.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... ... middle of paper ... ...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 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
Depending on which face of carbonyl the hydride attacks, the ketone could result in two different diastereomers of product. Since the two ketone faces are nonequivalent, there will be stereo selectivity in reduction which means that one diastereomer will be more prevalent than the other. There are three reduction conditions can be used to reduce the 4-tert-butylcyclohexanone : NaBH4, MPV , and L-selectride. For NaBH4, the hydride attach itself to the carbonyl oxygen to become the hydroxyl group and it more likely from the top because the hydride isn’t blocked by a bulky group (Fig mech prez). Both sodium borohydride and lithium aluminum hydride are less bulky hydride reducing agents so it is expected that they will be able to attack from the top face of the molecule since the bulky tert-butyl group will not hinder the attack. For L-selectride mechanism is similar to NaBH4, the L-selectride is a source of hydride for the carbonyl oxygen but there are bulky groups that block the hydride. Since L-selectride is much larger and bulkier hydride reagent so likely not be able to attack from the top face in the presence of the bulky tert-butyl group (fig 1 and 2 like web) For MPV, the ketone is reduced with aluminum isopropoxide in isopropanol. The carbonyl oxygen attack the aluminum which causes the carbonyl oxygen to have a +1 charge, a hydrogen as
Wittig reactions allow the generation of an alkene from the reaction between an aldehyde/ketone and an alkyl halide (derived from phosphonium salt).The mechanism for the synthesis of trans-9-(2-phenylethenyl) anthracene first requires the formation of the phosphonium salt by the addition of triphenylphosphine and alkyl halide. The phosphonium halide is produced through the nucleophilic substitution of 1° and 2° alkyl halides and triphenylphosphine (the nucleophile and weak base). An example is benzyltriphenylphosphonium chloride, which was used in this experiment. The second step in the formation of the of the Wittig reagent, which is primarily called a ylide and derived from a phosphonium halide. In the formation of the ylide, the phosphonium ion in benzyltriphenylphosphonium chloride is deprotonated by the base, sodium hydroxide to produce the ylide as shown in equation 1.
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.
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 competing enantioselective conversion method uses each enantiomer of a kinetic resolution reagent, in this case R-HBTM and S-HBTM, in separate and parallel reactions, where the stereochemistry of the secondary alcohol is determined by the rate of the reactions. When using the CEC method, the enantiomer of the secondary alcohol will react with one enantiomer of the HBTM acyl-transfer catalyst faster than with the other HBTM enantiomer. The mnemonic that identifies the absolute configuration of the secondary alcohol is as follows: if the reaction is faster with the S-HBTM, then the secondary alcohol has the R-configuration. In contrast, if the reaction is faster with the R-HBTM, then the secondary alcohol has the S-configuration. Thin layer chromatography will be used to discover which enantiomer of HBTM reacts faster with the unknown secondary alcohol. The fast reaction corresponds to a higher Rf spot (the ester) with a greater density and a slower reaction corresponds to a lower Rf spot with high de...
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.
"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.
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
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:
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.
Thickett, Geoffrey. Chemistry 2: HSC course. N/A ed. Vol. 1. Milton: John Wiley & Sons Australia, 2006. 94-108. 1 vols. Print.
...n initiated with Sn(Oct)2 were studied by conducting various reactions incorporating various ratio and amount of reagents, co-initiator and trapping agents. Furthermore, reaction kinetics were monitored and intermediate /trapped compounds were isolated and identified. The results indicated that propagation did not proceed as cationic polymerization. Reaction was co-initiated by alcohol or alkoxide compound and Sn was attached to the propagating group.
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.