Formation of phenyl ethers

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. 

Suspend 11 g (0.1 mol) of p-aminophenol in 30 ml of water contained in a 250-ml beaker or conical flask and add 12 ml (0.127 mol) of acetic anhydride. Stir (or shake) the mixture vigorously and warm on a water bath. The solid dissolves. After 10 minutes, cool, filter the solid acetyl derivative at the pump and wash with a little cold water. Recrystallise from hot water (about 75 ml) and dry upon filter paper in the air. The yield of p-hydroxyacetanilide, m.p. 169 °C (1), is 14 g (93%). 

Place 1.55 g (0.0675 mol) of clean sodium in a 250-ml round-bottomed flask equipped with a reflux condenser. Add 40 ml of absolute alcohol (or rectified spirit). If all the sodium has not disappeared after the vigorous reaction has subsided, warm the flask on a water bath until solution is complete. Cool the mixture and add 10 g (0.066 mol) of p-hydroxyacetanilide. Introduce 15 g (8 ml, 0.1 mol) of ethyl iodide slowly through the condenser and reflux the mixture for 45-60 minutes. Pour 100 ml of water through the condenser at such a rate that the crystalline product does not separate if crystals do separate, reflux the mixture until they dissolve. Then cool the flask in an ice bath collect the crude phenacetin with suction and wash with a little cold water. Dissolve the crude product in 80 ml of rectified spirit if the solution is coloured, add 2 g of decolourising carbon, boil and filter. Treat the clear solution with 125 ml of hot water and allow to cool. Collect the pure phenacetin at the pump and dry in the air. The yield is 9.5 g (80%), m.p. 137 °C. 

(1) If the m.p. is unsatisfactory, dissolve the product in dilute alkali in the cold 

Place 47 g (0.5 mol) of phenol, 60.5 g (0.5 mol) of allyl bromide (Expt 5.54), 69.1 g (0.5 mol) of anhydrous potassium carbonate and 100 ml of acetone in a 250-ml, two-necked round-bottomed flask fitted with a reflux condenser and sealed stirrer unit, and boil on a steam bath for 8 hours with stirring. Pour the reaction mixture into 500 ml of water, separate the organic layer and extract the aqueous layer with three 20 ml portions of ether. Wash the combined organic layer and ether extracts with 2 m sodium hydroxide solution, and dry over anhydrous potassium carbonate. Remove the ether with a rotary evaporator and distil the residue under reduced pressure. Collect the allyl phenyl ether, b.p. 85°C/19mmHg the yield is 57 g (85%). 

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The selective formation of phenyl ethers from one hydroxy-group of a diol has been achieved with triphenylbismuth diacetate, Ph3Bi(OAc)2. Two new protecting groups suitable for 1,2- and 1,3-diols are shown in the ketal (39) and the t-butylsilylene derivative (40). ... 

Photolytic. In a methanolic solution irradiated with UV light >290 nm), dechlorination of 4-chlorophenyl phenyl ether resulted in the formation of diphenyl ether (Choudhry et al., 1977). Photolysis of an aqueous solution containing 10% acetonitrile with UV light (X = 230-400 nm) yielded 4-hydroxybiphenyl ether and chloride ion (Dulin et al., 1986). 

Klumpp and Sinnige proceeded similarly, using ec-butyl alcohol to protodelithi-ate the anisoles and other lithiated aryl ethers in di-n-butyl ether. The protodelithiation enthalpies for all the lithiated aryl ethers, as monomers, from the latter study are listed in Table 3. The reaction enthalpies for the o- and p-lithioanisoles are ca 20 kJmop more negative from Reference compared to the ones from Reference, presumably due to differences in the reaction media. From the exchange reaction, equation 17, and the enthalpies of formation of phenyl lithium, benzene and the relevant aryl ether, the enthalpies of formation of the lithiated aryl ethers can be derived. The calculated values are shown in Table 3. 

Whereas the acetylation of phenyl ethers over zeolite catalysts leads to the desired products, acetylation of 2-MN occurs generally at the very activated C-l position with formation of l-acetyl-2-methoxynaphthalene (l-AMN). A selectivity for l-AMN close to 100% can be obtained over silicoaluminate MCM-41 mesoporous molecular sieves[22] and FAU zeolites,133 341 whereas with other large pore zeolites with smaller pore size (BEA, MTW, ITQ-7), 2-AMN (and a small amount of l-acetyl-7-methoxynaphthalene, 3-AMN) also appears as a primary product. Average pore size zeolites, such as MFI, are much less active than large pore zeolites. These differences were related to shape selectivity effects and a great deal of research work was carried out over BEA zeolites in order to specify the origin of this shape selectivity the difference is either in the location for the formation of the bulkier (l-AMN) and linear (2-AMN) isomers (only on the outer surface for l-AMN, preferentially within the micropores for 2-AMN)[19 21 24 28 381 or more simply in the rates of desorption from the zeolite micropores.126 32 33 351... 

Rylander and Kilroy studied the formation of cyclohexyl phenyl ether intermediate in the hydrogenation of phenyl ether over binary platinum-rhodium oxide catalysts in cyclohexane at room temperature and atmospheric hydrogen pressure. The yield of the intermediate varied greatly with the catalyst composition. The highest yield (48%) was obtained over the catalyst consisting of 30% Pt-70% Rh.149... 

TABLE 11.11 Hydrogenation of Phenyl Ether over Platinum Metals Selectivities for Formation of Products at Initial Stage ,fc... 

No formation of an ether substitution product is observed when the para-anilino position is substituted, e.g. when N-benzyl-p-toluidine is dehydrogenated with TPPO-. Substitution of the CH2-bonded phenyl ring does not occur 190). 

The laser jet system of irradiation allows the observation of multi-photon processes and is becoming more popular. Under these conditions, the keto ether (35) in carbon tetrachloride solution undergoes two processes to give 4-phenyl-benzaldehyde (one photon) and 4-phenylbenzyl chloride (two photons), while from ethanol solutions of (35), evidence is obtained to suggest that the formation of the ether (36) arises from a three-photon process (Adam and Schneider). 

Treatment of oestrone with tetraphenylbismuth monotrifluoroacetate gave oestrone phenyl ether and exemplified, in part, a new procedure for aryl ether formation.31 A detailed study was reported of the formation of benzyl ethers by sequential reaction of alcohols with chloro(phenylmethylene)dimethylammonium chloride and sodium hydrogen telluride.32 Steroidal alcohols, inter alia, were converted into hydrolytically stable silyl ethers by reaction with B N Sil or BulPh2I which were generated in situ from the selenosilane and iodine.33 The 5a-hydroxycholestane (21) was protected in this way. 

A different approach to the synthesis of sulfate esters was discussed by Buncel and co-workers (97 ). The sulfate monoester was obtained after neutral or alkaline methanolysis of methyl 4-nltro-phenyl sulfate. The methoxide Ion attacks only at the alkyl carbon with the formation of dimethyl ether and 4-nltrophenyl sulfate Ion as the leaving group. Other substituted methyl phenyl sulfates have been converted to phenyl sulfates In the same manner (98). Correspondingly l,2 5,6-dl-0-lsopropylldlne-a-D-glucofuranose was reacted with phenyl chlorosulfate to give the carbohydrate... 

Alkyl phenol ethoxylates have been over many years the workhorses as nonionic emulsifiers for emulsion polymerization. Depending on availability and price of buten and propen, nonyl (tripropylene)phenol ethoxylates or octyl (dibutylene) phenol ethoxylates have been very broadly used, whereas dodecyl (tetrapropylene or tributylene)phenol and tri tert-butylphenol ethoxylates were merely regarded as specialties. These aUcyl phenol ethoxylates can also be used as intermediates for the synthesis of anionic alkyl phenol ether sulphates. Sulphation by chlorosul-phonic acid or sulphur trioxide besides formation of the ether sulphate end group inevitably leads to certain amounts of ring sulphonation in the phenyl group, whereas amidosulphonic acid gives sulphonate-free aUcyl phenol ether sulphate ammonium salts. 

Of the methods of synthesis of cellulose esters, the one that has been most thoroughly studied is the reaction of trans-esterification, and this method is widely used for the synthesis of low-molecular-weight esters. The alcoholysis of a low-molecular-weight ester (methyl- and n -propyl-borate) with hydroxyl groups of cellulose was first used (37) for die preparation of cellulose borate. This was followed by the trans-esterification, with cellulose, of the esters of phosphorous acids (see above), i.e. mono-, di- and trimethylphosphites (71, 72, 75), esters of phosphonic acids (76), and also phenyl-/ -chloroethyl- and / -fluoroethylphosphites (77, 78). Of considerable interest is the reaction of alcoholysis, with cellulose, of the esters of aryl- and naphthalenesulphonic add, which results in the formation of cellulose ethers, rather than esters (79-81). 

When an alcohol is used as the reducing agent, the yield of deaminated aromatic compound is often very unsatisfactory owing to extensive formation of aryl ethers. Use of lower alcohols favors ether formation, whereas use of higher alcohols favors formation of the hydrocarbons for example, benzenediazonium chloride gives only anisole when methanol is used, a little benzene and much phenetole when ethanol is used, but much benzene and very little benzyl phenyl ether when benzyl alcohol is used. 

As noted in the introduction to this section, UUmann also reported the formation of biaryl ethers from phenol and phenyl bromide in the presence of copper and a base. This UUmann ether synthesis has been used extensively to prepare biaryl ethers. " However, the original reaction conditions involved high temperatures (150-200 C), neat phenol or highly polar aprotic solvents, and stoichiometric amounts of copper complexes. The yields for the reactions of unactivated aryl halides were often low. Conditions with catalytic amounts of copper at lower temperatures with broader scope have now been developed. 

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