Table 1 provides the results from this experiment by showing which halides did react with the 1% ethanolic silver nitrate solution and which ones did not react. Through the evaluation of the precipitate, 2-chloro-2-methylpropane reacted instantly with the silver nitrate solution. This reaction occurred instantaneously due to the fact that SN1 reactions favor steric hindrance and the leaving group, chlorine, was a tertiary substrate. On the other hand, the two substrates that had secondary leaving groups were 2-chlorobutane and 2-bromobutane. When 2-bromobutane was mixed with the 1% ethanolic silver nitrate solution, the precipitate that was formed, progressively became cloudier after heating and cooling in a water bath. Although 2-chlorobutane was expected to react, the halide did not show any precipitate before or after heating and cooling. This alkyl halide did not react due to the fact that the leaving group is chlorine, which does not have a strong attraction to the silver nitrate solution. The …show more content…
two substrates with primary leaving groups were 1-chlorobutane and 1-bromobutane. Bromine and silver have a very high attraction to each other, causing 1-bromobutane to react with the silver nitrate solution. The precipitate that formed from this reaction was dense and became more predominant after heating and cooling. On the contrary, 1-chlorobutane did not form a precipitate after being mixed with the silver nitrate solution. A precipitate did not form because chlorine is not as good of a leaving group as bromine and the leaving group was primary, which is not favored in SN1 reactions. The expected reactivity of the alkyl halides was 2-chloro-2-methylpropane, 2-bromobutane, 2-chlorobutane, 1-bromobutane, and 1-chlorobutane. This expected reactivity order was not seen in the results due to the fact that 2-chlorobutane did not provide a precipitate. This order of reactivity was expected due to the substrate steric hindrance and whether the leaving group was tertiary, secondary, or primary. The solvent used in this experiment, 1% ethanolic silver nitrate, is a polar protic solvent. SN1 reactions favor polar protic solvents due to the fact that ionization is favored. The first step in the SN1 reactions is ionization, which is also the rate-determining step. This occurs because the leaving group leaves the alkyl halide, taking its electrons with it, and forms a carbocation. The carbocation is attacked by the nucleophile, resulting in a chemical reaction. During this experiment, one error that occurred was using silver nitrate to classify the alkyl halides according to their reactivity.
The reason why using silver nitrate is discouraged is because silver has a strong attraction to bromine, resulting in a harshly formed complex. According to Le Chatelier’s Principle, this complex shifts the chemical equilibrium due to the formation of a salt precipitate. In order to improve this experiment, a different nucleophile, such as copper sulfate, could have been used in order to prevent the silver and bromine complex from forming. Instead of silver, lead is also a good alternative to act as a catalyst. Another improvement for this experiment, is to leave the solutions in reaction conditions for a longer period of time to form a precipitate. Another procedure that could have been used to improve this experiment is to use a different leaving group, rather than bromine or chlorine. Tosylate is an excellent alternative leaving
group. According to Professor Delmar Larson, an epoxide hydrolase reaction undergoes a nucleophilic substitution reaction that is specific to SN1. On “ChemWiki”, he states that epoxide hydrolases, the enzymes used to catalyze the hydrolytic ring-opening of epoxides, have been isolated from various food-providing plants. For example, the epoxide hydrolases from soybeans have the ability to catalyze the hydrolysis of an epoxide derivative of a common fatty acid. This common fatty acid is known as stearate. The enzymes active site determines how the epoxide is attacked and how it opens. This example explains how SN1 reactions are used in a biological setting.
The goal of this experiment is to determine which products are formed from elimination reactions that occur in the dehydration of an alcohol under acidic and basic conditions. The process utilized is the acid-catalyzed dehydration of a secondary and primary alcohol, 1-butanol and 2-butanol, and the base-induced dehydrobromination of a secondary and primary bromide, 1-bromobutane and 2-bromobutane. The different products formed form each of these reactions will be analyzed using gas chromatography, which helps understand stereochemistry and regioselectivity of each product formed.
In a small reaction tube, the tetraphenylcyclopentadienone (0.110 g, 0.28 mmol) was added into the dimethyl acetylene dicarboxylate (0.1 mL) and nitrobenzene (1 mL) along with a boiling stick. The color of the mixed solution was purple. The solution was then heated to reflux until it turned into a tan color. After the color change has occurred, ethanol (3 mL) was stirred into the small reaction tube. After that, the small reaction tube was placed in an ice bath until the solid was formed at the bottom of the tube. Then, the solution with the precipitate was filtered through vacuum filtration and washed with ethanol. The precipitate then was dried and weighed. The final product was dimethyl tertraphenylpthalate (0.086 g, 0.172mmol, 61.42%).
The unknown bacterium that was handed out by the professor labeled “E19” was an irregular and raised shaped bacteria with a smooth texture and it had a white creamy color. The slant growth pattern was filiform and there was a turbid growth in the broth. After all the tests were complete and the results were compared the unknown bacterium was defined as Shigella sonnei. The results that narrowed it down the most were the gram stain, the lactose fermentation test, the citrate utilization test and the indole test. The results for each of the tests performed are listed in Table 1.1 below.
The goal of this two week lab was to examine the stereochemistry of the oxidation-reduction interconversion of 4-tert-butylcyclohexanol and 4-tert-butylcyclohexanone. The purpose of first week was to explore the oxidation of an alcohol to a ketone and see how the reduction of the ketone will affect the stereoselectivity. The purpose of first week is to oxidize the alcohol, 4-tert-butylcyclohexanol, to ketone just so that it can be reduced back into the alcohol to see how OH will react. The purpose of second week was to reduce 4-tert-butylcyclohexanol from first week and determine the effect of the product's diastereoselectivity by performing reduction procedures using sodium borohydride The chemicals for this lab are sodium hypochlorite, 4-tert-butylcyclohexanone
The isomerization procedure was done in order to create dimethyl fumarate from dimethyl maleate. Dimethyl maleate and dimethyl fumarate are cis and trans isomers, respectively. This procedure was done via a free radical mechanism using bromine. The analysis of carvones reaction was done in order to identify the smell and optical rotation of the carvone samples that were provided. The odor was determined by smelling the compound and the optical rotation was determined using a polarimeter.
Alcohol, which is the nucleophile, attacks the acid, H2SO4, which is the catalyst, forming oxonium. However, the oxonium leaves due to the positive charge on oxygen, which makes it unstable. A stable secondary carbocation is formed. The electrons from the conjugate base attack the proton, henceforth, forming an alkene. Through this attack, the regeneration of the catalyst is formed with the product, 4-methylcyclohexene, before it oxidizes with KMnO4. In simpler terms, protonation of oxygen and the elimination of H+ with formation of alkene occurs.
Discussion and Conclusions: Interpreting these results have concluded that relative reactivity of these three anilines in order of most reactive to least reactive go; Aniline > Anisole > Acetanilide. Aniline, has an NH2 , the most active substituent , and adds to any ortho/para position available on the ring. This data is confirmed with the product obtained, (2,4,6 tribromoaniline, mp of 108-110 C). As for anisole, it has a strongly activating group attached, OMe an alkoxy group, and it added in two of the three available spots, both ortho. The results conclude: (2,4-Dibromoanisol mp 55-58 C ). Acetanilide has a strong activating group attached, acylamino group, but this group is large and the ortho positions are somewhat hindered so the majority of the product obtained added at the para position, results conclude: (p-bromoacetanilide mp 160-165 C). Since all the substituents attached to the aromatic rings were activators the only products able to be obtained were ortho/para products.
Triphenylmethyl Bromide. A 400 mL beaker was filled with hot water from the tap. Acetic acid (4 mL) and solid triphenylmethanol (0.199 g, 0.764 mmol) were added to a reaction tube, with 33% hydrobromic acid solution (0.6 mL) being added dropwise via syringe. The compound in the tube then took on a light yellow color. The tube was then placed in the beaker and heated for 5 minutes. After the allotted time, the tube was removed from the hot water bath and allowed to cool to room temperature. In the meantime, an ice bath was made utilizing the 600 mL plastic beaker, which the tube was then placed in for 10 minutes. The compound was then vacuum filtered with the crystals rinsed with water and a small amount of hexane. The crude product was then weighed and recrystallized with hexane to form fine white crystals, which was triphenylmethyl bromide (0.105 g, 0.325 mmol, 42.5%). A Beilstein test was conducted, and the crystals produced a green to greenish-blue flame.
This experiment was divided into two main steps. The first step was the addition of bromine to trans-stilbene. Trans-stilbene was weighted out 2.00g, 0.0111mol and mixed with 40ml of glacial acetic acid in 100ml Erlenmeyer flask on a hot bath. Pyridinium hydrobromide perbromide of 4.00g, 0.0125mol was added carefully into the flask.
barbier reaction: In a 50 mL round bottom flask that had a reflux condenser attachment, saturated ammonium chloride (5 mL), THF (1 mL), zinc powder (0.4 g), benzaldehyde (0.500 mL, 0.5225 g, 4.92 mmol), and allyl bromide (0.470 mL, 0.6533 g, 5.40 mmol) were charged with stir bar and stirred at room temperature for 45 minutes. Diethyl ether (10 mL) was added to the reaction mixture and stirred. The mixture was gravity filtered into a beaker that was topped with a watchglass. The filtrate was transferred to a separatory funnel and the organic layer was extracted with deionized water (10 mL) and diethyl ether (15 mL). The organic layer was placed into an Erlenmeyer flask and the aqueous layer was placed into a beaker, which was extracted with
Benzyl bromide, an unknown nucleophile and sodium hydroxide was synthesized to form a benzyl ether product. This product was purified and analyzed to find the unknown in the compound.
Purpose/Introduction: In this experiment, four elimination reactions were compared and contrasted under acidic (H2SO4) and basic (KOC(CO3)3) conditions. Acid-catalyzed dehydration was done on 2-butanol and 1-butanol; a 2o and 1o alcohol, respectively. The base-induced dehydrobromination was performed on 2-bromobutane and 1-bromobutane isomeric halides. The stereochemistry and regiochemistry of the four reactions were analyzed by gas chromatography (GC) to determine product distribution (assuming that the amount of each product in the gas mixture is proportional to the area under its complementary GC peak).
In this lab we had to figure out what our mystery compound was by performing two tests. One of the tests was called the Flame Test, which we use to find out the metal element in the compound. It is used to find the metal because each metal gives off its own unique flame color. The other test is called the Precipitate Test, which we use to find out the non-metal element in our compound by adding silver nitrate to it. It’s used to find the non-metal because each non-metal has its own unique reaction to silver nitrate.
Michael P. Broadribb, C. (2006). Institution of Chemical Engineers . Retrieved July 26, 2010, from IChemE: http://cms.icheme.org/mainwebsite/resources/document/lpb192pg003.pdf
Tollen's reagent (Ammoniacal AgNO3) 4. Benedict's solution 5. Iodine solution 6. Chloroform (CHCl3) 7.