.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.
The overall premise of the various experiments chronicled in this article is the determination of the mechanistic pathways and products formed via substitution reactions. Substitution reactions occur when one atom or functional group replaces another. For the purposes of this experiment, there were two types of substitution reactions: SN1 or unimolecular nucleophilic substitution, 1st order and SN2 or bimolecular nucleophilic substitution, 2nd order. 1
Substitution reactions, whether they are an SN1 or SN2 reaction, must contain molecules known as nucleophiles and electrophiles. The electrophile is a component of the substrate, in this case the starting alcohol, also commonly known as the “leaving group.” Electrophiles are electron deficient, while nucleophiles are “electron donating.” The mechanism of a substitution reaction is as follows: in the presence of the nucleophile, the leaving group separates from the substrate allowing the nucleophile to form a new bond with the substrate in place of the recently departed electrophile. 2
The key difference between the SN1 and SN2 me...
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...lpentane. 1H NMR (CDCl3, 200 MHz) δ 2.1-1.8 (nonet, 1H), 1.7 (d, 6H), 1.6 (s, 6H), 0.95-0.90 (d, 2H). 3-chloro-2,4-dimethylpentane. 1H NMR (CDCl3, 200 MHz) δ 3.6-3.5 (t, 1H), 2.6-2.4(octet, 2H) 1.1-1.0 (d, 12H). IR (cm-1) 2962.42, 743.14, 708.01. GC (TCD) 4.2 m (100%).
Acknowledgements. Special thanks go to the Department of Chemistry and Chemical Biology at IUPUI, Dr. Ryan E. Denton, Professor and Dan Preston, TA.
References. 4
1. Denton, R.E.; Audu, C. “Investigating Substitution Reactions of Various Alcoholic Compounds.” Fake Journal of Organic Chemistry 2010, 77, 3452-3453.
2. Klein, David. Organic Chemistry. Hoboken: John Wiley & Sons, Inc., 2012. Print
3. Balasubramanian, Satish. ChemWiki. University of California, Davis, (n.d.). Web. 29 APR 2014.
4. The Purdue Online Writing Lab. The Writing Lab and OWL at Purdue University, 2008. Web. 29 Apr. 2014.
The purpose of this experiment is to determine the absolute configuration of an unknown chiral secondary alcohol using the competing enantioselective conversion (CEC) method. This method uses both R- and S- enantiomers of a chiral acyl-transfer catalyst called homobenzotetramisole (HBTM), in separate parallel reactions, and thin layer chromatography to identify the stereochemistry of the secondary alcohol, whether it be an R- or S- enantiomer. Quantitative analysis was performed using a program called ImageJ after the appropriate picture was taken of the stained TLC plate. The molecular structure of the unknown alcohol was identified using 1H NMR spectroscopy by matching the hydrogens to the corresponding peak.
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.
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 percent yield of products that was calculated for this reaction was about 81.2%, fairly less pure than the previous product but still decently pure. A carbon NMR and H NMR were produced and used to identify the inequivalent carbons and hydrogens of the product. There were 9 constitutionally inequivalent carbons and potentially 4,5, or 6 constitutionally inequivalent hydrogens. On the H NMR there are 5 peaks, but at a closer inspection of the product, it seems there is only 4 constitutionally inequivalent hydrogens because of the symmetry held by the product and of this H’s. However, expansion of the peaks around the aromatic region on the NMR show 3 peaks, which was suppose to be only 2 peaks. In between the peaks is a peak from the solvent, xylene, that was used, which may account to for this discrepancy in the NMR. Furthermore, the product may have not been fully dissolved or was contaminated, leading to distortion (a splitting) of the peaks. The 2 peaks further down the spectrum were distinguished from two H’s, HF and HE, based off of shielding affects. The HF was closer to the O, so it experienced more of an up field shift than HE. On the C NMR, there are 9 constitutionally inequivalent carbons. A CNMR Peak Position for Typical Functional Group table was consulted to assign the carbons to their corresponding peaks. The carbonyl carbon, C1, is the farthest up field, while the carbons on the benzene ring are in the 120-140 ppm region. The sp3 hybridized carbon, C2 and C3, are the lowest on the spectrum. This reaction verifies the statement, ”Measurements have shown that while naphthalene and benzene both are considered especially stable due to their aromaticity, benzene is significantly more stable than naphthalene.” As seen in the reaction, the benzene ring is left untouched and only the naphthalene is involved in the reaction with maleic
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
...e 3. Both letters A and B within the structure of trans-9-(2-phenylethenyl) anthracene, that make up the alkene, have a chemical shift between 5-6 ppm and both produce doublets because it has 1 adjacent hydrogen and according to the N + 1 rule that states the number of hydrogens in the adjacent carbon plus 1 provides the splitting pattern and the number of peaks in the split signal, which in this case is a doublet.1 Letters C and D that consist of the aromatic rings, both are multiplets, and have a chemical shift between 7-8 ppm. 1H NMR could be used to differentiate between cis and trans isomers of the product due to J-coupling. When this occurs, trans coupling will be between 11 and 19 Hz and cis coupling will be between 5 and 14 Hz, showing that cis has a slightly lowered coupling constant than trans, and therefore have their respective positions in a product. 2
The IR spectrum that was obtained of the white crystals showed several functional groups present in the molecule. The spectrum shows weak sharp peak at 2865 to 2964 cm-1, which is often associated with C-H, sp3 hybridised, stretching in the molecule, peaks in this region often represent a methyl group or CH2 groups. There are also peaks at 1369 cm-1, which is associated with CH3 stretching. There is also C=O stretching at 1767 cm-1, which is a strong peak due to the large dipole created via the large difference in electronegativity of the carbon and the oxygen atom. An anhydride C-O resonates between 1000 and 1300 cm-1 it is a at least two bands. The peak is present in the 13C NMR at 1269 and 1299 cm-1 it is of medium intensity.
A weak peak was at a position between 1600-1620 cm-1 can also be seem in the IR, which was likely to be aromatic C=C functional group that was from two benzene rings attached to alkynes. On the other hand, the IR spectrum of the experimental diphenylacetylene resulted in 4 peaks. The first peak was strong and broad at the position of 3359.26 cm-1, which was most likely to be OH bond. The OH bond appeared in the spectrum because of the residue left from ethanol that was used to clean the product at the end of recrystallization process. It might also be from the water that was trapped in the crystal since the solution was put in ice bath during the recrystallization process. The second peak was weak, but sharp. It was at the position of 3062.93 cm-1, which indicated that C-H (sp2) was presence in the compound. The group was likely from the C-H bonds in the benzene ring attached to the alkyne. The remaining peaks were weak and at positions of 1637.48 and 1599.15 cm-1, respectively. This showed that the compound had aromatic C=C function groups, which was from the benzene rings. Overall, by looking at the functional groups presented in the compound, one can assume that the compound consisted of diphenylacetelene and ethanol or
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.
Single Replacement is the process of an element reacting with a compound and taking the place of another element. Substance C can take the place of Substance A in the compound of AB. A metal can only replace a metal and a nonmetal can only replace a nonmetal. To predict whether or not the reaction will occur, using an activity series table will help to compare the reactivities of the elements. The reactivity of a metals is based more on the electronegativity making it more difficult to predict the reactivity of the halogens. A real life example is in the Statue of Liberty, the inside structure was made out of steel. The iron in steel reacts with the oxidized copper which protects the color and integrity. The formula for this reaction is Fe + Cu2+ → Fe2+ + Cu. In a lab 17 single replacements reactions were tested however not all had a reaction. Some were quicker and some slower to react compared to others due to different reaction rates in each
We thank the University of Oklahoma and the chemistry faculty for providing the space, instructions, and equipment for the development of this report and experiment.
"Purdue OWL: Literary Theory and Schools of Criticism ." Welcome to the Purdue University Online Writing Lab (OWL). N.p., n.d. Web. 3 Oct. 2011.
Predictions may be made about the suitability of possible catalysts by assuming that the mechanism of catalysis consists of two stages, either of which can be first:
Thickett, Geoffrey. Chemistry 2: HSC course. N/A ed. Vol. 1. Milton: John Wiley & Sons Australia, 2006. 94-108. 1 vols. Print.
Alcohol is a class of organic compounds that is characterized by the presence of one or more hydroxyl groups (-OH) attached to a carbon atom. Alcohol was unknowingly produced centuries ago when fermentation occurred to crushed grapes (Pines, 1931). In today’s society alcohol is produced for the use of household products such as varnishes, cleaning products, but is more commercially important in the liquor business. A chemical process called fermentation accomplishes the production of ethanol, the alcohol or liquor. From there, the ethanol goes through distinct processes to become the dark and clear liquors on the store shelves.