Benzenols

Synonym(s) Benzenol, hydroxybenzene, monophenol, oxybenzene, phenyl alcohol, phenyl hydrate, phenyl hydroxide, phenylic acid, phenylic alcohol Lewis 1996... 

Synonyms AI3-01814 AIDS-352 Baker s P and S liquid and ointment Benzenol BRN 0969616 Carbolic acid Carbolic oil Caswell No. 649 CCRIS 504 CRS EINECS 203-632-7 EPA pesticide chemical code 064001 FEMA No. 3223 Fenosmolin Fenosmoline Hydroxy-benzene IPH Izal Monohydroxybenzene Monophenol NA 2821 NCI-C50124 NSC 36808 Oxybenzene Phenic acid Phenic alcohol Phenol alcohol Phenyl hydrate Phenyl hydroxide Phenylic acid Phenylic alcohol RCRA waste number U188 UN 1671 UN 2312 UN 2821. 

Benzenediol, see Hydroquinone p-Benzenediol, see Hydroquinone Benzeneformic acid, see Benzoic acid Benzene hexachloride, see Lindane Benzene hexachloride-a-isomer, see a-BHC Benzene-crs-hexachloride, see p-BHC Benzene-y-hexachloride, see Lindane a-Benzene hexachloride, see a-BHC p-Benzene hexachloride, see p-BHC 6-Benzene hexachloride, see 8-BHC y-Benzene hexachloride, see Lindane frans-a-Benzene hexachloride, see p-BHC Benzene hexahydride, see Cyclohexane Benzene methanoic acid, see Benzoic acid Benzene methanol, see Benzyl alcohol Benzene tetrahydride, see Cyclohexene Benzenol, see Phenol... 

The reactivities of aryl halides, such as the halobenzenes, are exceedingly low toward nucleophilic reagents that normally effect displacements with alkyl halides and activated aryl halides. Substitutions do occur under forcing conditions of either high temperatures or very strong bases. For example, chlorobenzene reacts with sodium hydroxide solution at temperatures around 340° and this reaction was once an important commercial process for the production of benzenol (phenol) ... 

Exercise 14-20 In the hydrolysis of chlorobenzene-1-14C with AM aqueous sodium hydroxide at 340°, the products are 58% benzenol-1-14C and 42% benzenol-2-14C. Calculate the percentage of reaction proceeding (a) by an elimination-addition mechanism, and (b) by direct nucleophilic displacement. Would you expect the amount of direct displacement to increase, or decrease, if the reaction were carried out (a) at 240° and (b) with lower concentrations of sodium hydroxide Give your reasoning. 

As with most organic halides, aryl halides most often are synthetic intermediates for the production of other useful substances. For example, chlorobenzene is the starting aryl halide for the synthesis of DDT it also is a source of benzenol (phenol, Section 14-6C) which, in turn, has many uses (Section 26-1). 

An extreme example of the stabilization of an enol by electron de-localization is benzenol (phenol), which exists 100% in the enol form. In this case the extra stability of the benzene ring is the important factor ... 

Exercise 22-5 Predict the effect on the ultraviolet spectrum of a water solution of benzenamine when hydrochloric acid is added. Explain why a solution of sodium benzenoxide absorbs at longer wavelengths than a solution of benzenol (see Table 22-3). 

This effect is made clear in the valence-bond structures for the ortho-para substitution intermediates from benzenol (phenol) ... 

Other cyclohexyl compounds are obtained by catalytic hydrogenation of the corresponding benzene derivatives. Thus cyclohexanol is obtained from benzenol, and cyclohexanamine is obtained from benzenamine (aniline) ... 

Exercise 23-33 Benzenediazonium chloride solvolyzes in water to give a mixture of benzenol and chlorobenzene. Some of the facts known about this and related reactions... 

Cuprous-catalyzed replacement reactions are called Sandmeyer reactions aryl chlorides, bromides, cyanides, and nitro compounds are prepared in this way formation of aryl iodides requires no catalyst, fluorides are obtained by heating diazonium fluoroborates (i.e., Schiemann reaction) benzenols are obtained by warming aqueous diazonium salt solutions. 

Exercise 25-33 a. The lactim-lactam equilibrium of 2-hydroxypyrimidine lies on the side of the lactam, yet the benzenol-cyclohexadienone equilibrium lies far on the side of benzenol (Section 26-1), Explain what factors make for the large difference in the positions of these two equilibria. (Bond energies and review of Section 24-1A may help in showing you the differences between these systems,)... 

The situation is different for phenols because of the inclusion of the carbon-carbon double bond into the aromatic ring and the associated aromatic stabilization. Phenol (benzenol) exists exclusively in the enol form ... 

The physical properties of some representative phenols are summarized in Table 26-1. In general, phenols are somewhat more polar than the corresponding saturated alcohols. The magnitudes of the differences are well illustrated by comparison of the physical properties of benzenol and cyclohexanol, shown in Table 26-2. The determining factor appears to be the greater acidity of the phenolic hydroxyl group, which means that, in the undissociated... 

Benzenol and the 2-, 3-, and 4-methylbenzenols (cresols) can be isolated from coal tar (Section 22-11). Benzenol itself is used commercially in such large quantities that alternate methods of preparation are necessary and most of these start with benzene or alkylbenzenes. Direct oxidation of benzene is not satisfactory because benzenol is oxidized more readily than is benzene. 

At one time, benzenol was made industrially by sulfonating or chlorinating benzene and then introducing the hydroxyl group by nucleophilic substitution with strong alkali ... 

Current commercial syntheses of benzenol involve oxidation of methyl-benzene or isopropylbenzene (Section 16-9E). Oxidation of isopropylbenzene is economically feasible for the production of benzenol because 2-propanone... 

Enols are stronger acids than alcohols because of the increase in electron delocalization in enolate anions as compared to the neutral enols (see Section 15-8A). The stabilization energy of benzenol (Table 21-1) is 48 kcal mole-1, 5 kcal greater than that of benzene. We can ascribe this increase to delocalization of an unshared electron pair from oxygen ... 

We can be confident that substituent groups that stabilize the anion will increase the acidity. Thus 4-nitrobenzenol is about 500 times stronger as an acid than benzenol, because of the increased delocalization of charge to the nitro group ... 

It is possible to prepare esters of phenols with carboxylic acid anhydrides or acid halides, and phenyl ethers by reaction of benzenolate anion with halides, sulfate esters, sulfonates, or other alkyl derivatives that react well by the SN2 mechanism ... 

Almost all phenols and enols (such as those of 1,3-diketones) give colors with ferric chloride in dilute water or alcohol solutions. Benzenol... 

These reactions do not work well with simple benzenols because the key step is formation of the keto isomer of the arenol —a process that is unfavorable for simple benzenols ... 

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