Organic Lab Report: 1-Bromobutane from 1-Butanol, Incomplete

PREPARATION OF 1-BROMOBUTANE FROM 1-BUTANOL VIA SN2 REACTION

By: A. Nguyen (99141754)

ABSTRACT: 1-bromobutane was synthesised from 1-butanol with sodium bromide and sulfuric acid via nucleophilic substitution (SN2 mechanism). Conversion of the functional group in butanol, -OH to a better leaving group, required a catalyst in which sulfuric acid was used. In order for 1-bromobutane to be synthesised methods of purification including refluxing, simple distillation and separation was carried out. The end product of 1-bromobutane resulted in a yield of 10.78g.

AIM

The purpose of this experiment was to synthesise 1-bromobutane from 1-butanol.

1. INTRODUCTION

Methods for the synthesis of haloalkanes include addition reactions of alkenes and substitution reactions of alcohols, with the latter method focused on in this experiment. Naturally, nucleophilic substitution reactions do not occur with alcohols since their -OH group is strongly basic and a poor leaving group, hence SN1 and SN2 cannot produce alkyl bromide by heating alcohols with bromide salts. However, if the -OH group is activated in the presence of a nucleophile it can now leave as a weakly basic water molecule as opposed to a strongly basic -OH ion. This activation occurs via protonation with a strong acid, hence now an SN2 reaction can readily take place, where the nucleophile displaces the protonated hydroxyl.

For this particular experiment the reaction consists of 1-butanol with sodium bromide and sulfuric acid which yields 1-bromobutane. This is demonstrated below:

[pic 1]

Like most organic reactions, there will be an unpreventable side reaction as sodium bromide and sulfuric acid react to form hydrogen bromide gas.

[pic 2]

1. EXPERIMENTAL METHOD

1. RESULTS

1. Physical Constants

1. Quantities of reactants and products