Para-chlorophenol

CTC-HC1 is the HC1 salt of amphoteric CTC it is multifunctional with two chromophores. It is a para-chlorophenol with an ot,3-unsaturated ketone in conjugation. 

Procedure Transfer about 300 mg of Camphorated Para-chlorophenol, accurately weighed, to a 200 ml pressure bottle containing 50 ml of freshly prepared dinitrophenyl-hydrazine TS. Close the pressure bottle, immerse it in a water bath, and maintain it at about 75° for k hours. Cool to room temperature, then transfer the contents to a beaker with the aid of 100 ml of dilute sulfuric acid (l in 12), and allow it to stand overnight. Collect the precipitate on a tared filter crucible, wash with 100 ml of dilute sulfuric acid (l in 12) and then with 75 ml of cold water, in divided portions, to remove the acid. Dry at 80° for 2 hours, cool and weigh. The weight of the precipitate so obtained, multiplied by O.U58I, represents the weight of C qH- O in the sample taken. 

Quantitative analysis of both camphor and para-chlorophenol in champhorated parachlorophenol by high-pressure liquid chromatography is described (186). 

Fig. 31.13 Hydroxylation of chlorobenzene in the rat yields the three isomers, i.e. ortho-, meta- and para-chlorophenol.

In a typical reaction, the dipropynyldialkylbenzene 12 (0.500 g) and the catalyst system consisting of Mo(CO)6 (5 mol%)/substituted phenol (1 equiv of either para-chlorophenol or para-trifluorocresol) are dissolved in 30 mL of 1,2-dichlorobenzene and stirred at temperatures between 120-170 °C overnight, removing butyne by a slow stream of nitrogen. The formed fluorescent solution is cooled and any precipitated polymer dissolved by the addition of CH2CI2. The organic layer is washed with 100 mL of each H2O, 10% NaOH, and 25% HCl. Addition of methanol precipitates yellow PPE 13, which is filtered and vacuum dried. This reaction works very well for all dialkyldipropynylbenzenes 12. 

The main characteristics and physical properties of the chlorophenols are brought together in Table 1. With the exception of o-chlorophenol, they are all sohds at room temperature. The refractive indexes of the monochlorophenols, C H CIO, are as follows ortho, 1.5524 meta, 1.5565 para, 1.5579. The piC values of chlorophenols depend on the number and the position of the substituents. 

Chlorination with SO2CI2, which is favorable to the para isomer at the monochlotination stage, gives an excellent yield of 2,4-dichlorophenol. Startiag with (9-chlorophenol, it is possible to attain a selectivity for 2,4-dichlorophenol of 98%, if chlotination is carried out ia Hquid SO2 at low temperature (20). 2,6-Dichlorophenol is also used as an iatermediate. It is obtained by chlotinatiag o-chlorophenol ia the presence of a catalytic quantity of an amine, with or without a solvent medium (21,22), giving a yield of 90%. 

The irradiation of a mixture of ortho- or para-nitrochlorobenzenc and ethanol in the presence of sodium hydroxide and a phase-transfer agent yields the corresponding ethoxy aromatic compounds within a few minutes (Eq. 52) [72], The same procedure was subsequently applied to 2-chlorophenol [73]. In both reactions PEG 400 was shown to be the most efficient catalyst (Tab. 5.23). 

The dotted lines represent the same data connected via a constant base hne i. e., the acid is varied for the same base. Numbers are utilized to represent all of the points on the constant-base hne 1 for CsHgN, 2 for EtOAc, and 4 for DMA. On the EtOAc hne, for example, number 2 labels the enthalpies for the alcohols HFIP, p-chlorophenol, phenol, and butanol toward this donor. It should be noted that while the constant-acid hnes have different nonzero intercepts, the constant-base lines have zero intercepts within the accuracy of the measured para-... 

Phenols are generally named as derivatives of the simplest member of the family, phenol, e.g. < -chlorophenol. Sometimes trivial or special names are also used, e.g. m-cresol. Occasionally, phenols are named as hydroxy-compounds, e.g. para-hydroxybenzoic acid. Numbering is often used to denote the position(s) of the substituent(s) on a phenol skeleton, e.g. 2,4-dinitrophenol. 

Chloro- and bromophenols and A -acylhaloanilines can be fluorinated in the ortho or para position by 1-fluoropyridinium triflates and the fluorophenols and iV-acylfluorohaloanilines thus obtained reduced to fluorophenols and iV-acylfluoroanilincs. For example, 4-chlorophenol reacts with 2-chloro-l-fluoro-6-(trichloromethyl)pyridinium tetrafluoroborate in 1,2-dichlo-roethane at 45°C for three hours to give 4-chloro-2-fluorophenol in 68% yield.51... 

These investigations have shown significant associations with several types of cancer, but the most consistent findings have been for soft-tissue sarcoma and non-Hodgkin lymphoma. Although the odds ratios in some case-control studies may have been inflated by recall bias, this cannot explain all of the findings. Nor are they likely to have arisen by chance. It is not possible, however, to exclude a confounding effect of polychlorinated dibenzo-para-dioxins which occur as contaminants in chlorophenols. 

The weak hydrogen bond in o-chlorophenol stabilizes the gas molecule relative to those of the meta and para isomers, whereas the crystalline and liquid phases of the three substances, in which hydrogen bonds can be formed between adjacent molecules, have about the same stabil-... 

Halogenated phenols correlate well with Hammett s constant (a). Figure 6.24 shows the linear trend of the c values of 3-chlorophenol, 4-chlorophenol, 3,4-dichlorophenol, and 3,5-dichlorophenol with respect to their first-order reaction rate constants. Aromatic compounds with substituents in the meta and para positions have pronounced steric differences and result in a well-defined trend. Table 6.9 summarizes all the QSAR models discussed above. 

Kaiser, K.L.E., Dixon, D.G., Hodson, P.V. (1984) QSAR studies on chlorophenols, chlorobenzenes and para-substituted phenols. In QSAR in Environmental Toxicology. Kaiser, K.L.E., Ed., pp. 189-206, D. Reidel Publ. Co., Dordrecht, The Netherlands. 

Kaiser, K.L.E., Dixon, D.G., Hodson, PV. (1984) QSAR studies on chlorophenols, chlorobenzenes and para-substituted phenols. In QSAR in Environmental Toxicology. Kaiser, K. L. E., Ed., pp. 189-206, D. Reidel Publishing Co., Dordrecht, The Netherlands. Kamlet, M.J., Doherty, R.M., Carr, P.W., Mackay, D., Abraham, M.H., Taft, R.W. (1988) Linear solvation energy relationship. 44. Parameter estimation rules that allow accurate prediction of octanol/water partition coefficients and other solubility and toxicity properties of polychlorinated biphenyls and polycyclic aromatic hydrocarbons. Environ. Sci. Technol. 22, 503-509. Kanazawa, J. (1981) Measurement of the bioconcentration factors of pesticides by fresh-water fish and their correlation with physicochemical properties of acute toxicities. Pest. Sci. 12, 417-424. 

Pelizetti et al. detailed the photocatalytic mineralisation of ortho-, para-and mefa-cresols [116]. As with chlorophenol, methyl catechol and hydro-quinone were detected as major by-products. The o- and p-crcsols were observed to degrade with first order kinetics while the m-cresol degradation followed zero order kinetics at pH 3. Under 3 h photocatalysis time in alkaline conditions m-cresol kinetics become first order which was proposed to be due to lower surface coverage of the cresol at this pH due to electrostatic repulsion with the titania surface. In air saturated solutions the time for mineralisation was around 8 h. The mineralisation time was, however, reduced to 2.5 h in suspensions sparged with oxygen. 

The reaction mixture is then distilled in vacuum through a fractionating column. At a pressure of 20 mm., the o-chlorophenol goes over at 75-90°, the para isomer at 110-115°. About 130 grams of o-chlorophenol (25 per cent) and 320 grams of p-chlorophenol (62 per cent) are obtained. 

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