DOCSLIB.ORG

Synthesis of Amorphous Silica-Supported Titanium Catalysts with Triethanolamine Titanate for Alkene Epoxidation with Dilute Hydrogen Peroxide

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Synthesis of Amorphous Silica-Supported Titanium Catalysts with Triethanolamine Titanate for Alkene Epoxidation with Dilute Hydrogen Peroxide Synthesis of amorphous silica-supported titanium catalysts with triethanolamine titanate for alkene epoxidation with dilute hydrogen peroxide M. C. Capel-Sanchez, J.M. Campos-Martín, J. L. G. Fierro Instituto de Catálisis y Petroleoquímica, CSIC, Campus Cantoblanco, 28049 Madrid, Spain. http://www.icp.csic.es/eac/index.htm Introduction Despite numerous reports in the literature, the epoxidation of terminal alkenes remains a challenge in petrochemistry. Many different methods have been developed for the preparation of epoxides. Among the non-zeolitic substrates, Ti–SiO2- supported catalysts remain prominent for the effective in the epoxidation of alkenes with organic hydroperoxides, though it is generally believed that they do not effectively epoxidize alkenes with hydrogen peroxide. Nevertheless, we have reported a very simple route for the preparation titanium-silica-supported catalysts which are very active and selective in the epoxidation of alkenes with hydrogen peroxide [1,2]. Along the preparation, the tetra-isopropyl titanate precursor reacts with moisture in air that difficult catalyst synthesis. In this work, we describe the preparation of highly active and selective catalysts employing triethanolamine titanate as titanium precursor. Results and Discussion Catalysts were prepared as follows: 0.65 g of commercial triethanolamine titanate solution (80 % in 2-propanol) was added to 25 ml of 2-propanol heated at 353 K; then 5 g of silica (Grace Davison, XPO-2407) were added and the suspension stirred for 2 h. The solid was filtered and washed three times with 25 ml of 2-propanol. Two different replicas were prepared. To understand the mechanism by which the titanium precursor is anchored to the silica surface, these solids were characterized by elemental analysis, FT-IR of self-supported wafers, DRS UV-Vis and X-ray photoelectron spectroscopy (XPS) techniques. Aliquots of the resulting materials were calcined at 773 K, and then used in the epoxidation of 1-octene. In a typical run, a suspension of alkene (0.2 mol), tert- butanol (11 g) and 1 g of catalyst was heated at 333 K, and then 4 g of an organic solution of 5 wt % of H2O2 (in 1-phenylethanol) were added to the reaction vessel. The organic compounds were analysed by GC-FID (Hewlett Packard 6890-plus, equipped with a HP-WAX capillary column). The hydrogen peroxide was measured by standard iodometric titration. Elemental analyses showed that composition of replica samples was almost identical, indicating reproducibility of the synthesis. On the other hand, the atomic ratio Ti/N, in two samples, was unity, as it is in the titanium precursor. However, carbon contents were higher than the estequiometric value probably due to remaining solvent adsorbed on the surface of the solid. FT-IR spectra of the outgassed specimens under high vacuum at room temperature showed differences with that of the calcined counterpart (Fig. 1). Calcined sample showed a band at 3700 cm-1 due to isolated silanol groups, which was absent in the non-calcined one, this effect could be due to an interaction between titanium precursor species and surface OHs. Non-calcined 723 K samples showed several overlapping peaks between 3000 to 2800 cm-1 typical of C-H vibrations in organic 623 K compounds, and a peak centred at 1500 cm-1 attributed to titanium bonded with alkoxide species. To 523 K evaluate the stability of these compounds the sample was Absorbance (AU) outgassed at 523, 623 and 723 K. FT-IR spectra of outgassed samples RT at 523 and 623 K resulted quite similar to sample outgassed at room temperature. This is clear indication Calcined of the strong interaction of adsorbed species. The peaks due to adsorbed 4000 3500 3000 2500 2000 1500 titanium species disappeared upon -1 outgassing at 773 K. Wavenumber (cm ) DRS UV-Vis spectra of both Figure 1 FT-IR spectra of solids outgassed calcined and non-calcined samples under high vacuum were clearly different. While calcined sample showed a band centred at 225 nm, typical of titanium in a tetrahedrally hydrtated environment, the non-calcined counterpart exhibited a band at 300 nm typical of titanium in octahedral coordination. The binding energy of Ti2p core-levels of samples outgassed “in situ” exhibited only one peak at 459.0 eV, associated to titanium in a distorted octahedral- (or even penta-) coordination. The calcines sample exhibited, however, a component at 460.0 eV, which is typical of titanium in a tetrahedral environment. Quantitative surface analysis of the non-calcined sample showed a C/N atom ratio of 6 and a N/Ti ratio slightly higher than 1. Characterization data clearly indicated that titanium precursor reacts with the support surface and triethanolamine remains coordinated with Ti until sample calcination. These catalysts exhibited high hydrogen peroxide conversion and high selectivity to epoxide, a behaviour similar to that of the Ti/SiO2 ex-tetra-isopropyl titanate [1,2]. References 1. M. C. Capel-Sanchez J. M. Campos-Martin, J. L. G. Fierro, M. P. de Frutos, A. Padilla Polo, Chem. Commun., (2000) 855-856 2. M. C. Capel-Sanchez J. M. Campos-Martin, J. L. G. Fierro, M. P. de Frutos, A. Padilla Polo, XVIII Simp. Iber. Catal. (2002) .
Load more

Recommended publications
  • Safe Hydroformylation of Aliphatic Alkene in a Flow Reactor
    International Journal of Organic Chemistry, 2018, 8, 135-141 http://www.scirp.org/journal/ijoc ISSN Online: 2161-4695 ISSN Print: 2161-4687 Safe Hydroformylation of Aliphatic Alkene in a Flow Reactor Hisashi Masui, Eiki Honda, Sakura Niitsu, Mitsuru Shoji, Takashi Takahashi* Department of Pharmaceutical Sciences, Yokohama University of Pharmacy, Yokohama, Japan How to cite this paper: Masui, H., Honda, Abstract E., Niitsu, S., Shoji, M. and Takahashi, T. (2018) Safe Hydroformylation of Aliphatic Despite hydroformylation being a very efficient method for the transforma- Alkene in a Flow Reactor. International tion of alkenes, it is not commonly employed in laboratories owing to the Journal of Organic Chemistry, 8, 135-141. flammable/toxic nature of hydrogen and carbon monoxide gases and the ne- https://doi.org/10.4236/ijoc.2018.81009 cessity of high-pressure equipment in a batch system. Flow chemistry often Received: November 30, 2017 raises the safety profiles against high-pressure and toxic gases because the Accepted: March 6, 2018 diameter of the flow reactor is small. Herein, we show that aliphatic alkenes Published: March 9, 2018 can be safely hydroformylated in a flow reactor. In our flow method, although Copyright © 2018 by authors and the target hydroformylated product was obtained in a low yield (19%), toxic Scientific Research Publishing Inc. gases were safely treated using a flow reactor. Better yields could possibly be This work is licensed under the Creative achieved by recycling of the unreacted alkene. Commons Attribution International License (CC BY 4.0). http://creativecommons.org/licenses/by/4.0/ Keywords Open Access Hydroformylation, Flow Synthesis, Alkene, Carbon Monoxide, Aldehyde 1.
    [Show full text]
  • Catalytic Systems Based on Cp2zrx2 (X = Cl, H), Organoaluminum
    catalysts Article Catalytic Systems Based on Cp2ZrX2 (X = Cl, H), Organoaluminum Compounds and Perfluorophenylboranes: Role of Zr,Zr- and Zr,Al-Hydride Intermediates in Alkene Dimerization and Oligomerization Lyudmila V. Parfenova 1,* , Pavel V. Kovyazin 1, Almira Kh. Bikmeeva 1 and Eldar R. Palatov 2 1 Institute of Petrochemistry and Catalysis of Russian Academy of Sciences, Prospekt Oktyabrya, 141, 450075 Ufa, Russia; [email protected] (P.V.K.); [email protected] (A.K.B.) 2 Bashkir State University, st. Zaki Validi, 32, 450076 Ufa, Russia; [email protected] * Correspondence: [email protected]; Tel.: +7-347-284-3527 i i Abstract: The activity and chemoselectivity of the Cp2ZrCl2-XAlBu 2 (X = H, Bu ) and [Cp2ZrH2]2- ClAlEt2 catalytic systems activated by (Ph3C)[B(C6F5)4] or B(C6F5)3 were studied in reactions with 1-hexene. The activation of the systems by B(C6F5)3 resulted in the selective formation of head- to-tail alkene dimers in up to 93% yields. NMR studies of the reactions of Zr complexes with organoaluminum compounds (OACs) and boron activators showed the formation of Zr,Zr- and Zr,Al-hydride intermediates, for which diffusion coefficients, hydrodynamic radii, and volumes were estimated using the diffusion ordered spectroscopy DOSY. Bis-zirconium hydride clusters of type x[Cp ZrH ·Cp ZrHCl·ClAlR ]·yRnAl(C F ) − were found to be the key intermediates of alkene 2 2 2 2 6 5 3 n dimerization, whereas cationic Zr,Al-hydrides led to the formation of oligomers. Citation: Parfenova, L.V.; Kovyazin, P.V.; Bikmeeva, A.K.; Palatov, E.R.
    [Show full text]
  • Petrochemistry and Chemical Engineering November 18-20, 2013 Hilton San Antonio Airport, TX, USA
    Gordadze G. N et al., J Pet Environ Biotechnol 2013, 4:6 http://dx.doi.org/10.4172/2157-7463.S1.002 World Congress on Petrochemistry and Chemical Engineering November 18-20, 2013 Hilton San Antonio Airport, TX, USA Formation of n-alkanes by bacteria Arthrobacter sp. RV and Pseudomonas aeruginosa RM Gordadze G. N and Stroeva A.R Gubkin Russian State University of Oil and Gas, Russia rocesses of petroleum hydrocarbons (HC) formation in literature have been discussing for 200 years. At present time there Pare two main theories of oil formation: organic (sedimentary-migration) and inorganic (abiotic). It is believed that n-alkanes formed from n-saturated fatty acids by decarboxylation. It is known that in the original organic matter (OM) fatty acids with an even number of carbon atoms in the molecule are prevail. In case sapropelic OM, low molecular weight acids (n-C16, n-C18 and n-C20) are mainly produced and if OM is humus higher molecular (n-C26, n-C28 and n-C30) are produced. It is important to note there are high molecular n-alkanes C23, C25, C27, C29, C31 and C33 in soil OM. Bacterial synthesis of n-alkanes could be accounted by decarboxylation with relatively high temperatures. However, this phenomenon doesn’t support by experiment. In this work we studied, if n-alkanes with an odd number of carbon atoms in the molecule formed by bacteria. The objects of study were the hydrocarbon aerobic bacteria Arthrobacter sp. RV and the bacteria Pseudomonas aeruginosa RM, that are able to both aerobic and anaerobic growth in the process of denitrification.
    [Show full text]
  • Petrochemistry April 25-27, 2018 Rome, Italy
    J-M. Basset et al., Int J Petrochem Res. 2018 http://dx.doi.org/10.18689/2638-1974.a2.002 2nd International Conference on Petrochemistry April 25-27, 2018 Rome, Italy Predictive Heterogeneous Catalysis by Design: Well-Defined Single-Site Catalysts J-M. Basset1*, M. K. Samantaray1, S. Barman1, S. Kavitake1, N. Morlanes1, L Cavallo1, A. Hamieh1, R. Dey1, Abou Hamad1, J. Pelletier1, S. Ould-Chikh1, A. Bendjeriou-Sedjerari1, Eva B. Pump1, N. Merle2, F. Le Quemener2, K. C. Szeto2, A. De Mallmann2, Laurent Delevoye3, R. Gauvin3 and Mostafa Taoufik3 1KAUST Catalysis Center, King Abdullah University of Science and Technology, Saudi Arabia 2Laboratoire de Chimie, Catalyse, Polymères et Procédés, France 3Univ. Lille, CNRS, Centrale Lille, ENSCL, Univ. Artois, Unité de Catalyse et Chimie du Solide, France redictive catalysis” or “catalysis by design” in heterogeneous catalysis has recently benefited from using “surface “Porganometallic fragments” (SOMF) or Surface Coordination fragments (SCF) to enter any presumed catalytic cycle. These conceptual tools in which one or several fragments of the molecule are linked to metal grafted on the surface (M-H, M-R, M=CR2, M≡CR, M=O, M=NR) became the logical continuation of the abundant work published in the field of Surface Organometallic Chemistry (SOMC). To note, SOMC has produced new catalytic reactions (e.g. Ziegler Natta depolymerisation, alkane metathesis, non-oxidative methane coupling etc…) and had improved the activity or selectivity or life time of known ones. The catalytic mechanisms employs the concepts of molecular chemistry (organic, organometallic, coordination chemistry) to explain how bonds can be broken and reformed. In this context, the reactivity of “surface organometallic fragments” (SOMF) or Surface Coordination fragments (SCF) is pivotal to the outcome of the catalysis.
    [Show full text]
  • Alkyne Selective Hydrogenation with Mono- and Bimetallic-Anchored Catalysts Bimetallic-Anchored Catalysts
    Provisional chapter Chapter 2 Alkyne Selective Hydrogenation with Mono- and Alkyne Selective Hydrogenation with Mono- and Bimetallic-Anchored Catalysts Bimetallic-Anchored Catalysts Cecilia Lederhos, Carolina Betti, Domingo Liprandi, EdgardoCecilia Lederhos, Cagnola Carolina and Mónica Betti, Quiroga Domingo Liprandi, Edgardo Cagnola and Mónica Quiroga Additional information is available at the end of the chapter Additional information is available at the end of the chapter http://dx.doi.org/10.5772/64866 Abstract Partial hydrogenation of alkynes has industrial and academic relevance on a large scale; industries such as petrochemical, pharmacological and agrochemical use these compounds as raw material. Finding an economic, active and selective catalyst for the production of alkenes through partial hydrogenation of alkynes is thus an important challenge. Mono- and bimetallic catalysts (palladium, ruthenium and nickel) were synthetized by the incipient wetness technique using gamma alumina and an activated carbon as supports. The catalysts were characterized by inductively coupled plasma, hydrogen chemisorption, temperature-programmed reduction and X-ray photoelec- tronic spectroscopy (XPS). The objective of this work is to study 1-heptyne-selective hydrogenation using supported catalysts influenced by different factors: (a) pretreat- ment reduction temperature, (b) reaction temperature, (c) type of support, (d) metal loading, (e) precursor salt and (f) addition of a second metal to monometallic palladium catalyst. The Lindlar commercial catalyst, commonly used in these types of reactions, was used for comparative purposes. XPS technique allowed verifying that the presence of electron-deficient species on the catalyst surface with high metal loading affects the conversion and selectivity to the desired product. Nevertheless, the influence of geometrical effects and/or mixed active sites in the catalysts, as well as metal-metal and metal-support interactions, cannot be neglected.
    [Show full text]
  • General and Prospective Views on Oxidation Reactions in Heterogeneous Catalysis
    Preprints (www.preprints.org) | NOT PEER-REVIEWED | Posted: 13 September 2018 doi:10.20944/preprints201809.0225.v1 Peer-reviewed version available at Catalysts 2018, 8, 483; doi:10.3390/catal8100483 Review General and Prospective Views on Oxidation Reactions in Heterogeneous Catalysis Sabine Valange 1,* and Jacques C. Védrine2,* 1 Institut de Chimie, des Milieux et Matériaux de Poitiers (IC2MP), UMR CNRS 7285, Université de Poitiers, ENSI Poitiers, B1, 1 rue Marcel Doré, TSA41105, F-86073, Poitiers Cedex 9, France 2 Sorbonne Université, Faculté des Sciences et Ingénierie, Laboratoire de Réactivité de Surface, UMR-CNRS 7197, 4 place Jussieu, F-75252 Paris, France * Correspondence: [email protected]; [email protected]; Tel.: +33-5-49454048 (S.V.); +33-1-44275560 (J.C.V.) Abstract: In this short review paper we have assembled the main characteristics of partial oxidation reactions (oxidative dehydrogenation and selective oxidation to olefins or oxygenates, as aldehydes and carboxylic acids and nitriles), as well as total oxidation, particularly for depollution, environmental issues and wastewater treatments. Both gas-solid and liquid-solid media have been considered with recent and representative examples within these fields. We have also discussed about their potential and prospective industrial applications. Particular attention has been brought to new raw materials stemming from biomass and to liquid-solid catalysts cases. This review paper also summarizes the progresses made in the use of unconventional activation methods for performing oxidation reactions, highlighting the synergy of these technologies with heterogeneous catalysis. Focus has been centered on usual catalysts activation methods but also on less usual ones, such as the use of ultrasounds, microwaves, grinding (mechanochemistry) and photo-activated processes, as well as their combined use.
    [Show full text]
  • User:Smallman12q/Articles/Chemistry 1 User:Smallman12q/Articles/Chemistry
    User:Smallman12q/articles/Chemistry 1 User:Smallman12q/articles/Chemistry Chemistry (from Egyptian kēme (chem), meaning "earth"[1] ) is the science concerned with the composition, structure, and properties of matter, as well as the changes it undergoes during chemical reactions.[2] It is a physical science for studies of various atoms, molecules, crystals and other aggregates of matter whether in isolation or combination, which incorporates the concepts of energy and entropy in relation to the spontaneity of chemical processes. Modern chemistry evolved out of alchemy following the chemical revolution (1773). Disciplines within chemistry are traditionally grouped by the type of matter being studied or the kind of study. These include inorganic chemistry, the study of inorganic matter; organic chemistry, the study Chemistry is the science concerned with the composition, structure, and properties of matter, of organic matter; biochemistry, the study of substances found in as well as the changes it undergoes during biological organisms; physical chemistry, the energy related studies of chemical reactions. chemical systems at macro, molecular and submolecular scales; analytical chemistry, the analysis of material samples to gain an understanding of their chemical composition and structure. Many more specialized disciplines have emerged in recent years, e.g. neurochemistry the chemical study of the nervous system (see subdisciplines). Summary Chemistry is the scientific study of interaction of chemical [3] substances that are constituted of
    [Show full text]
  • Recycling of Carbone Oxides (Co, Co ) Conversion Into
    Reports on research (2016), «EUREKA: Physics and Engineering» projects Number 6 RECYCLING OF CARBONE OXIDES (CO, CO2) CONVERSION INTO METHANOL AT ATMOSPHERIC PRESSURE OVER MECHANOCHEMICAL ACHTIVATED U N L C O-Z O-A 2O3 CATALYST Nataliia Khimach Department of Homogeneous Catalysis and Additives to Oil Products Institute of Bioorganic Chemistry and Petrochemistry of the National Academy of Sciences of Ukraine 1 Murmanska str., Kyiv, Ukraine, 02660 [email protected] Vitaly Yevdokymenko Department of Organic and Petrochemical Synthesis Institute of Bioorganic Chemistry and Petrochemistry of the National Academy of Sciences of Ukraine 1 Murmanska str., Kyiv, Ukraine, 02660 [email protected] Ievgen Polunkin Department of Homogeneous Catalysis and Additives to Oil Products Institute of Bioorganic Chemistry and Petrochemistry of the National Academy of Sciences of Ukraine 1 Murmanska str., Kyiv, Ukraine, 02660 [email protected] Abstract The catalytic process for methanol production by synthesis gas conversion under the conditions of mechanochemical activa- tion (MCA) of copper-zinc-aluminum oxide catalyst in the temperature range 160–280 °C at a pressure of 0.1 MPa are investigated. The use of mechanical action force is one of the promising ways to improve the activity of heterogeneous catalysts designed to simplify the manufacturing process lines, improving the efficiency of catalytic processes and reduce the cost of the target product. Given the importance of technology for methanol production on copper-zinc-aluminum oxide catalysts and high demand for metha- nol in the world [1–3], clarification of the peculiarities of the process of methanol production by synthesis gas conversion in terms of mechanical load on the catalyst is important in scientific and applied ways.
    [Show full text]
  • General and Prospective Views on Oxidation Reactions in Heterogeneous Catalysis
    catalysts Review General and Prospective Views on Oxidation Reactions in Heterogeneous Catalysis Sabine Valange 1,* and Jacques C. Védrine 2,* 1 Institut de Chimie, des Milieux et Matériaux de Poitiers (IC2MP), UMR CNRS 7285, Université de Poitiers, ENSI Poitiers, B1, 1 rue Marcel Doré, TSA41105, F-86073 Poitiers Cedex 9, France 2 Sorbonne Université, Faculté des Sciences et Ingénierie, Laboratoire de Réactivité de Surface, UMR-CNRS 7197, 4 place Jussieu, F-75252 Paris, France * Correspondence: [email protected] (S.V.); [email protected] (J.C.V.); Tel.: +33-5-49454048 (S.V.); +33-1-44275560 (J.C.V.) Received: 12 September 2018; Accepted: 18 October 2018; Published: 22 October 2018 Abstract: In this review paper, we have assembled the main characteristics of partial oxidation reactions (oxidative dehydrogenation and selective oxidation to olefins or oxygenates, as aldehydes and carboxylic acids and nitriles), as well as total oxidation, particularly for depollution, environmental issues and wastewater treatments. Both gas–solid and liquid–solid media have been considered with recent and representative examples within these fields. We have also discussed about their potential and prospective industrial applications. Particular attention has been brought to new raw materials stemming from biomass, as well as to liquid–solid catalysts cases. This review paper also summarizes the progresses made in the use of unconventional activation methods for performing oxidation reactions, highlighting the synergy of these technologies with heterogeneous catalysis. Focus has been centered on both usual catalysts activation methods and less usual ones, such as the use of ultrasounds, microwaves, grinding (mechanochemistry) and photo-activated processes, as well as their combined use.
    [Show full text]
  • Terminal and Non Terminal Alkynes Partial Hydrogenation Catalyzed By
    Chapter 6 Terminal and Non Terminal Alkynes Partial Hydrogenation 8 Catalyzed by Some d Transition Metal Complexes in Homogeneous and Heterogeneous Systems Domingo Liprandi, Edgardo Cagnola, Cecilia Lederhos, Juan Badano and Mónica Quiroga Additional information is available at the end of the chapter http://dx.doi.org/10.5772/47742 1. Introduction The synthesis and manufacture of food additives, flavours and fragrances, as well as pharmaceutical, agrochemical and petrochemical substances, examples of fine and industrial chemicals, are closely related to selective alkyne hydrogenation [1,2]. Regarding alkyne partial hydrogenation, the main goal is to avoid hydrogenation to single bond and in the case of non-terminal alkynes is to give priority to the highest possible conversion and selectivity to the (Z)-alkene [3-5]. These kind of reactions are carried out by means of a catalytic process where control over conversion and selectivity can be exerted in different ways, e.g.: by varying a) the active species or b) the support, and/or by adding c) a promoter / a poison / a modifier, and finally, and not less important, by modifying the reaction temperature. Examples of factor b) are: mesoporous [6] and siliceous [7] materials, a pumice [8], carbons [9], and hydrotalcite [3]. Cases of factor c) are the typical Lindlar catalyst (palladium heterogenized on calcium carbonate poisoned by lead acetate or lead oxide, Pd-CaCO3-Pb) [10] and the presence of quinoline and triphenylphosphine [11,12]. Research on factors a) and c) include bi-elemental systems such as Ni-B, Pd-Cu, etc. [13-19]. An example of the effect of the reaction temperature is a paper by Choi and Yoon, who found that the selectivity to (Z)-alkene increases when the temperature decreases using a Ni catalyst [20].
    [Show full text]
  • Phytochemical, Antioxidant and Antimicrobial Characterization of Hedera Helix L
    Journal of Plant Development ISSN 2065-3158 print / e-ISSN 2066-9917 Vo l . 27, Dec 2020: 47-53 Available online: www.plant-journal.uaic.ro doi: 10.33628/jpd.2020.27.1.47 PHYTOCHEMICAL, ANTIOXIDANT AND ANTIMICROBIAL CHARACTERIZATION OF HEDERA HELIX L. EXTRACT Ioana Raluca SUICA-BUNGHEZ1, Ana Alexandra SORESCU1,2*, Sanda Maria DONCEA1, Mariana CONSTANTIN1, Iuliana RAUT1, Rodica Mariana ION1,2 1 National R&D Institute for Chemistry and Petrochemistry – ICECHIM, 060021 Bucharest – Romania 2 Valahia University of Targoviste, Materials Engineering Department, 130004 Targoviste – Romania * Corresponding author. E-mail: [email protected] Abstract: The present research describes the components of the ivy (Hedera helix L.) plant extract. It is known that ivy presents a lot of health benefits, like antibacterial, antimicrobial, anticancer properties or skin care, due to their components. So, the aim of our study was to characterize quantitative (polyphenols, tannins, flavonoids, terpenoids) and qualitative (saponins, proteins, steroids) screening for phytochemical compounds and antioxidant activity of the hydroalcoholic extract obtained by ivy leaves. The sample was analyzed by UV-VIS, FTIR, TLC techniques. The antioxidant activity was evaluated using DPPH method. The antimicrobial activity was demonstrated on bacteria, yeast and mold species. Keywords: analytical techniques, antioxidant activity, Hedera helix L., phytocompounds, phytosynthesis. Introduction Ivy (Hedera helix L.), is a genus containing approximately 15 species of climbing evergreen plants. On suitable surfaces, trees and rock faces, ivy has the ability to climb 25- 30 m above the ground and hold fast to vertical surfaces, like liana [XIA & al. 2011; LUTSENKO & al. 2010]. Hedera helix contains saponins, flavonoids, polyacetylenes and phenolic compounds (flavonoids, anthocyanins, coumarins and phenolic acids), aminoacids, steroids, vitamins, volatile and fixed oils, which are reported for medicinal benefits: antifungal, antispasmodic, antimicrobial, antimutagenic or cytotoxic activities [BUSECK & al.
    [Show full text]
  • Separation Processes
    6.2 Separation processes 6.2.1 Characteristics kerosene, which is an oily combustible material used for of separation processes heating plants and as a propellant for jet planes, condenses between 250°C and 160°C; naphtha, which is The separation of solutions and mixtures into their single used as a fuel and as a raw material for pesticides, components is an operation of great importance for the fertilizers, and plastic materials, condenses between chemical, petrochemical, and oil industries. Almost all 160°C and 70°C. Gasoline, mainly used as a fuel for chemical processes need preliminary raw material planes and cars, condenses between 70°C and 20°C. At purification or the separation of primary from secondary 20°C only gaseous products like methane, ethane, products. These operations go against the tendency of propane, and butane remain. Butane and propane, in substances to intimately and spontaneously mix, which is, as particular, form the fuel called LPG (Liquefied is well-known, a consequence of the second law of Petroleum Gas). thermodynamics. For instance, salt mixed in water dissolves The above example shows how a separation process to give a homogeneous solution and the separation of the makes it possible to transform a mixture of substances components in the mixture requires the use of energy. In this into two or more products with different compositions. A case separation can be performed in one of the following separation process is fed by one or more streams, ways: whereas streams of products of different compositions • By heating the solution to make the water evaporate, and leave the separation equipment.
    [Show full text]