Phenoxypropyl Bromide

SubmiLled by C S Marvel and A L Tanenbaum. Checked by H T, Clarke and C J Malm. 

The reaction may be run without stirring but a longer period of refluxing is necessary and the yield is lower. 

If less water is used in the reaction mixture, sodium bromide separates. 

The large excess of trimethylene bromide must be used in order to avoid the formation of large amounts of diphenoxypropane. 

Phenoxypropyl bromide attacks rubber stoppers quite readily and the side arm of the distillation flask should be set in (Org. Syn. 1, 40) in order to avoid contamination of the distillate. 

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Our results conci red with those above when 3-bromo-l-phenoxypropane was added to our Mg at room temperature the reaction was quite vigorous(40). Upon carbonation, followed by hydrolysis, the only acidic product isolated was phenol in 70% yield. It was very satisfying to note that at -78 °C the reaction of 3-phenoxypropyl bromide proceeded smoothly. 

The use of recovered trimethylene bromide does not result in as good a yield of phenoxypropyl bromide, because a little phenoxypropyl bromide is already present and during the reaction is converted to diphenoxypropane. 

Phenoxypropyl bromide has been prepared by the action of sodium phenoxide on trimethylene bromide in alcohol solution.1 The method described in the procedure has been published by Marvel and Tanenbaum.2... 

Halo ethers are prepared by adding an alcoholic solution of the sodium alkoxide to the polymethylene halide, X(CHj) X, in anhydrous ether or benzene, as illustrated by the preparation of l-bromo-6-methoxyhexane (47%). In a somewhat different manner, an aromatic halo ether such as y-phenoxypropyl bromide is synthesized by the action of phenol and the dihalide in the presence of hot aqueous sodium hydroxide (85%). The syntheses of o- and p-chlorophenyl phenyl ethers have been successfully accomplished by the Ullmann procedure (40-55%), whereas chlorination of diphenyl ether yields an inseparable mixture of isomers. ... 

Slaugh (56) has shown that in the Kharasch reaction of 3-phenoxypropyl bromide the radical PhOCH2CH2CH2 does not seem to be the intermediate, but that PhOCH2CH2CH2mg would explain the observations. 

Apart from these ring closures with y-bromophosphonium salts, phosphonium salts carrying other nucleofuges at the y-position can be utilized in a similar way, albeit in lower yield. 3-(Phenoxypropyl)triphenylphosphonium bromide with butyllithium in tetrahydrofuran was converted into cyclopropyltriphenylphosphonium bromide in 19% yield. ... 

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