Gy, the photofluorescence signal is somewhat greater than in the lower dose rate range. The estimated random uncertainty limits (1σ) of readings of absorbed dose by the dosimeter are approximately ±2% at a dose of 10 Gy. The fluorescence signal is very much affected by the hydrogen ion concentration of the solution and the intensity of the signal is greatest in the pH range 5–9.5. The radiation chemical yield of the fluorescing species is little influenced by moderate changes in the concentration of phenylacetic acid or by deaeration of the solution. The signal is stable up to at least four weeks, if the solution after irradiation is stored at low temperature (ca. 5°C). However, when stored at room temperature, and in room light, the signal is stable only up to about four days. 相似文献
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Adipic acid is an important industrial intermediate for the manufacture of nylon-6,6. We propose a recyclable and environmentally friendly process for the oxidation of cyclohexene by hydrogen peroxide in microemulsions. These organized nano-structured media have been formulated in using the molecular economy principle. The main interests of the present work are the easy recovery of pure adipic acid and the reuse of the reaction media, what are promising for developing a future green industrial process. 相似文献
6.
Pseudomonas solanacearum utilized phenylalanine as sole source of carbon and nitrogen. Phenylalanine-grown cells rapidly oxidized phenylacetic acid
and homogentisic acid. Gentisic and protocatechuic acids were also oxidized, after an initial lag. Phenylacetate-grown cells
rapidly oxidized gentisic acid, slowly oxidizedo-hydroxyphenylacetic acid and catechol, and did not oxidizem-hydroxymandelic andm-hydroxyphenylacetic acids. Phenylalanine was degraded via phenylacetic acid-r-lactone andβ ketoadipate; Rothera’s test indicatedortho cleavage of the aromatic ring. 相似文献
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Simulation of a hybrid fermentation-separation process for the production of butyric acid (BA) based on published data was
done. A unit consisting of a bioreactor with immobilized cells in the fibrous bed and of separation by pertraction through
supported liquid membranes (SLM) was considered. Productivities of the unit volume of a fixed bed bioreactor in continuous
and fed-batch fermentation at pH 5.5 and 6.0 were used. Concentration of BA in the bioreactor outlet stream was assumed to
be in the interval from 0.11 kmol m−3 to 0.45 kmol m−3. Data on the pertraction through SLM with phosphonium ionic liquid (IL) and bulk liquid membrane with trioctylamine (TOA)
as carriers were used. A strong increase in the required membrane area was found for both carriers at the pH of pertraction
above 4. pH values of fermentation and pertraction should be optimized independently. It is advantageous to have pH of the
feed into the pertraction unit of about 4. Dependences of the membrane area on the pertraction efficiency are nearly linear
and not very sharp, especially for IL, what enables working at the pertractor efficiency exceeding 90 %. Application of phosphonium
IL is promising compared to classical extractant TOA because of lower demand of the membrane area in a large interval of BA
concentrations in the pertractor feed. 相似文献
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Jean‐Baptiste Arlin Alan R. Kennedy Kenneth Shankland 《Acta Crystallographica. Section C, Structural Chemistry》2012,68(2):m29-m33
Three alkaline earth metal salts of phenylacetic acid were examined and all were found to have similar structural types to analogous salts of benzoic and halobenzoic acids. Thus, a synchrotron study shows that the cations in catena‐poly[[[tetraaquamagnesium(II)]‐μ‐phenylacetato‐κ2O:O′] phenylacetate], {[Mg(C8H7O2)(H2O)4](C8H7O2)}n, form a one‐dimensional coordination polymer that propagates through Mg—O—C—O—Mg interactions involving both crystallographically independent Mg centres (Z′ = 2) and through translation along the a axis. The polymeric chains pack to give alternate inorganic layers and organic bilayers. The Ca and Sr species catena‐poly[[[diaqua(phenylacetato‐κ2O,O′)calcium(II)]‐μ3‐phenylacetato‐1′:1:1′′κ4O:O,O′:O′] monohydrate], {[Ca(C8H7O2)2(H2O)2]·H2O}n, and catena‐poly[[[diaqua(phenylacetato‐κ2O,O′)strontium(II)]‐μ3‐phenylacetato‐1′:1:1′′κ4O:O,O′:O′] monohydrate], {[Sr(C8H7O2)2(H2O)2]·H2O}n, are essentially isostructural. Both form one‐dimensional coordination polymers through a carboxylate group that forms four M—O bonds. The polymeric chains propagate via 21 screw axes parallel to the b axis and are further linked in the bc plane by hydrogen bonding involving the non‐metal‐bound water molecule. Similarly to the Mg salt, both have inorganic layers that alternate with organic bilayers. 相似文献
10.
Mangani G Canestrari F Berloni A Maione M Pagliarani S Mangani F 《Annali di chimica》2004,94(9-10):715-719
Phenyl acetic acid, a metabolite of 2-phenyl ethylamine, acts as a neuromodulator in the nigrostriatal dopaminergic pathway stimulating the release of dopamine. The evaluation of phenyl acetic acid concentration in the biological fluid reflects phenyl ethylamine levels thus allowing the assessment of the modulatory role of this endogenous substance. Changes in biological fluids levels of 2-phenylethylamine and/or in its metabolite have been reported in affective disorders, such as depression and schizophrenia. Recently, the occurrence of the "attention deficit hyperactivity syndrome" has been frequently reported in childhood population and involvement of dopaminergic dysfunction in this disease has been suspected. A fast, reliable and reproducible method for the determination of phenyl acetic acid in human blood, is therefore needed in order to have a screening tool for monitoring both healthy childhood population and suspected "attention deficit hyperactivity syndrome" patients. The gas chromatographic-mass spectrometric method here described makes use of a deuterated internal standard in order to overcome problems related to the lack of reproducibility often encountered when a derivatization step is performed. 相似文献
11.
A new process for acetic acid production by direct oxidation of ethylene which was established and commercialized is described. The catalyst system consisting of Pd and heteropoly acid exhibits excellent activity and selectivity. The addition of Se or Te to the catalyst system is effective to suppress the formation of carbon dioxide. This new process is applicable to a plant of a wide range of size corresponding to the local demand. Because this new process produces little waste water, it is very friendly to the environment. 相似文献
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Mieczys?aw M?kosza Krystyna Kamieńska-Trela Maciej Paszewski Ma?gorzata Bechcicka 《Tetrahedron》2005,61(50):11952-11964
Oxidative nucleophilic substitution of hydrogen (ONSH) in nitroarenes with carbanion of isopropyl phenyl acetate gives various products depending on the conditions and oxidant. The reaction carried out in liquid ammonia and KMnO4 oxidant gives iso-propyl α-hydroxy-α-nitroarylphenylacetates formed via hydroxylation of the initial ONSH products. In some cases additionally dimeric, trimeric and tetrameric products are formed. In THF and Bu4N+MnO4− or DDQ oxidants simple ONSH products are formed whereas oxidation by dimethyl dioxirane (DMD) gave iso-propyl hydroxyaryl phenyl acetates. The dimeric and trimeric products are apparently formed via coupling of nitrobenzylic radicals generated in course of oxidation with nitrobenzylic carbanions of the ONSH products. 相似文献
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A comparison has been made of phenylacetic, diphenylacetic, naphthylacetic and 2-naphthoxyacetic acids as extracting agents for metal ions. Phenylacetic acid is much superior to the others. 相似文献
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Pyatnitsky Y. I. Dolgikh L. Yu. Senchilo L. M. Staraya L. A. Strizhak P. E. 《Theoretical and Experimental Chemistry》2019,55(1):50-55
Theoretical and Experimental Chemistry - On the basis of analysis and thermodynamic calculations of the reaction paths of the catalytic conversion of ethanol a two-step process is proposed for the... 相似文献
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P. V. Krishna Rao A. Kodanda Ramaiah M. S. Frank 《Reaction Kinetics and Catalysis Letters》1980,13(1):7-12
The title reaction was studied in aqueous perchloric acid medium in the presence of 15% acetic acid by volume. It was observed that the reaction proceeds via an intermediate 11 oxidant-substrate complex. The reaction is inhibited by H+ ions. A mechanism consistent with the experimental results is proposed.
(V) - 15% . - - 11. , .相似文献
17.
H. Ben Abdelouahed N. Reguigui 《Journal of Radioanalytical and Nuclear Chemistry》2011,289(1):103-111
In the phosphoric acid production process, the time a particle spends inside the chemical reactor (residence time) is of paramount importance to process engineers. Residence time distribution (RTD) gives information on the efficiency of the chemical reactor, on the efficiency of the process, and also the availabilities of the reactive volume for the reaction (active volume vs. dead volume). Traditionally, chemical engineers used chemical tracer to determine the RTD. However, first disadvantage is that the chemical tracer could not allow an online diagnosis: the samples containing chemical tracer have to go to a lab for analysis, second disadvantage is that the chemical tracer is less sensitive than radioactive ones because of its adsorption onto strata or its retention in rocks. Consequently, chemical tracer results are not always precise and cannot convincingly explain the multiple flow-path model. Radioactive tracers are the only tracers capable of measuring the active RTD with high degree of precision and give information on the internal recirculation rate. In this work, we will describe the application of radiotracer method for RTD measurement in the phosphoric acid production process and give results and discussion of each case encountered. 相似文献
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[reaction: see text] FSM-16, a mesoporous silica, was found to catalyze oxidative photodecarboxylation of alpha-hydroxy carboxylic acid and phenyl acetic acid derivatives to afford the corresponding carbonyl compounds. Furthermore, FSM-16 proved to be reuseable by recalcination at 450 degrees C after the reaction. 相似文献
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F Karoum L W Chuang A D Mosnaim R A Staub R J Wyatt 《Journal of chromatographic science》1983,21(12):546-550
A rapid and reliable mass-fragmentographic method for assay of plasma and cerebrospinal fluid (CSF) concentrations of free and conjugated phenylacetic acid (PAA) is described. The method is used to compare plasma and CSF concentrations of PAA in humans and monkeys. Both packed and capillary columns are used. In humans approximately 45% of total plasma PAA is conjugated in contrast to approximately 60% in monkeys. Both free and conjugated PAA concentrations tend to be higher in monkeys than in humans. Plasma mean concentration of total PAA in humans and monkeys are, respectively, 459.1 and 838 ng/ml. Approximately 55 and 25% of total PAA in the CSF are conjugated in humans and monkeys, respectively. Total PAA mean concentrations in human and monkey CSF are 41.6 and 84.2 ng/ml. Because over 90% of total urine PAA in humans is conjugated, it is concluded that over 50% of urine phenylacetylglutamine may be derived from kidney conjugation of free plasma PAA and/or from the kidney's preferential filtration of conjugated PAA as contrasted with free PAA. 相似文献
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The pyrolysis of eucalyptus wood was carried out in a batch reactor to optimize the yield of bio-oil.Effect of various parameters like feed(particle) size,temperature,presence of catalyst and heating rate on the yield of bio-oil was investigated.The optimum conditions for high yield of bio-oil are for the particle size 2 mm~5 mm(average l/d=12.84/2.03 mm) at 450 ℃ in high heating rate.The reaction kinetics and the quality of bio-oil produced are independent of the presence of different catalysts like mordenite,kaoline clay,fly ash and silica alumina.The physical properties like odour,colour,PH,viscosity,heating value were determined.The FT-IR analysis of bio-oil indicates the presence of different functional groups such as monomeric alcohol,phenol,ketones,aldehydes,carboxylic acid,amines,and nitro compounds.The composition of the bio-oil at different conditions was analyzed using GC-MS and found that the components are temperature dependent but independent of catalysts used. 相似文献