The reactivity of alcohols can be accounted for by their molecular structure – particularly by the attachment of their hydroxyl functional group. The isomers of butanol are used as examples of 1°,2° and 3° alcohols to examine this relationship. Each of the three isomers of butanol will be mixed with concentrated hydrochloric acid. The presence of an alkyl halide product is indicated by cloudiness of the mixture, as the halides are only slightly soluble in water. This test indicates that a halogenation reaction has taken place. Each alcohol is also separately mixed with dilute potassium permanganate solution, which…
An SN1 reaction is a nucleophilic substitution reaction where the rate determining step of the reaction is unimolecular, thus, the rate equation is often shown as having first-order dependence on electrophile and zero-order dependence on nucleophile. This relationship holds for situations where the amount of nucleophile is much greater than that of the carbocation intermediate. The reaction (which involves a carbocation intermediate) is commonly seen in reactions of secondary or tertiary alkyl halides under strongly basic conditions or, under strongly acidic conditions (in this case strongly acidic conditions), with secondary or tertiary alcohols. In this reaction, the alcohol will be protonated by the hydrochloric acid. H2O will then “leave” the molecule in the rate-determining step, forming a relatively stable tertiary carbocation (which is highly substituted). The chloride ion, acting as a Lewis base will donate a pair of electrons to the carbocation (acting as a Lewis acid) forming the…
In this experiment, we alkylate sodium saccharin to N-ethylsaccharin with iodoethane in an aprotic solvent N,N dimethylformamide. Nucleophiles in this experiment will react better in an aprotic solvent. Aprotic solvents have dipoles due to its polar bonds but they do not have H atoms that can be donated into a H-bond. The anions which are the O- and N- of sodium saccharin are not solvated therefore are “naked” and the reaction is not inhibited and preceded in an accelerated rate. The reaction was an SN2 reaction. Since the Oxygen and Nitrogen are more electronegative than the carbon on which they’re attached electrons are pulled towards O- and N- attracting the ethane from Iodoethane. Iodine being more electronegative breaks off from ethane and joins the Na+. Since, the Oxygen of sodium saccharin is more electronegative than the nitrogen therefore this gives oxygen a higher partial negative charge therefore an attack on Oxygen will give a product that is formed faster; this can be called a kinetic product. The transition state energy is lower than a product formation by thermodynamic control. At thermal equilibrium at 80°C a more stable product is form from a higher transitional state energy. The nucleophiles in the molecule sodium saccharin are O- and N- and the major product formed depending on which oh the nucleophile was attacked most in the reaction. Nucleophilic attack by nitrogen will yield N-ethylsaccharin and nucleophilic attach by oxygen will yield O-ethylsaccharin. “N-saccharin is more stable than O- ethylsaccharin because the Ethyl group is attached to the Nitrogen giving the same spacial configuration for the five membered ring (which is flat or planar).” (Richard y.a.). The carbonyl carbon is sp2 and flat. This has little ring strain and is stable. The first bond between carbon and oxygen in a carbonyl group is created by overlapping an sp2 hybrid orbital from carbon with an sp2 hybrid orbital from oxygen (sigma bond). The second bond…
“A nucleophile is any neutral or uncharged molecule with an unshared pair of electrons. In the substitution reaction, the nucleophile donates an electron pair to the substrate, leading to the formation of a new bond to the nucleophile, while breaking the existing bond to the leaving group” (Solomons and Fryhle 99-102). The two types of nucleophilic substitution reactions, SN1 and SN2, are identified based on whether the different steps occur simultaneously (SN1) or in two separate steps (SN2). To synthesize the t-butyl chloride, the t-butyl alcohol goes through an SN1 reaction. Also, the nature of the solvent can affect which substitution reaction will occur. Polar protic solvents typically favor SN1 reactions. This is because the SN1 mechanism is carried out in two steps and the polar protic solvent produces both a cation and an anion which are capable of stabilizing the charges on the ions formed during the reaction. Because an SN2 reaction occurs in one step, this is unfavorable; however, the SN2 reactions tend to favor polar aprotic solvents. Another factor affecting the type of substitution reaction is the nature of the leaving group. Since the SN1 reactions occur in one step,…
Introduction: The purpose of this experiment is to understand the kinetics of the hydrolysis of t-butyl chloride.The kinetic order of reaction was studied under the effects of variations in temperature, solvent polarity, and structure. It is particularly observed in tertiarhalides i.e. in SN1mechanism, Nucleophilic Substitution which is in 1storder. It is basically a reaction that involves substitution by a solvent that pretendslikea nucleophile i.e. it donates electrons. The reaction being in firstorder means the rate of the reaction depends on the concentration of only one reactant.…
Introduction: This lab experimented on the reactions of the chemicals that undergoes SN1 or SN2 reaction. Nine different compounds were given to be examined with two reagents - NaI in acetone and AgNO3 in ethanol. The SN1 reaction happens in AgNO3 in ethanol reagents, and SN2 reaction is in NaI in acetone.…
The purpose of this experiment was to compare the nucleophilicities of chloride and bromide ions toward the n-butyl and t-pentyl alcohols. We were able to analyze this by using refractometry to measure the amounts of alkyl chloride and alkyl bromide in each reaction.…
The Hydroxyl group on alcohols relates to their reactivity. This concept was explored by answering the question “Does each alcohol undergo halogenation and controlled oxidation?” . Using three isomers of butanol; the primary 1-butanol, the secondary 2-butanol and the tertiary 2-methyl-2-propanol, also referred to as T-butanol, two experiments were performed to test the capabilities of the alcohols. When mixed with hydrochloric acid in a glass test tube, the primary alcohol and secondary alcohols were expected to halogenate, however the secondary and tertiary ended up doing so. This may have been because of the orientation of the Hydroxyl group when butanol is in a different shape than 1-butanol. As hypothesised, when 1-butanol and 2-butanol samples were mixed with potassium permanganate in a test tube, signs of oxidation reactions resulted.…
The purpose of this lab was to use gas chromatography to determine the relative amounts of the three components of gas products from the dehydration reaction of 1- and 2-Butanol with sulfuric acid and the dehydrobromination reaction of 1- and 2-Bromobutane with potassium tert-butoxide.…
The reaction mixture was refluxed at 78 °C for 2 h. The mixture was filtered and washed with methanol to give white solid (sodium 6-oxidonaphthalene-2-sulfonate). 1,4-bis(bromomethyl)benzene, M5 (4.54 g, 17.2 mmol) and sodium 6-oxidonaphalene-2-sulfonate (0.84 g, 3.13 mmol) were dissolved in 30 ml of DMSO. The mixture was stirred at room temperature overnight. The mixture was poured into ice cold acetone with continuous stirring.…
In this experiment, extraction and distillation techniques were used to synthesize pure samples of n-Butyl Bromide and t-Pentyl Chloride. Our percent yield was low for both of the samples. I believe that too much of the drying agent (granular NaSO4) was used, thus causing a low yield. Although there was a low percent yield, and the samples were somewhat impure (based on boiling points), it is evident from the IR spectroscopy of both samples that the formation of the alkyl halides was successful, and the water was successfully removed from each of the samples. This is true because of the absence of any type of OH…
Background: Alcohols are capable of being converted to metal salts, alkyl halides, esters, aldehydes, ketones, and carboxylic acids. In this experiment the conversion from alcohol to alkyl halides was investigated. Alkyl halides are a group of chemical compounds derived from alkanes containing one or more halogens. They are used as flame retardants, refrigerants, propellants, solvents, and pharmaceuticals. As a group, students convert three alcohols to alkyl halides under acidic conditions and record the 13C NMR spectrum in each case. The reaction that takes place in the conversion is a bimolecular nucleophilic substitution, or SN2 reaction. Alcohols do not undergo the same SN2 reactions commonly observed with alkyl halides. There are four aspects that determine the rate of the SN2 reaction: nucleophile, substrate, solvent and the leaving group. This reaction requires a lone pair from a nucleophile to donate an electron-pair in the formation of a chemical bond; it then attacks the bonds to an electrophilic…
The overall goal of this experiment is to understand and be familiar of SN1 reactivity. We also learned how to prepare 2-Bromobutane by learning how to distill and extract this product from its organic layer. Finally, another goal was to specifically understand the relative reactivity of alkyl halides under SN1 conditions by reacting the alkyl halide and silver nitrate in ethanol.…
In this experiment, the objective is to successfully perform an SN1 reaction to determine the reactivity of tert-butyl chloride, through the usage of sodium iodide/silver nitrate reagents and to synthesize tert-butyl chloride. The tert-butyl chloride was synthesized through the use of separation (aqueous and organic layers) and distillation. Tert-butyl chloride is the alkyl halide which is being synthesized throughout the course of the experiment. Alkyl halides are derived from alkanes. Once an alkane has its original hydrogen atom replaced with a halogen, it is now considered an alkyl halide (UC 2016).…
In the first step, 2’-OH proton of the ribonuclease sugar undergoes deprotonation by the basic imidazole ring of His12. This produces a 2’-O-, which subsequently acts as a nucleophile for attack towards the phosphorus atom of the phosphate group bonded to the 3’-C end of the same ribonuclease sugar. During this process, it causes His12 to become protonated, thus causing it to become acidic. 21-22 Conversely, His119 acts as an acid to facilitate the departure of the leaving 3’-monophosphate group. This is achieved when the acidic imidazolium ion of His119 simultaneously protonate the oxygen of the phosphate oxyanion group.…