1.2- Dichlorobenzene, structure

Repeat the analysis with 1,2-dichlorocyclohexatriene to 1,2-dichlorobenzene. Are there one or two energy minima If two, which is more stable, the structure with the short C1C2 bond or the long C1C2 bond Explain. 

There are three isomers of dichlorobenzene (empirical formula C3H CI). Draw the structural formulas of the isomers. 

The symmetric series provides functional cyclohexadienes, whereas the non-symmetric one serves to build deuterated and/or functional arenes and tentacled compounds. In both series, several oxidation states can be used as precursors and provide different types of activation. The complexes bearing a number of valence, electrons over 18 react primarily by electron-transfer (ET). The ability of the sandwich structure to stabilize several oxidation states [21] also allows us to use them as ET reagents in stoichiometric and catalytic ET processes [18, 21, 22]. The last well-developed type of reactions is the nucleophilic substitution of one or two chlorine atoms in the FeCp+ complexes of mono- and o-dichlorobenzene. This chemistry is at least as rich as with the Cr(CO)3 activating group and more facile since FeCp+ activator is stronger than Cr(CO) 3. 

Structural evidence Only one dichlorobenzene in which the two chlorine atoms are attached to adjacent carbon atoms exists. 

If the Kekule structure were correct, there would be two distinct dichlorobenzenes in which the chlorine atoms are attached to adjacent carbon atoms (13), one in which the carbon atoms are joined by a single bond and one with a double bond. In fact, only one such compound is known. 

As far as polymer supports for microwave-assisted SPOS are concerned, the use of cross-linked macroporous or microporous polystyrene (PS) resins has been most prevalent. In contrast to common belief, which states that the use of polystyrene resins limits reaction conditions to temperatures below 130 °C [14], it has been shown that these resins can withstand microwave irradiation for short periods of time, such as 20-30 min, even at 200 °C in solvents such as l-methyl-2-pyrrolidone or 1,2-dichlorobenzene [15]. Standard polystyrene Merrifield resin shows thermal stability up to 220 °C without any degradation of the macromolecular structure of the polymer backbone, which allows reactions to be performed even at significantly elevated temperatures. 

The synthetic route may be exemplified by the preparation of a tetra-chloroisoindolinone pigment. A mixture of one mole of 1,4-diaminobenzene in o-dichlorobenzene with a solution of two moles of 3,3,4,5,6,7-hexachloroisoindoline-1-one in o-dichlorobenzene is heated to 160 to 170°C for 3 hours. Closed filtration equipment is used to filter the hot product, which is then washed with o-dichlorobenzene and alcohol, dried, and milled. The resulting product is a reddish yellow pigment with the structure 45 ... 

Compounds with the structure 116 carrying ethoxy or methoxy groups in D-position are prepared from o-alkoxyanilines. Not only are cyclization and condensation achieved at comparatively lower temperature, between 170 and 175°C, but the reaction also proceeds at a higher rate than for compounds with D =H. One of the above-mentioned condensation agents is similarly necessary in this case. o-Dichlorobenzene, for instance, is a suitable organic solvent. The list of solvents for condensation and cyclization also includes trichlorobenzene and nitrobenzene. The reaction conditions are not markedly affected by the type of substitution in positions A and B. 

Colloidal liquid aphrons (CLAs), obtained by diluting a polyaphron phase, are postulated to consist of a solvent droplet encapsulated in a thin aqueous film ( soapy-shell ), a structure that is stabilized by the presence of a mixture of nonionic and ionic surfactants [57]. Since Sebba s original reports on biliquid foams [58] and subsequently minute oil droplets encapsulated in a water film [59], these structures have been investigated for use in predispersed solvent extraction (PDSE) processes. Because of a favorable partition coefficient for nonpolar solutes between the oil core of the CLA and a dilute aqueous solution, aphrons have been successfully applied to the extraction of antibiotics [60] and organic pollutants such as dichlorobenzene [61] and 3,4-dichloroaniline [62]. 

Quantitative absorption studies are not available for 1,4-dichlorobenzene in either humans or animals. This compound has some structural similarities to benzene and the smaller chlorinated aliphatics, and is thus assumed to be 100% absorbed when administered orally. Available data on 1,4-dichlorobenzene itself shows that under specific conditions, about 20% was absorbed via inhalation during a 3-hour exposure period. The potential for dermal absorption has not been assessed. 

The specific toxicokinetic behavior of 1,4-dichlorobenzene in children (and immature laboratory animals) has not been reported. It is not known if appreciable amounts of 1,4-dichlorobenzene penetrate or adversely affect the parental germ cells (or supporting cellular structures) in humans or laboratory... 

Based on a combination of available human case studies and experiments with laboratory animals, the major public health concerns associated with exposure to 1,4-dichlorobenzene are effects on the liver, kidneys, and blood. Some immunological, dermatological, and neurological effects have also been reported in exposed humans. There is information from animal studies which raises the question of whether 1,4-dichlorobenzene can cross the placenta and elicit structural effects on the developing fetus. Data from a study conducted in rats using the intraperitoneal route have demonstrated sperm abnormalities. Cancer of the liver as a result of lifetime exposure to 1,4-dichlorobenzene has been shown in mice, and renal cancer has been reported in male rats. However, recent studies related to the mechanism of renal carcinogenesis in rats suggest that these tumors may not be expected to occur in exposed humans. Issues relevant to children are explicitly discussed in Section 2.6, Children s Susceptibility, and Section 5.6, Exposures of Children. 

Ariyoshi T, Ideguchi K, Iwasaki K, et al. 1975. Relationship between chemical structure and activity. II. Influences of isomers of dichlorobenzene, trichlorobenzene and tetrachlorobenzene on the activities of drug-metabolizing enzymes. Chem Pharm Bull 23 82... 

In 58 workers exposed for an average of 4.8 years (range 8 months to 25 years) to p-dichlorobenzene at levels of 10-725 ppm, there was no evidence of hematologic effects despite the structural similarity to benzene, a potent bone marrow depressant. Painful irritation of the eyes and nose was noted at levels between 50 and 80 ppm, and pain was severe at 160 ppm. 

Consider planar molecules, such as 1,2-dichlorobenzene (C2v), glyoxal (Fig. 1, structure 6 point group C2A), orthoboric acid [B(OH)3 structure 7 point group C3h), naphthalene (D2h), or benzene (D6h). Such a molecule will have all its atoms in one principal axes plane, say the yz plane, so that x, = 0 for all i. 

The polymerization in bulk requires relatively high temperatures, and, in addition, the polyurethane formed is exposed to the action of the diisocyanate throughout the duration of the reaction, so that secondary reactions can easily take place (see Sect. 4.2.1). For the preparation of polyurethanes with a high molecular weight and with as linear a structure as possible, polymerization in solution is, therefore to be preferred. Suitable inert solvents are toluene, xylene, chlorobenzene, and 1,2-dichlorobenzene. The diisocyanate is normally dripped into the solution of the dihydroxy compound at the desired temperature, which may conveniently be the boiling point of the solvent. The resulting polyurethane often separates from the reaction mixture and is so much less vulnerable to secondary reactions than when the polymerization is carried out in bulk. 

The formation of crystalline fulleride salts at the electrode occurs when less polar solvents and bulky cations are used for the electrosynthesis. The first fulleride salt was synthesized by Wudl by bulk electrolysis of in o-dichlorobenzene with tetraphenylphosphonium chloride as supporting electrolyte [39, 80]. This black microcrystalline material with the composition (Ph4P )3(Cgg )(Cr)2 exhibits an ESR line with a g-value of 1.9991 and a line width of 45 G at room temperature. Single crystals of the slightly different salts (Ph4P )2(Cgg )(Cr) and (Ph4P )2(C50 )(Br ) could be obtained by electrocrystallization and their crystal structure was determined [82, 83]. Magnetic measurements showed the presence of unpaired spins. 

In contrast to the unsuccessful early attempts to produce [W2(02CR)4], the heteronuclear compound [MoW(02CCMe3)4] was obtained by reacting a 3 1 mixture of W(CO)6 and vlo(CO)6 in refluxing dichlorobenzene.334 The heteronuclear complex was freed from Mo2(02CCMe3)4] by careful oxidation with I2. Structure analysis of MoW(02CCMe3)4]I-MeCN shows the expected idealized Dih symmetry with a short W—Mo separation of 2.194 A. The iodide ion is coordinated to the W atom and the MeCN molecule is coordinated to the molybdenum atom. 

The structures for three odoriferous organic compounds containing one or more benzene rings toluene, naphthalene, and 1,4-dichlorobenzene. 

SAMPLE SOLUTION (a) The two isotopes of chlorine are 35CI and 37CI. There will be three isotopically different forms of p-dichlorobenzene present. They have the structures shown as follows. Each one will give an M+ peak at a different value of m/z. 

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