Cleavage of Alkyl Aryl Ethers

Cleavage of alkyl aryl ethers by hydrogen halides always proceeds so that the alkyl-oxygen bond is broken and yields an alkyl halide and a phenol as the final prod nets Either hydrogen bromide or hydrogen iodide is normally used... 

Section 24 12 The cleavage of alkyl aryl ethers by hydrogen halides yields a phenol and an alkyl halide... 

Cleavage of alkyl aryl ethers with sodium or potassium metal shows excellent regio-selectivity [275]. Using limiting radical anion structures to analyze the results and noting the preference for such structures as dependent on the substituents, it is possible to formulate reaction pathways leading to the observed products. 

The cleavage of alkyl aryl ethers is more important as a preparative method for phenols than for alkyl halides (method 97). The procedure has been employed as the final step in a synthesis proposed as a means for increasing the carbon chain of an alkyl halide, viz., ... 

Cleavage of alkyl aryl ethers ArOR - ArOH. Alkyl aryl ethers are cleaved in high yield when treated with lithium iodide in dry 2,4,6-collidine. The reaction mixture becomes mildly basic as the cleavage proceeds but can be buffered with an acid such as benzoic acid. The reactions can also be carried out with Lil-3H20 at 180-200° in the absence of solvent. 

Aluminum bromide is superior to the chloride for cleavage of alkyl aryl ethers it is soluble in indifferent solvents such as benzene, carbon disulfide, and light petroleum. According to Pfeiffer and Haack,24 the reaction takes place according to the scheme ... 

PotassiumI biphenyl Regiospecific cleavage of alkyl aryl ethers... 

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