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Preparation of phenols

Phenol is prepared industrially via a multistep process involving the formation and oxidation of cumene. [Pg.590]

A by-product of this process is acetone, which is also a commercially important compound. Over two million tons of phenol is produced each year in the United States. Phenol is used as a precursor in the synthesis of a wide variety of pharmaceuticals and other commercially useful compounds, including bakelite (a synthetic polymer made from phenol and formaldehyde), adhesives for plywood, and antioxidant food additives (BHT and BHA, discussed in Chapter 11). [Pg.590]


For the preparation of phenol, the aqueous solution should be heated carefully to 50-55°, at which temperature the reaction proceeds smoothly above this temperature, how ever, the reaction may rapidly become veiy vigorous, and the heat of reaction will then cause a marked rise in the temperature and the production of a large amount of tarry byproducts. [Pg.195]

The solution must be strongly acid in order to avoid the coupbng reaction between the undecomposed diazonium salt and the phenol (see under Azo Dyes). For the preparation of phenol and the cresols, the aqueous solution of the diazonium compound is warmed to about 50° at higher temperatures the reaction may become unduly vigorous and lead to appreciable quantities of tarry compounds... [Pg.595]

Preparation of phenols Heating its aqueous acidic solution converts a diazonium salt to a phenol This IS the most general method for the synthesis of phenols... [Pg.960]

One of the mdustnal processes for the preparation of phenol discussed in Section 24 6 includes an acid catalyzed rearrangement of cumene hydroperoxide as a key step This reaction proceeds by way of an intermediate hemiacetal... [Pg.1023]

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. [Pg.145]

Other routes for the preparation of phenol are under development and include the Dow process based on toluene. In this process a mixture of toluene, air and catalyst are reacted at moderate temperature and pressure to give benzoic acid. This is then purified and decarboxylated, in the presence of air, to phenol (Figure 23.5). [Pg.637]

Figure 23.16. Diagrammatic representation of resin kettle and associated equipment used for the preparation of phenolic resins. (After Whitehouse, Pritchett and Barnett )... Figure 23.16. Diagrammatic representation of resin kettle and associated equipment used for the preparation of phenolic resins. (After Whitehouse, Pritchett and Barnett )...
Reaction of benzenesulfonic acid with sodium hydroxide This is the oldest method for the preparation of phenol. Benzene is sulfonated and the benzenesulfonic acid heated with molten sodium hydroxide. Acidification of the reaction mixture gives phenol. [Pg.1000]

A very similar rearrangement takes place during the acid-catalysed decomposition of hydroperoxides, RO—OH, where R is a secondary or tertiary carbon atom carrying alkyl or aryl groups. A good example is the decomposition of the hydroperoxide (84) obtained by the air-oxidation of cumene [(l-methylethyl)benzene] this is used on the large scale for the preparation of phenol and acetone ... [Pg.128]

It is well-known that the anodic trifluoroacetoxylation of benzene derivatives is a useful method for the preparation of phenol derivatives (Eq. 30). Schafer et al. have successfully achieved CH-functionalization of various hydrocarbons by anodic oxidation in 0.05 M Bu4NPF6/CH2Cl2 containing 20% TFA and 4% (CF3C0)20 as shown in Eqs 31 and 32 [75]. [Pg.43]

Uses Preparation of phenol, 4-chlorophenol, chloronitrobenzene, aniline, 2-, 3-, and 4-nitro-chlorobenzenes carrier solvent for methylene diisocyanate and pesticides solvent for paints insecticide, pesticide, and dyestuffs intermediate heat transfer agent. [Pg.282]

Uses Wetting agent dyestuffs preparation of phenolic antioxidants plastics, resins, solvent, disinfectant, pharmaceuticals, insecticides, fungicides, and rubber chemicals manufacturing lubricant and gasoline additive possibly used as a pesticide plasticizers. [Pg.491]

Give the equations of reactions for the preparation of phenol from cumene. [Pg.75]

You are given benzene, cone. H2SO4 and NaOH. Write the equations for the preparation of phenol using these reagents. [Pg.75]

This diazotization reaction is compatible with the presence of a wide variety of substituents on the benzene ring. Arenediazonium salts are extremely important in synthetic chemistry, because the diazonio group (N=N) can be replaced by a nucleophile in a radical substitution reaction, e.g. preparation of phenol, chlorobenzene and bromobenzene. Under proper conditions, arenediazonium salts react with certain aromatic compounds to yield products of the general formula Ar-N=N-Ar, called azo compounds. In this coupling reaction, the nitrogen of the diazonium group is retained in the product. [Pg.139]

Phenol has a wide range of uses, including in the preparation of phenolic and epoxy resins (bisphenol-A), nylon-6 (caprolactam), 2,4-D, selective solvents for refining lubricating oils, adipic acid, salicylic acid, phenolphthalein, pentachlorophenol and other derivatives in germicidal paints as a laboratory reagent and in dyes and indicators and as a slimicide, biocide and general disinfectant (Lewis, 1993). The world demand for phenol by use in 1993 was reported as (%) phenolic resins, 35 bisphenol-A, 30 caprolactam, 15 alkylphenols, 7 aniline, 5 and others, 8 (Wallace, 1996). [Pg.750]

Section 24.6 Table 24.3 listed the main industrial methods for the preparation of phenol. Laboratory syntheses of phenols are usually carried out by hydrolysis of aryl diazonium salts. [Pg.1023]

Reaction XXVII. Condensation of Chloroform with Phenols and simultaneous Hydrolysis of the Product (Reimer-Tiemann). (B., 15, 2585.) —This is a well-known method for the preparation of phenolic-aldehydes. The phenol is treated with chloroform and an alkaline hydroxide, when — CHC12 enters the ortho- and to a lesser extent the para-position to the hydroxyl group hydrolysis to an aldehyde then takes place. [Pg.104]

Yield.—75—80% theoretical. Na and Ca salts, white powders, soluble in water used in preparation of phenol, see p. 210. [Pg.311]

The use of a-thiophenyl enones (106 Scheme 12) allows the preparation of phenols such as (107) from cyclic ketones (18).30 The same product can also be obtained by normal Robinson annulation of methyl vinyl ketone (30) and the p-keto sulfoxide (lOS).30 Acceptors other than a, 3-unsaturated carbonyls have been used in both the Michael reaction and the Robinson annulation process. For example, nu-... [Pg.8]

Dialkyl sulfates can replace the halogen derivatives, and this modification is especially useful for the preparation of phenolic ethers ... [Pg.426]

Note. (1) It is important in this preparation to ensure an excess of zinc chloride over sodium cyanide. If the la.tter is in excess, the zinc cyanide generally precipitates as a sticky mass, which is difficult to filter and unsatisfactory for the preparation of phenolic aldehydes. [Pg.468]


See other pages where Preparation of phenols is mentioned: [Pg.376]    [Pg.430]    [Pg.430]    [Pg.502]    [Pg.169]    [Pg.180]    [Pg.173]    [Pg.282]    [Pg.46]    [Pg.339]    [Pg.132]    [Pg.68]    [Pg.68]    [Pg.69]    [Pg.216]    [Pg.84]   
See also in sourсe #XX -- [ Pg.590 ]




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Phenols preparation

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