Aryl-Alkyl Ethers

Dienols with 2 equiv. of 1 gave the corresponding bimetallic alkoxide organozir-conocene complexes however, protolysis allowed recovery of the alcohol functionality (Scheme 8-29) [107]. Alcohols can also be easily converted to ethers. Alkyl, aryl, silyl [85,112,183, 210] and THP [17, 153, 211, 219] ethers are stable under hydrozirconation conditions side products were observed only with the trimethylsUyl group [220, 221]. 

C2BioHi2 derivatives with, e.g., R = ester, amine, amide, acyl halide, halogen, ether, alkyl, aryl, alkenyl or alkynyF , although a dialkyne will lead to some bis-carborane ... 

Chem. Descrip. Proprietary blend of alkylaryl polyoxyalkane ethers, alkyl aryl polyethoxy ethanol phosphates, free fatty adds, IPA Ionic Natum NonlonIdanlonIc... 

Formation of 2 naphthyl ethers. Alkyl halides and aryl-alkyl halides (e.g. benzyl chloride) are converted into 2-naphthyl ethers thus ... 

Oxonium salt formation. Shake up 0 5 ml. of ether with 1 ml. of cone. HCl and note that a clear solution is obtained owing to the formation of a water-soluble oxonium salt. Note that aromatic and aliphatic hydrocarbons do not behave in this way. In general diaryl ethers and alkyl aryl ethers are also insoluble in cone. HCl. 

Alkylethers (269), R2 = alkyl, are obtained by the action of phosphorus pentasulfide on alkyl esters of a-acylamino acids (64, 334, 711) by means of the GabriePs synthesis (Section II.4), while aryl ethers (269), = aryl,... 

The analogous band m alkyl aryl ethers (ROAr) appears at 1200-1275 cm (Section 24 15)... 

The reaction between an alkoxide ion and an aryl halide can be used to prepare alkyl aryl ethers only when the aryl halide is one that reacts rapidly by the addition-elim mation mechanism of nucleophilic aromatic substitution (Section 23 6)... 

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... 

The first step in the reaction of an alkyl aryl ether with a hydrogen halide is pro tonation of oxygen to form an alkylaryloxonium ion... 

Section 24 11 Phenoxide anions are nucleophilic toward alkyl halides and the prepara tion of alkyl aryl ethers is easily achieved under 8 2 conditions... 

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

Alkyl aryl ether Hydrogen halide A phenol Alkyl halide... 

Me3SiI, CHCI3, 25-50°, 12-140 h. lodotrimethylsilane in quinoline (180°, 70 min) selectively cleaves an aryl methyl group, in 72% yield, in the presence of a methylenedioxy group. Me3SiI cleaves esters more slowly than ethers and cleaves alkyl aryl ethers (48 h, 25°) more slowly than alkyl alkyl ethers (1.3-48 h, 25°), but benzyl, trityl, and /-butyl ethers are cleaved quite rapidly (0.1 h, 25°). ... 

Electrochemical oxidation of alkyl aryl ethers results m oxidative dealkylation and coupling of the intermediate radicals ElectrooxidaUon m the presence of hydrogen fluonde salt leads to fluonnated dienones [66] (equation 58)... 

ArH = dimethoxybenzenes, anisol, xylenes, fluorene, diphenyl ether, etc R = alkyl, aryl... 

Protonation of the anion [SN2] by acetic acid in diethyl ether produces the thermally unstable sulfur diimide S(NH)2. Like all sulfur diimides, the parent compound S(NH)2 can exist as three isomers (Scheme 5.5). Ab initio molecular orbital calculations indicate that the (cis,cis) configuration is somewhat more stable than the (cis,trans) isomer, while the (trans,trans) isomer is expected to possess considerably higher energy. The alternative syn,anti or E,Z nomenclatures may also be used to describe these isomers. The structures of organic derivatives S(NR)2 (R = alkyl, aryl) are discussed in Section 10.4.2. 

Aryl and alkyl trimethylsilyl ethers can often be cleaved by refluxing in aqueous methanol, an advantage for acid- or base-sensitive substrates. The ethers are stable to Grignard and Wittig reactions and to reduction with lithium aluminum hydride at —15°. Aryl -butyldimethylsilyl ethers and other sterically more demanding silyl ethers require acid- or fluoride ion-catalyzed hydrolysis for removal. Increased steric bulk also improves their stability to a much harsher set of conditions. An excellent review of the selective deprotection of alkyl silyl ethers and aryl silyl ethers has been published. ... 

Alkyl aryl ethers and enol ethers are also accessible by the Mitsunobu method. Cyclic ethers can be obtained by an intramolecular variant, which is especially suitable for the synthesis of three- to seven-membered rings ... 

The rearrangement of an ether 1 when treated with a strong base, e.g. an organo-lithium compound RLi, to give an alcohol 3 via the intermediate a-metallated ether 2, is called the Wittig rearrangement. The product obtained is a secondary or tertiary alcohol. R R can be alkyl, aryl and vinyl. Especially suitable substrates are ethers where the intermediate carbanion can be stabilized by one of the substituents R R e.g. benzyl or allyl ethers. 

Alkyl aryl ethers (CXVII) undergo rearrangement in the presence of Lewis acid and strong acid catalysts to give the corresponding alkyl phenols (CXVIII and CXIX), viz. 

Aughel and coworkers [63] studied the phase behavior of hydrocarbon-water mixtures in the presence of alkyl(aryl)polyoxyethylene carboxylates for enhanced oil recovery and found good salt tolerance with an alkyl ether carboxy-late (C13-C15) with 7 mol EO and a good microemulsion forming effect with the 3 EO type. 

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