Formation Of Condensation Products Research Articles

Synthesis of long chain alkanes via aldol condensation over modified chitosan catalyst and subsequent hydrodeoxygenation

In this paper, jet fuel range alkanes were produced by aldol condensation of furfural and levulinic acid over modified chitosan catalyst and subsequent hydrodeoxygenation. NaOH modified chitosan was developed and used as a solid catalyst in the aldol condensation of furfural and levulinic acid to produce long carbon chain compounds. At room temperature, the total yield of condensation products reached 94.4% over NaOH/CT-4 catalyst. The amine of chitosan plays an important role in the aldol condensation, which reacted with the aldehyde group of the furfural, producing an intermediate Schiff base and promoting the formation of condensation products. This new route avoided the occurrence of side reactions caused by NaOH. Therefore, the yield of the products was greatly increased. Moreover, kinetic analysis of the condensation reaction and the test of catalyst repeatability were also conducted with NaOH/CT-4. The condensation products were further converted to long-chain branched alkanes by hydrodeoxygenation over the 5 wt% Pd/NbOPO4 catalyst. As a potential application, these alkanes could be mixed with and used as the components of jet fuels.

Expulsinator assessment of oil/ gas generation and expulsion characteristics of different source rocks

Investigation of expulsion and primary migration usually suffers from inadequate methodologies failing to simulate natural conditions prevailing during oil and gas formation. The Expulsinator device provides a unique methodology to study these processes under near-natural conditions of pressure as well as near-natural constellation of source rock and reservoir. Eight source rocks, differing in lithology and kerogen type ((type-I, type-II, type-IIS and type-III) were treated with the Expulsinator to simulate oil and gas generation and expulsion with increasing subsidence. A standardised pressure and temperature program covering the main oil window was used, simulating pressure regimes, corresponding to 2000 m, 2500 m and 3000 m of depth at pyrolysis temperatures of 300 °C, 330 °C and 360 °C, respectively. The semi-open setup of the Expulsinator enabled the sampling of the products generated during the experiment, providing unique generation/expulsion profiles for each source rock. Expulsinator treatment by continuous withdrawal prevents the formation of condensation products and solid pyrobitumen, which are common artefacts of closed-mode pyrolysis and misleading in maturity assessment. In particular, the Rock-Eval Tmax-value is affected by pyrobitumen formation. The oil and gas generation/expulsion profiles show large differences between the source rocks, controlled by the organic matter composition, as well as the lithological characteristics. Earliest onset of hydrocarbon generation and expulsion was observed for source rocks containing kerogen type-III, followed by sulfur-rich type-IIS and type-II. Lacustrine type-I source rocks showed the latest onset of hydrocarbon generation. Lithology was an important factor for the observed generation/expulsion behaviour under the experimental pressure and temperature conditions. Competent lithologies with a high degree of cementation and/or low permeability showed limited expulsion efficiency; in contrast, expulsion was enhanced by pressure-induced “squeezing” effects in ductile lithologies. A highly permeable but competent sample reached only moderate expulsion efficiency due to low “squeezing” response upon burial pressure.

Isomerization of Styrene Oxide to Phenyl Acetaldehyde over Different Modified Beta Zeolites

The catalytic performance of the isomerization of styrene oxide to phenyl acetaldehyde was investigated over different modified beta catalysts under gas-phase atmosphere free of solvents. The physicochemical properties were characterized by a combination of X-ray diffraction (XRD), N2 adsorption, Fourier transform infrared spectroscopy (FT-IR), Magic Angle Spinning Nuclear Magnetic Resonance (MAS-NMR), NH3-Temperature programmed desorption (NH3-TPD) and thermo gravimetric analysis (TGA), etc. Acid sites with stronger strength are responsible for the formation of condensation products and fast deactivation of catalysts. The obtained results also demonstrate that the introduction of boron atoms can create suitable acid strength and acid distribution without significantly destroying its microporous structures. Therefore, BAl-BEA sample is highly active and selective for the rearrangement of styrene oxide as well as very stable to deactivation.

Activity and Deactivation of ZSM–5 Catalysts in the Dimethyl Ether Synthesis from CO and H<sub>2</sub> and Methanol Dehydration

The increasing demand for producing dimethyl ether from synthesis gas explains the renewed interest in studying the activity and stability of catalysts. In the present work, resource catalytic testing of ZSM-5 zeolites was carried out in the one-step synthesis of dimethyl ether from synthesis gas for 120 hours. Formation of condensation products was observed on zeolite surface after catalytic tests which leads to lower catalytic activity of samples. Condensation products were investigated by thermal analysis in an oxidizing atmosphere. Textural characteristics of zeolites before and after reaction were investigated. It was shown that methanol significantly contribute to formation of condensation products on the catalyst surface in the process of dimethyl ether production.

Economic assessment for the production of 1,2‐Propanediol from bioglycerol hydrogenolysis using molecular hydrogen or hydrogen donor molecules

The 1,2‐propanediol can be obtained from bio‐glycerol through hydrogenolysis reactions. The hydrogen required in the process can be supplied using high molecular hydrogen pressure or hydrogen donor molecules, formic acid being the most attractive donor. An economical assessment of both alternatives for hydrogen supply was carried out. Results from the conceptual design of the 1,2‐propanediol purification process revealed that the separation of water from glycols is the most expensive step. The use of formic acid can be cost effective only if it is available at a price lower than 0.12 € kg−1 and high initial glycerol aqueous solutions are used. The formation of condensation products from highly concentrated glycerol solutions when using hydrogen donors needs to be avoided. © 2015 American Institute of Chemical Engineers Environ Prog, 35:447–454, 2016

PRODUCTION OF 5-HYDROXYMETHYLFURFURAL (HMF) VIA FRUCTOSE DEHYDRATION: EFFECT OF SOLVENT AND SALTING-OUT

5-Hydroxymethylfurfural (HMF) is a key renewable platform compound for production of fuels and chemical intermediates. The production of 5-hydroxymethylfurfural (HMF) from fructose dehydration was studied using H3PO4 as catalyst, in organic/water system with different solvents (acetone, 2-butanol and ethyl ether). The effect of fructose concentration, temperature and acid concentration was investigated in acetone/water medium. The increase in fructose concentration favors the formation of condensation products and rehydration products are favored at high acid concentration. The solvents exhibited similar performance when the volume ratio of organic to aqueous phase was 1:1, but when this ratio increases to 2:1, the HMF yield obtained with ether was much lower. NaCl addition to the aqueous phase promoted the extraction of HMF to the organic phase, with an HMF yield of 80% in the case of 2:1 acetone/water medium.

Involvement of the endogenous opioid system in the psychopharmacological actions of ethanol: the role of acetaldehyde

Significant evidence implicates the endogenous opioid system (EOS) (opioid peptides and receptors) in the mechanisms underlying the psychopharmacological effects of ethanol. Ethanol modulates opioidergic signaling and function at different levels, including biosynthesis, release, and degradation of opioid peptides, as well as binding of endogenous ligands to opioid receptors. The role of β-endorphin and µ-opioid receptors (OR) have been suggested to be of particular importance in mediating some of the behavioral effects of ethanol, including psychomotor stimulation and sensitization, consumption and conditioned place preference (CPP). Ethanol increases the release of β-endorphin from the hypothalamic arcuate nucleus (NArc), which can modulate activity of other neurotransmitter systems such as mesolimbic dopamine (DA). The precise mechanism by which ethanol induces a release of β-endorphin, thereby inducing behavioral responses, remains to be elucidated. The present review summarizes accumulative data suggesting that the first metabolite of ethanol, the psychoactive compound acetaldehyde, could participate in such mechanism. Two lines of research involving acetaldehyde are reviewed: (1) implications of the formation of acetaldehyde in brain areas such as the NArc, with high expression of ethanol metabolizing enzymes and presence of cell bodies of endorphinic neurons and (2) the formation of condensation products between DA and acetaldehyde such as salsolinol, which exerts its actions via OR.

Systematic evaluation of acetone and acetonitrile for use in hydrophilic interaction liquid chromatography coupled with electrospray ionization mass spectrometry of basic small molecules

Sub-2-µm particle size hydrophilic interaction liquid chromatography [HILIC] combined with mass spectrometry has been increasing in popularity as a complementary technique to reversed-phase LC for the analysis of polar analytes. The organic-rich mobile phase associated with HILIC techniques provides increases in compound ionization, due to increased desolvation efficiency during electrospray ionisation mass spectrometric (ESI-MS) analysis. Although recent publications illustrated selectivity and response comparisons between reversed-phase LC/MS and HILIC LC/MS, there are limited discussions evaluating the optimisation of the mass spectrometry parameters regarding analytes and alternative mobile phases. The use of acetone as an alternative organic modifier in HILIC has been investigated with respect to signal-to-noise in ESI-MS for a variety of polar analytes. Analyte reponses were measured based on a variety of cone and capillary voltages at low and high pH in both acetone and acetonitrile. In order to visualise compound behaviour in the ESI source, surface plots were constructed to assist in interpreting the observed results. The use of acetone in ESI is complicated at low m/z due to the formation of condensation products. Favourable responses were observed for certain analytes and we envisage offering an insight into the use of acetone as an alternative to acetonitrile under certain analytical conditions for particular compound classifications for small molecule analysis. We also highlight the importance of optimising source voltages in order to obtain the maximum signal stability and sensitivity, which are invariably, highly solvent composition dependent parameters.

Synthesis of quinolizin-2-one and pyrido[1,2-a]azepin-2-one derivatives from difluoroboron complexes of aroylacetones and O-methyllactims

O-Methyllactims react at the methyl group of difluoroboron complexes of aroylacetones with the formation of condensation products, novel difluoroboron chelates of 1-aryl-4-(piperi-din-2-ylidene)butane-1,3-diones and 1-aryl-4-(azepan-2-ylidene)butane-1,3-diones, which upon the action of concentrated HCl in ethanol are transformed into the corresponding quino-lizin-2-one and pyrido[1,2-a]azepin-2-one derivatives.

Coloring characteristics of in situ lignin during heat treatment

To investigate the effects of lignin on the discoloration of Black locust (Robinia pseudoacacia) wood during heat treatment, chromatic indexes of the extractive-free wood samples are examined at different moisture contents (MC) under oxygen and nitrogen environment, respectively. The organic acids are produced during heat treatment, resulting in pH decrease in the samples. Components absorbing visible light are formed during heat treatment, and oxygen and moisture contents have obvious effects on the decrease in L*, increase in a* value, yellowness (b*) and total color difference (ΔE) of the samples. It is found that the β-5, C α C β unsaturated bond, the conjugated carbonyl group, quinones structures, α, β-unsaturated ketone and α-C = O in lignin increased after heat treatment. The formation of condensation products, the low-molecular-weight phenolic substances and the oxidation products in lignin result in the increment of the light absorption within the entire visible region.

Synthesis and Some Chemical Transformations of Adamantyl-Substituted Pyrazolones

1-Substituted 3-(1-adamantyl)-4,5-dihydro-1H-pyrazol–5-ones and 3-(1-adamantyl)-4,5-dihydroiso-xazol-5-one were synthesized by reaction of ethyl 3-(1-adamantyl)-3-oxopropanoate with various hydrazine derivatives and hydroxylamine hydrochloride. Nitrosation of adamantyl-substituted pyrazolones with sodium nitrite in acetic acid gave the corresponding 4-hydroxyimino derivatives. Reactions of 3-(1-adamantyl)-4,5-di-hydro-1H-pyrazol–5-ones and 3-(1-adamantyl)-4,5-dihydroisoxazol–5-one with aromatic and heterocyclic aldehydes led to the formation of condensation products at position 4 of the heteroring.

Removal of herbicide diuron and thermal degradation products under Catalytic Wet Air Oxidation conditions

The Catalytic Wet Air Oxidation (CWAO) of diuron (N-(3,4-dichlorophenyl)-N,N-dimethylurea), a herbicide widely used in agriculture and belonging to the phenylurea family, has been investigated in aqueous solution in the presence of a Ru/TiO2 catalyst at 140–180°C and 5MPa total air pressure. Diuron and Total Organic Carbon (TOC) have been analyzed. Some reaction products were identified by LC–ES/MS, and the amount of the inorganic ions and organic products generated during the process have been measured. Thermal degradation is the main initial process yielding mainly 3,4-dichloroaniline (DCA) and dimethylamine (DMA). Further oxidations lead to ring opening and smaller organic molecules from DCA, but the DMA fragment was more difficult to eliminate. Reactions between DCA and carboxylic acids conducted to the formation of condensation products. On the other hand, dechlorination was fast and complete. The work points out that CWAO over Ru supported catalysts may not a viable technique for degradation of diluted aqueous solutions of diuron. The mineralization is incomplete compared to other Advanced Oxidation Processes, and a possible leaching of the metal by the amines formed by thermal degradation of diuron may be critical.

High-selective Ni-MgO catalysts for a clean obtention of 2-phenylethanol

High-selective to 2-phenylethanol Ni-MgO catalysts have been obtained for the hydrogenation of styrene oxide in the liquid phase. This catalytic process constitutes an environment friendly alternative to the industrial traditional methods used to obtain this product, which is widely applied in the perfume industry due to its pleasant roses smell. Three bulk Ni and two Ni-MgO catalysts were prepared, characterized and tested for this reaction. Also, a commercial Raney-Ni catalyst was studied at the same reaction conditions for comparison. The nickel morphologic characteristics and the presence of magnesia in the catalysts play an important role in their catalytic behaviour. The bulk nickel catalysts prepared not only show high selectivity to 2-phenylethanol (60–95%) but also give to the formation of condensation products, which block the active centres, decreasing their conversion. On the other hand, the presence of magnesia, through its basicity, minimizes the ethylbenzene formation, and avoids the formation of the condensation products. Thus, the Ni-MgO catalyst prepared with the highest magnesia content showed 100% of selectivity to 2-phenylethanol for a total conversion despite having much lower metallic area than a commercial Raney-Ni.

Proposed mechanism for the degradation of pelargonidin 3-glucoside by caffeic acid o-quinone

Abstract Caffeic acid o -quinone (CQ) was prepared by oxidation of caffeic acid with o -chloranil in organic media. The reaction between the purified CQ and pelargonidin 3-glucoside (Pg 3-glc, non- o -diphenolic anthocyanin) was monitored by HPLC and spectrophotometric analysis. Quantitative analyses were performed to establish the stoichiometry of the reactions. The results showed that Pg 3-glc reacted with the hydroxycaffeic acid o -quinone formed by dismutation of CQ in aqueous media. This reaction led to the formation of condensation products with a stoichiometry close to 1:1. The degradation products were isolated by gel filtration on Sephadex G-25. The UV-vis spectra and chemical analysis of the degradation products suggested that they contained both caffeic acid (or secondary products of oxidation) and anthocyanin moieties. HPLC analysis showed that the purified fractions contained several degradation products.

99/02463 Two forms of condensation products on a silver catalyst for methanol oxidation and a possible mechanism of their formation

The formation of condensation products in the oxidation of methanol to formaldehyde over a commercial silver-pumice catalyst containing 37 wt % Ag was studied by electron spectroscopy and thermogravimetric analysis. Two forms of condensation products (polycrystalline and filamentous) were found, and the mechanism of their formation was suggested.

Mukaiyama aldol and Michael reactions catalyzed by lanthanide iodides

Samarium diiodide is an efficient catalyst precursor which allows the formation of condensation products between various carbonyl compounds and ketene silyl acetals or enoxysilanes. With α,β-unsaturated carbonyl compounds, 1,2- or 1,4-additions are observed according to the structure of the substrate. α,β-Unsaturated ketones yield to enoxysilanes by selective Michael additions. Aldol poducts are isolated as silyl ethers. The mechanisms of the reactions are discussed.

Evidence for a unified pathway of dioxin formation from aliphatic hydrocarbons

Acetylene is readily converted to perchlorinated gas-phase intermediates including hexachlorobenzene, hexachlorobutadiene, and tetrachloroethylene and heavier perchlorinated species via heterogeneous gas-solid reactions with HCl and cupric oxide on borosilicate under postcombustion conditions. Experiments were conducted using an integrated gas-solid flow-reactor and analytical system at temperatures ranging from 150 to 500°C for gas-phase residence times of 2.0 s and total reaction times of 60 min. Chlorine addition and chlorine net substitution mechanisms mediated by the conversion of Cu(II)Cl2 to Cu(I)Cl are proposed to account for the observed or inferred C2 reaction products including tetrachloroethylene, trichloroethylene, and dichloroacetylene. The formation of condensation products including tetrachlorovinylacetylene, hexachlorobutadiene, and hexachlorobenzene are proposed to be catalyzed by copper chloride species and involve the following steps: (1) chemisorption of a chlorinated ethylene or acetylene by HCl elimination or 1,2-Cu−Cl addition, respectively: (2) physisorption of additional chlorimated ethylenes or acetylenes followed by cis-insertions: and (3) carbon-to-copper chlorine transfer followed by desorption of the molecular growth product. The mechanism accounts for product isomer distributions and branching desorption of the higher molecular weight products, and regeneration of the copper chloride catalyst.

Formation of Condensation Products in Advanced Oxidation Technologies: The Photocatalytic Degradation of Dichlorophenols on TiO2

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTFormation of Condensation Products in Advanced Oxidation Technologies: The Photocatalytic Degradation of Dichlorophenols on TiO2Claudio. Minero, Ezio. Pelizzetti, Pierre. Pichat, Michela. Sega, and Marco. VincentiCite this: Environ. Sci. Technol. 1995, 29, 9, 2226–2234Publication Date (Print):September 1, 1995Publication History Published online1 May 2002Published inissue 1 September 1995https://doi.org/10.1021/es00009a012RIGHTS & PERMISSIONSArticle Views362Altmetric-Citations77LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (962 KB) Get e-Alerts Get e-Alerts

Decomposition of 2-propanol on an intermetallic compound for hydrogen storage

Decompositon of 2-propanol has been carried out on the hydrogen storage material Mg2Cu and its modified form (OH−Mg2Cu) to study their catalytic behavior. The reaction was carried out in a continuous flow type reactor in the temperature range of 403–513 K at various flow rates. Mg2Cu showed good catalytic activity with large amounts of condensation products. Its modified form gave acetone as the only products. The reason for these differences is explained in terms of differences in the structure of the catalyst as determined by XRD and XPS, as well as by surface area measurements. The reason for the formation of condensation products is discussed.

The selective hydrogenation of acetonitrile on supported nickel catalysts

The catalytic behavior of several supported nickel catalysts in the hydrogenation of acetonitrile was studied. It was established that the selectivity of this process is greatly influenced by the nature of the support used. Catalysts consisting of nickel supported on acidic supports catalyzed the formation of condensation products, diethyl- and triethylamine. Nickel supported on basic supports was highly selective with respect to the formation of the primary amine, ethylamine. It was shown that modification of the intrinsic acidity of alumina-based supports by the application of alkaline additives has a large impact on the selectivity of the resulting catalyst. Based on the results obtained from measurements on a basic catalyst diluted with either an acidic or a basic support, a dual-function mechanism is suggested. The mechanism implies that the hydrogenation function of the catalyst is located on the metal, while the acid function, responsible for the condensation reactions, is located on the support. A mechanism, accounting for the occurrence of the acid-catalyzed condensation reactions, is proposed.