DOCSLIB.ORG

Tuning Color Through Substitution

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Tuning Color Through Substitution Tuning Color Through Substitution Introduction In this experiment, the effect of substituents on the absorbance spectra of molecules will be related to the structure of the molecular orbitals involved in the transition. Both the nature and the position of the substituent on the ring will be investigated and related to theoretical predictions based on the structure of the frontier molecular orbitals of the molecule. Molecular Orbitals Molecular Orbital Theory (MO theory) can be used to relate the formation and nature of chemical bonds to properties of molecules. This experiment will expand on the discussion of structure-property relationships by considering changes in optical properties within a family of similar compounds upon structural modifications. The molecular orbital approaches are used to (1) rationalize these changes and (2) guide the structural design to obtain compounds with desired absorption characteristics. As you have read through the text associated with this course, you have learned about the use of various theoretical tools chemists use to understand electrons, atoms and chemical bonding. In the particle-in-a-box experiment, the structure of the molecule was shown to affect the absorbance spectrum of the molecule in a predictable way. In another experiment, the valence electron-pair repulsion theory, VSEPR, was used to approximate the geometry of multi-atom molecules, and the molecular orbitals were calculated. One of the challenges associated with the Schrödinger equation is the difficulty in solving the equation for multi-atom systems. However, one can use a simplified approach to approximate energies of the electrons in a multi-atom molecule. By mathematically combining wavefunctions of simpler systems, it is possible to approximate the description of a more complex molecule. This technique is designated as the LCAO, Linear Combination of Atomic Orbitals, method and involves constructing molecular orbitals (MOs) for the molecule using the atomic orbitals of the individual atoms. Your textbook provides the details of the mathematics and theory behind this method. As the atomic orbitals combine to form molecular orbitals, the general rules of filling these molecular orbitals with electrons are as follows: (1) electrons occupy orbitals of the lowest energy in the ground state; (2) no more than two electrons can be placed in a single molecular orbital; and (3) two electrons in a single orbital must have anti-parallel spins (i.e., be “paired”). In addition, the total number of molecular orbitals must be equal to the total number of atomic orbitals used in the MO construction and the total number of electrons distributed among the molecular orbitals must equal the total number of electrons from all of the bonding atoms. 1 In compounds, electrons can be excited from one molecular orbital to another of higher energy by using electromagnetic radiation (usually in the UV-visible range). This process can be used to evaluate the energies of molecular orbitals by means of spectrophotometric techniques, as was done with the Particle-in-a-Box model. Typically, the lowest energy transitions involve what are termed Frontier Molecular Orbitals. The highest energy molecular orbital filled with (an) electron(s) is called the Highest Occupied Molecular Orbital (HOMO). The lowest energy vacant molecular orbital (i.e., containing no electrons) is called the Lowest Unoccupied Molecular Orbital (LUMO). The difference in energy between the HOMO and the LUMO can sometimes be determined using UV-visible spectroscopy. Compounds of Interest The two images above are ball and stick models of benzene (C6H6, left) and naphthalene (C10H8, right). Both of these molecules are highly conjugated, as were the molecules in the Particle-in-a-Box lab. These particular species belong to a special class of compounds known as aromatic. A cyclic planar molecule is aromatic if its conjugated π-system has 4n+2 electrons, where n is an integer (n = 1, 2, 3, …). For example, n = 1 for benzene (6 π electrons) and n = 2 for naphthalene (10 π electrons). The term “aromatic” has historic roots and most of the time has nothing to do with the actual odor of the compound. To be even more specific, benzene and naphthalene are members of the benzenoid aromatic hydrocarbon family because they are both based on the six- membered ring of benzene. While benzenoid aromatic compounds are the most abundant, non-benzenoid aromatic molecules are known as well. The two images below are ball and stick models of naphthalene (left) and azulene (right). Although both of these molecules have the same molecular formula, C10H8, they have very different physical and chemical properties. Naphthalene is composed of two fused 6-membered rings and has three chemically different kinds of carbon atoms. Azulene is an unusual aromatic hydrocarbon that comprises an edge sharing combination of five- and seven- membered sp2-carbon rings. Due to the difference in arrangement of the carbon atoms, these structural isomers exhibit different spectroscopic behavior upon substitution. In particular, you will analyze and rationalize the impact of 2 hydrogen atom substitution in azulene by various functional groups on the color of the molecule. Many branches of science use the electronic nature of molecules to design novel materials for various applications. For instance, advances in the design and fabrication of flat screen televisions and computer monitors have exposed the importance of developing molecules and/or materials that have specific and controllable optical properties (e.g., color) to improve the viewing experience of consumers. One such technology employs liquid crystals as the means for communicating a color scheme to viewers. The ability to accurately predict the color of a particular compound is a significant challenge. Regiospecific (e.g., controlled) substitution in a molecule may also be a difficult task that many synthetic chemists perform every day. To a first approximation, the C-H substitution at a benzenoid aromatic ring (e.g. benzene, naphthalene, anthracene) alters the energies of both the HOMO and the LUMO of the molecule in the same way (i.e. the energies of the Frontier MOs shift in the same direction by the same magnitude). Thus, such a structural modification will hardly affect the energy of the HOMOLUMO transition in the electronic spectrum of a benzenoid compound regardless of the nature of the substituent. Typically chemists create colored materials by working with highly conjugated polar organic molecules (dyes) or metal-containing compounds. The energy separation between the HOMO and LUMO of transition metal-based molecules often falls in the visible region of the electromagnetic spectrum, as was seen in the “Introduction to Spectroscopy” lab. Because of its deep color and the relatively simple structure, the azulenic framework has been attracting chemists’ attention as a potential optical marker that could be incorporated into larger molecular ensembles. In addition, azulene is planar (flat) and polar (the dipole moment of azulene is 1 Debye), which makes it attractive for liquid crystal design. In this two-week experiment, you will investigate Molecular Orbital Theory (MO theory) and use this theory to rationalize and predict certain structure-property relationships. In this experiment, you will calculate the contour plots and the energies of the HOMO and LUMO orbitals for a variety of structurally similar molecules and experimentally acquire their absorbance spectra. The effect of the structure of the HOMO and LUMO orbitals on the shift in absorption energy upon substitution will be determined. Additionally, you will determine the feasibility of using substituted azulenes to control the 3 color observed and absorbed. You will also relate the type of substituent and its position on the azulenic scaffold to the impact on color by analyzing changes in the energy of the HOMOLUMO electronic transition upon substitution. Pre-lab Familiarize yourself with the structures of the naphthalene and azulene molecules involved in this experiment. Note the differences between the different types of molecules studied. Read the paper referenced below by Lui et al. in J. Chem. Ed. and be prepared to answer questions about this paper and use it as a reference to understand your data. Pre-lab Assignment: Please answer the following questions in your lab notebook. This assignment is due at the beginning of lab. This pre-lab assignment is due at the beginning of lab. You will not be allowed to start the experiment until this assignment has been completed and submitted to your TA. List the following chemicals for this experiment: ethanol, naphthalene, azulene, and anthracene. (You are not required to look up safety information for the other chemicals used in this experiment.) For each chemical, list specific safety precaution(s) that must be followed. To find specific safety information, obtain a Materials Safety Data Sheet (MSDS) on the chemical of interest. MSDSs can be found through an internet search (e.g., google) or from the following website: www.hazard.com Read the MSDS and find specific safety concerns for each chemical. Be sure to include the route(s) of entry and the possible acute and chronic effects of exposure, if given. Using your own words, complete the OBJECTIVE and PROCEDURE sections in your lab notebook. (See the Maintaining Your Laboratory Notebook link on the lab website to learn what these lab notebook sections entail.) Also, please write out answers to the questions below. For Week 1: 1) Define the term isomer. What are structural isomers? 2) Draw the naphthalene and azulene molecules and number the carbon atoms according to convention. 3) What is meant by the terms electron donating group (EDG) and electron withdrawing group (EWG) with respect to functional groups? 4) What are major differences between the HOMO and LUMO orbitals of naphthalene and azulene (Hint: Use Figure 2 in the Liu et al. article to help with this question). 4 For Week 2: 5) Predict what effect the different functional groups (see pre-lab question 3 from Week 1 above for types) will have.
Load more

Recommended publications
  • Characterization of Heat Reformed Naphtha Cracking Bottom Oil Extracts
    Carbon Vol. 9, No. 4 December 2008 pp. 289-293 Letters Characterization of Heat Reformed Naphtha Cracking Bottom Oil Extracts Jong Hyun Oh 1, Jae Young Lee1, Seok Hwan Kang2, Tai Hyung Rhee3 and Seung Kon Ryu1,♠ 1Departmentl of Chemical Engineering, Chungnam National University, Daejeon 305-764, Korea 2Uniplatek co., Ltd. Of “themoQ” 104-10 Munji-dong Yuseong, Daejeon 305-380, Korea 3Chemical Matrials Team, TECHNO SEMICHEM Co., Ltd., Kongju 314-240, Korea ♠email: [email protected] (Received November 13, 2008; Accepted December 12, 2008) Abstract Naphtha Cracking Bottom (NCB) oil was heat reformed at various reforming temperature and time, and the volatile extracts were characterized including yields, molecular weight distributions, and representative compounds. The yield of extract increased as the increase of reforming temperature (360 ~ 420oC) and time (1 ~ 4 hr). Molecular weight of the as-received NCB oil was under 200, and those of extracts were distributed in the range of 100-250, and far smaller than those of precursor pitches of 380-550. Naphtalene-based compounds were more than 70% in the as-received NCB oil, and most of them were isomers of compounds bonding functional groups, such as methyl (CH3-) and ethyl (C2H5-). When the as-received NCB oil was reformed at 360oC for 1 hr, the most prominent compound was 1,2-Butadien, 3-phenyl- (24.57%), while naphthalene became main component again as increasing the reforming temperature. Keywords : NCB oil, pitch, extract analysis, heat reforming 1. Introduction preparation of precursor pitch for pitch-based carbon fiber. The extracts were characterized to investigate the molecular 860 million barrel per year of petroleum oil was refined in weight distribution, representative compounds, yield, and Korea, 2004 [1].
    [Show full text]
  • Chem 22 Homework Set 12 1. Naphthalene Is Colorless, Tetracene
    Chem 22 Homework set 12 1. Naphthalene is colorless, tetracene is orange, and azulene is blue. naphthalene tetracene azulene (a) Based on the colors observed for tetracene and azulene, what color or light does each compound absorb? (b) About what wavelength ranges do these colors correspond to? (c) Naphthalene has a conjugated π-system, so we know it must absorb somewhere in the UV- vis region of the EM spectrum. Where does it absorb? (d) What types of transitions are responsible for the absorptions? (e) Based on the absorption wavelengths, which cmpd has the smallest HOMO-LUMO gap? (f) How do you account for the difference in absorption λs of naphthalene vs tetracene? (g) Thinking about the factors that affect the absorption wavelengths, why does azulene not seem to follow the trend seen with the first two hydrocarbons? (h) Use the Rauk Hückelator (www.chem.ucalgary.ca/SHMO/) to determine the HOMO-LUMO gaps of each compound in β units. The use of this program will be demonstrated during Monday's class. 2. (a) What are the Hückel HOMO-LUMO gaps (in units of β) for the following molecules? Remember that we need to focus just on the π-systems. Use the Rauk Hückelator. (b) Use the Rauk Hückelator to draw some conjugated polyenes — linear as well as branched. Look at the HOMO. What is the correlation between the phases (ignore the sizes) of the p- orbitals that make up the HOMO and the positions of the double- and single-bonds in the Lewis structure? What is the relationship between the phases of p-orbitals of the LUMO to those of the HOMO? (c) Use your answer from part b and the pairing theorem to sketch the HOMO and LUMO of the polyenes below (again, just the phases — don't worry about the relative sizes of the p- orbitals).
    [Show full text]
  • Iridium-Catalyzed Borylation of Arenes and Heteroarenes Via C–H Activation*
    Pure Appl. Chem., Vol. 78, No. 7, pp. 1369–1375, 2006. doi:10.1351/pac200678071369 © 2006 IUPAC Iridium-catalyzed borylation of arenes and heteroarenes via C–H activation* Tatsuo Ishiyama and Norio Miyaura‡ Division of Chemical Process Engineering, Graduate School of Engineering, Hokkaido University, Sapporo 060-8628, Japan Abstract: Direct C–H borylation of aromatic compounds catalyzed by a transition-metal complex was studied as an economical protocol for the synthesis of aromatic boron deriva- tives. Iridium complexes generated from Ir(I) precursors and 2,2'-bipyridine ligands effi- ciently catalyzed the reactions of arenes and heteroarenes with bis(pinacolato)diboron or pinacolborane to produce a variety of aryl- and heteroarylboron compounds. The catalytic cycle involves the formation of a tris(boryl)iridium(III) species and its oxidative addition to an aromatic C–H bond. Keywords: iridium catalyst; arylboron compounds; C–H activation; pinacolborane; bis(pina- colato)diboron. INTRODUCTION Aromatic boron derivatives are an important class of compounds, the utility of which has been amply demonstrated in various fields of chemistry. Traditional methods for their synthesis are based on the re- actions of trialkylborates with aromatic lithium or magnesium reagents derived from aromatic halides [1]. Pd-catalyzed cross-coupling of aromatic halides with tetra(alkoxo)diborons or di(alkoxo)boranes is a milder variant where the preparation of magnesium and lithium reagents is avoided [2,3]. Alternatively, transition-metal-catalyzed aromatic C–H borylation of aromatic compounds by pina- colborane (HBpin, pin = O2C2Me4) or bis(pinacolato)diboron (B2pin2) is highly attractive as a con- venient, economical, and environmentally benign process for the synthesis of aromatic boron com- pounds without any halogenated reactant, which has been studied extensively by Hartwig, Marder, and η4 Smith [4–6].
    [Show full text]
  • Azulene—A Bright Core for Sensing and Imaging
    molecules Review Azulene—A Bright Core for Sensing and Imaging Lloyd C. Murfin * and Simon E. Lewis Department of Chemistry, University of Bath, Bath BA2 7AY, UK; [email protected] * Correspondence: lloyd.murfi[email protected] Abstract: Azulene is a hydrocarbon isomer of naphthalene known for its unusual colour and fluores- cence properties. Through the harnessing of these properties, the literature has been enriched with a series of chemical sensors and dosimeters with distinct colorimetric and fluorescence responses. This review focuses specifically on the latter of these phenomena. The review is subdivided into two sec- tions. Section one discusses turn-on fluorescent sensors employing azulene, for which the literature is dominated by examples of the unusual phenomenon of azulene protonation-dependent fluorescence. Section two focuses on fluorescent azulenes that have been used in the context of biological sensing and imaging. To aid the reader, the azulene skeleton is highlighted in blue in each compound. Keywords: fluorescence; azulene; sensor; dosimeter; bioimaging; chemosensor; chemodosimeter 1. Introduction Azulene, 1, is an isomer of naphthalene, 2, composed of fused 5- and 7-membered ring systems (Figure1) and named for its vibrant blue colour. Unlike naphthalene, azulene is a non-alternant hydrocarbon, possessing nodal points at C-2 and C-6 of the HOMO and C-1 and C-3 of the LUMO [1]. The location of these nodes results in low electronic repulsion in the S1 singlet excited state, affording a relatively small HOMO-LUMO gap. Hence, the S0!S1 transition arises from absorption in the visible region. Conversely, in naphthalene, coefficient magnitudes remain consistent for each position in both the HOMO Citation: Murfin, L.C.; Lewis, S.E.
    [Show full text]
  • Coulomb Pairing Resonances in Multiple-Ring Aromatic Molecules
    Coulomb pairing resonances in multiple-ring aromatic molecules D.L. Huber* Physics Department, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA Abstract We present an analysis of pairing resonances observed in photo-double-ionization studies of CnHm aromatic molecules with multiple benzene-like rings. The analysis, which is based on the Coulomb pairing model, is applied to naphthalene, anthracene, phenanthrene, pyrene and coronene, all of which have six-member rings, and azulene which is comprised of a five-member and a seven-member ring. There is a high energy resonance at ~ 40 eV that is found in all of the molecules cited and is associated with paired electrons localized on carbon sites on the perimeter of the molecule, each of which having two carbon sites as nearest neighbors. The low energy resonance at 10 eV, which is found only in pyrene and coronene, is attributed to the formation of paired HOMO electrons localized on arrays of interior carbon atoms that have the point symmetry of the molecule with each carbon atom having three nearest neighbors. The origin of the anomalous increase in the doubly charged to singly charged parent-ion ratio that is found above the 40 eV resonance in all of the cited molecules except coronene is discussed. *Mailing address: Physics Department, University of Wisconsin-Madison, 1150 University Ave., Madison, WI 53711, USA; e-mail: [email protected] 1 1. Introduction Recent studies of photo-double-ionization in CnHm multiple-ring (polycylic) aromatic molecules have revealed the existence of anomalous resonances in the ratio of the cross sections of doubly charged parent ions to singly charged parent ions I(2+)/I(1+) [1-4].
    [Show full text]
  • 1 Towards a Solution of the Polycyclic Aromatic
    TOWARDS A SOLUTION OF THE POLYCYCLIC AROMATIC HYDROCARBON – DIFFUSE INTERSTELLAR BAND HYPOTHESIS Xiaofeng Tan ([email protected]) Abstract. A novel theoretical method is developed to study the polycyclic aromatic hydrocarbon – diffuse interstellar band (PAH-DIB) hypothesis. In this method, a computer program is used to enumerate all PAH molecules with up to a specific number of fused benzene rings. Fast quantum chemical calculations are then employed to calculate the electronic transition energies, oscillator strengths, and rotational constants of these molecules. An electronic database of all PAHs with up to any specific number of benzene rings can be constructed this way. Comparison of the electronic transition energies, oscillator strengths, and rotational band contours of all PAHs in the database with astronomical spectra allows one to identify possible individual PAH carriers of some of the intense narrow DIBs. Using the current database containing up to 10 benzene rings we have selected 8 closed-shell PAHs as possible carriers of the intense λ6614 DIB. 1. Introduction The diffuse interstellar bands (DIBs) are absorption features in the near ultraviolet (UV) to near infrared (IR) spectral range seen in the spectra of stars obscured by diffuse interstellar clouds. Since their discovery in 1922,1 the identification of the carriers of these bands has been a long-standing challenge for scientists of the 20th century. In the past two decades, the hypothesis that free gas-phase PAHs may carry some of the DIBs has become a consensus – which
    [Show full text]
  • And Trisubstituted Azulenes Using a Danheiser Annulation As the Key Step: an Advanced Organic Laboratory Experiment Rebecca M
    Masthead Logo Smith ScholarWorks Chemistry: Faculty Publications Chemistry 10-15-2012 Synthesis of Di- and Trisubstituted Azulenes Using a Danheiser Annulation as the Key Step: An Advanced Organic Laboratory Experiment Rebecca M. Thomas Kevin M. Shea Smith College, [email protected] Follow this and additional works at: https://scholarworks.smith.edu/chm_facpubs Part of the Chemistry Commons Recommended Citation Thomas, Rebecca M. and Shea, Kevin M., "Synthesis of Di- and Trisubstituted Azulenes Using a Danheiser Annulation as the Key Step: An Advanced Organic Laboratory Experiment" (2012). Chemistry: Faculty Publications, Smith College, Northampton, MA. https://scholarworks.smith.edu/chm_facpubs/13 This Article has been accepted for inclusion in Chemistry: Faculty Publications by an authorized administrator of Smith ScholarWorks. For more information, please contact [email protected] Synthesis of Di- and Trisubstituted Azulenes Using a Danheiser Annulation as the Key Step: An Advanced Organic Laboratory Experiment Rebecca M. Thomas and Kevin M. Shea* Department of Chemistry, Smith College, Northampton, Massachusetts 01063, United States ABSTRACT: This three-week experiment provides students with an inquiry-based approach focused on learning traditional skills like primary literature interpretation, reaction design, flash column chromatography, and NMR analysis. Additionally, students address higher order concepts like the origin of azulene’s blue color, the mechanism of the Danheiser annulation (step 1), identification of an unknown
    [Show full text]
  • Aromaticity of Polycyclic Conjugated Hydrocarbons
    Chem. Rev. 2003, 103, 3449−3605 3449 Aromaticity of Polycyclic Conjugated Hydrocarbons Milan Randic´* National Institute of Chemistry, Ljubljana, Slovenia Received December 13, 2001 Contents I. Prologue 3451 II. Introduction 3455 III. Dilemmas 3456 A. Qualitative versus Quantitative Approaches 3456 B. Observables versus Non-observables 3458 C. Structural Criteria versus Properties as Criteria 3459 D. Valence Bond Theory versus Molecular Orbital 3460 Theory E. On Interlocking of the MO and the VB 3461 Methods F. Chemical Graph Theory versus Quantum 3462 Chemistry G. Clar 6n Rule versus Hu¨ckel 4n + 2 Rule 3464 H. Hydrocarbons versus Heteroatomic Systems 3465 Milan Randic´ is a native of Croatia, born in 1930, and is a citizen of the IV. Hidden Treasures of Kekule´ Valence Structures 3466 United States and Croatia. He studied theoretical physics at the University A. Conjugated Circuits 3467 of Zagreb (1954) under Professor Ivan Supek (a student of Werner B. Innate Degree of Freedom 3470 Heisenberg). Supek introduced him to the book by Linus Pauling, The Nature of the Chemical Bond, with a request to get involved in quantum C. Clar Structures 3472 chemistry. He got his Ph.D. degree in Cambridge in 1958, studying high- V. Graph Theoretical Approach to Chemical Structure 3473 resolution infrared molecular spectra with Dr. Norman Sheppard. At the A. Metric 3473 Rudjer Bosˇkovic´ Institute in Zagreb, Croatia, in 1960, he founded the B. Chemical Graphs 3473 theoretical chemistry group. Since 1971, he has visited several U.S. universities. From 1980 to 2000, he was in the Department of Mathematics C. Isospectral Graphs 3473 and Computer Science at Drake University, Des Moines, Iowa.
    [Show full text]
  • Safety Assessment of Chamomile Ingredients As Used in Cosmetics
    Safety Assessment of Chamomile Ingredients as Used in Cosmetics Status: Scientific Literature Review for Public Comment Release Date: February 11, 2013 Panel Date: June 10-11, 2013 All interested persons are provided 60 days from the above date to comment on this Tentative Report and to identify additional published data that should be included or provide unpublished data which can be made public and included. Information may be submitted without identifying the source or the trade name of the cosmetic product containing the ingredient. All unpublished data submitted to CIR will be discussed in open meetings, will be available at the CIR office for review by any interested party and may be cited in a peer-reviewed scientific journal. Please submit data, comments, or requests to the CIR Director, Dr. F. Alan Andersen. The 2012 Cosmetic Ingredient Review Expert Panel members are: Chair, Wilma F. Bergfeld, M.D., F.A.C.P.; Donald V. Belsito, M.D.; Curtis D. Klaassen, Ph.D.; Daniel C. Liebler, Ph.D.; Ronald A Hill, Ph.D. James G. Marks, Jr., M.D.; Ronald C. Shank, Ph.D.; Thomas J. Slaga, Ph.D.; and Paul W. Snyder, D.V.M., Ph.D. The CIR Director is F. Alan Andersen, Ph.D. This report was prepared by Wilbur Johnson, Jr., M.S., Manager/Lead Specialist and Bart Heldreth, Ph.D., Chemist. © Cosmetic Ingredient Review 1101 17TH STREET, NW, SUITE 412 ◊ WASHINGTON, DC 20036-4702 ◊ PH 202.331.0651 ◊ FAX 202.331.0088 ◊ [email protected] ii Table of Contents INTRODUCTION .............................................................................................................................................................. 1 CHEMISTRY ..................................................................................................................................................................... 1 PHYSICAL AND CHEMICAL PROPERTIES ..................................................................................................................................
    [Show full text]
  • Pdf 877.25 K
    E. S. Moosavi et al. / Journal of Chemical and Petroleum Engineering, 52 (1), June 2018 / 23-33 23 Deasphalting of Olefin Pyrolysis Fuel Oil by Combination of Chemical–Physical Methods E. S. Moosavi1, M. Gharibi*2, R. Karimzadeh*3, B. Asbaghi2, 2 3 3 S. S. Shahabi , S. Aalizad and M. Zare 1. Chemical and Materials Engineering Department, Buein Zahra Technical University, Buein Zahra, Qazvin, Iran. 2. National Petrochemical Company, Petrochemical Research and Technology Company, P.O. Box 1435884711, Tehran, Iran. 3. Chemical Engineering Faculty, Tarbiat Modares University, P.O. Box 14155-4838, Tehran, Iran. (Received 14 August 2017, Accepted 26 February 2018) [DOI: 10.22059/jchpe.2018.239677.1207] Abstract Keywords Fuel Oil (PFO) thermal cracking of two PFO samples on liquid, solid This work investigated the effect of different conditions of Pyrolysis Asphaltene; Naphthalene; and gas product yields and asphaltene removal efficiency in a newly- Product yield; designed experimental setup. There is no need to use a catalyst, simple Pyrolysis fuel oil (PFO); operating system and experiment conditions. The ability to use wa Thermal cracking. ter as a cheap carrier gas and high asphaltene extraction efficiency- paredwithout in thevarious use of operating solvents conditionsare outstanding and the benefits optimum of this experimental method in upgrading PFO. The yields of liquid, solid and gas products were com- ing condition of PFO in terms of liquid yield and asphaltene removal in conditions were obtained. The results revealed the best thermal crack this setup for samples. The optimum conditions were 390 and 380°C rate.for the In reactorthese circumstances temperature aboutof PFO-1 70 and 53PFO-2, wt% respectively; of the liquid 150°Cprod- uct,for the 25 temperaturewt% of the solid of carrier products, gas and and 100 5 wt% ml/min of the for gascarrier product gas flow are generated and the asphaltene separation was reached about 95 and 96.5%.
    [Show full text]
  • Computational Investigation on the Large Energy Gap Between the Triplet Excited-States in Acenes Cite This: RSC Adv.,2017,7, 26697 Y
    RSC Advances View Article Online PAPER View Journal | View Issue Computational investigation on the large energy gap between the triplet excited-states in acenes Cite this: RSC Adv.,2017,7, 26697 Y. Y. Pan, *ab J. Huang,a Z. M. Wang,a D. W. Yu,a B. Yang*b and Y. G. Ma c The large energy gap between the two triplet excited-states in acenes has a huge impact on their optical and electronic properties. Accurate calculation and full use of this gap have always been a major challenge in the field of organic semiconductor materials. In the present study, we focus on the precise description of the large gap between the T1 and T2 states, and taking a series of acenes (benzene, Received 2nd March 2017 naphthalene, anthracene, tetracene, and pentacene) as examples, investigate their excited state behavior Accepted 4th May 2017 to verify the energy gap structure. The results show that the symmetry of the transition molecular orbital DOI: 10.1039/c7ra02559a and the excited state properties have a great influence on the transition energy, and may be the main rsc.li/rsc-advances cause of the large energy gap. Creative Commons Attribution-NonCommercial 3.0 Unported Licence. 1. Introduction mechanism, the energy of the T1 state is greater than the S1 but less than T2 (ES1 <2ET1 < ET2), that is, there are energy gaps 11 In an electroluminescent device, electrons and holes driven by between the S1,T1 and T2, as shown in Fig. 1(c). The third the electric eld generate excitons. Generally, initially formed example is singlet ssion (SF) in which two triplet excitations excitons tend to relax to the lowest singlet (S1) and triplet (T1) are produced from an excited singlet.
    [Show full text]
  • Towards Sustainable Production of Chemicals and Fuels from the Fast Pyrolysis of Waste Polyolefin Plastics
    Michigan Technological University Digital Commons @ Michigan Tech Dissertations, Master's Theses and Master's Reports 2019 TOWARDS SUSTAINABLE PRODUCTION OF CHEMICALS AND FUELS FROM THE FAST PYROLYSIS OF WASTE POLYOLEFIN PLASTICS Ulises Gracida Alvarez Michigan Technological University, [email protected] Copyright 2019 Ulises Gracida Alvarez Recommended Citation Gracida Alvarez, Ulises, "TOWARDS SUSTAINABLE PRODUCTION OF CHEMICALS AND FUELS FROM THE FAST PYROLYSIS OF WASTE POLYOLEFIN PLASTICS", Open Access Dissertation, Michigan Technological University, 2019. https://doi.org/10.37099/mtu.dc.etdr/797 Follow this and additional works at: https://digitalcommons.mtu.edu/etdr Part of the Catalysis and Reaction Engineering Commons, Computer-Aided Engineering and Design Commons, Other Chemical Engineering Commons, Polymer and Organic Materials Commons, and the Sustainability Commons TOWARDS SUSTAINABLE PRODUCTION OF CHEMICALS AND FUELS FROM THE FAST PYROLYSIS OF WASTE POLYOLEFIN PLASTICS By Ulises Raymundo Gracida Alvarez A DISSERTATION Submitted in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY In Chemical Engineering MICHIGAN TECHNOLOGICAL UNIVERSITY 2019 © 2019 Ulises Raymundo Gracida Alvarez This dissertation has been approved in partial fulfillment of the requirements for the Degree of DOCTOR OF PHILOSOPHY in Chemical Engineering. Department of Chemical Engineering Dissertation Co-Advisor: Dr. David R. Shonnard Dissertation Co-Advisor: Dr. Julio C. Sacramento Rivero Committee Member: Dr. Gerard T. Caneba
    [Show full text]