P- Dichlorobenzene

Two other types of equilibrium curves are occasionally encountered with the system of two components forming a continuous series of solid solutions. These are shown in Figs. 1,16, 3 and 1,16, 4. In the former the freezing or melting curve passes through a minimum (examples p-chloroiodobenzene, m.p. 57° - p-dichlorobenzene, m.p. 53° naphtha-... 

From among the compounds chlorobenzene o dichlorobenzene and p dichlorobenzene choose the one that... 

Figure 22-8 shows the features of a horizontal center-fed column [Brodie, Au.st. Mech. Chem. Eng. Tran.s., 37 (May 1979)] which has been commercialized for continuous purification of naphthalene and p-dichlorobenzene. Liquid feed enters the column between the hot purifying section and the cold freezing or recovery zone. Ciystals are formed internally by indirect cooling of the melt through the walls of the refining and recovery zones. Residue liquid that has been depleted or product exits from the coldest section of the column. A spiral conveyor controls the transport of solids through the unit. 

Nofsinger license Nofsinger design construct p-Dichlorobenzene TSK license TSK design construct Confidential Monsanto Co. 1989—Sauget, IL... 

Poly-p-phenylene has been prepared in the laboratory by a variety of methods, including the condensation of p-dichlorobenzene using the Wurtz-Fittig reaction. Although the polymer has a good heat resistance, with decomposition... 

These materials have been prepared by polymerisation of p-halothiophenoxide metal compounds both in the solid state and in solution. They have also been prepared by condensation of p-dichlorobenzene with elemental sulphur in the presence of sodium carbonate while the commercial polymers are said to be produced by the reaction of p-dichlorobenzene with sodium sulphide in a polar solvent. 

The Phillips Corporation have recently introduced interesting copolymers related to PPS. In addition to the use of p-dichlorobenzene and Na2S, a second aromatic dichloro compound is used. For the marketed material PAS-2 this is 4,4 -dichlorodiphenylsulphone whilst for the developmental products PAS-1 and PAS-B the compounds are 4,4 -dichlorodiphenyl and 4,4 -dichlorodiphenyl-ketone. Each of these copolymers is amorphous, so that a high heat deformation resistance requires a high value for. ... 

Dichloro-1 -nitroethane o-Dichlorobenzene p-Dichlorobenzene 3,3 -Dichlorobenzidine Dichlorodifluoromethane (Refrigerant 12)... 

Figure 2.21 A gas cluomatogram of a sample of river water (2.25 ml) spiked at 5 ppb levels with 1, toluene 2, ethylbenzene 3, methoxybenzene 4, p-dichlorobenzene 5, dimethylphe-nol 6, dimethylaniline 7, chloroaniline 8, indole 9, dichlorobenzonitrile 10, tiichlorophe-nol 11, dinitrobenzene 12, tiifluranil 13, atrazine 14, phenantlnene. Reprinted from Journal of High Resolution Chromatography, 16, H. G. J. Mol et al., Use of open-tubular tapping columns for on-line extraction-capillary gas cluomatography of aqueous samples , pp. 413-418, 1993, with permission from Wiley-VCH.

Typical liquid-phase reaction conditions for the chlorination of benzene using FeCls catalyst are 80-100°C and atmospheric pressure. When a high benzene/Cl2 ratio is used, the product mixture is approximately 80% monochlorobenzene, 15% p-dichlorobenzene and 5% o-dichlorobenzene. 

Another group of reactions can be classified as intermolecular dehalogenations or dehydrohalogenations, based on Wurtz-, Fittig-, Ullmann-, Grignard-, or Friedel-Crafts reactions. Thus, polyphenylenes may be obtained by polycondensations of p-dichlorobenzene in the presence of Na/K alloy83-85. ... 

The kinetic effect of increased pressure is also in agreement with the proposed mechanism. A pressure of 2000 atm increased the first-order rates of nitration of toluene in acetic acid at 20 °C and in nitromethane at 0 °C by a factor of about 2, and increased the rates of the zeroth-order nitrations of p-dichlorobenzene in nitromethane at 0 °C and of chlorobenzene and benzene in acetic acid at 0 °C by a factor of about 559. The products of the equilibrium (21a) have a smaller volume than the reactants and hence an increase in pressure speeds up the rate by increasing the formation of H2NO. Likewise, the heterolysis of the nitric acidium ion in equilibrium (22) and the reaction of the nitronium ion with the aromatic are processes both of which have a volume decrease, consequently the first-order reactions are also speeded up and to a greater extent than the zeroth-order reactions. 

Which would you expect to have the higher boiling point, p-dichlorobenzene (3) or o-dichlorobenzene (4) ... 

The two C—Cl bonds in p-dichlorobenzene lie directly across the ring and their dipole moments cancel, thereby producing a nonpolar molecule. 

An o-dichlorobenzene molecule is polar because the two C—Cl bond dipoles do not cancel. We therefore predict that o-dichlorobenzene will have a higher boiling point than that of p-dichlorobenzene. 

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