Phenol as a solvent

Cl Disperse Violet 26 is prepared by the reaction of l,4-diamino-2,3-dichloroanthraquinone (Cl Disperse Violet 28 (35)) with potassium phenoxide in phenol as a solvent at high temperature. Introduction of phenoxy groups into the 2,3-position shifts the shade to bright, reddish violet and improves the lightfastness and sublimation resistance. 

The solvent can also affect regioselectivity. Consider O- vs C-alkylation of phenoxide ion with allyl chloride or bromide. In water, with allyl chloride the O- to C-alkylation ratio is 49 41 with phenol as a solvent it is 22 78 with methanol, dimethylformamide, and dioxane 100% O-alkylation is achieved. The selective solvation of the more electronegative O by the more protic solvents perhaps leads to some C-alkylations. 

Advantage can be drawn from the positive effect of phenol on PA transformation into p-HAP to improve the yield and selectivity of p-HAP production.[82 84] Thus, with a HBEA zeolite the yield and selectivity for p-HAP passes from ca. 5 and 28 % respectively with cumene solvent to 24 and 60% with phenol as a solvent .[84] Again sulfolane was shown to have a very positive effect on the selectivity for p-HAP and limits the catalyst deactivation. To explain these observations as well as the effect of P and PA concentrations on the reaction rates, it was proposed that sulfolane plays two independent roles in phenol acylation solvation of acylium ion intermediates and competition with P and PA for adsorption on the acid sites.1831... 

Another instructive example of electrophilic or H-bonding assistance of protic solvents (or co-solvents) in SnI reactions is the accelerated acetolysis rate of 2-bromo-2-methylpropane upon the addition of phenols to a tetrachloromethane/acetic acid solution of the reactant [582] see reference [582] for further examples. The usefulness of phenol as a solvent for SnI solvolysis reactions, in particular phenolysis of 1-halo-l-phenylethanes, has been stressed by Okamoto [582], In spite of its low relative permittivity (fir = 9.78 at 60 °C), its low dipolarity fi = 4.8 10 Cm = 1.45 D), and its low nucleophihcity, it represents a solvent of high ionizing power due to its electrophilic driving force. 

Separation of toluene from closeboiling nonaromatic compounds by using phenol as a solvent to improve the separability. (Vol. 20, p. 541)... 

Phenol-Water Rectification Example. A plant using phenol as a solvent desires to rectify a mixture containing 1.0 mol per cent phenol in water. As the bottoms are to be discarded in a nearby river, they must not exceed 0.001 mol per cent phenol. A system similar to that shown in Fig. 8-6 will be employed. The overhead vapors from the bubble-plate columns to be used are condensed and cooled to 20°C. Under these conditions the condensate separates into two saturated layers. The water layer is reheated to its boiling point and refluxed to column 1, and the... 

Dimethjlphenol (2,6-xylenol) is produced by the gas phase alkylation of phenol with methanol using modified alumina catalysis. The cmde product contains 2-methylphenol, 2,6-dimethylphenol, a minor amount of 2,4-dimethylphenol, and a mixture of trimethylphenols. The 2,6-dimethylphenol is purified by fractional distillation. The mixture of di- and trimethylphenols is sold as cresyHc acid for use as a solvent. 2,6-Dimethylphenol [576-26-1] is available in 55-gal dmms (208-L) and in bulk shipments in tank wagons and railcars. 

Cyclohexanol [108-93-0] is a colorless, viscous liquid with a camphoraceous odor. It is used chiefly as a chemical iatermediate, a stabilizer, and a homogenizer for various soap detergent emulsions, and as a solvent for lacquers and varnishes. Cyclohexanol was first prepared by the treatment of 4-iodocyclohexanol with ziac dust ia glacial acetic acid, and later by the catalytic hydrogenation of phenol at elevated temperatures and pressures. 

The variable that has the most significant impact on the economics of an extractive distillation is the solvent-to-feed (S/F) ratio. For closeboiling or pinched nonazeotropic mixtures, no minimum-solvent flow rate is required to effect the separation, as the separation is always theoretically possible (if not economical) in the absence of the solvent. However, the extent of enhancement of the relative volatihty is largely determined by the solvent concentration and hence the S/F ratio. The relative volatility tends to increase as the S/F ratio increases. Thus, a given separation can be accomplished in fewer equihbrium stages. As an illustration, the total number of theoretical stages required as a function of S/F ratio is plotted in Fig. 13-75 7 for the separation of the nonazeotropic mixture of vinyl acetate and ethyl acetate using phenol as the solvent. 

The largest user of phenol in the form of thermosetting resins is the plastics industry. Phenol is also used as a solvent and in the manufacture of intermediates for pesticides, pharmaceuticals, and dyestuffs. Styrene is used in the manufacture of synthetic rubber and polystyrene resins. Phthalic anhydride is used in the manufacture of DMT, alkyd resins, and plasticizers such as phthalates. Maleic anhydride is used in the manufacture of polyesters and, to some extent, for alkyd resins. Minor uses include the manufacture of malathion and soil conditioners. Nitrobenzene is used in the manufacture of aniline, benzidine, and dyestuffs and as a solvent in polishes. Aniline is used in the manufacture of dyes, including azo dyes, and rubber chemicals such as vulcanization accelerators and antioxidants. 

One large outlet is its use as a solvent for nitrocellulose lacquers. Toluene is used to make phenol, benzaldehyde, benzole acid and a variety of other derivatives. 

Phenol was the first commercial antiseptic its introduction into hospitals in the 1870s led to a dramatic decrease in deaths from postoperative infections. Its use for this purpose has long since been abandoned because phenol burns exposed tissue, but many modern antiseptics are phenol derivatives. Toluene has largely replaced benzene as a solvent because it is much less toxic. Oxidation of toluene in the body gives benzoic acid, which is readily eliminated and has none of the toxic properties of the oxidation products of benzene. Indeed, benzoic acid or its sodium salt (Na+, C6H5COO ions) is widely used as a preservative in foods and beverages, including fruit juices and soft drinks. 

Almost all of the isopropylbenzene produced is used for making phenol and acetone. The largest use of acetone is as a chemical intermediate to methyl methacrylate and along with phenol to make bisphenol A for preparation of polymers. Acetone is also used widely as a solvent. 

It is a misconception that most chemicals are manufactured in organic solvents. Most high-volume bulk chemicals are actually produced in solvent-free processes, or at least ones in which one of the reactants also acts as a solvent. Typical examples of such large-scale processes include the manufacture of benzene, methanol, MTBE, phenol and polypropylene. In addition, some heterogeneous gas-phase catalytic reactions, a class of solvent-free processes, are discussed in Chapter 4. 

Standardisation of EPDM characterisation tests (molecular composition, stabiliser and oil content) for QC and specification purposes was reported [64,65]. Infrared spectroscopy (rather than HPLC or photometry) is recommended for the determination of the stabiliser content (hindered phenol type) of EP(D)M [65]. Determination of the oil content of oil-extended EPDM is best carried out by Soxhlet extraction using MEK as a solvent [66], A round robin test was reported that evaluated the various techniques currently used in the investigation of unknown rubber compounds (passenger tyre tread stock formulations) [67]. 

Besides N-alkylation reactions, there are also reports in the literature concerning microwave-promoted O-alkylations. A mild method for the O-alkylation of phenols with alkyl bromides and chlorides has been developed by Wagner and coworkers (Scheme 6.117 a) [235], The protocol is applicable to substrates that are sensitive to strong bases or to hydrolysis, or are difficult to extract from an aqueous phase. The procedure uses methanol as a solvent and a stoichiometric amount of potassium carbonate as a weak base. Optimum yields were obtained by heating the phenol with 1.2 equivalents of the alkyl bromide (or 3 equivalents of the less reactive chloride) at 100-140 °C for 15-30 min. 

Trlethylamlne, because of its basic properties was chosen as the solvent for the end-capper 1 synthesis. Reactions were run at reflux for times ranging from 2 to 30 hours. Reaction progress was followed by gas chromatography (GC) using phenol as a standard. 

Ketones.have the characteristic -C- signature group imbedded in them. Acetone, CH3COCH3, comes from two different routes. It is a by-product in the cumene to phenol/acetone process. It is the on-purpose product of the catalytic dehydrogenation of isopropyl alcohol. Acetone is popular as a solvent and as a chemical intermediate for the manufacture of MIBK, methyl methacrylate, and Bisphenol A. 

Uses A mixture of cis and trans isomers is used as a solvent for fats, phenols, camphor ingredient in perfumes low temperature solvent for sensitive substances such as caffeine refrigerant organic synthesis. 

Initially the process utilized butyl acetate as a solvent, but more recently isopropyl ether has been used, although the latter has a much lower partition coefficient for phenol. The reason for this choice of solvent is that the separation of solvent and phenol by distillation is easier and less costly. 

The chromophore of phenylephrine is not extended but its structure includes a phenolic hydroxyl group. The phenolic group functions as an auxochrome under both acidic and alkaline conditions. Under acidic conditions it has two lone pairs of electrons, which can interact with the benzene ring and under basic conditions it has three. Figure 4.11 shows the bathochromic and hyperchromic shift in the spectrum of phenylephrine, which occurs when 0.1 M NaOH is used as a solvent instead of 0.1 M HCl. Under acidic conditions the X max is at 273 and has an A (1 %, 1 cm) value of 110 and under alkaline conditions the X max is a 292 nm and has an A (1%, 1 cm) value of 182. 

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