Hydroxy compounds phenols

The usual method of acetylation by means of acetic anhydride or a mixture of acetic acid and anhydride is to reflux the hydroxy compound and the anhydride for 10-15 minutes. In the present instance, the temperature is kept low by the presence of ice and the hydrolysis of the anhydride is inhibited, permitting it to react with the hydroxy compound. Phenol and other aromatic hydroxy compounds can be acetylated by this method. 

VI VI, 1st 1923 499-608 Hydroxy Compounds. Phenol Aromatic Acohols, Phenol-... 

Diasomethane Method. Diazomethane readily methylates phenolic hydroxy-compounds, primary and secondary amines, and carboxylic acids,... 

A fairly general procedure consists in coupling a phenol or naphthol with a diazotised amine, reducing the product to an aminophenol or aminonaphthol, and oxidising the hydroxy compound with acid ferric chloride solution. This method is illustrated by the preparation of (3 (or 1 2)-naphthoquinone ... 

Reactions with Alcohols, Phenols, and Other Hydroxy Compounds... 

The reaction with sodium sulfite or bisulfite (5,11) to yield sodium-P-sulfopropionamide [19298-89-6] (C3H7N04S-Na) is very useful since it can be used as a scavenger for acrylamide monomer. The reaction proceeds very rapidly even at room temperature, and the product has low toxicity. Reactions with phosphines and phosphine oxides have been studied (12), and the products are potentially useful because of thek fire retardant properties. Reactions with sulfide and dithiocarbamates proceed readily but have no appHcations (5). However, the reaction with mercaptide ions has been used for analytical purposes (13)). Water reacts with the amide group (5) to form hydrolysis products, and other hydroxy compounds, such as alcohols and phenols, react readily to form ether compounds. Primary aUphatic alcohols are the most reactive and the reactions are compHcated by partial hydrolysis of the amide groups by any water present. 

A diazonium salt is a weak electrophile, and thus reacts only with highly electron-rich species such as amino and hydroxy compounds. Even hydroxy compounds must be ionized for reaction to occur. Consequendy, hydroxy compounds such as phenols and naphthols are coupled in an alkaline medium (pH > of phenol or naphthol typically pH 7—11), whereas aromatic amines such as N,N diaLkylamines are coupled in a slightly acid medium, typically pH 1—5. This provides optimum stabiUty for the dia2onium salt (stable in acid) without deactivating the nucleophile (protonation of the amine). 

The reaction of alcohols and acid chlorides in the presence of magnesium has been described (68). With primary and secondary alcohols the reaction is very smooth, and affords high and sometimes quantitative yields. Difficulty esteritiable hydroxy compounds such as tertiary alcohols and phenols can be esteritied by this method. The reaction carried out in ether or benzene is usually very vigorous with evolution of hydrogen. 

In many cases, substituents linked to a pyrrole, furan or thiophene ring show similar reactivity to those linked to a benzenoid nucleus. This generalization is not true for amino or hydroxyl groups. Hydroxy compounds exist largely, or entirely, in an alternative nonaromatic tautomeric form. Derivatives of this type show little resemblance in their reactions to anilines or phenols. Thienyl- and especially pyrryl- and furyl-methyl halides show enhanced reactivity compared with benzyl halides because the halogen is made more labile by electron release of the type shown below. Hydroxymethyl and aminomethyl groups on heteroaromatic nuclei are activated to nucleophilic attack by a similar effect. 

The most common impurities are the corresponding acid and hydroxy compound (i.e. alcohol or phenol), and water. A liquid ester from a carboxylic acid is washed with 2N sodium carbonate or sodium hydroxide to remove acid material, then shaken with calcium chloride to remove ethyl or methyl alcohols (if it is a methyl or ethyl ester). It is dried with potassium carbonate or magnesium sulfate, and distilled. Fractional distillation then removes residual traces of hydroxy compounds. This method does not apply to esters of inorganic acids (e.g. dimethyl sulfate) which are more readily hydrolysed in aqueous solution when heat is generated in the neutralisation of the excess acid. In such cases, several fractional distillations, preferably under vacuum, are usually sufficient. 

As already indicated, the polycarbonates may be produced from a wide range of polyfunctional hydroxy compounds. In practice only the diphenyl compounds have proved of much interest and the only polycarbonate of commercial significance is derived from bis-phenol A 2,2-bis-(4-hydroxyphenyl) propane. 

Heterocyclic compounds carrying hydroxyl groups may be compared with phenols. Thomson has reviewed the tautomeric behavior of phenols often both tautomeric forms of polycyclic compounds such as naphthols can be isolated. Early work on hydroxy-thiophenes and -furans was also reviewed by Thomsond but until recently their chemistry has been in a somewhat confused state. A pattern is now beginning to emerge, at least for the a-substituted compounds, which appear to exist as A -oxo derivatives and to attain equilibrium slowly with the corresponding A -oxo forms. For the a-hydroxy compounds, the equilibrium generally favors the A -oxo form. 

Deoxygenation of the nitroarene in the presence of phenol or an enol (acetyl acetone) fails to yield the 3//-azepine. On the basis of these studies it is concluded that there is a correlation between azepine formation and the p/(a of the hydroxy compound and only those hydroxy compounds of pATa >12 yield 3//-azepines. The detrimental effect of acid conditions on 3H-azepine formation has been referred to earlier.214... 

In this discussion phenyl , phenol and phenoxide refer not only to the specific entities C6H5 —, C6H5OH, and C6H50 but also include naphthols and other aromatic hydroxy compounds. 

The reagent reacts with primary and secondary amines and phenols but not aliphatic alcohols and is, thus, particularly useful for determining phenols in the presence of aliphatic hydroxy compounds. 

Reaction with alcohols is general for diazo compounds, but it is most often performed with diazomethane to produce methyl ethers or with diazo ketones to produce ot-keto ethers, since these kinds of diazo compounds are most readily available. With diazomethane the method is expensive and requires great caution. It is used chiefly to methylate alcohols and phenols that are expensive or available in small amounts, since the conditions are mild and high yields are obtained. Hydroxy compounds react better as their acidity increases ordinary alcohols do not react at... 

Hydroxy compounds in the aromatic series behave dilferently depending on whether the hydroxy group is phenolic, benzylic or more remote from the ring. 

Esters of sulfonic acids give different products depending on the reducing agent, on the structure of the parent sulfonic acid, and especially on the structure of the hydroxy compound, alcohol or phenol. 

Catalytic hydrogenation over Raney nickel converted benzenesulfonates of both alcohols and phenols to parent hydroxy compounds, benzene and nickel sulfide. p-Toluenesulfonates of alcohols are reduced similarly while p-tolu-enesulfonates of phenols gave nickel p-toluenesulfinates and aromatic hydrocarbons. The yields of the hydroxy compounds range from 25 to 96% [698]. 

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