Alkyl Halides

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.

The Diels-Alder reaction was discovered and named after the Nobel Prize winning scientists Kurt Alder and Otto Diels in 1928. Such a reaction occurs when a diene with two adjacent double bonds is mixed with a dienophile consisting of a double bond in order to create a cyclohexene. The diene must be in the s-cis conformation in order for the electron transfer to engage correctly. If the diene in question is in s-trans conformation then the access to the molecules is limited, thus, no reaction can occur. The dienophile we used was maleic anhydride. Maleic anhydride possesses high electron withdrawing characteristics which caused a very quick reaction. The reaction will

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

6. Purpose: to clarify the mechanism for the cycloaddition reaction between benzonitrile oxide and an alkene, and to test the regiochemistry of the reaction between benzonitrile oxide and styrene; to purify the crude product of either trans-stilbene, cis-stilbene, or styrene reaction.

Many reactions that exist in nature involve a double displacement between ions and reactants with solvents. A bimolecular nucleophilic substitution, or SN2 reaction, involves a nucleophilic attack on a substrate and the departure of a leaving group. A nucleophile is a compound or ion that donates electrons to promote bond formation (Caldwell, 1984). In order for a leaving group in a compound to leave, it must possess the characteristics of a weak base and be able to occupy electrons. Several factors affect the rate and favorability of such reaction, such as (Bateman, 1940). In addition, the substrate that is attacked by the nucleophile is commonly an unhindered primary substrate to allow the reaction to occur quicker. An SN2 reaction follows the second-order rate law.

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.

Aromatic compounds can undergo electrophilic substitution reactions. In these reactions, the aromatic ring acts as a nucleophile (an electron pair donor) and reacts with an electrophilic reagent (an electron pair acceptor) resulting in the replacement of a hydrogen on the aromatic ring with the electrophile. Due to the fact that the conjugated 6π-electron system of the aromatic ring is so stable, the carbocation intermediate loses a proton to sustain the aromatic ring rather than reacting with a nucleophile. Ring substituents strongly influence the rate and position of electrophilic attack. Electron-donating groups on the benzene ring speed up the substitution process by stabilizing the carbocation intermediate. Electron-withdrawing groups, however, slow down the aromatic substitution because formation of the carbocation intermediate is more difficult. The electron-withdrawing group withdraws electron density from a species that is already positively charged making it very electron deficient. Therefore, electron-donating groups are considered to be “activating” and electron-withdrawing groups are “deactivating”. Activating substituents direct incoming groups to either the “ortho” or “para” positions. Deactivating substituents, with the exception of the halogens, direct incoming groups to the “meta” position. The experiment described above was an example of a specific electrophilic aromatic

Anti-Markovnikov’s rule expresses the opposite. In an anti-Markovnikov reaction, the halide group attaches at the less substituted carbon, while the hydrogen attaches at the more substituted carbon. The term “less substituted carbon” refers to the carbon with the most surrounding hydrogens, and the term “more substituted carbon” refers to the carbon with the least surrounding hydrogens. The objective of the experiment was to determine which mechanism was used to create the product of either 1-hexanol or 2-hexanol after hydration of

During the halogenation reactions of 1-butanol, 2-butanol, and 2-methyl-2-propanol, there is a formation of water from the OH atom of the alcohol, and the H atom from the HCl solution. The OH bond of the alcohol is then substituted with the Cl atom. Therefore all of the degrees of alcohol undergo halogenation reactions, and form alkyl halides as products. This is because the functional group of alkyl halides is a carbon-halogen bond. A common halogen is chlorine, as used in this experiment.

Objective: The objective of this lab is to observe the synthesis of 1-bromobutane in an SN2 reaction, to see how a primary alky halide reacts with an alcohol.

2nd step involves the carbocation intermediate being attacked by water that acts as a nucleophile to form protonated alcohol intermediate. This is the fast step and does not determine rate of reaction.

The scientific aim of this experiment was to determine which reagents sped up and slowed down the time it took for the reaction to occur.  In addition, an aim was to observe how temperature affects the reaction time, and to be

One way scientist gets alkyl halides is by using the manipulation of an alcohol. When alcohols are treated with HBr or HCl; they can undergo a nucleophile substation reaction to generate an alkyl halide and water2. Using the structure of the alcohols they are able to use SN1 or SN2 mechanisms. For both these mechanisms though, the –OH group must be pronated shown in Figure 1.

A substitution is when two separate reactants exchange parts in a chemical reaction. Predicting how a particular reaction might occur is useful in many aspects, such as determining how a new compound might react under certain external conditions. In the substitution of an alkyl halide, the reaction can proceed through three options: bimolecular nucleophilic substitution (SN2), unimolecular nucleophilic substitution (SN1), or a mixture of the both SN1 and SN2. The type of reaction that occurs depends on four main factors, which include the nucleophile, the electrophile, also called the alkyl halide substrate, the leaving group, and the solvent.

In the first reaction using NaI in acetone, we could compare the rate of reaction of two substrates, 1-bromobutane and 2-bromo-2-methylpropane. 1-bromobutane has a partial positive carbon atom attached to a partial negative bromide. This partial positively charged carbon is classified as primary alkyl halide. As the nucleophile I- in NaI approached the partial positively charged carbon, it induced the bromide to leave the substrate . An unstable primary carbocation is formed, which has a higher energy and is highly favorable to undergo a reaction. The negative iodine charge was attracted to the primary carbocation in the substrate. This nucleophilic reaction is a type of SN2 reaction, given the participation of the substrate and the nucleophile in ionizing the halogenoalkane. The rate of reaction of 1-bromobutane was 9.091E-5 M/s whereas the rate of reaction of 2-bromo-2-methylpropane was around 3.367E-05 M/s. 2-bromo-2-methylpropane is a tertiary alkyl halide and shows steric hindrance. In this case, for a nucleophile, it was impossible to get at the partial positively charged carbon, given the obstruction of the methyl groups and the bromide. The halogenoalkane will ionize slowly and that is why the rate of the reaction took a longer time, around 297 seconds. As soon as the bromide is repelled from the substrate, the nucleophile rapidly