DOCSLIB.ORG

Chemistry of High Energy Materials 2012-08-18

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text

Load more

Baran GM R.A. Rodriguez Chemistry of High Energy Materials 2012-08-18 History of Explosives High Energy Materials 7th century A.D.- "Greek Fire" petroleum distillate used by Byzantines of Constantinopole 13th century - black powder (aka gunpowder) Chinese alchemists Explosives Non-explosive materials 18th century - black powder composition became standardized: KNO3/charcoal/sulfur (75/15/10 w/w) 19th century - NH4NO3 replacement for KNO3 in black powder 1846 - Italian Chemist Ascanio Sobrero invented nitroglycerin (NG) High Explosives Low Explosives 1863 - German chemist Julius Wilbrand invented 2,4,6-trinitrotoluene (TNT) [detonate] [deflagrate-burn rapidly] originally used as a yellow dye. Potential as an explosive not appreciated due to difficulty to detonate (insensative). 1866 - Mixing of NG with silica (PBX) to make malleable paste (dynamite) 1° Explosives 2° Explosives Propellants Pyrotechnics [detonate by ignition] [need detonator] - Black powder - Fireworks late 19th century - nitration chemistry on common materials (resins,cotton, etc.) - Lead azide - TNT - liquid/solid - Color/flash/sound - Tetrazene - RDX 1910 - military use of TNT for artillery shells and armour-piercing shells 1939-1945 - World War II - Research on explosives intesified (nitration chemistry) Developlment of cyclotrimethylenetrinitramine (RDX) and Organic Chemistry of Explosives by J.P. Agrawal and R.D. Hodgson cyclotetramethylenetetranitramine (HMX). Prof. Thomas Klapotke - Ludwig-Maximilians-Universität München - Germany Introduction to high energy materials terminology Chair of inorganic chemistry Brisance: Shattering capabiliy of explosive. Measure of rate an explosive develops its maximum pressure. Dr. Michael A. Hiskey - Los Alamos National Laboratory Relative effectiveness factor (R.E. factor): Measurement of an explosive's power for military purposese. It is used to compare an explosive's What makes an explosion? effectiveness relative to TNT by weight (TNT equivalent/kg or TNTe/kg). Exothermic chemical reaction comprised of an oxidant and fuel, which releases Detonation velocity (VoD): The velocity at which the shock wave front travels energy (gas and heat) in a given time interval. through a detonated explosive. Difficult to measure in practice so use gas theory to make prediction. Whats the difference between explosive, propellants and pyrotechnics? Specific impulse (Isp): The force with respect to the amount of propellant used per unit time. Used to calculate propulsion performance. Rate at which it burns (Flamming gummy bear vs. rocket booster vs. TNT) Speed of reaction will determine subsonic vs. supersonic blast pressure waves Oxygen balance (OB%): Expression used to indicate degree to which explosive can be oxidized. If explosive contains just enough oxygen to form carbon dioxide from carbon, water from hydrogen molecules and all metal oxides from metals with no excess, the explosive is said to have zero oxygen balance. Baran GM R.A. Rodriguez Chemistry of High Energy Materials 2012-08-18 Chemical types/class of organic explosives Aromatic C-nitro compounds Aliphatic C-nitro compounds NO2 NO2 NO2 R2 NO2 Me HO acidic protons (NO2)x R NO2 R1 NO2 R NO2 (condensation NO NO x ≥ 4 chemistry) O N NO O2N 2 O2N 2 1° nitroalkane 2° nitroalkane Terminal 2 2 poor chemical TNT 1,3,5-trinitrobenzene 2,4,6-trinitrophenol gem-dinitroalkane stability (TNB) (picric acid) R 2 NO2 R R 3 NO 2 R2 2 high explosive with Aliphatic O-nitro compounds Aliphatic N-nitro compounds R1 R NO NO 1 2 high thermal and R1 NO2 2 NO2 chemical stability Internal NO O N NO 3° nitroalkane Trinitromethyl O2NO ONO2 2 2 2 gem-dinitroalkane N N ONO2 N NO2 Nitroglycerin (VOD=7750 m/s) heterocycles O2NN NNO2 N N N N ONO NO2 2 O2N NO2 O N NO O NO 2 2 2 RDX (VOD=8440 m/s) HMX (VOD=9110 m/s) O O N NO O2NN NNO2 2 2 ONO2 NO2 N O NO O2N NO2 N H S O 2 N N Pentaerythritol tetranitrate H H H N NH Nitro derivatives of pyrroles, thiopenes, and furans are not practical explosives: (PETN) (VOD=8310 m/s) N,N'-dinitrourea 2 2 1. heat of formation offers no benefits over standard arylene hydrocarbons (DNU) nitroguanadine NO2 2. during nitration, these heterocycles are much more prone to oxidation and O2NO ONO2 acid cat. ring opening compared to arenes O2N NO2 O N 2 NO2 O2N O O2NO ONO2 N N H-bonding H2N NO2 NO 2 O2N NO2 reduction in O2NN NNO N N novel energetic nitrate eseter 2 sensativity N NH N N N N O2N N O ONO2 F2N NF2 O2N NO H O2NO 2 NO2 N 3,3-bis(difluoroamino) 4-amino-3,5-dinitropyrazole 2,4-dinitroimidazole furazans/benzofurazans Si Hexanitrohexa- octahydro-1,5,7,7- (LLM-116) (2,4-DNI) furoxans/benzofuroxans ONO azaisowurtzitane 2 tetranitro-1,5-diazocine O2NO (HNIW or CL-20) NH O 2 NH2 (TNFX) O2N N Si-PETN (VOD=9380 m/s) O2N NO2 O O2N N NO2 N N N H N H N H 2 2 N N N N O N O N N N N 2 H N N NH 2 2 H2N N NH2 O Ar Ar Ar NO2 N N N O N NH NO2 NH2 N N O O benzotriazoles H H 1,3,4-oxadiazoles 3-nitro-1,2,4-triazol-5-one pyridine N-oxide pyrazine N-oxide tetrazine N-oxide tetrazoles 1,2,4 triazoles (NTO) Baran GM R.A. Rodriguez Chemistry of High Energy Materials 2012-08-18 Nitration chemistry NO2 TMS NO AcONO2 2 NO2 O The nitro gorup whether attached to aromatic or aliphatic carbon, is probably the most widely studied of the functional groups and this is in part attributed to its use as an 'explosophore' in many energetic materials. ONO2 ONO2 [2+2] Borgardt et al. Chem Rev 1964. 64, 19 (polynitro functionality) _ OAc Nef _ OAc AcONO2 TMS NO NO Routes to C-Nitro functionality O 2 O 2 NO + O N 2 N Direct nitration of aliphatic and alicyclic hydrocarbons possible in the vapor N O O O OAc phase using HNO3 or NO2 (toxic redish-brown gas) at elevated temperatures. H NO2 O2N NO2 HNO3 alkaline nitration NO Nitration with HNO3 is difficult 25% H 2 NO Me Me Me Me 2 NO2 NO2 NO2 O2N 1. NaHMDS O2N O2N O2N NO2 N2O4 2. N2O4 Me Me O2N NO2 O2N ONO O N ONO 2 2 O2N O N O N O N NO2 2 NO 2 NO 2 NO O O + + 74% 2 2 2 Me Me Me Me Me Me Me Me N N Me Me Me Me Me Me O O dinitro nitro-nitrite nitro-nitrate Br NO2 1. nBuLi - colorless liquid 2. N2O4 -78 °C S S Radical methods 77% OH O2N Cl 1 atm NO NItration selectivity on arene/heteroarene NO2 NO + 2 Ph Ph Ph Kakiuchi, et al. Synlett 1999. 901 N DCE/ rt KNO 76% 23% 3 Al2O3 H2SO4 Cl traditional N NO2 + Mukaiyama et al. Chem Lett 1995. 505 Ph [NO2 ] CO2R 92% N 44% NaNO xs, H H 3 Fe(NO ) 9H O CAN 2eq H NO2 R 3 3 2 R Cl FeCl3 Cl AcOH/CHCl R R 3 R R MeCN, reflx N R R NO2 N 80 - 90% CO R TBAN NO 80 - 90% 2 2 H NO2 H NO2 TFAA NO2BF4 NHAc O O TBAN O * No rxn in H Ph 76% presence of H NO N R R R R MeCN NO2 2 TEMPO Ph F3C O CF3 F3C O CO R Hwu et al. J Chem Soc Chem Commun 1994. 1425 84% 2 Taniguchi et al. JOC 2010. 75, 8126 Baran GM R.A. Rodriguez Chemistry of High Energy Materials 2012-08-18 1° and 2° nitro compounds O NOH NO2 CF3CO3H O OH Victor Meyer rxn N only useful - alkyl chlorides too slow 1.KOtBu oxidant - only good for 1° (2° alkyl halide gives nitrate ester) 1. NBS amyl nitrate + - nitrate ester arises from desproportionation of silver nitrate acc. by heat/light 2. [O] NO2 2. H+ S O 2- 3. [H] 2 8 O O2N NO N ether + 2 + + AgX NO O O O H R X R NO R O O2N NO2 OAg 2 NO2 N NO2H + NO2 O2N NO2 modified VM (alkali metal nitrites e.g. NaNO2) time and solubility is VIMP (low yields) Kaplan R NaNO2 R R N O R NO R Shechter Rxn DMSO NaNO2 X NO2 + O NO2 OH fast slow NO2 R R R nitrite ester R R Synthesis of an energetic nitrate ester O2NO ONO2 O H+ OH O N Chavez, D.E. et al. Angew. 2008, 47, 8307 OR O2NO ONO2 R NO2 NO2 HO OH O O O O 0 R phloroglucinol NO NaOH N 1. NaNO O N NO Ag Kornblum et al. JACS 1956. 78, 1497 2 2 2 2 Fluorotrinitromethane 2. AgNO + 3 R1 R2 Ag R1 R2 R1 R2 NO2 nitronate NO2 NO 2 NO2 + Ag NO (or) NO O O Ag 2 2 O O 0 O O O N NO N O O -Ag 2 2 F NO2 F NO2 N N O O O N N O O N N O R R gem-dinitros from acids 1 2 R R O 1 2 R1 R2 N R1 R2 R R HNO NO2 NO2 CO H 3 HNO3 O Na 2 MeO C CO H Original Target/Route via modified Kaplan Shechter Rxn 20 - 30% 2 2 60 % R R NO2 MeO2C NO2 NO retro Me O 2 Me O O oxidation of amines aldol Me O NO2 Me NH Me N NH +Cl- Me 3 NO2 -CH2O O NH O O O OH DMDO N N Acetone N C+H3N O2N Fe NH3+C 91% NO2 C+H3N O2N O O O O O O N activation N [O] N oxidation of isocyanates Me O Me O R Me NH Me NH NH NCO NO2 via amine thus O NH R DMDO H2O essential O NH NH N N Acetone/H O Eaton et al.
Recommended publications
  • Field-Based Analytical Methods for Explosive Compounds

    Field-Based Analytical Methods for Explosive Compounds

    Field-Based Analytical Methods for Explosive Compounds Dr. Thomas F. Jenkins Marianne E. Walsh USA Engineer Research and Development Center– Cold Regions Research and Engineering Laboratory 72 Lyme Road, Hanover NH 03755 603-646-4385 (FAX-4785) [email protected] [email protected] 1 1 Outline of Presentation • Important properties of nitroaromatic (TNT) and nitramine (RDX) explosives • Accepted laboratory methods for explosives chemicals • Detection criteria for explosives-related chemicals • Why should you consider using on-site methods? • Sampling considerations for explosives in soil and water • Verified methods for on-site determination of explosives in soil and water • Advantages / disadvantages of various on-site methods 2 Overview of topics to be covered in the presentation. 2 ***Safety*** • Chunks of high explosives often found at contaminated sites • Concentrations of TNT or RDX in soil greater than 12% are reactive (can propagate a detonation)* • Neither chunks nor soil with concentrations of TNT and RDX greater than 10% can be shipped off site using normal shipping procedures *Kristoff et al. 1987 3 The most important property of all is the ability of these compounds to detonate if they are subjected to the right type of stimulus (spark, shock). This is one of the major reasons why on-site analysis is so important for explosives. Kristoff, F.T., T.W. Ewing and D.E. Johnson (1987) Testing to Determine Relationship Between Explosive Contaminated Sludge Components and Reactivity. USATHAMA Report No. AMXTH-TE-CR-86096,
  • Development of a Correlation Between

    Development of a Correlation Between

    DEVELOPMENT OF A CORRELATION BETWEEN ROTARY DRILL PERFORMANCE AND CONTROLLED BLASTING POWDER FACTORS by JOHN CHARLES LEIGHTON B.A.Sc, The University of British Columbia, 1978 A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF APPLIED SCIENCE in THE FACULTY OF GRADUATE STUDIES Department of Mining and Mineral Process Engineering We accept this thesis as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA August 1982 © John Charles Leighton, 1982 In presenting this thesis in partial fulfilment of the requirements for an advanced degree at the University of British Columbia, I agree that the Library shall make it freely available for reference and study. I further agree that permission for extensive copying of this thesis for scholarly purposes may be granted by the head of my department or by his or her representatives. It is understood that copying or publication of this thesis for financial gain shall not be allowed without my written permission. John Charles Leighton Department of MIVMVI3 The University of British Columbia 1956 Main Mall Vancouver, Canada V6T 1Y3 Date DE-6 (.3/81) - i i - ABSTRACT Despite the availability of established, sophisticated methods for plan• ning and designing stable slopes in rock, comparatively little attention is usually paid to the problems of carrying out the excavation. Blasting should be carefully planned to obtain optimum fragmentation as well as steep, stable pit walls for a minimum stripping ratio. The principal difficulty facing a blast designer is the lack of prior information about the many critical blasting characteristics of the rock mass.
  • The Russian Job

    The Russian Job

    The Russian Job The rise to power of the Federal Security Service of the Russian Federation “We did not reject our past. We said honestly: The history of the Lubyanka in the twentieth century is our history…” ~ Nikolai Platonovich Patrushev, Director of the FSB Between August-September 1999, a series of explosions in Russia killed 293 people: - 1 person dead from a shopping centre explosion in Moscow (31 st August) - 62 people dead from an apartment bombing in Buynaksk (4 th September) - 94 people dead from an apartment bombing in Moscow (9th September) - 119 people dead from an apartment bombing in Moscow (13 th September) - 17 people dead from an apartment bombing in Volgodonsk (16 th September) The FSB (Federal Security Service) which, since the fall of Communism, replaced the defunct KGB (Committee for State Security) laid the blame on Chechen warlords for the blasts; namely on Ibn al-Khattab, Shamil Basayev and Achemez Gochiyaev. None of them has thus far claimed responsibility, nor has any evidence implicating them of any involvement been presented. Russian citizens even cast doubt on the accusations levelled at Chechnya, for various reasons: Not in living memory had Chechen militias pulled off such an elaborated string of bombings, causing so much carnage. A terrorist plot on such a scale would have necessitated several months of thorough planning and preparation to put through. Hence the reason why people suspected it had been carried out by professionals. More unusual was the motive, or lack of, for Chechens to attack Russia. Chechnya’s territorial dispute with Russia predates the Soviet Union to 1858.
  • University of Southampton Research Repository Eprints Soton

    University of Southampton Research Repository Eprints Soton

    University of Southampton Research Repository ePrints Soton Copyright © and Moral Rights for this thesis are retained by the author and/or other copyright owners. A copy can be downloaded for personal non-commercial research or study, without prior permission or charge. This thesis cannot be reproduced or quoted extensively from without first obtaining permission in writing from the copyright holder/s. The content must not be changed in any way or sold commercially in any format or medium without the formal permission of the copyright holders. When referring to this work, full bibliographic details including the author, title, awarding institution and date of the thesis must be given e.g. AUTHOR (year of submission) "Full thesis title", University of Southampton, name of the University School or Department, PhD Thesis, pagination http://eprints.soton.ac.uk UNIVERSITY OF SOUTHAMPTON FACULTY OF SCIENCE DEPARTMENT OF CHEMISTRY Doctor of Philosophy CHEMICAL AND ELECTROCHEMICAL NITRATIONS OF ALKENES AND DIENES by Andrew Jonathan Bloom ACKNOWLEDGEMENT I wish to thank the following: My parents for their support; Dr. John Mellor and Professor Martin Fleischmann, my supervisors; Dr. Philip Parsons for his faith and encouragement; Neil Smith, Ivan Pinto, Jeff Buchannan and Neil Carlson for the proof-reading and Suzanne Salt for the typing. Financial support from The Procurement Executive, Ministry of Defence, for my maintenance grant, and NATO, for travel expenses, is gratefully acknowledged. Table of Contents Chapter 1 Introduction 1 I'l Electrochemical
  • Toxicological Profile For

    Toxicological Profile For

    RDX 107 6. POTENTIAL FOR HUMAN EXPOSURE 6.1 OVERVIEW RDX has been identified at 31 out of the 1,699 hazardous waste sites that have been proposed for inclusion on the EPA National Priorities List (NPL) (HazDat 2007). However, the number of sites evaluated for RDX is not known. The frequency of these sites can be seen in Figure 6-1. RDX is a military explosive produced by the nitrolysis of hexamine with nitric acid (Boileau et al. 2009). It is a synthetic compound and is not known to exist in nature. Effluents and emissions from ammunition plants are responsible for the release of RDX into the environment (Pennington and Brannon 2002; U.S. Army 1984a). RDX is expected to exist as a particulate in the atmosphere. When released to water, RDX is subject to photolysis (half-life of 9–13 hours). Photoproducts include formaldehyde and nitrosamines (U.S. Army 1980a). Alkaline hydrolysis can also occur (Balakrishnan et al. 2003; Heilmann et al. 1996). RDX undergoes biodegradation in water and soil under anaerobic conditions (Funk et al. 1993; Pennington and Brannon 2002; U.S. Army 1984f). Its biodegradation products include MNX; DNX; TNX; hydrazine; 1,1-dimethyl-hydrazine, 1,2-dimethyl-hydrazine; formaldehyde; and methanol (McCormick et al. 1981). RDX is mobile in soil, and can leach into groundwater (U.S. Army 1980c), and can be transported from soils or water to terrestrial and aquatic plants (Best et al. 1999; Harvey et al. 1991, 1997; Pennington and Brannon 2002; Simini and Checkai 1996). RDX has been identified in environmental samples, primarily near army munition depots (Bishop et al.
  • Explosive Weapon Effectsweapon Overview Effects

    Explosive Weapon Effectsweapon Overview Effects

    CHARACTERISATION OF EXPLOSIVE WEAPONS EXPLOSIVEEXPLOSIVE WEAPON EFFECTSWEAPON OVERVIEW EFFECTS FINAL REPORT ABOUT THE GICHD AND THE PROJECT The Geneva International Centre for Humanitarian Demining (GICHD) is an expert organisation working to reduce the impact of mines, cluster munitions and other explosive hazards, in close partnership with states, the UN and other human security actors. Based at the Maison de la paix in Geneva, the GICHD employs around 55 staff from over 15 countries with unique expertise and knowledge. Our work is made possible by core contributions, project funding and in-kind support from more than 20 governments and organisations. Motivated by its strategic goal to improve human security and equipped with subject expertise in explosive hazards, the GICHD launched a research project to characterise explosive weapons. The GICHD perceives the debate on explosive weapons in populated areas (EWIPA) as an important humanitarian issue. The aim of this research into explosive weapons characteristics and their immediate, destructive effects on humans and structures, is to help inform the ongoing discussions on EWIPA, intended to reduce harm to civilians. The intention of the research is not to discuss the moral, political or legal implications of using explosive weapon systems in populated areas, but to examine their characteristics, effects and use from a technical perspective. The research project started in January 2015 and was guided and advised by a group of 18 international experts dealing with weapons-related research and practitioners who address the implications of explosive weapons in the humanitarian, policy, advocacy and legal fields. This report and its annexes integrate the research efforts of the characterisation of explosive weapons (CEW) project in 2015-2016 and make reference to key information sources in this domain.
  • A Catalog of Instructional Films for College Chemistry, Serial Publication Number 42

    A Catalog of Instructional Films for College Chemistry, Serial Publication Number 42

    DOCUMENT RESUME ED 040 035 SE 007 910 AUTHOR Schrager Samuel; And Others TITLE A Catalog of Instructional Films for College Chemistry, Serial Publication Number 42. INSTITUTION Advisory Council on Coll. Chemistry. PUB DATE 69 NOTE 118p. EDRS PRICE EDRS Price MF-$0.50 HC-$6.00 DESCRIPTORS *Catalogs, *Chemistry, *College Science, *Instructional Films, Physical Sciences, *Resource Materials, Secondary School Science IDENTIFIERS Advisory Council on College Chemistry ABSTRACT This is a catalog of instructional films for college chemistry, designed for use by chemistry and other science teachers. The films in this catalog are listed in topical arrangement, which consists of (1) preparatory topics,(2) structure,(3) interaction of radiation with matter, (4) physical states,(5) formulas, equations and calculations,(6) dynamics,(7) thermochemistry, thermodynamics, and electrochemistry,(8) equilibria, (9) inorganic chemistry, (10) organic chemistry,(11) biochemistry, (12) laboratory techniques, (13) physics review,(14) miscellaneous, and(15) special interest. Each topic is divided into one or more sub-topics. Each film is listed alphabetically by title, and is identified further by its producer, length, film type (16mm, 8mm, Super 8), color or black/white, catalog number, and price. A brief description of the contents of each film is included. Starred films in the catalog are those which have been personally used and recommended by members of the panel who compiled this catalog. (LC) U S. DEPARTMENT OF HEALTH, EDUCATION & WELFARE OFFICE OF EDUCATION THIS DOCUMENT HAS BEEN REPRODUCED EXACTLY AS RECEIVED FROM THE i PERSON OR ORGANIZATION ORIGINATING IT POINTS OF VIEW OR OPINIONSI- I. STATED DO NOT NECESSARILY REPRESENT OFFICIAL OFFICE OF EDUCATION POSITION OR POLICY A CATALOG OF INSTRUCTIONAL FILMS FOR COLLEGE CHEMISTRY O v) Al CATALOG OF INSTRUCTIONAL FILMS (16mm, Super 8, and 8mm) FOR COLLEGE CHEMISTRY Advisory Council on College Chemistry Department of Chemistry Stanford University Stanford, California 94305 SERIAL PUBLICATION No.
  • Factors Affecting Anfo Fumes Production

    Factors Affecting Anfo Fumes Production

    FACTORS AFFECTING ANFO FUMES PRODUCTION James H. Rowland III and Richard Mainiero ABSTRACT For many years there have been small scale tests available for evaluating the toxic fumes production by cap- sensitive explosives (DOT Class 1.1), but these could not be used with blasting agents due to the large charge sizes and heavy confinement required for proper detonation. Considering the extensive use of blasting agents in construction and mining, there is a need to determine the quantities of toxic fumes generated by blasting agents. At the International Society of Explosive Engineers Twenty Third Annual Conference on Explosives and Blasting Technique in 1997, the authors reported on a facility for detonating large (4.54 kg), confined blasting agent charges in a controlled volume that had been constructed at the National Institute for Occupational Safety and Health’s Pittsburgh Research Lab’s Experimental Mine. Since 1997, this facility has been used to collect data on toxic fumes produced by the detonation of various ammonium nitrate/fuel oil (ANFO) mixtures and several cap-sensitive explosives. ANFO composition ranging from 1 to 10 percent (pct) fuel oil have been studied. As expected from previous studies, with an increase in fuel oil content the carbon monoxide production increases, while nitric oxide and nitrogen dioxide production decrease. The detonation velocity varies from 3,000 to 4,000 m/sec for the 1 to 10 pct range of fuel oil content, suggesting that ANFO mixes with improper fuel oil content may appear to detonate properly, while their fume production differs significantly from optimum. The study also considers such factors as degree of confinement, water contamination, and aluminum content on blasting agent fume production.
  • Reactions of Aromatic Compounds Just Like an Alkene, Benzene Has Clouds of  Electrons Above and Below Its Sigma Bond Framework

    Reactions of Aromatic Compounds Just Like an Alkene, Benzene Has Clouds of  Electrons Above and Below Its Sigma Bond Framework

    Reactions of Aromatic Compounds Just like an alkene, benzene has clouds of electrons above and below its sigma bond framework. Although the electrons are in a stable aromatic system, they are still available for reaction with strong electrophiles. This generates a carbocation which is resonance stabilized (but not aromatic). This cation is called a sigma complex because the electrophile is joined to the benzene ring through a new sigma bond. The sigma complex (also called an arenium ion) is not aromatic since it contains an sp3 carbon (which disrupts the required loop of p orbitals). Ch17 Reactions of Aromatic Compounds (landscape).docx Page1 The loss of aromaticity required to form the sigma complex explains the highly endothermic nature of the first step. (That is why we require strong electrophiles for reaction). The sigma complex wishes to regain its aromaticity, and it may do so by either a reversal of the first step (i.e. regenerate the starting material) or by loss of the proton on the sp3 carbon (leading to a substitution product). When a reaction proceeds this way, it is electrophilic aromatic substitution. There are a wide variety of electrophiles that can be introduced into a benzene ring in this way, and so electrophilic aromatic substitution is a very important method for the synthesis of substituted aromatic compounds. Ch17 Reactions of Aromatic Compounds (landscape).docx Page2 Bromination of Benzene Bromination follows the same general mechanism for the electrophilic aromatic substitution (EAS). Bromine itself is not electrophilic enough to react with benzene. But the addition of a strong Lewis acid (electron pair acceptor), such as FeBr3, catalyses the reaction, and leads to the substitution product.
  • Nitration of Toluene (Electrophilic Aromatic Substitution)

    Nitration of Toluene (Electrophilic Aromatic Substitution)

    Nitration of Toluene (Electrophilic Aromatic Substitution) Electrophilic aromatic substitution represents an important class of reactions in organic synthesis. In "aromatic nitration," aromatic organic compounds are nitrated via an electrophilic aromatic substitution mechanism involving the attack of the electron-rich benzene ring on the nitronium ion. The formation of a nitronium ion (the electrophile) from nitric acid and sulfuric acid is shown below. The sulfuric acid is regenerated and hence acts as a catalyst. It also absorbs water to drive the reaction forward. Figure 1: The mechanism for the formation of a nitronium ion. The methyl group of toluene makes it around 25 times more reactive than benzene in electrophilic aromatic substitution reactions. Toluene undergoes nitration to give ortho and para nitrotoluene isomers, but if heated it can give dinitrotoluene and ultimately the explosive trinitrotoluene (TNT). Figure 2: Reaction of nitric acid and sulfuric acid with toluene. Procedure: 1. Place a 5 mL conical vial, equipped with a spin vane, in a crystallizing dish filled with ice-water placed on a stirrer. 2. Pour 1.0 mL of concentrated nitric acid into the vial. While stirring, slowly add 1.0 mL of concentrated sulfuric acid. 3. After the addition of sulfuric acid is complete, add 1.0 mL of toluene dropwise and slowly over a period of 5 minutes (slow down if you see boiling. Reaction produces a lot of heat). 4. While Stirring, allow the contents of the flask to reach the room temperature. Stir at room temperature for another 5 minutes. 5. Add 10 mL of water into a small separatory funnel.
  • Toxic Fume Comparison of a Few Explosives Used in Trench Blasting

    Toxic Fume Comparison of a Few Explosives Used in Trench Blasting

    Toxic Fume Comparison of a Few Explosives Used in Trench Blasting By Marcia L. Harris, Michael J. Sapko, and Richard J. Mainiero National Institute for Occupational Safety and Health Pittsburgh Research Laboratory ABSTRACT Since 1988, there have been 17 documented incidents in the United States and Canada in which carbon monoxide (CO) is suspected to have migrated through ground strata into occupied enclosed spaces as a result of proximate trench blasting or surface mine blasting. These incidents resulted in 39 suspected or medically verified carbon monoxide poisonings and one fatality. To better understand the factors contributing to this hazard, the National Institute for Occupational Safety and Health (NIOSH) carried out studies in a 12-foot diameter sphere to identify key factors that may enhance the levels of CO associated with the detonation of several commercial trenching explosives. The gaseous detonation products from emulsions, a watergel, and ANFO blasting agents as well as gelatin dynamite, TNT, and Pentolite boosters were measured in an argon atmosphere and compared with those for the same explosives detonated in air. Test variables included explosive formulation, wrapper, aluminum addition, oxygen balance, and density. Major contributing factors to CO production, under these laboratory test conditions, are presented. The main finding is the high CO production associated with the lack of afterburning in an oxygen poor atmosphere. Fumes measurements are compared with the manufacturer’s reported IME fume class and with the Federal Relative Toxicity Standard 30 CFR Part 15 in order to gain an understanding of the relative toxicity of some explosives used in trench blasting. INTRODUCTION Toxic gases such as CO and NO are produced by the detonation of explosives.
  • Study on the Formation of Dinitramide Using Mixed Acid Nitrating Agents

    Study on the Formation of Dinitramide Using Mixed Acid Nitrating Agents

    Articles Indian Journal of Chemical Technology Vol. 9, May 2002, pp. 223-226 Study on the formation of dinitramide using mixed acid nitrating agents G Santhosh, S Venkatachalam*, M Kanakavel & K N Ninan Polymers and Special Chemicals Division, Vikram Sarabhai Space Centre, Trivandrum 695 022, India Received 9 August 2001; revised received 27 February 2002; accepted 21 March 2002 Nitration of ammonium sulphamate was carried out using a mixture of sulphuric acid and nitric acid at -30 to - 40°C. The mole ratio of sulphuric acid to nitric acid was varied from 0 to 4 and the extent of formation of ammonium dinitramide (ADN) was meas:red. The initial yield of ADN increases with increase of sulphuric acid content in the acid mixture and starts decreasing as the reaction time is increased. The variation of product yield with change in reaction time and total acid concentration was studied. There has been a lot of interest in recent years for the Experimental Procedure development of new high energy halogen-free Materials oxidizers like ammonium dinitramide(ADN), Ammonium sulphamate AR (SRL, Bombay) was hydrazinium nitroformate(HNF), hexanitrohexaaza­ powdered well in a mortar and pestle and was further isowurtzitane(CL-20), 1,3,3-trinitroazetidine (TNAZ) dried in vacuum. Conc. H S0 98% (Qualigens, Bombay) was used etc., having high density and heat of formation I. 2 4 as received. Ammonium dinitramide (ADN) is the ammonium salt Fuming HN0 > 98% was distilled in the laboratory of 1,1 ,3,3-tetraoxo-l ,2,3-triazapropene anion. 3 from a mixture of 1: 1 by weight of fuming HN0 Dinitramide salts are useful oxidizers for high energy 3 (92%) with conc.