Investigation Of The Hydrolysis Of T Butyl Chloride

This reaction is spontaneous for almost all esters but can be very slow under typical conditions of temperature and pressure. The reaction occurs at a much faster rate if there is a significant amount of base (OH-) in the solution. In this lab experiment, the rate of this reaction will be studied using an ester called para-nitrophenyl acetate (PNA), which produces an alcohol,

3) Adding less enzyme caused the reaction to proceed more slowly than when more enzyme was utilized.

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

As the substrate in increased the initial reaction rate will increase until it is fully submerged and then will not increase any more. The relationship is linear. As the substrate concentration increases, the initial reaction rate increases.

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.

A unimolecular nucleophilic substitution or SN1 is a two-step reaction that occurs with a first order reaction. The rate-limiting step, which is the first step, forms a carbocation. This would be the slowest step in the mechanism. The addition of the nucleophile speeds up the reaction and stabilizes the carbocation. This reaction is more favorable with tertiary and sometimes secondary alkyl halides under strong basic or acidic conditions with secondary or tertiary alcohols. In this experiment, the t-butyl halide underwent an SN1 reaction. Nucleophiles do not necessarily effect the reaction because the nucleophile is considered zero order, (which makes it a first order reaction.) The ion that should have the strongest effect in an SN1 reaction is the bromide ion. The bromide ion should be stronger because it has a lower electronegativity than chloride as well as a smaller radius.

SN1 reactions are considered unimolecular nucleophilic substitution mechanisms and are a first-order process. Meaning that the reaction forms a carbocation intermediate and that the concentration of the nucleophile does not play a role in the rate-determining step, which is the slowest step in the reaction. All of the SN1 reaction mechanisms in this procedure can react two different ways. The expected mechanism for these reactions would be that the carbocation would react with the weak nucleophile nitrate, attaching the nitrogen to the positively charged carbon. However, while nitrate is the intended nucleophile in all of the reactions, it is a poor nucleophile. The ethanol used in this reaction is a polar protic ionizing solvent,

The hydrogen chloride was added in this experiment is because it recombined the previously separated hydrogen back to the O- on PABA, and return the hydroxyl group

The products of the primary alcohol reaction, 1-butanol and HCl, are 1-chlorobutane and water; products of the secondary alcohol, 2-butanol and HCl are 2-chlorobutane and water; products of the tertiary alcohol, 2-methyl-2-propanol are 2-methyl-2-chloropropane and water.

Based on prior calculations, expected yield for the alkene products was 79.5%. The actual yield was not as high, resulting in a 28.4% yield. Even with this relatively small yield, the reaction still went to completion as indicated by the GC results in Figure 2. This is known because there is no presence of 2-methyl-1-butanol within the GC spectra. Only the two desired alkene products with

SN1 reactions only occur with certain reagents under very specific conditions. These reactions have an intermediate and occur in two distinct steps. The first step is the formation of the carbocation once the leaving group departs from the molecule. The type of leaving group is vital in determining if an SN1 reaction will occur. In general, the efficiency of the leaving group increases as the size of the halide ion increases.

This lab consisted of the conversion of alcohols into alkyl halides through common substitution methods. These methods include SN1 and SN2 mechanism, both of which can occur for this type of reaction. For both reactions, the first step of protonation will be to add hydrogen to the –OH group and then the rest of the reaction will proceed according to the type of mechanism. SN1 reactions form a cation intermediate once the H2O group leaves, then allowing a halide (such as Br) to attack the positively charged reagent1. On the other hand, SN2 reactions are one-step mechanism in which no intermediate is formed and the halide attaches as the leaving

The synthesis of the alkyl halide n-Butyl Bromide from alcohol is the foundation for the experiment. During the isolation of the n-butyl bromide, the crude product is washed with sulfuric acid, water, and sodium bicarbonate to remove any remaining acid or n-butyl alcohol. The primary alkyl halide halide n-butyl bromide is prepared by allowing n-butyl alcohol to react with sodium bromide and sulfuric acid. The sodium bromide reacts with sulfuric acid to produce hydrobromic acid . Excess sulfuric acid acts to shift the equilibrium and speed up the reaction by producing a higher concentration of hydrobromic acid. The

The diagram above shows the theory that the rate of reaction will continue to climb until all the active sites are being used and the rate will level off but does not stop.

As an enzyme-catalyzed reaction may be the main reason for a reaction to occur faster, many factors can