...CH3Cl. Tertiary halides are very inert to SN2 reactions because they have too much steric bulk for efficient backside attack. (d) H2C=CHCH2Br. Allylic bromides react via SN2 reactions. Vinylic ones do not as the sp2-hybridized carbon they are attached to cannot undergo backside attack efficiently. 12.40 What effect would you expect the following changes to have on the rate of the reaction of ethanol with 2-iodo-2-methylbutane? (a) The concentration of the halide is tripled. (b) The concentration of the ethanol is halved by adding diethyl ether as the inert solvent. First step is to figure out what reaction is occurring here. The starting material is a tertiary halide that is reacting with ethanol, presumably to generate the substitution product. This has to be an SN1 mechanism because the halide is tertiary. The rate of SN1 reactions is directly proportional to...
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...VERSUS SUBSTITUTION IN HALOGENOALKANES This page discusses the factors that decide whether halogenoalkanes undergo elimination reactions or nucleophilic substitution when they react with hydroxide ions from, say, sodium hydroxide or potassium hydroxide. Details for each of these types of reaction are given elsewhere, and you will find links to them from this page. The reactions Both reactions involve heating the halogenoalkane under reflux with sodium or potassium hydroxide solution. Nucleophilic substitution The hydroxide ions present are good nucleophiles, and one possibility is a replacement of the halogen atom by an -OH group to give an alcohol via a nucleophilic substitution reaction. In the example, 2-bromopropane is converted into propan-2-ol. Note: If you want to read about nucleophilic substitution in this reaction in detail, follow this link. Elimination Halogenoalkanes also undergo elimination reactions in the presence of sodium or potassium hydroxide. The 2-bromopropane has reacted to give an alkene - propene. Notice that a hydrogen atom has been removed from one of the end carbon atoms together with the bromine from the centre one. In all simple elimination reactions the things being removed are on adjacent carbon atoms, and a double bond is set up between those carbons. Note: If you want to read about elimination in this reaction in detail, follow this link. What decides whether you get substitution or elimination...
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...Competition Between Elimination and Substitution in Haloalkane 1.0 ABSTRACT The main focus of this study is to study the competition between substitution and elimination of haloalkanes. Substitution of haloalkanes This report will explain the two types of SN1 and SN2 reactions. Later, the factors which influence both SN1 and SN2 reactions will be explained and competition between the two different types of substitutions will be further elaborated to see which conditions favour each type of reactions. Next, the elimination process of haloalkanes will be discussed and similar to the substitution reaction, the elimination process is also comprised of two types, namely the E1 and E2 reactions. The factors that influence E1 and E1 reactions will be listed and competition between the two types of reactions will be discussed to see which conditions favour which type of elimination reaction. Later on, to ease the process of determining which reaction is favoured on the haloalkane, we will divide the process to see if the reaction is favoured on SN1/E1 or SN2/E2 reaction as each pairs of reactions are favoured by the same conditions. Then, the primary, secondary or tertiary structure of the haloalkane will further determine whether the major product of each reaction is a substitution product, elimination product or both. As a conclusion, the details of each reaction need to be taken into account to determine the product of the reaction of haloalkanes. Many factors are taken into...
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...Nucleophilic Substitution (SN1 Vs SN2) Nucleophilic substitution is the reaction of an electron pair donor (the nucleophile, Nu) with an electron pair acceptor (the electrophile). An sp3-hybridized electrophile must have a leaving group (X) in order for the reaction to take place. Mechanism of Nucleophilic Substitution The term SN2 means that two molecules are involved in the actual transition state: The departure of the leaving group occurs simultaneously with the backside attack by the nucleophile. The SN2 reaction thus leads to a predictable configuration of the stereocenter - it proceeds with inversion (reversal of the configuration). However, in the SN1 reaction, a planar carbocation is formed first, which then reacts further with the nucleophile. Since the nucleophile is free to attack from either side, this reaction is associated with racemization. In both reactions, the nucleophile competes with the leaving group. Because of this, one must realize what properties a leaving group should have, and what constitutes a good nucleophile. For this reason, it is worthwhile to know which factors will determine whether a reaction follows an SN1 or SN2 pathway. Very good leaving groups, such as triflate, tosylate and mesylate, stabilize an incipient negative charge. The delocalization of this charge is reflected in the fact that these ions are not considered to be nucleophilic. Hydroxide and alkoxide ions are not good leaving groups; however, they can be activated by means...
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...Alcohols and alkyl halides are similar because they both contain an electronegative element bonded to a sp3 hybridized carbon atom. However, they are also dissimilar alkyl halides has a leaving group (X-) while alcohols do not. Nucleophilic substitution with ROH as starting material would displace –OH, a strong base and therefore a poor leaving group (McMurry, 2012). Structure (Smith) The OH group must be first converted into a better leaving group for an alcohol to undergo a nucleophilic substitution or elimination. This can be done by reaction with an acid. The O atom in an alcohol will be protonated with the treatment of an alcohol with a strong acid via acid-base reaction. This transforms the –OH leaving group into H20, a weak base therefore a good leaving group (McMurry, 2012). Most alcohols are prepared industrially by hydration of alkenes. The reverse reaction canbe used in the laboratory to prepare olefins from commercially available alcohols. The reaction is believed to occur in three steps wherein all are readily reversible (Smith, 2011). Structure(manual) Acid catalyzed dehydrations usually follows Zaitsev’s rule wherein it yields the more stable alkene as the major product. The reaction is an E1 process and occurs by the three step mechanisms. Unimolecular loss of water to generate a carbocation intermediate and final loss of proton from the neighboring carbon atom happens after the protonation of the alcohol oxygen to complete the process. Tertiary alcohols...
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...day life or it may be a part of the processes living organisms undergoes. Similarly, nucleophilic addition reaction helps in the biological synthesis of compounds in metabolic processes of living organisms. The reactions also form part of the pharmaceutical preparation processes in industries and academia. The reaction helps in the formation of new complex organic chemicals. Therefore, nucleophilic addition reactions are central to organic chemistry. Read through this topic to learn more about nucleophilic addition reaction. Nucleophilic addition reactions We will be able to convert multiple bonds into different functional groups with the help of addition reactions. The reaction will help to convert the unsaturated compounds to saturated and more functional species. In this topic,...
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...1.0 ABSTRACT The main focus of this study is to study the competition between substitution and elimination of haloalkanes. Substitution of haloalkanes This report will explain the two types of SN1 and SN2 reactions. Later, the factors which influence both SN1 and SN2 reactions will be explained and competition between the two different types of substitutions will be further elaborated to see which conditions favour each type of reactions. Next, the elimination process of haloalkanes will be discussed and similar to the substitution reaction, the elimination process is also comprised of two types, namely the E1 and E2 reactions. The factors that influence E1 and E1 reactions will be listed and competition between the two types of reactions will be discussed to see which conditions favour which type of elimination reaction. Later on, to ease the process of determining which reaction is favoured on the haloalkane, we will divide the process to see if the reaction is favoured on SN1/E1 or SN2/E2 reaction as each pairs of reactions are favoured by the same conditions. Then, the primary, secondary or tertiary structure of the haloalkane will further determine whether the major product of each reaction is a substitution product, elimination product or both. As a conclusion, the details of each reaction need to be taken into account to determine the product of the reaction of haloalkanes. Many factors are taken into account, namely the leaving group, the nucleophilicity, type of...
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...SN2 vs. E2 SN2 and E2 reactions share a number of similarities. Both require good leaving groups, and both mechanisms are concerted. SN2 reactions require a good nucleophile and E2 reactions require a strong base. However, a good nucleophile is often a strong base. Since the two reactions share many of the same conditions, they often compete with each other. The outcome of the competition is determined by three factors: the presence of antiperiplanar β -hydrogens, the degree of α and β branching, and the nucleophilicity vs. basicity of the reactant species. In order for an E2 elimination to occur, there must be antiperiplanar β -hydrogens to eliminate. If there are none, the SN2 reaction will dominate. On the same token, the SN2 nucleophile needs a free path to the σ * C-LG antibond. α and β branching block this path and reduce the proportion of SN2 relative to E2 . E2 occurs even with extensive branching because it relies on the β -hydrogens, which are much more accessible than the σ * C-LG antibond. The identity of the nucleophile or base also determines which mechanism is favored. E2 reactions require strong bases. SN2 reactions require good nucleophiles. Therefore a good nucleophile that is a weak base will favor SN2 while a weak nucleophile that is a strong base will favor E2. Bulky nucleophiles have a hard time getting to the α-carbon, and thus increase the proportion of E2 to SN2. Polar, aprotic solvents increase nucleophilicity, and thus increase the rate of SN2. SN2 ...
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...Abstract: The nitration processes of methyl benzoate and recrystallization of crude product Methyl-3-nitrobenzoate were successful with the confirmation of the product’s Infrared spectrum analysis and MelTemp observation. An amount 6.566g Methyl-3-nitrobenzoate was recovered with 75.7% yield comparing to 8.66g of theoretical yield. Statement and purpose The purpose of this experiment was to nitrate methyl benzoate to generate Meta substituted Methyl-3-nitrobenzoate (C8H7NO4) Introduction Nitration of 6ml of methyl benzoate by nitronium ions which are supplied by the mixture of HNO3 and H2SO4 are typical electrophilic aromatic substitution reaction. The ester group of methyl benzoate is electron withdrawing group will deactivate the aromatic...
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...Organic Chemistry Name: Rochelle Bailey Lab #: 7 Date: March 9, 2015 Introduction: Aldehydes and ketones are two of several types of compounds that contain the carbonyl group. Reactions that occur because of the presence of the carbonyl group include nucleophilic addition reactions and base catalysed condensations. Aldehydes are also easily oxidized, which provides a convenient means to distinguish them from ketones. The carbonyl group in aldehydes and ketones is highly polarized; the carbonyl carbon bears a substantial partial positive charge and is susceptible to nucleophilic attack. Further, since it is sp2 hybridized it is relatively open to attack. Because the carbonyl contains no good leaving group, addition occurs rather than substitution. Aldehydes and ketones are polar compounds; however, the pure compounds do not undergo hydrogen bonding as the alcohols do. Thus the boiling points of aledehydes and ketones are lower than alcohols, but higher than alkanes or ethers. Low molecular weight carbonyl compounds are water soluble. Tests used to classify aldehydes and ketones Question 1 Identify the tests used to classify aldehydes and ketones. For each test identify the reagent(s) used and tell what observations/ results are expected. Write equations to show reactions (where appropriate). There are various tests that can be used to identify aldehydes and ketones. Some tests can be used to identify the carbonyl group in compounds while others can be used to distinguish...
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...electron-rich by the electropositive metal giving the carbon atom a partial negative charge (δ-), and the metal a partial positive charge (δ+). This unique charge distribution allows carbon to act as a nucleophile in chemical reactions. However, when carbon is bonded to a more electronegative atom, such as a halogen (structure 2) or to oxygen (structure 3), it acts as an electrophile in chemical reactions (Gilbert, Martin 639). Figure 1. Structure of an organometallic reagent (structure 1), an alkyl halide (structure 2), and a carbonyl compound (structure 3). * Due to the nucleophilic properties, organometallic compounds are commonly used in reactions to form new carbon-carbon bonds. Equation 1 is a general example of a reaction between an alkyl halide and an organometallic compound. Equation 2 is an example of a reaction of a carbonyl and an organometallic compound. In both reactions the nucleophilic carbon atom of the organometallic compound bonds to the electrophilic carbon of the other reagent (Gilbert, Martin 640). Equation 1 Equation 2 Grignard reagents R-MgX or Ar-MgX are prepared through the reaction of an alkyl halide (R-X) or an aryl halide (Ar-X) with magnesium metal in an anhydrous ethereal solvent (equation 3). Grignard reagents are commonly represented by R-MgX or Ar-MgX; however the...
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...Classification Tests for Hydroxyl- and Carbonyl-containing Compounds Miguel, K.D., Moron, R.S.S., Pazon, A.D., Ramirez, C.V., Raquepo, T.M.R., Razon, D.N.A.Jr. 2B-PH, Group No. 6, Department of Pharmacy, Faculty of Pharmacy, University of Santo Tomas, España Boulevard, 1015 Manila, Philippines Abstract In organic chemistry it is very common to see molecules comprised mainly of a carbon backbone with functional groups attached to the chain. The functional group gives the molecule its properties, regardless of what molecule contains it.[1] Examples of functional groups are that of hydroxyl (-OH) which is usually seen in alcohols, and carbonyl (C=0) which is seen in aldehydes and ketones. In this experiment, several tests were conducted to distinguish and differentiate various sample compounds such as ethanol, n-butyl alcohol, sec-butyl alcohol, tert-butyl alcohol, benzyl alcohol, n-butyraldehyde, benzaldehyde, acetone, acetophenone, isopropyl alcohol, and acetaldehyde. The tests are the following: solubility test of alcohols in water, which gave a soluble result in ethanol, sec-butyl alcohol and tert-butyl alcohol. Next is the Lucas test, which is used to differentiate 1°, 2° & 3° alcohols. In Lucas test, tert-butyl alcohol gave an immediate turbid result; the rate of reaction was noted. Chromic Acid test (Jones Oxidation) which gave a positive result by producing a blue-green solution with the sample n-butyl alcohol, acetaldehyde, benzaldehyde, and isopropyl alcohol. 2...
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...CH 220C ORGANIC CHEMISTRY LABORATORY Spring, 2015 Section Page 1. General Information 2 2. Safety Information 2 3. Attendance 3 Make-Up Policy 3 4. Laboratory Protocol 3 Assigned Reading 3 Pre-Lab Quizzes 3 Lab Notebook 5 Chemicals 5 Due Dates for Reports 5 5. Orientation 5 In-Lab Information 5 Library Information 5 6. Check-In 6 7. Grading Procedure 6 8. Policy on Cheating 7 9. TA Office Hours 8 10. Faculty Course CoordinatorS 8 11. Course Web Page 8 12. Hints to Minimize Frustration IN ORGANIC CHEMISTRY 8 13. Work Schedule 10 Lab Report Due Date Schedule 10 Experiments 10 14. Supplements 17 A. Extraction of Unknown 17 B. Recrystallization of Unknown Products 18 C. Methyl Benzoate 19 D. Synthesis of Luminol 20 E. Azo Violet 23 1. GENERAL INFORMATION PRE- and CO-REQUISITES Pre- and co-requisites for CH 220C listed in the Course Schedule. Important: Because the lecture and laboratory courses are co-requisites of each other, dropping one of them requires that you drop the other as well, unless the drop occurs during ...
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...Review Paper Inulin - a versatile polysaccharide with multiple pharmaceutical and food chemical uses. Thomas Barclaya, Milena Ginic-Markovica, Peter Cooperb,c, Nikolai Petrovskyc,d a Flinders University, Adelaide, Australia 5042 Cancer Research Laboratory, ANU Medical School at the Canberra Hospital, Australian National University, Canberra, Australia 2605 c Vaxine Pty Ltd, Flinders Medical Centre, Adelaide Australia 5042 d Department of Endocrinology, Flinders Medical Centre, Adelaide, Australia 5042 b Received: 27 August 2010 Accepted: 10 October 2010 ABSTRACT á-D-glucopyranosyl-[â-D-fructofuranosyl](n-1)-D-fructofuranoside, commonly referred to as inulin, is a natural plant-derived polysaccharide with a diverse range of food and pharmaceutical applications. It is used by the food industry as a soluble dietary fibre and fat or sugar replacement, and in the pharmaceutical industry as a stabiliser and excipient. It can also be used as a precursor in the synthesis of a wide range of compounds. New uses for inulin are constantly being discovered, with recent research into its use for slow-release drug delivery. Inulin, when in a particulate form, possesses anti-cancer and immune enhancing properties. Given its increasing importance to industry, this review explains how inulin's unique physico-chemical properties bestow it with many useful pharmaceutical applications. KEY WORDS: Inulin, polysaccharide, fructose, excipient, vaccine, adjuvant INTRODUCTION ...
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...2014-2015 Undergraduate Academic Calendar and Course Catalogue Published June 2014 The information contained within this document was accurate at the time of publication indicated above and is subject to change. Please consult your faculty or the Registrar’s office if you require clarification regarding the contents of this document. Note: Program map information located in the faculty sections of this document are relevant to students beginning their studies in 2014-2015, students commencing their UOIT studies during a different academic year should consult their faculty to ensure they are following the correct program map. i Message from President Tim McTiernan I am delighted to welcome you to the University of Ontario Institute of Technology (UOIT), one of Canada’s most modern and dynamic university communities. We are a university that lives by three words: challenge, innovate and connect. You have chosen a university known for how it helps students meet the challenges of the future. We have created a leading-edge, technology-enriched learning environment. We have invested in state-of-the-art research and teaching facilities. We have developed industry-ready programs that align with the university’s visionary research portfolio. UOIT is known for its innovative approaches to learning. In many cases, our undergraduate and graduate students are working alongside their professors on research projects and gaining valuable hands-on learning, which we believe is integral...
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