Experiment 5 : The Bomination Of An Alkene

Two forms of stereochemistry can form product for the bromination of trans-cinnamic acid. Cis addition, also known as syn addition, is one way of forming product. This form of stereochemistry allows for the components of the reagent to add to the same side of the double bond. Trans, also known as anti addition, is the second form of addition that can create product for this experiment. Tran stereochemistry occurs when the components of the reagent add to opposite sides of the double bond. In this experiment, the formation of either erythro-2,3-dibromo-3-phenylpropanoic acid (trans/anti-R,S or S,R) or threo-2,3-dibromo-3-phenylpropanoic acid (cis/syn-R,R or S,S) was expected to occur.

Discussion: In the synthesis of 1-bromobutane alcohol is a poor leaving group; this problem is fixed by converting the OH group into H2O, which is a better leaving group. Depending on the structure of the alcohol it may undergo SN1 or SN2. Primary alky halides undergo SN2 reactions. 1- bromobutane is a primary alkyl halide, and may be synthesized by the acid-mediated reaction of a 1-butonaol with a bromide ion as a nucleophile. The proposed mechanism involves the initial formation of HBr in situ, the protonation of the alcohol by HBr, and the nucleophilic displacement by Br- to give the 1-bromobutane. In the reaction once the salts are dissolved and the mixture is gently heated with a reflux a noticeable reaction occurs with the development of two layers. When the distillation was clear the head temperature was around 115oC because the increased boiling point is caused by co-distillation of sulfuric acid and hydrobromic acid with water. When transferring allof the crude 1-bromobutane without the drying agent,

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.

In the formation of stilbene dibromide, there are three possible products. The first is meso-stilbene dibromide in which the bromines are on opposite sides of the former double bond. The other two products, d-stilbene dibromide and L-stilbene dibromide, are enantiomers with the two bromines on the same side of the former double bond. As enantiomers, d-stilbene dibromide and L-stilbene dibromide are non-superimposable mirror images of each other. Meso-stilbene dibromide makes up 90% of the yield of this reaction, while d-stilbene dibromide and L-stilbene dibromide make up only 10%.

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.

1. 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.

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.

For this test, it was broken into three separate examinations. The investigations contained: dehydrohalogenation, bromination and corrosive catalyzed hydration. All together for these responses to happen, they need to respond with alkenes. Alkenes are natural exacerbates that have a carbon-carbon twofold bond as the useful gathering for that compound. The best approach to get a carbon-carbon twofold out of an atom if isn't as of now display is the utilization of alkyl halides and alcohols. The response between an alkyl halide and a liquor that delivers a carbon-carbon P bond is called a disposal response.

On the other hand, the heating assists the reflux process by lowering the activation energy therefore heating triggers a catalyst increasing the reaction rate. In the reflux process, the 1-hexene pronates and forms a carbocation. This carbocation occurs due to the electrons from the pi bond of the carbons approaching the hydrogen electrons in HBr. After this, the reflux reaction is completed by the electrons of bromine approaching the carbocation resulting in the product of 2-bromohexane. After the reflux process, the solution is cooled to room temperature then add both 7mL of water and 7mL petroleum ether in order to separate the solution into organic and aqueous layers based on their differing solubilities and densities. In this addition, the tetrabutylammonium bromide enables the amount of addition to increase by enabling the HBr to be more reactive. After removing the aqueous layer, add sodium bicarbonate to further separate the organic layer into aqueous and organic. Then add anhydrous sodium sulfate until the solution is clear or the bottom of the flask is

The first purpose of the lab was to prepare an unknown organomagnesium bromide, an organometallic reagent, reacting an unknown aryl bromide with magnesium in anhydrous ether. The unknown was chosen from a predetermined list of benzoic acid derivatives with varying molecular weights and melting points (see Supplement C). The second purpose of this lab was to prepare an unknown carboxylic acid by reacting the unknown aryl-magnesium bromide with carbon dioxide and diethyl ether then protonating.The third purpose of this lab was to determine the neutralization equivalence point of the unknown carboxylic acid by titrating with sodium hydroxide. The fourth purpose of this lab was to ascertain the identity of the unknown carboxylic acid, and thus the original unknown aryl bromide, using its molecular weight determined from neutralization and melting point.

Bromide molecule from pyridinium tribromide was attacked by pi bond creating a positive charge on the bromide. To stabilize the structure, the negative bromide was introduced via frontside attack and made an syn product.

The purpose of this lab is to understand the process of eliminating an alkyl halide to form an alkene. The experiment is carried out by first converting the alcohol, 2-methy-2-butanol, into the alkyl halide of 2-chloro-2-methylbutane that will then be put through dehydrohalogenation that favors elimination reaction (E2) to create a mixture of 2-methyl-2-butene and 2-methyl-1-butene. A fractional distillation will be taken to purify the mixture and an additional gas chromatography will be done to further analyze the mixture composition. A bromide test will be done to determine the product of an alkene in the experiment.

The Bromide Test and permanganate test were performed with cyclohexane and cyclohexene, to further understand how these tests work. Both test were positive for the cyclohexene and negative for the cyclohexane. These test were positive for the Cyclohexene because of the Double bond present. This double bond, which is present in limonene and eugenol as well, reacts with the bromine and permanganate to produce a new compound. The production of the new compound id confirmed by the fading of the brown color of bromide and the change from purple to brown of the permanganate. These test did not work for the cyclohexane because no double bond was present. The lack of the double bond means that the reaction had not place to occur and therefor did not. These standards help in the understanding of what the outcomes of Eugenol and Limonene should be. Since these outcomes were reasonable and both compounds were purified, this lab was

I this experiment, it was concluded that the time in which it took the substrates to react by indication of a cloudy color in the the Sn1 reactions and a yellow color in the Sn2 reactions, was a direct result of reactivity of the alkyl halides in this

When dealing with alkyl halides it is important to note that the carbons attached to the halogens and the carbons attached to those carbons are involved in the reaction process, therefore we designate these carbons with special symbols to differentiate them from the rest of the molecule. The carbon atom that is bonded to the halogen is designated the α (alpha) carbon. The carbons that are