Phenol synthesis method

KOLBE - SCHMIDT Salicylic Acid Synthesis Caiboxylation (usually ortho) of phenols. Industrial method to obtain salicylic acid derivatives... 

This phenol synthesis complements the analogous reaction (see below) from arylthallium ditrifluoroacetates (147). Although yields are only moderate, the procedure represents a viable conversion of aryl Grignard reagents to phenols. It is a practical method, however, only when the diarylthallium trifluoroacetate precursor is formed via the Grignard route the alternative synthesis via symmetrization of arylthallium ditrifluoroacetates is obviously circuitous, since the latter compounds may be converted directly to phenols. 

Figure 10. Synthesis of the 1,2- and 3,4-dihydrodiols of phen-anthrene from the related phenols by Method IV (47). Reagents (i) (KSO ) NO or (PhSe0>20 (ii) LiAlH or NaBH,, 0 (iii) di-azonium salt of sulfanilic acid (iv) Na O S (vJ (JrO. ...

Table 10.6 shows the catalytic performances of the selective benzene oxidation on the zeolite-supported Re catalysts under steady-state reaction conditions [107]. Catalyhc activity and selectivity largely depended on the types of zeolites and the preparation methods. The Re catalysts prepared by CVD of MTO exhibited higher catalyhc achvity and phenol selechvity than those prepared by the convenhonal impregnation method as supports (Table 10.6). Physical mixing of MTO with the supports provided poor phenol synthesis.

Phenol Synthesis A new method for obtaining arenes from easily available furans was reported by Hashmi et al. [19]. In this first paper, AuCl3 was used to produce a highly substituted phenol without side products. 

In 1987, the successful startup of a new process was announced for the production of 10,000 tons/year of catechol and hydroquinone by the selective oxidation of phenol with H202 catalyzed by TS-1 at the Enichem plant in Ravenna, Italy (Notari, 1988). Soon thereafter, it was disclosed that another new process for the production of cyclohexanone oxime from cyclohexanone, H202, and NH3 with TS-1 as the catalyst was being developed (Roffia et al., 1990).The fact that a material with unusual catalytic properties had been obtained was then finally recognized, and the interest in titanium-containing catalysts spread rapidly in the scientific community, especially in industrial research laboratories. In the meantime, the synthesis method was studied and described in more detail and when all the necessary precautions were taken, TS-1 was reproduced in other laboratories, as were the highly selective catalytic reactions. The subsequent work confirmed that Ti v can assume the tetrahedral coordination necessary for isomorphous substitution of SiIV and added valuable information about the structure, properties and catalytic performance of the material. New reactions catalyzed by TS-1 have been discovered, and new synthetic methods... 

The most important methods for producing phenol commercially and for obtaining phenol by methods other than direct synthesis (natural phenol) are briefly summarized in Table XVI. The essential features of... 

The crucial step of the new phenol synthesis is oxidizing the obtained benzoic acid to phenol. Early literature data indicated that heating copper benzoate or benzoic acid in the presence of copper salts gave various phenol precursors—e.g., phenyl benzoate and salicylic acid, as well as phenol itself (3, 10, 13, 24, 26, 36). In one of the initial approaches, by Dow Chemical Co., mixtures of benzoic acid vapors, air, and steam were passed over a CuO catalyst promoted with metal salts, giving phenol and phenyl benzoate (5). However, much tar was produced, probably because of the high reaction temperature, which led to excessive decomposition. Because of this, the vapor-phase method was abandoned in favor of the liquid-phase process. Next, benzoic acid was oxidized in aqueous solution with inorganic copper salts, as shown below (18) ... 

Syper, L. The Baeyer-Villiger oxidation of aromatic aldehydes and ketones with hydrogen peroxide catalyzed by selenium compounds. A convenient method for the preparation of phenols. Synthesis 1989, 167-172. 

Thallinm(ni) °, particnlarly as its triflnoroacetate salt , has been successfully used for the synthesis of phenols. This method can be carried out in a single step and is subject to isomer orientation control" . The aromatic compound to be hydroxylated is first thallated with thallium trifluoroacetate (TTFA)" and, by treatment with lead tetraacetate followed by triphenylphosphine and then dilute NaOH, it is converted to the corresponding phenol (equation 57). Table 1 shows some examples of these transformations . ... 

The Mitsunobu reaction proved to be useful for the synthesis of aryl alkyl ethers from alcohols and phenols. The method proceeds under mild conditions and tolerates many functional groups with inversion of configuration, as exemplified by the reactions of lactate and ewrfo-5-norbornen-2-ol (equations 4 and Neighboring group participation,... 

Reactions with persulfate and pyrosulfate. The persulfate (peroxy-dlsulfate Ion, S2O8 ) reaction, also known as the Elba persulfate oxidation, has been Important In synthesis of hydroxylated phenols. The method has occasionally been used for synthesis of 0-sulfate conjugates. For example, 4-hydroxy-2-nltrophenyl sulfate was obtained when 3-nltrophenolate was stirred with potassium peroxydlsulfate at room temperature for 2 days (91,). The persulfate reaction has been used for the sulfation of various phenols and aromatic amines however the yields are usually low to moderate (77 ). The sulfate group Is preferentially Introduced In the 4-posltlon of phenols and In the 2-posltlon of aromatic amines but If these positions are blocked substitution at the 2- and... 

The hydroxylation reaction of phenol with hydrogen peroxide and zeolite encapsulated MePc has received considerable attention. With the perchlorinated phthalocyanine (ClnPc) and tetra-nitro ((N02)4Pc) substituted ligands, catalysts with superior activity have been obtained [32], Such catalysts have been prepared via the zeolite synthesis method around the individual complexes. With the former more bulky complex only the slimmer hydroquinone (HQ) has been obtained, while with the encapsulated perchloroPc equal ratios of catechol (CAT) and the para-isomer have been obtained (see table). The unsubstituted Pc in zeolite Y both with Co and Cu as metallating ion, show an excess of the ortho-isomer (CA T) [32J, corresponding to the approximate thermodynamic ratio. This points to the critical importance of the available space close to the encapsulated Pc as selectivity determining parameter when there is more space, the catalyst yields more catechol. 

It has been presented here that there is not a unique Ti-Beta material, but the characteristics and catalytic performance strongly depend on chemical composition and synthesis procedure. Then, new synthesis procedures which allow to prepare samples with much lower A1 content than any one reported before have been developed. Moreover, by using highly reactive and stable seeds, crystals of Ti-Beta zeolite have been produced, which have an inner core of aluminosilicate composition, covered by an outer shell of Titanosilicate which accounts for about 98 % of the mass. These synthesis methods have lead to samples which present an improved catalytic behaviour for reactions such as olefin oxidation and phenol hydroxylation using H202 as oxidant. 

A variety of approaches has been adopted in the following methods which involve comparatively unusual and neglected routes to phenols. Syntheses described in this section have been employed to obtain cycloaromatic structures and bicyclic heterocyclic compounds containing the phenolic group. Methods involving the use of noble and transition metal compounds have invariably produced polyalkylphenols and these procedures are more appropriately considered in Chapter 6 although it is clear that there is a considerable overlap between the synthesis of monoalkylphenols and polyalkyl compounds. 

Since cardanols can be obtained from anacardic acids and cardols from orsellinic acids, the methods outlined have a general applicability to a range of phenolic lipids. Reference has been made largely to the phenols of the Anacardiacae but the methods are likely to be applicable to other phenolic systems, and those with methylene-interrupted structures at different side-chain positions. Alkynes and phosphorans have both proved invaluable in synthetic studies but attention should be drawn to the very elegant use of ailenic compounds in the polyethenoid (arachidonic) series (ref. 168) which has a potential application with phenolic lipids. Methods for the synthesis of leukotrienes are also relevant for the methylene group-interrupted structures of phenolic lipids (169). 

The first large-scale synthesis of phenol was based on benzene sulfonation and subsequent alkali fusion other methods of phenol synthesis were developed during the first half of the present century. 

The classical method for preparing hydroquinone is based on the oxidation of aniline with manganese dioxide or sodium dichromate in sulfuric acid. The qui-none which is obtained as an intermediate is reduced to hydroquinone with iron filings in dilute hydrochloric acid. This process, which is still used e.g. in India and China, is characterized by the simultaneous production of large amounts of manganese or chromium and iron salts, together with ammonium sulfate. For this reason, oxidative cleavage of p-diisopropylbenzene similarly to phenol synthesis was developed for the production of hydroquinone. 

Hashmi s group surveyed a modular library of 21 Au-ADC complexes prepared by the isocyanide method in the catalytic phenol synthesis using alkyne-... 

EAN IL was used in various reactions such as Biginelli reaction, condensation reaction, nitration of phenol, synthesis of P-amino ketone, ete. Nitration of phenol using ferric nitrate and clayfen in the IL, EAN, has been reported imder irltrasound irradiation [102]. Jaeger and Tucker in 1989 reported the Diels-Alder reaction involving EAN IL [ 103], IL EAN was prepared as per the literature method. EAN was found to be a more suitable solvent and catalyst for these reactions. In the presence of EAN, the reactions proceed in a shorter time, under milder conditions, and with excellent yield of products. EAN is liqttid at room temperature and is miscible with water thus, the separation and isolation of the product becomes easier. Its autoprotolysis constant is high, and the large electroactivity area and conductivity allow it to be used as a potential solvent. Araos et al. [104] reported the stability of a variety of lyotropic liquid crystals formed by a nttmber of polyoxyethylene nonionic surfactants in the room-temperature IL EAN. 

GattermaDD synthesis A method for the synthesis of aromatic hydroxyaldehydes. E.g. AICI3 is used to bring about the condensation of phenol with a mixture of gaseous hydrochloric acid and hydrocyanic acid an aldimine hydrochloride is formed and on hydrolysis gives p-hydroxybenzaldehyde... 

The phenolic hydroxyl group of tyrosine, the imidazole moiety of histidine, and the amide groups of asparagine and glutamine are often not protected in peptide synthesis, since it is usually unnecessary. The protection of the hydroxyl group in serine and threonine (O-acetylation or O-benzylation) is not needed in the azide condensation procedure but may become important when other activation methods are used. 

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