Cresol as a solvent

A novel photoactive thermally stable polymer (xv) containing the triazine moiety has been synthesized by Khoee and Zamani [27] by the reaction of A,A-(4,4 -oxy bis (4,l-phenylene))-bis-(l,3-dioxo-l,3-dihydroisobenzofuran-5-carboxamide) and A-(4,6-diamino-l,3,5-triazin-2-yl) anthracene-9-carboxam-ide in presence of a small amount of o-cresol as a solvent under microwave condition. 

Measured for a 1% mim solution in m-cresol at 25 °C (PETP and PBTP), or for a 1% mlv solution in o-chlorophenol at 25 °C (PBTP-PPG) Total end groups in sum of OH + COOH + methyl ester end groups MN measured by gel permeation chromatography in m-cresol as a solvent Calculated from OH + COOH content Reprinted with permission from G.D.B. von Houwelingen, Analyst, 1981, 106, 1267, 1057. 1981, Royal Society of Chemistry [13] ... 

Total end groups in sum of OH + COOH + methyl ester end groups M] measured by gel-permeation chromatography in m-cresol as a solvent Calculated from OH + COOH content... 

The fabrication of blend membranes is relatively simple compared with that of inorganic flller mixed or cross-linked composite membranes. Bi et al. prepared a series of cross-linked sulfonated poly(arylene ether sulfone)/sulfonated polyimide (cSPAES/SPl) blend membranes by mixing a certain amount of cSPAES and SPI in their triethylamine (TEA) salt forms using m-cresol as a solvent, followed by filtration and casting onto a Petri dish and dried at 80°C for 2 h, 100°C for 2 h, and 120°C for 15 h, respectively, followed by proton exchange with 2 M HCl to obtain the blend hydrocarbon polyelectrolytes. 

A limited number of reports have appeared in the literature showing the use of water as a solvent for the microwave-promoted synthesis of thermoplastics. An example is the synthesis of water-borne polyimides using the standard polycondensation reaction of a dianhydride with a diamine (Seheme 3.1). In a scientific microwave unit, polymers with high molecular weights (Af up to 35.460 g/mol) were obtained within 22 min of heating using a one-pot two-step procedure. The dianhydride was first hydrolyzed in water to obtain the corresponding tetracarboxylic acid. This was then condensed with the diamine. The obtained polymers were completely comparable in their chemical and thermal properties to those obtained by conventional polymerization in m-cresol as solvent. 

In the Pott-Broche process, tetralin was used as a solvent for coal extraction in a mixture with cresols (80/20). This method was used to produce 30,000 tpa of coal extract in a plant operated by Ruhrol in Welheim (Bottrop), Germany between 1938 and 1944. Extraction was carried out under a pressure of around 100 bar at a temperature of 415 to 435 °C. The coal extract was used as a low-sulfur fuel, for the production of electrode coke, or refined by hydrogenation to yield benzole, middle oil and heavy oil. The solvent had to be regenerated, i.e. hydrogenated, before each extraction. 

Cresylic acid is mainly used as degreasing agent and as a disinfectant of a stabilized emulsion in a soap solution. Cresols are used as flotation agents and as wire enamel solvents. Tricresyl phosphates are produced from a mixture of cresols and phosphorous oxychloride. The esters are plasticizers for vinyl chloride polymers. They are also gasoline additives for reducing carbon deposits in the combustion chamber. 

A trade-off between selectivity and solvability should be considered when selecting a solvent. Adding co-solvents can make tough separations technically and economically feasible. Lee and Gentry (1997) have tabulated dielectric constants of selected solvents. A new class of solvents is based on the use of an aqueous. solution of hydrotropes. Gaikar and Sharma (1989) have reported the separation of close-boiling p-cresol and 2,6-xylenol with aqueous solutions of hydrotropes, such as the sodium salt of p-toluene sulphonic acid, as a novel solvent in extractive distillation. 

HOAc in the equations of the original papers will be replaced in our description by HS as a designation of protogenic solvents in general (see later its use for m-cresol). 

Room-temperature solution polycondensation is used for the preparation of hexafluoroisopropylidene-unit-containing poly(azomethine)s. At the end of the reaction, the water liberated by the reaction is thoroughly taken off as an azeotrope by vacuum distillation to allow the reaction to go to completion. Among DMF, DMSO, HMPA, NMP, and m-cresol used as reaction solvents, m-cresol yields a polymer with higher reduced viscosity in higher yield. The reaction proceeds rapidly and is essentially completed in 30 min. 

FIGURE 6.3 Molecular weight of polystyrene (PS) as a function of solvent and solvent concentration A = -butylmercaptan, B = carbon tetrabromide, C = carbon tetrachloride, D = o-cresol, E = p-cresol, F = m-cresol, G = phenol, H = s-ec-butylbenzene, 1 = cumene, J = ethylbenzene, K = chloroform, L = -heptant, M = toluene, N = benzene, where [S] = concentration of chain-transfer agent and [M] = concentration of styrene monomer. 

A considerable amount of o-cresol is consumed directly as either a solvent or disinfectant. o-Cresol is also used as a chemical intermediate for a wide variety of products. o-Cresol is hydrogenated to... 

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