Alkyl iodides phenols

Higher alkyl ethers are prepared by treating the sodium derivative of the phaiol (made by adding the phenol to a solution of sodium ethoxide in ethyl alcohol) with the alkyl iodide or bromide (Williamson synthesis), for example ... 

The cleavage products are a phenol and an alkyl iodide, which will serve to characterise the ether. 

Dialkyl and alkyl aryl ethers can be cleaved with iodotrimethylsilane ROR -bMe3SiI — Rl-bMe3SiOR. A more convenient and less exjjensive alternative, which gives the same products, is a mixture of chlorotrimethylsilane and Nal. Alkyl aryl ethers can also be cleaved with Lil to give alkyl iodides and salts of phenols in a reaction similar to 10-73. Triphenyldibromophosphorane (Ph3PBr2) cleaves dialkyl ethers to give 2mol of alkyl bromide. ... 

Since vinyl anions generally retain configuration 39> while isomeric vinyl radicals rapidly interconvert 40) these results constitute evidence that reductions of alkyl iodides do proceed via radical intermediates. Isomerization of stereoisomeric vinyl anions is ruled out by the lack of effect of phenol on the stereochemistry of the products (Scheme III). Since cis and trans-3-hexene are formed in differing proportions from the two halides, it may be concluded that the stereoisomeric vinyl radicals are being intercepted by electron trans-... 

SYNTHESIS and CHARACTERIZATION of O-ALKYLATED EXTRACTS. Alkylation occurs when tetrabutylanunonium hydroxide is used to promote the reaction of the alkyl iodide with the coal in tetrahydrofuran.(14) The alkylation reaction occurs primarily on acidic oxygen functionalities such as phenolic hydroxyl and carboxylic acid groups, as shown below. 

It should be noted that owing to the great affinity of the phenol for sodium, no sodium alcoholate remains to react with the ethyl iodide. Diethyl ether, however, may be prepared in a similar manner, using the same quantities of sodium, alcohol and ethyl iodide as above. The ether and excess of alcohol are distilled off and the ether separated from the alcohol by the addition of salt solution. Anisole (phenylmethyl ether, B.P. 154°, see p. 218) can also be prepared in a similar way, using corresponding quantities of methyl alcohol and methyl iodide. The alkyl iodides give the best yields, but alkyl chlorides can also be employed. 

Conversion of phenols into their methyl or ethyl ethers by reaction with the corresponding alkyl sulphates in the presence of aqueous sodium hydroxide affords a method which avoids the use of the more expensive alkyl halides (e.g. the synthesis of methyl 2-naphthyl ether and veratraldehyde, Expt 6.111). Also included in Expt 6.111 is a general procedure for the alkylation of phenols under PTC conditions.38,39 The method is suitable for 2,6-dialkylphenols, naphthols and various functionally substituted phenols. The alkylating agents include dimethyl sulphate, diethyl sulphate, methyl iodide, allyl bromide, epichlorohy-drin, butyl bromide and benzyl chloride. 

HSAB is particularly useful for assessing the reactivity of ambident nucleophiles or electrophiles, and numerous examples of chemoselective reactions given throughout this book can be explained with the HSAB principle. Hard electrophiles, for example alkyl triflates, alkyl sulfates, trialkyloxonium salts, electron-poor car-benes, or the intermediate alkoxyphosphonium salts formed from alcohols during the Mitsunobu reaction, tend to alkylate ambident nucleophiles at the hardest atom. Amides, enolates, or phenolates, for example, will often be alkylated at oxygen by hard electrophiles whereas softer electrophiles, such as alkyl iodides or electron-poor alkenes, will preferentially attack amides at nitrogen and enolates at carbon. 

Palladium(0)-mediated intramolecular addition of aryl and vinyl halides to polarized olefins is a well-known and useful synthetic protocol. Zin and Fuchs extended this methodology to include vinyl sulfones.145 Oxygen alkylation of phenol 275 with cyclic y-bromo vinyl sulfone 274, using phase transfer conditions, gave aryl iodide 276. Treatment of this system with 5% refrak/s(triphenylphos-... 

Cleavage of ethers. All, cleaves alkyl phenyl ethers in refluxing CH,CN or CS, selectively to phenols and alkyl iodides. The regioselectivity is the same as that shown by AICI but the reagent is more reactive. Cleavage of dialkyl ethers requires elevated temperatures and long reaction times. 

Noteworthy is the use of fluoride ions as base for the coupling of phenols with primary alkyl iodides or benzyl chloride, and ihe exploitation of bis(acetylacetonato)nickel for the synthesis of tertiary ethers (yield 8%). ... 

Caddick [19] has reported the use of a novel polymer-supported tetra-fluorophenol-Unked acrylate as an activated acceptor for intermolecular radical reactions. Treatment of immobiUzed acrylate 132 with a variety of alkyl iodides in the presence of tributyltin hydride and AIBN gave the corresponding esters 133 (Scheme 29). NucleophiUc cleavage using amines gave amides 134 in good overall yield whilst regenerating phenol resin 131. 

Dialkoxyaldehydes of the type RCH(OCHj)CR(OCH,)CHO ate prepared from the corresponding a,/3-dichloroaldehydes by the action of very dilute solutions of sodium alkoxide below 15° (70-85%). In these preparations, the presence of potassium iodide or an alkyl iodide has been helpful. The yield of phenoxyacetone from chloroacetone and sodium phenoxide is increased from 16-23% to more than 90% chiefly by the presence of potassium iodide in the reaction mixture. The reaction of alkyl iodides with phenolic aldehydes in methanolic potassium hydroxide gives p-alkoxy-benzaldehydes (60-75%). ... 

Most Williamson reactions proceed by the 8 2 mechanism, but there is evidence (see p. 446) that in some cases the SET mechanism can take place, especially with alkyl iodides. Secondary alcohols have been converted to the corresponding methyl ether by reaction with methanol in the presence of ferric nitrate nonahy-drate. Vinyl ethers have been formed by coupling tetravinyl tin with phenols, in the presence of cupric acetate and oxygen. " The palladium-catalyzed coupling of vinyl triflates and phenols has also been reported. ... 

The approximate location of a phenol-type -> absorption has been obtained in alkyl iodides (external heavy atom effect) for SAA (92) Sq - (00) 15,000 cm i-, in good agreement with the... 

The decomposition of the ethers of phenols is also designated as saponification. Such decomposition cannot be effected by the methods hitherto given. Hydriodic acid is used which, when heated with phenol-ethers, decomposes them into the phenol and the alkyl iodide -. 

W(Tp)(NO)(PMe3)(r]2-benzene)] reacted with an excess of phenol to yield the two steroisomers of [W(Tp)(NO)(PMe3)(r]2-2H-phenol)] (Fig. 2.44), which in the presence of base and electrophilic species such as benzaldehyde, alkyl iodides, and Michael acceptors, is able to form new C-C bonds. Methyl and ethyl iodide react at C2 to form 2-alkyl-2H-phenol complexes, whereas the Michael acceptors react at C4 to give 4-alkyl-4H-phenol complexes. The crystal and molecular structures of the 2-ethyl-2H-phenol and of the phenyl o-quinone methide complexes have been reported.190... 

Scheme 2. Reaction scheme for precursor catalyst The system includes initiator, phenol, and alkyl iodide (shown as polymer-1 in this scheme).

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