Analyzing the Products of Substitution Reactions with Alcoholic Compounds
Adam Schroeder, Jessica Vecera, Brandon Guth
Department of Chemistry and Chemical Biology, IUPUI, 402 N. Blackford St., Indianapolis, IN 46202
Three different substitution reactions were completed using different alcoholic compounds. Substitution reactions can either be Sn1 or Sn2 depending on the reactive properties of the reactants and catalysts. The reactive properties are also dependent upon the shape and whether the substitution happens on a primary, secondary, or tertiary carbon. Reaction 1 proceeded via an Sn2 mechanism, reaction 3 proceeded via an Sn1 mechanism and reaction 2 is assumed to be Sn2 based upon the data received. The products (1), (2),
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There are Sn1 and Sn2 substitution reactions. Sn1 reactions are unimolecular nucleophilic substitution reactions that are of the first order, whereas Sn2 reactions are bimolecular nucleophilic substitution of the second order.1 Molecules that contribute to a substitution reaction are called an ‘electrophile’ which contains the ‘leaving group’ which is the substituted group. It also contains a …show more content…
The tertiary product forms as a result of a hydride shift in order to form a more stable carbocation whereas the secondary (minor) product forms as a result of a direct substitution. The reaction was done via a hot water bath at approximately 55 degrees Celsius in order to overcome some of the activation energy requirements. The analysis of Infrared spectroscopy data showed that there was still a slight amount of alcohol left in the product therefore highlighting that this reaction did not go to completion. This could have been because of an excess of lucas
As a final point, the unknown secondary alcohol α-methyl-2-naphthalenemethanol had the R-configuration since it reacted the fastest with S-HBTM and much slower with R-HBTM. TLC was a qualitative method and ImageJ served as a quantitative method for determining which reaction was the faster esterification. Finally, 1H NMR assisted in identifying the unknown from a finite list of possible alcohols by labeling the hydrogens to the corresponding peaks.
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 purpose of this lab was to perform an electro-philic aromatic substitution and determine the identity of the major product. TLC was used to detect unre-acted starting material or isomeric products present in the reaction mixture.
The ratios for NaBH4, MPV, and L-selectride are 24.2:75.8, 43.6:56.3, 91.3:.86 respectively. According to analysis of the 1H-NMR spectrum, it is shown that the trans product formed over the cis. The mechanism for L-selectride is very similar to that of NaBH4, but NaBH4 primarily yields the more trans isomer whereas the L-selectride primarily the cis isomer. The reason for this is because in NaBH4, the hydride is not being blocked when convert to OH so it’s free to do a top attack to make a lot more of the the trans isomer. Whereas the L-selectride has bulky groups that block from the carbonyl oxygen which means that it must perform bottom attack and because of this, the isomer that gets made is the cis at 91%. In MPV, the proton is free to attack the carbonyl oxygen in a frontside attack to give more of the trans isomer The MPV reaction using aluminum isopropoxide gives reversible reduction of ketones and aldehydes and the cis or trans can revert back to starting ketone. Each step in the mechanism is reversible so the reaction is driven by the formation of the more stable product which favored thermodynamic. Overall, the stereoselectivity of reaction is affected how the hydride is opened was when it was attacking the carbonyl
Discussion The reaction of (-)-α-phellandrene, 1, and maleic anhydride, 2, gave a Diels-Alder adduct, 4,7-ethanoisobenzofuran-1,3-dione, 3a,4,7,7a-tetrahydro-5-methyl-8-(1-methylethyl), 3, this reaction gave white crystals in a yield of 2.64 g (37.56%). Both hydrogen and carbon NMR as well as NOESY, COSY and HSQC spectrum were used to prove that 3 had formed. These spectroscopic techniques also aided in the identification of whether the process was attack via the top of bottom face, as well as if this reaction was via the endo or exo process. These possible attacks give rise to four possible products, however, in reality due to steric interactions and electronics only one product is formed.
The product was recrystallized to purify it and the unknown filtrate and nucleophile was determined by taking the melting points and performing TLC. Nucleophilic substitution reactions have a nucleophile (electron pair donor) and an sp3 electrophile (electron pair acceptor) with an attached leaving group. This experiment was a Williamson ether synthesis usually SN2, with an alkoxide and an alkyl halide. Conditions are favored with a strong nucleophile, good leaving group, and a polar aprotic solvent.
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
.This experiment was performed to determine the structure of alkyl-halides formed as a result of substitution reactions, and whether the reaction used an SN1 or SN2 mechanism. The structure of the starting alcohol determined the mechanistic pathway of the substitution reaction. Reaction 1 involved the substitution of a primary alcohol which produced one primary alkyl-halide via SN2 reaction. Reactions 2 and 3 began with a secondary alcohol, forming two products as the result of direct substitution and/or a hydride shift, via SN1 reaction. Reaction 2 formed two secondary alkyl-halides, and Reaction 3 formed one secondary and one tertiary alkyl-halide.
Overall, this experiment went as planned. The equilibrium constant for this reaction was calculated, as well as finding the mole fraction at which this reaction would produce the most significant reaction. Even though some calculations weren’t as expected, this reaction was completed and made sense from a superficial view.
The better leaving group is Bromine. From the SN1 reactions, all alkyl bromides, with the exception of Bromobenzene, produced precipitates at room temperature. Although only the first tube in the SN2 reactions produced precipitate at room temperature, the back side attack happened where expected. It is notable, that in the SN¬2 reaction, eventually all alkyl bromides produced precipitate still with the exception prior.
A secondary alcohol, such as cyclohexanol, undergoes dehydration by an E1 mechanism. The key intermediate in the mechanism is a cyclohexyl cation, which can undergo substitution as well as elimination. To prepare a cyclohexene (olefin) in good yield, it is necessary to suppress the substitution reaction. In this experiment, the substitution reaction is suppressed by: (1) the use of strong acids with anions that are relatively poor nucleophiles ; (2) a high reaction temperature,
In this lab experiment, various solutions of different concentrations were created with Fe(NO3)3 (mL), KSCN (mL), and H2O (mL). When these chemicals were combined, a solution that was pale orange in color was created. These solutions were placed into a Colorimeter and their absorbance values were determined. Once these absorbance values were obtained, many calculations were done, including the Law of Mass Action (Keq = ([C]c x [D]d) / ([A]a x [B]b)) to determine the final answer of 159.7. This value is compared to the accepted Kc value of 133, revealing a percent error of around 20.08%.
Hydration of alkenes is the acid-catalyzed addition of water to a carbon-carbon double bond leading to the formation of an alcohol. An equilibrium is established between two competing processes, hydration and the opposite reaction of dehydration. The position of the equilibrium depends on the reaction conditions. These conditions include hydration of a double bond that requires excess water to drive the reaction to completion and dehydration of an alcohol requires water removal in order to complete the reaction. In this experiment, the alkene is norbornene and the product alcohol is exo-norborneol. The mechanism involves formation of a carbocation by addition of a proton to the double bond of norbornene. The less sterically hindered side of
Alcohols are a family of organic compounds containing the hydroxyl (-OH) functional group. In this experiment the five different alcohols used will be:
2, 4-dihydroxy benzaldehyde (2.83 g), Cl-SBA-15 (2 g) and triethylamine (2 g) in 50 mL of toluene was refluxed for 3 hours at 80-90 ºC in the water bath. Then, the solid was filtered, rinsed sequentially with ethanol and dried in a vacuum oven at 80 oC. Then, 1.96 mL of ethanolamine was added on the resulting substance in 50 mL of toluene and refluxed at 110ºC for 48 hours in oil bath under a nitrogen atmosphere. The product was centrifuged, washed with 50 mL of ethanol, diethyl ether, distilled water and dried in vacuum for 10 h at 90ºC. Finally, any residual template and organosilane was removed by Soxhlet extraction over diethylether and dichloromethane (1:1) at 100 ºC for 24 h and heated for 10 h at 40ºC under vacuum. Synthesis steps are presented in Scheme 1.