Phenol, methylation preparation

Ciesol and xylenol can be prepared by the methylation of phenol with methanol over both acid and base catalysts. It is postulated that phenol methylation on acid catalysts proceeds through the initial formation of anisole (methoxybenzene [100-66-3]) followed by intramolecular rearrangement of... 

Mel, K2CO3, acetone, reflux, 6 h. This is a veiy common and often veiy efficient method for the preparation of phenolic methyl ethers it is also applicable to the. formation of phenolic benzyl ethers. 

Cu-Mn mixed-oxide binary spinel catalysts (CuxMn3 x04, where x = 0, 0.25, 0.5, 0.75 and 1) prepared through co-precipitation method exhibit phenol methylation activity imder vapor phase conditions [75]. All of the catalysts, irrespective of the compositions, produced only C-methylated phenols. However, a total ortho selectivity of 100% with 2,6-xylenol selectivity of 74% was observed over x = 0.25 compositions at 400°C. This composition was found to be relatively stable under reaction conditions compared with the other compositions studied. The catalysts with high copper content suffered severe reduction under methylation conditions whereas, catalysts with low copper content had a hausmannite phase (Mu304) that sustained... 

The methods outlined here deal with methylation and other techniques used to prepare samples of oxidation products for GLC analysis. Aliphatic acids have been determined either as free acids or methyl esters. Aromatics have been determined as methyl ethers of phenolics, methyl esters of carboxylic acids, or methyl ether esters of phenolic acids. 

Phenolic methyl ethers were usually prepared by treatment of the alkaloid with dimethyl sulfate and sodium hydroxide or with diazomethane 17). In the first case a side reaction was N-methylation or even cleavage of the lactone (3). In decodine (6) the C-17 OH group was methylated on treatment with ethereal diazomethane. The hindered C-21 OH group was alkylated with methanolic CH2N2 (77). 

The enantiomerically pure diarylmethylpiperzine derivative, (-)-3-((S)-((2S,5R)-4-allyl-2,5-dimethyl-l-piperazinyl)-(3-thienyl)-methyl)phenol, (VI), prepared by Chang (5) was effective as an opioid receptor antagonist and used as a therapeutic agent in treating drug and alcohol addictions. 

On controlled electrolysis (950 mV V5. SCE, 2 FmoH ) in 2 1 MeOH-THF, the phenol 137 prepared from 3,4-dihydroxybenzaldehyde underwent 2e oxidation resulting in the formation of 9-oxaisotwist-8-en-2-one 138, in 82% yield, which was smoothly converted to deoxysilydianin methyl ether 139 (Scheme 26) . ... 

Mel, K2CO3, acetone, reflux, 6 h. This is a very common and often very efficient method for the preparation of phenolic methyl ethers. The method is also applicable to the formation of phenolic benzyl ethers. Stronger bases are not required because of the increased acidity of a phenol versus a typical alcohol. In the following case the ortho OH is more acidic by about 1 pA), unit therefore more reactive. ... 

Cleavage of phenol methyl ethers [1, 965, after line 2]. A disadvantage of the Prey procedure is that preparation of the reagent is a little troublesome. A group at St. Louis University5 has found that the reagent can be obtained very easily by distillation of a mixture of pyridine with a slight excess of coned, hydrochloric acid at 210°. The ether to be cleaved is stirred into the hot salt and then the reaction mixture is basified and steam distilled to remove pyridine. Yields for the most part are 80-90%. 

Novolacs are linear polymers. Metacresol, a very reactive derivative of phenol, is typically used to prepare novolac resins. The presence of a methyl group at the meta (3 or 5) position of the henzene ring of phenol enhances the reactivity of the compound toward polymerization with formaldehyde. Novolac resins made with metacresol are also more moisture resistant than those with phenol. After preparation, novolac s ability to resist further polymerization is attributed to the fact that the chains terminate with phenol groupings, having been prepared with an excess of phenol. ... 

The synthesis and characterization of optically active amino acidate alkynyl complexes of formula CpRh(aa)(C=CR) (aa = L-prolinate (Pro), R = CMcs) were reported. A series of dirhodium cr-alkynyl complexes were also studied. The sterically demanding phosphine 2-(di-o-tolylphosphino)phenol was prepared and used to create a series of esters with A -acylated amino acids. The phosphine-containing esters reacted with [Rh(/t-Cl)(cyclooctene)2]2 to give products of oxidative addition of the ester carbonyl-oxygen bond to the Rh center, 231 and 232. The ligand 2- (diphenylphosphino)methyl)quinolin-8-acetate reacted with [Rh( -Cl)(cyclooctene)2]2 affording only one of the three possible diastereomers, 233. ... 

Usually prepared from the corresponding sulphonic acids by alkali fusion, methylation of phenol or from the aminotoluene by treatment with nitrous acid followed by boiling. Both o- and p-cresol are used as end components in azo dyes. 

For the preparation of 4-substituted coumarins, a phenol may be condensed with ethyl acetoacetate under the influence of sulphuric acid. Thus resorcinol (II) readily undergoes this condensation (which is represented diagrammatically above) to give 7-hydroxy-4-methyl-coumarin (III). Note that the coumarins, like all 2 pyrones, are systematically lactones. 

The above is a general procedure for preparing trialkyl orthophosphates. Similar yields are obtained for trimethyl phosphate, b.p. 62°/5 mm. triethyl phosphate, b.p. 75-5°/5 mm. tri-n-propyl phosphate, b.p. 107-5°/5 mm. tri-Mo-propyl phosphate, b.p. 83-5°/5 mm. tri-wo-butyl phosphate, b.p. 117°/5-5 mm. and tri- -amyl phosphate, b.p. 167-5°/5 mm. The alkyl phosphates are excellent alkylating agents for primary aromatic amines (see Section IV,41) they can also be ua for alkylating phenols (compare Sections IV,104-105). Trimethyl phosphate also finds application as a methylating agent for aliphatie alcohols (compare Section 111,58). 

Methyl and ethyl ethers of phenols are most conveniently prepared by alkylation with dimethyl sulphate and diethyl sulphate respectively in weakly alkaline solution, for example ... 

Long-chain esters of pentaerythritol have been prepared by a variety of methods. The tetranonanoate is made by treatment of methyl nonanoate [7289-51-2] and pentaerythritol at elevated temperatures using sodium phenoxide alone, or titanium tetrapropoxide in xylene (12). PhenoHc esters having good antioxidant activity have been synthesized by reaction of phenols or long-chain aUphatic acids and pentaerythritol or trimethyl olpropane (13). 

In step 2, phenol or trifluorethanol is used, but phenol is preferred. Examples of (21) prepared by this method iaclude R = methyl [138815-47-17, ethyl [146525-87-3], phenyl [138815-48-2], and 4-fluorophenyl [146525-88-4], Another preparation is shown ia equation 9, where R OH is phenol or trifluoethanol. 

A Methylamino)phenol. This derivative, also named 4-hydroxy-/V-methy1ani1ine (19), forms needles from benzene which are slightly soluble in ethanol andinsoluble in diethyl ether. Industrial synthesis involves decarboxylation of A/-(4-hydroxyphenyl)glycine [122-87-2] at elevated temperature in such solvents as chlorobenzene—cyclohexanone (184,185). It also can be prepared by the methylation of 4-aminophenol, or from methylamiae [74-89-5] by heating with 4-chlorophenol [106-48-9] and copper sulfate at 135°C in aqueous solution, or with hydroquinone [123-31 -9] 2l. 200—250°C in alcohoHc solution (186). 

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