Other Simple Bromoalkanes

Marine algae biosynthesize and emit several other simple bromoalkanes, including dibromomethane (CH2Br2), tribromomethane (bromoform, CHBr3), bromoethane 

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The alkylation process possesses the advantages that (a) a wide range of cheap haloalkanes are available, and (b) the substitution reactions generally occur smoothly at reasonable temperatures. Furthermore, the halide salts formed can easily be converted into salts with other anions. Although this section will concentrate on the reactions between simple haloalkanes and the amine, more complex side chains may be added, as discussed later in this chapter. The quaternization of amines and phosphines with haloalkanes has been loiown for many years, but the development of ionic liquids has resulted in several recent developments in the experimental techniques used for the reaction. In general, the reaction may be carried out with chloroalkanes, bromoalkanes, and iodoalkanes, with the reaction conditions required becoming steadily more gentle in the order Cl Br I, as expected for nucleophilic substitution reactions. Fluoride salts cannot be formed in this manner. 

Route 2 uses cyclohexylmethanol (Structure 2.10), which contains a hydroxyl group in the position at which bromine substitution is required. Simple primary alcohols, such as ethanol, react with HBr to give the corresponding bromoalkane, and if this reaction can be extended to other primary alcohols, such as Structure 2.10, it would provide a good way of preparing bromocyclohexylmethane (Structure 2.8). 

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