Sn1 Reaction Lab Report

Theory: One of the methods of preparing alkyl halides is via the nucleophilic substitution reactions of alcohols. Alcohols are inexpensive materials and easy to maintain. However, they are a poor leaving group the OH group is a problem in nucleophilic substitution, this problem is fixed by converting the alcohol into H2O.

The objective of this laboratory experiment is to study both SN1 and SN2 reactions. The first part of the lab focuses on synthesizing 1-bromobutane from 1-butanol by using an SN2 mechanism. The obtained product will then be analyzed using infrared spectroscopy and refractive index. The second part of the lab concentrates on how different factors influence the rate of SN1 reactions. The factors that will be examined are the leaving group, Br – versus Cl-; the structure of the alkyl group, 3◦ versus 2◦; and the polarity of the solvent, 40 percent 2-propanol versus 60 percent 2-propanol.

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

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

This supports our hypothesis that the amplitude being adjusted doesn't effect the rate at which it swings. Now we move on to our question: Would mass be a factor? The first bob was replaced with something much smaller in weight. We returned the displacement back to 10 cms while keeping the length the same. We recorded the 10 periods and the average seems to be around the same approximate rate of 2.01. This debunks the theory of the pendulum being dependent on mass. Changing both the displacement and weight seems to not affect the rate in anyway.

Using SN1 reaction mechanism with hydrochloric acid, t-Pentyl alcohol was converted to t-Pentyl chloride in an acid catalyzed reaction. The reaction took place in a separatory funnel designed to separate immiscible liquids. The crude product was extracted by transferring a solute from one solvent to another. The process of washing the solutions by phase transfer was used in order to remove impurities from the main solvent layer. Finally, the crude product was dried with anhydrous Calcium chloride and purified once more by simple distillation technique.

The solvolysis of t-butyl bromide is an SN1 reaction, or a first order nucleophilic substitution reaction. An SN1 reaction involves a nucleophilic attack on an electrophilic substrate. The reaction is SN1 because there is steric obstruction on the electrophile, bromine is a good leaving group due to its large size and low electronegativity, a stable tertiary carbocation is formed, and a weak nucleophile is formed. Since a strong acid, HBr, is formed as a byproduct of this reaction, SN1 dominates over E1. The first step in an SN1 reaction is the formation of a highly reactive carbocation, in which a leaving group is ejected. The ionization to form a carbocation is the rate limiting step of an SN1 reaction, as it is highly endothermic and has a large activation energy. The subsequent nucleophilic attack by solvent and deprotonation is fast and does not contribute to the rate law for the reaction. The Hammond Postulate predicts that the transition state for any process is most similar to the higher energy species, and is more affected by changes to the free energy of the higher energy species. Thus, the reaction rate for the solvolysis of t-butyl bromide is unimolecular and entirely dependent on the initial concentration of t-butyl bromide.

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The solution that was performed in this experiment was to use sulfuric acid in order to form a protonated alcohol, so when the halogen or nucleophile back attacks the compound, water is displaced. Once the alcohol is protonated, the solution reacts in either an SN1 or SN2 mechanism.

For the first part of this experiment, six dry test tubes were obtained and labeled accordingly to test the following halides: 2-chlorobutane, 2-bromobutane, 1-chlorobutane, 1-bromobutane, 2-chloro-2-methylpropane, and bromobenzene. To each of the six test tubes 2ml of 15% sodium iodide in acetone was added. 4 drops of the appropriate halide was added to the test tube labeled for that specific halide. After adding the halide, the test tube was then shaken to mix thoroughly. If a precipitate formed the time it took was recorded. Since none of the solutions formed a precipitate at room temperature after five minutes, the test tubes were placed inside of a hot bath at about 50°C. After one minute, the test tubes were taken out of the hot bath and allowed to cool. If any test tubes formed a precipitate, the time it took was recorded on a table.

The purposes of this experiment were to model a bimolecular nucleophilic substitution reaction between potassium hydroxide (KOH) with 1-bromopropane and determine whether it follows a second-order rate law mechanism. A rate constant of 0.0684 M-1 min-1 was obtained for this reaction at 45.1°C, which was determined through equilibrating the reaction and performing titrations of 0.390 M KOH with 0.1000 M hydrochloric acid (HCl). The activation energy calculated from class data was 50.188 kJ/mol, which deviated largely from the literature range value of 72.80–83.76 kJ/mol. It was concluded that the reaction was consistent with the predicted SN2 mechanism, based on the regression of a trendline.

The reaction took place in a conical vial and .2mL of each of the reactant samples were added to it along with some 95% ethanol. Two drops of NaOH were added shortly after and stirred at room temperature for fifteen minutes. The vial was cooled in and ice bath and crystallized. Vacuum filtration was performed to filter the crude product. The crude product was recrystallized using methanol and filtered again. We made one change to the procedure and instead of using .7mL of ethanol we

Adding 3μl of 20mM ATP solution to the reaction mixture started the reactions. Control reactions were carried

The bromide ion is the better nucleophile than the chloride ion because of its larger size and since it is a weaker base. The chloride ion is more electronegative than bromide ion, so it tends to hold electrons in closerE. Since the bromide ion is less electronegative and has more electrons, it is able to share unpaired electrons easier than the chloride ion. In the case of this laboratory experiment, bromide was the better nucleophile in the protic solvent containing hydrogen bonded to oxygen of 1-butanol and 2-methyl-2-butanol as the protic solvent molecules formed strong ion-dipole interactions with the negative-charged nucleophile of the bromide ion, which created a solvent barrier around the nucleophileG. For the electrophile to be attacked

Mechanism: Key features of the Fischer Esterification mechanism are: a. protonation of the carbonyl group, b. the