Hydrogen phenol hydrogenation

AROMATIC HYDROGEN ALIPHATIC HYDROGEN PHENOLIC HYDROGEN... 

C, b.p. 16UC. Manufactured by heating phenol with hydrogen under pressure in the presence of suitable catalysts. Oxidized to adipic acid (main use as intermediate for nylon production) dehydrogenated to cyclohexanone. 

Phenols formed by the substitution of a hydrogen atom by a hydroxyl group, OH, in an aromatic ring ( I t)... 

Now heat the tube very gently at first and then more strongly. A non-conden-sible product such as hydrogen or methane is best detected by collecting a sample of the gas in a test-tube as shown in Fig. 71(A). A condensible product such as benzene or phenol should be collected by twisting the delivery-tube downwards and collecting the liquid in a few ml. of water in a test-tube as shown In Fig. 71(B). 

Dimethyl sulphate is of particular value for the methylation of phenols and sugars. The phenol is dissolved in a slight excess of sodium hydroxide solution, the theoretical quantity of dimethyl sulphate is added, and the mixture is heated on a water bath and shaken or stirred mechanically (compare Section IV, 104). Under these conditions only one of the methyl groups is utilised the methyl hydrogen sulphate formed in the reaction reacts with the alkali present. -... 

The phenyl propionate may be prepared by slowly adding 196 g. (120 ml.) of redistilled thionyl chloride to a mixture of I50g. of pure phenol and 132 g. (133 ml.) of propionic acid (compare Fig. 111,31, 1), warming to drive all the sulphur dioxide and hydrogen chloride, and distilling 190 g. of phenyl propionate, b.p. 202-212° (the pure substance boils at 211°) are obtained. 

Heat 0 5 g. of pseudo-saccharin chloride with an excess of the phenol to 125-140° for 15-20 minutes hydrogen chloride is evolved. Wash the product with dilute sodium hydroxide solution and then with water. Recrystallise the derivative from ethanol. 

By interaction of hydrogen cyanide and hydrogen chloride with an anxnatic compound (hydrocarbon, phenol or phenol ether) in the presence of aluminium chloride (or zinc chloride). This is known as the Gattermann... 

By the condensation of a nitrile with a phenol or phenol ether in the presence of zinc chloride and hydrogen chloride a hydroxyaryl- or alkoxyaryl-ketone is produced. The procedure is termed the Hoesch reaction and is clearly an extension of the Gattermann aldehyde reaction (Section IV,121). The reaction gives the best results with polyhydric phenols and their ethers with simple monohydric phenols the imino ester hydrochloride is frequently the sole product for example ... 

Compounds containing one or more —OH or —SH groups, such as water, alcohols, phenols, oximes, hydrogen sulphide and thiols. 

In a 500 ml. conical flask place 50 ml. of glachtl acetic acid, 25 ml. of 40 per cent, formaldehyde solution (formalin) and 20 g. of phenol. Wrap a cloth or towel loosely around the neck and opening of the flask. Pass dry hydrogen chloride gas (Section 11,48,1) into the mixture. Within 5 minutes, a large mass of pink plastic is formed the reaction is sometimes very vigorous. The yield is 36 g. It is frequently necessary to break the flask in order to remove the product completely for this reason a beaker, or metal flask or beaker, is preferable. 

The derivative selected in any particular instance should be one which clearly singles out one compound from among all the possibilities and thus enables an unequivocal choice to be made. The melting points of the derivatives to be compared should differ by at least 5-10°. Whenever possible, a derivative should be selected which has a neutralisation equivalent as well as a melting point (e.g., an aryloxyacetic acid derivative of a phenol. Section IV,114,4, or a hydrogen S nitrophthalate of an alcohol. Section 111,25,5). 

Band 1, 3 OSyL (3242 cm.". ) Hydrogen bonded 0—H absorption of the phenolic group (Table II). 

Two synthetic bridged nitrogen heterocycles are also prepared on a commercial scale. The pentazocine synthesis consists of a reductive alkylation of a pyridinium ring, a remarkable and puzzling addition to the most hindered position, hydrogenation of an enamine, and acid-catalyzed substitution of a phenol derivative. The synthesis is an application of the reactivity rules discussed in the alkaloid section. The same applies for clidinium bromide. 

Hydroxide ion lies below phenol m Table 1 7 hydrogen carbonate ion lies above phe nol The practical consequence of the reactions shown is that NaOH is a strong enough base to convert phenol to phenoxide ion but NaHCOs is not... 

Some ortho substituted phenols such as o mtrophenol have significantly lower boiling points than those of the meta and para isomers This is because the intramolec ular hydrogen bond that forms between the hydroxyl group and the substituent partially compensates for the energy required to go from the liquid state to the vapor... 

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... 

Because phenols are not converted to aryl halides by reaction with hydrogen halides reac tion proceeds no further than shown m the preceding general equation For example... 

The —OH group of phenols makes it possible for them to participate m hydrogen bonding This contributes to the higher boiling points and greater water solubility of phenolic compounds compared with arenes and aryl halides... 

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... 

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