Phenol synthesis, byproducts

The three-step cumene process, including the liquid-phase reactions and using sulfuric acid, is energy-consuming, environmentally unfavorable and disadvantageous for practical operation the process also produces as an unnecessary byproduct acetone, stoichiometrically. Furthermore, the intermediate, cumene hydroperoxide, is explosive and cannot be concentrated in the final step, resulting in a low one-path phenol yield, ( 5%, based on the amount of benzene initially used). Thus, direct phenol synthesis from benzene in one-step reaction with high... 

Acetophenone can be hydrogenated catalytically to 1-phenylethanol. It is obtained as a byproduct in the Hock phenol synthesis and is purified from the high-boiling residue by distillation. The quantitites obtained from this source satisfy the present demand. 

Liittringhaus et al. 68) have isolated many interesting substances from the byproducts ( 8%) of the Bayer process. The mechanism has been fully clarified and shown to be an aryne route. When chlorobenzene or diphenylether are treated with sodium phenyl, the products are ortho metalated derivatives and benzyne. These give the same products which are formed in the industrial phenol synthesis. The most interesting compounds are 2- and 4-hydroxy biphenyl, 2,6-diphenyl- and 2,4-diphenyl-phenol l). For similar syntheses see 69). 

The use of a fixed-bed cell with Cu particles as the cathode 576 has been suggested for the synthesis. p-Aminophenol, produced by electrochemical reduction of nitrobenzene, was used for the synthesis of hydroquinone 577). According to recent work, the addition of emulsifiers, for example, trialkylamine oxides 578), is supposed to suppress the formation of aniline as a byproduct. The electrosynthesis of p-amino-phenol from nitrobenzene is carried out industrially in India 276). 

Description Acetone and excess phenol are reacted in a BPA synthesis reactor (1), which is packed with a cation-exchange resin catalyst. Higher acetone conversion and selectivity to BPA and long lifetime are characteristic of the catalyst. These properties reduce byproduct formation and catalyst volume. Unreacted acetone, water and some phenol are separated from the reaction mixture by distillations (2-4). Acetone is recycled to the BPA reactor (1) water is efficiently discharged phenol is mixed with feed phenol and purified by distillation (5). The crude-product stream containing BPA, phenol and impurities is transferred to the ciystallizer (6), where ciystalline product is formed and impurities are removed by the mother liquor. Sep-... 

These other products represent carbon lost to products other than synthesis gas. They have to be extracted downstream and disposed of In the other hydrocarbons category are coal tar products - phenol and cresols - and can be extracted and sold as by-product. Otherwise the byproducts need to be separated and burned to produce electricity. 

The commercial dinitrophenol mixture is produced by heating phenol with dilute sulfuric acid, cooling the product, and then nitrating while keeping the temperature below 50 °C, or by nitrating with a mixed acid under careful temperature control (Sax and Lewis 1987). 2,3-, 2,5-, and 3,4-DNP are prepared by nitration of m-nitrophenol. 3,5-DNP is prepared by the replacement of one nitro group by methoxyl in 1,3,5-trinitrobenzene and demethylation of the dinitroanisole by anhydrous aluminum chloride. 2,6-DNP is prepared by sulfonation and nitration of o-nitrophenol (Harvey 1959). 2,6-DNP is also produced as a byproduct in the synthesis of 2,4-DNP by way of 2,4-dinitrochlorobenzene. 

Numerous studies concerning O-alkylation of phenol were reported (refs. 3-9). Described catalysts belong to all the catalyst families oxides (ref. 3) phosphates (refs. 4, 5) metallosilicates (ref. 6) aluminophosphates (ref. 7) ion exchange resin (ref. 8). On the other hand, the selective mono-O-alkylation of diphenols was little reported and mainly in patent literature (ref. 9). The main studies deal with synthesis of guaiacol by methylation of 1-2-dihydroxybenzene 2 (catechol) (eqn. 1) catalyzed by boronphosphate eventually doped or supported (ref. 9). The main difficulties of this reaction consists in physical instability of the catalyst which is eluted in the reaction stream conducting to the formation of methylborate as a byproduct which has to be separated. It is then needed to add some new catalyst continuously. 

The Pschorr reaction was described in connection with the synthesis of the papaverine (3) derivatives (350, 351). The synthesis of petaline (5b) was accomplished (352, 353). Escholamine (4a) and takatonine (4c) were synthesized by a modified Pomeranz-Fritsch reaction (354). The phenolic oxidation of (f )-(-)-N-methylcoclaurine (7c) and (S)-(+)-reticuline (7f) with peroxidase proved to be a failure (355). The oxidation of reticuline with ferricyanide yielded isoboldine (24c) and pallidine (43b) and the byproducts vanillin and thalifoline (2c) (355). A new synthesis of 3-oxo-papaverine was developed (356), and the Eschweiler-Clark method for the synthesis of codamine (7r) was modified (357). Oxidation of reticuline (7f) by enzymatic systems from homogenized P. rhoeas in the presence of hydrogen peroxide gave ( )-/3-hydroxyreticuline (10) (358). 

Cumene [98-82-8] is the principal constituent of heavy naphtha which is the feedstock for phenol and acetone synthesis by the Hock process. It is also a byproduct in the production of sulfite pulp. 

For many reactions, in particular alcohol dehydrations, olefin isomerization, methylchloride synthesis, and phenol alkylations, the proton forms of zeolites are reported to be more active than alumina. However, alumina is preferably applied because of fewer byproducts and slower coking. Thus, the strong Lewis acidity and perhaps also the medium—weak Bronsted acidity of alumina provide an optimal balance between activity and stability these sites have sufficient activity while they deactivate only slowly. 

Chemical synthesis at the cost of generating a hazardous byproduct is not unique to adipic acid production. This and other problems characteristic of the chemical industry are illustrated by further examination of adipic acid synthesis. Benzene, the primary starting material in adipic acid manufacture, is a proven carcinogen (9). Benzene is used widely in the chemical industry, particularly as a feedstock ( ). For example, benzene is used to make phenol (4), the starting material from which a small percentage of adipic acid is currently synthesized. The United States alone product over 12 billion pounds of benzene in 1993 (10). Benzene is derived exclusively from petroleum (4,5), a non-renewable fossil fuel. Of the chemicals in the United States which are produced in excess of 10 million pounds per year, 98% are derived from petroleum feedstocks (4). Finally, extreme reaction conditions which are used in adipic acid manufacture include temperatures up to 250°C and pressures which reach 800 psi. Reaction conditions such as these are used routinely by the chemical industry. 

The most common preparative method to prepare the aryl allyl ether is the Williamson s ether synthesis [la,b]. Typically, aryl allyl ethers can be obtained from phenol derivatives and allylic halide under basic conditions (KjCOj) in refluxing acetone. This method is convenient for the preparation of simple allyl aryl ethers. However, some side reactions such as a competitive C-allylation (Sn2 type reaction) often accompany the formation of undesired byproducts. Mitsunobu reaction of phenol derivatives with allylic alcohols instead of allylic halides can be used under mild conditions [13]. In particular, when the allyl halide is unstable, this procedure is effective instead of the Williamson s ether synthesis. This method is also useful for the preparation of chiral allyl aryl ether from chiral allylic alcohol with inversion at the chiral center. Palladium catalyzed O-allylation of phenols is also applicable, but sometimes a lack of site-selectivity with unsymmetrical allylic carbonate [14] may be a problematic issue. 

As it was mentioned earlier, many byproducts are formed in the conventional BPA synthesis from acetone and phenol that unfavorably results in the necessity of very costly purification steps and loss of the raw materials. Thus, recently the method of BPA... 

Pillar[n]arenes were accidentally produced as an unexpected byproduct during our investigation towards the synthesis of new phenolic polymers via the reactiOTi of 1,4-dimetoxybenzene with paraformaldehyde in the presence of a Lewis acid... 

It can be seen that cleaning up the crude synthesis gas from a Lurgi gasifier is a complicated operation. Part or all of the cost of this cleanup is offset by the value of the recovered byproducts,—ammonia, phenols, hydrogen cyanide, aromatics, tar oil, tar, and sulfur. The gas cleanup in a Winkler or Koopers-Totzek gasifier is considerably simpler. 

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