Gas Chromatography Lab
The purpose of this lab was to use gas chromatography to determine the relative amounts of the three components of gas products from the dehydration reaction of 1- and 2-Butanol with sulfuric acid and the dehydrobromination reaction of 1- and 2-Bromobutane with potassium tert-butoxide.
E1 reactions are two-step unimolecular reactions. The first step of an E1 reaction occurs when a leaving group, which consists of a weak base, leaves an organic compound, leaving an intermediate carbocation. In the second step, a carbon on the organic compound is deprotonated by a Lewis base, resulting in the formation of an alkene. The dehydration reactions of 1- and 2-Butanol with sulfuric acid occur through an E1 mechanism, so they follow the steps previously …show more content…
Because of the unfavorable steric interactions between the methyl groups on cis-2-butene, trans-2-butene is the major …show more content…
The dehydrobromination reactions of 1- and 2-Bromobutane with potassium tert-butoxide occur through an E2 mechanism. In the dehydrobromination of 1-bromobutane, potassium tert-butoxide, a strong base, deprotonates the beta carbon while bromine leaves, forming a monosubstituted alkene. Because the leaving group, bromine, in 1-bromobutane is located on the first carbon, the formation of a disubstituted alkene is not possible, which is why the gas chromatogram for this reaction should only have one peak, suggesting only one product is formed. The case is not the same in the reaction of 2-bromobutane with potassium tert-butoxide. In 2-bromobutane, the leaving group is attatched to the second carbon. This allows potassium tert-butoxide to deprotonate either the number one carbon, which results in a monosubstituted alkene (1-butene), or the number three carbon, which results in a disubstituted alkene that is either cis or trans (trans-2-butene or cis-2-butene). Due to the “bulkiness” of potassium tert-butoxide, it is easier for potassium tert-butoxide to deprotonate carbon one on 2-butanol than it is for it to deprotonate carbon three because carbon three is located between two other carbons. For this reason, the gas chromatogram from this reaction should
E1 reactions are two-step unimolecular reactions. The first step of an E1 reaction occurs when a leaving group, which consists of a weak base, leaves an organic compound, leaving an intermediate carbocation. In the second step, a carbon on the organic compound is deprotonated by a Lewis base, resulting in the formation of an alkene. The dehydration reactions of 1- and 2-Butanol with sulfuric acid occur through an E1 mechanism, so they follow the steps previously …show more content…
Because of the unfavorable steric interactions between the methyl groups on cis-2-butene, trans-2-butene is the major …show more content…
The dehydrobromination reactions of 1- and 2-Bromobutane with potassium tert-butoxide occur through an E2 mechanism. In the dehydrobromination of 1-bromobutane, potassium tert-butoxide, a strong base, deprotonates the beta carbon while bromine leaves, forming a monosubstituted alkene. Because the leaving group, bromine, in 1-bromobutane is located on the first carbon, the formation of a disubstituted alkene is not possible, which is why the gas chromatogram for this reaction should only have one peak, suggesting only one product is formed. The case is not the same in the reaction of 2-bromobutane with potassium tert-butoxide. In 2-bromobutane, the leaving group is attatched to the second carbon. This allows potassium tert-butoxide to deprotonate either the number one carbon, which results in a monosubstituted alkene (1-butene), or the number three carbon, which results in a disubstituted alkene that is either cis or trans (trans-2-butene or cis-2-butene). Due to the “bulkiness” of potassium tert-butoxide, it is easier for potassium tert-butoxide to deprotonate carbon one on 2-butanol than it is for it to deprotonate carbon three because carbon three is located between two other carbons. For this reason, the gas chromatogram from this reaction should