M- Cresol

Dissolve a few crystals of phenol in water and add ferric chloride solution a violet coloration is produced. Repeat, using i 2 drops of m-cresol shaken up with about i ml. of water a violet coloration is again produced. Catechol (in dilute solution) gives a green coloration. 

Physical properties. All solid except m -cresol, CH3CJH4OH, which is a liquid. All colourless when pure, but frequently slightly coloured due to atmospheric oxidation. All have in varying degrees a characteristic odour of carbolic acid. Phenol, the cresols and resorcinol have a caustic action on the skin. 

Moat phenols are crystalline solids notable exceptions are m-cresol and o-bromophenol. The monohydric phenols generally have characteristic odours. The solubihty in water increases with the number of hydroxl groups in the molecule. 

The melting points of some 0-aryl saccharin derivatives are phenol, 182° o-cresol, 163° m-cresol, 146° p-cresol, 172° o-nitrophenol, 236° p-nitrophenol, 192°. 

FIGURE 13 24 The NMR spectrum of m cresol Each of the seven carbons of m cresol gives a separate peak Integrating the spectrum would not provide useful information because the intensities of the peaks are so different even though each one corresponds to a single carbon... 

NMR spectrum of 3 methylphenol m cresol) Notice that contrary to what we might expect for a compound with seven peaks for seven different carbons the intensities of these peaks are not nearly the same The two least intense signals those at 8 140 and 8 157 correspond to carbons that lack attached hydrogens... 

Bromcresol green, tetrabromo-m-cresol-sulfonphthalein (indicator) dissolve 0.1 g in 7.15 mL 0.02 N NaOH and dilute with water to 250 mL or, 0.1 g in 100 mL 20% alcohol pH range yellow 4.0-5.6 blue. 

Metacresol purple, m-cresol-sulfonphthalein (indicator) dissolveO.l g in 13.6 mL 0.02A NaOH and dilute with water to 250 mL acid pH range red 0.5-2.5 yellow, alkaline pH range yellow 7.4-9.0 purple. 

Displacement-purge forms the basis for most simulated continuous countercurrent systems (see hereafter) such as the UOP Sorbex processes. UOP has licensed close to one hundred Sorbex units for its family of processes Parex to separate p-xylene from C3 aromatics, Molex tor /i-paraffin from branched and cyclic hydrocarbons, Olex for olefins from paraffin, Sarex for fruc tose from dextrose plus polysaccharides, Cymex forp- or m-cymene from cymene isomers, and Cresex for p- or m-cresol from cresol isomers. Toray Industries Aromax process is another for the production of p-xylene [Otani, Chem. Eng., 80(9), 106-107, (1973)]. Illinois Water Treatment [Making Wave.s in Liquid Processing, Illinois Water Treatment Company, IWT Adsep System, Rockford, IL, 6(1), (1984)] and Mitsubishi [Ishikawa, Tanabe, and Usui, U.S. Patent 4,182,633 (1980)] have also commercialized displacement-purge processes for the separation of fructose from dextrose. 

An azo coupling reaction of monatomic phenols with diazotized 4-nitroaniline has been investigated. By HPLC, NMR, elemental analysis, UV and IR spectroscopy it has been shown that the azo derivatives of o-guaiacol, o- and m-cresols interact with an excess of diazonium in pH interval of 4,5-9,5 and form corresponding 4,4-di(4-nitrophenylazo)-2,5-cyclohexadien-1 -ones. 

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