Nucleophilic Substitution Lab Report

Nucleophilic Substitution: Preparation of 1-Bromobutane and
Alkyl Halide Classification Tests
Introduction
This procedure was undertaken in order to convert a primary alcohol, 1-butanol, into a primary alkyl halide, 1-bromobutane. This was done using hydrobromic acid. Additionally, tests were performed to assess the degree of the alkyl halide: primary, secondary or tertiary. These tests were the silver nitrate test and the sodium iodide test. The goal of these tests was to verify that 1-bromobutane, a primary alkyl halide, had in fact been formed.

Data and Results 0.844 grams of product were collected. As 1-bromobutane has a molecular weight of 137.02 grams/mole, this gives 0.00616 moles of 1-bromobutane. The limiting reagent in this reaction

In these tests, the formation of a precipitate confirms the presence of a halogen and the rate that the precipitate is formed indicates the degree of saturation of the alkyl halide. Sodium iodide reacts with alkyl halides through the SN2 mechanism. As such, the reaction occurs, and thus the precipitate forms, most quickly when reacting with primary alkyl halides. The precipitate formed in 1 minute and 20 seconds, which is indicative of a primary alkyl halide, so this test was successful and correctly identified the primary alkyl halide. Silver nitrate reacts with alkyl halides via the SN1 mechanism. As such, the reaction occurs, and thus the precipitate forms, more quickly when reacting with tertiary alkyl halides. This is because tertiary alkyl halides are better able to form carbocation transition states than primary alkyl halides because the charge can be better distributed. However, a precipitate formed in this test after only 1 minute and 5 seconds. This is a false positive and thus the test failed to distinguish between the different degrees of alkyl

As different bonds require different amounts of energy to bend and stretch, they absorb and transmit different amounts of radiation. This data is then collected by the spectrometer and transposed into graph form. The different amounts of absorbance for various functional groups and types of bonds have been established and can be used to identify compounds. Also, an IR spectrum can be compared to known “fingerprint” spectra in order to identify the compound. When compared to the fingerprint spectrum for 1-bromobutane found in Experimental Organic Chemistry, the IR spectrum collected from the data was very similar. This indicates that the product was indeed