Higher alkyl phenols

Among the tertiary-butyl phenols, the o- and p-derivatives and 2,6-di-tert-butylphenol are commerically important. They are used in the production of antioxidants. o-tert-Butylphenol and 2,6-di-tert-butylphenol are produced by alkylation of phenol with isobutene at a reaction temperature of 100 °C in the presence of aluminum phenolate as catalyst. 

Suitable catalysts for the butylation of phenol with isobutene to p-tert-butylphe-nol are sulfuric acid, phosphoric add, boron trifluoride or macroporous, pelleted, strongly acidic sulfonated styrene/divinylbenzene resins. 

Among the long-chain alkylphenols, p-tert-octylphenol, nonylphenol and dode-cylphenol have special commercial significance. Alkylation can take place with straight-chain or branched olefins. 

To produce p-tert-octylphenol, phenol and diisobutylene (a mixture of 2,4,4-trimethyl-l-pentene and 2,4,4-trimethyl-2-pentene) are fed through a bed of ion-exchange resin in the ratio 1.5 1 the resin is maintained at a temperature of 100 to 105 °C by internal cooling tubes. The alkylation is restricted to 95% diisobutylene conversion, to avoid the formation of undesirable by-products. The reaction mixture, which is separated into its constituents by vacuum distillation, consists of 93 to 96% p-tert-octylphenol the concentration of o-tert-octylphenol is between 2 and 3%. 

Nonylphenol is produced by the reaction of phenol with propylene trimer at a temperature of 70 to 125 °C. An ion-exchange resin is used as catalyst. The reaction is normally carried out in two stages to avoid overheating. 

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Cresex [Cresol extraction] One of the Sorbex processes. This one extracts p- or m-cresol from mixed cresols, and ciesols as a class from higher alkyl phenols. By 1990, one plant had been licensed. 

Cresylic acids or tar acids are other names under which mixed cresols containing all the isomers of cresols, some quantities of phenol and mixed xylenols and even some higher alkylated phenols are available in the market. 

In the following chapters monomethyl phenols or cresols and their downstream derivatives will be discussed. Uses of the mother compound in the group of hydroxybenzenes i.e., phenol and also Cs phenols i.e., xylenols and mixed cresols have been shown in Figures 1.1-1.3. Some relevant higher alkyl phenols will be examined at appropriate places. 

Methylation of phenol is commonly used to produce o-cresol and 2,6-xylenol. It is carried out in the gas phase at slightly increased pressure and temperatures of from 300 to 400 °C with AI2O3 catalysts in multitubular reactors. After removing the water, subsequent distillation separates the dried mixture into the products anisole/phenol, 99%-pure o-cresol and 2,6-xylenol. Phenol and anisole are recycled. Higher alkylated phenols can be recovered from the distillation residue. 

Higher alkylated phenols are obtained by the interaction of phenol and C16-C18 olefins from wax cracking. The corresponding alkylated salicylic acids (formed by Kolbe-Schmitt carboxylation) are lubricants for diesel engines. 

Instructions for the TLC of the phenols expected as products of thermolysis were abundantly available already Preliminary experiments owed that the phenol mixtures to be expected were best separated by double development using benzene in a run of IS cm. For speed and reproducibility this solvent gives the best results although superposition of phenol with m- and p-cresols and also some higher alkyl-phenols (cf. Table 8) is unavoidable. Partition-TLC on layers impregnated with formamide has been used successfully to separate these critical homolc ous or isomeric phenols 3°). We have studied thoroughly the scope of application and... 

Higher alkyl ethers are prepared by treating the sodium derivative of the phaiol (made by adding the phenol to a solution of sodium ethoxide in ethyl alcohol) with the alkyl iodide or bromide (Williamson synthesis), for example ... 

The in situ process is simpler because it requires less material handling (35) however, this process has been used only for resole resins. When phenol is used, the reaction system is initially one-phase alkylated phenols and bisphenol A present special problems. As the reaction with formaldehyde progresses at 80—100°C, the resin becomes water-insoluble and phase separation takes place. Catalysts such as hexa produce an early phase separation, whereas NaOH-based resins retain water solubiUty to a higher molecular weight. If the reaction medium contains a protective coUoid at phase separation, a resin-in-water dispersion forms. Alternatively, the protective coUoid can be added later in the reaction sequence, in which case the reaction mass may temporarily be a water-in-resin dispersion. The protective coUoid serves to assist particle formation and stabUizes the final particles against coalescence. Some examples of protective coUoids are poly(vinyl alcohol), gum arabic, and hydroxyethjlceUulose. 

Mercaptan extraction is used to reduce the total sulfur content of the fuel. When potassium isobutyrate and sodium cresylate are added to caustic soda, the solubility of the higher mercaptans is increased and they can be extracted from the oil. To remove traces of hydrogen sulfide and alkyl phenols, the oil is pretreated with caustic soda in a packed column or other mixing device. The mixture is allowed to settle and the product water washed before storage. 

The number of isomers of alkylated aromatics is enormous. Lower members of alkylated benzenes such as xylenes are well resolved and detected by FID and MS. Increased alkylation causes an increase in the number of isomers. In the case of both alkylated phenols and aromatics various isomers are existing in a continuous pattern. The lower alkylation gives few well resolved isomers. The higher alkylation gives a large number of isomers but in smaller concentrations. 

Heat-setting resins cannot be plasticized by low molecular weight plasticizers. Polyvinyl acetals have been claimed for these products. American Cyanamid Co. has suggested polyvinyl acetals or butyrals in an amount of 10 to 25% of the resin for urea and melamine resins. For varnishes and adhesives, combinations of phenolic resins and polyvinyl formal are recommended. Polyvinyl acetals with higher alkyl radicals are suitable for cellulose esters and improve elasticity as well as resistance against water. 

Nafion-H is also very efficiently catalyzes the rearrangement of anisole, methy-lanisoles, and phenetole to ring-alkylated phenols and products of transalkylation when vapors of the alkyl aryl ethers are passed over it at temperatures higher than 160°C. At these reaction temperatures, some of the starting alkyl phenyl ethers... 

Aryl amine intermediates for azo and triphenylmethane dyes, as well as a number of vat dye (anthraquinone) intermediates, are made from compounds such as benzene, alkyl benzenes (toluene and higher homologues), phenol and naphthalene. A limited number of reactions are used to produce the most important dye intermediates, including nitration, reduction, halogenation, sulfonation, /V-alkylation, /V-acylation and alkali fusion33,34. 

Cresols are an isomeric mixture of the simplest of alkyl phenols, i.e., monomethyl phenol or monohydroxy-toluenes. Similarly xylenols are the next higher homologues of cresols and are known as dimethyl phenols or hydroxy xylenes. 

Particles of the enzymatically synthesized phenolic polymers were also formed by reverse micellar polymerization. A thiol-containing polymer was synthesized by peroxidase-catalyzed copolymerization of p-hydroxythiophenol and p-ethylphenol in reverse micelles [70], CdS nanoparticles were attached to the copolymer to give polymer-CdS nanocomposites. The reverse micellar system was also effective for the enzymatic synthesis of poly(2-naphthol) consisting of qui-nonoid structure [71], which showed a fluorescence characteristic of the naphthol chromophore. Amphiphilic higher alkyl ester derivatives were enzymatically polymerized in a micellar solution to give surface-active polymers at the air-water interface [72, 73]. 

A convenient method of obtaining diphenyl alkylphosphonates is to heat triphenyl phosphite with an alcohol at 220-250° in the presence of a catalytic amount of the corresponding alkyl iodide sodium iodide or iodine may also be used as the catalyst. The best results are obtained when the alcohol used boils appreciably higher than phenol (180°), so that the phenol distils off continuously.339... 

For a wide variety of (13 0), (15 0), (17 0) and higher alkyl substituted phenolic lipids a universally applicable method of preparation has been reaction of an OH-protected phenolic aldehyde with an even carbon number n-alkylmagnesium halide, followed by reduction (or dehydration and reduction) and removal of the protective group. This technique has been used with 3-methoxybenzaldehyde, 3,5-dimethoxybenzaldehyde or their isomers and further substituted versions. 

Surfactants are used to control cell size and structure. The most common surfactants are siloxane-oxyalkylene copolymers, polyoxyethylene sorbitan fatty acid esters, and the condensation products of ethylene oxide with castor oil and alkyl phenols. A commonly added additive is urea which is used as a formaldehyde scavenger. Very fine particle size inorganic fillers can be added to act as nucleating sites and to promote finer, more uniform cell structure, as well as increased compressive strength, but at a cost of higher density. 

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