Benzene, halogenation

By heating halogenated benzenes or naphthalenes with cuprous cyanide, for example, a-naphthonitrile from a-bromonaphthalene and cuprous cyanide (Section IV,163). 

For alkylbenzenes, nitrobenzenes, halogenated benzenes and for secondary or tertiary amines where at least one aromatic group is connected to an amino nitrogen, add the following corrections for each aromatic nuclei is. If N < 16, increase AN by 0.60 if N > 16, increase AN by 3.055 — 0.161N for each aromatic group. For any N, increase AB by (—140.04 + 13.869 ). 

By introducing reasonable values (about 2 for nitrogen, 4 for oxygen) for the electron affinity parameter relative to carbon, 8, and for the induced electron affinity for adjacent atoms (32/8i = Vio), we have shown that the calculated permanent charge distributions for pyridine, toluene, phenyltrimethylammonium ion, nitrobenzene, benzoic acid, benzaldehyde, acetophenone, benzo-nitrile, furan, thiophene, pyrrole, aniline, and phenol can be satisfactorily correlated qualitatively with the observed positions and rates of substitution. For naphthalene and the halogen benzenes this calculation does not lead to results... 

The oxidation of benzene to phenol and 1,4-dihydroxybenzene (Figure 2.11a) (Hyman et al. 1985), both side chain and ring oxidation of ethyl benzene, and ring-hydroxylation of halogenated benzenes and nitrobenzene (Keener and Arp 1994). 

For substituted benzenes, ring activators (electron-releasing groups) increase sensitivity and ring deactivators (electron-withdrawing groups) decrease sensitivity (exception halogenated benzenes)... 

The mechanistic details of sulphonation have been less closely explored than those of nitration or halogenation. Benzene itself is sulphonated fairly slowly by hot concentrated sulphuric acid, but rapidly by oleum (the rate then being related to its S03 content) or by S03 in inert solvents. The nature of the actual electrophile depends on the conditions, but is probably always S03 either free or linked to a carrier , e.g. H2S04S03 (H2S207) in sulphuric acid. A small concentration of S03 is developed in H2S04 itself through the equilibrium ... 

Horvath, A.L., Getzen, F.W. Eds. (1985) IUPAC Solubility Data Series Vol. 20. Halogenated Benzenes, Toluenes and Phenols with Water. Pergamon Press, Oxford. 

Wallington, T.J., Neuman, D.M., Kurylo, M.J. (1987) Kinetics of the gas phase reaction of hydroxyl radicals with ethane, benzene, and a series of halogenated benzenes over the temperature range 234 -38 K. Int. J. Chem. Kinet. 19, 725-739. 

Figure 6.4 Relationship of log k values measured on ODS-bonded silica gel to Bondi s van der Waals volumes. Column, Develosil ODS, 15 cm x 4.6 mm i.d. eluent, 70% aqueous acetonitrile at 30 °C. Numbers beside symbols see Table 6.4 <>, Polycyclic aromatic hydrocarbons x, alkylbenzenes O, halogenated benzenes A, alkanols and , alkanes.

Jasper, J.J. and Wood, T.D. The temperature-interfacial tension studies of some halogenated benzenes against water, J. Phys. C/tem, 59(6) 541-542, 1955. 

Mohtashamipur E, Triebel R, Straeter H, et al. 1987. The bone marrow clastogenicity of eight halogenated benzenes in male NMRI mice. Mutagenesis 2 111-113. 

Ware SA, Weast WL. 1977. Investigation of selected potential environmental contaminants Halogenated benzenes. Washington, DC U.S. Enviromnental Protection Agency, Office of Toxic Substances. EPA 560/2-77-004. 

Sijm, D. T. H. M., M. Schipper, and A. Opperhuizen, Toxicokinetics of halogenated benzenes in fish Lethal body burden as toxicological end point , Environ. Tox. Chem., 12,1117-1127 (1993). 

The reacting species is a rather weak electrophile and, therefore, only particularly reactive aromatics are suitable substrates. Consequently, the reaction is restricted for polyhydric phenols and their ethers, and reactive heterocycles. With strong acidic systems, such as AICI3 in halogenated benzene solvents, alkylben-zenes can react at more elevated temperatures (>50°C). Trichloroacetonitrile works also well with nonactivated aromatics. The 12 chloroimine, the protonated nitrile (13), or the nitrile coordinated with the Lewis acid are possible involved electrophiles. 

A discussion of nuclear electric quadrupole coupling in the vinyl halides has led to the estimate of about 6 percent double-bond character for the C—Cl bond in vinyl chioride and 3 percent for the C—I bond in vinyl iodide.87 Values of electric dipole moments of mono-halogenated benzenes have been interpreted as corresponding to 4 percent of double-bond character for the C—X bonds.68... 

Doucette and Andren [4] have compared six methods to estimate Kow for highly hydrophobic aromatic compounds such as halogenated benzenes, biphenyls, diben-zofurans, and dibenzo-p-dioxins with log Kow values ranging from 2.13 to 8.58. The comparison includes the GCM of Hansch and Leo, the GCM of Nys and Rekker, and correlations based on the following molecular descriptors HPLC retention times, M, TSA, and MCIs. The method using MCIs had the smallest average percent error. The method is... 

TABLE D.7 AWPC- Temperature Functions (Eq. 12.5.1) for Halogenated Benzenes and ... 

The Hammett correlation was also established for substituted benzenes and halogenated benzenes. A good correlation could not be established using halogenated and substituted benzenes in the same equation. Halogenated... 

Hammett s correlation for rate constants of halogenated benzenes reacting with hydroxyl radical. Experimental conditions elementary hydroxyl radical rate constants (l/m tsec t108). 

Reaction pathway for halogenated benzenes reacting with hydroxyl radical. 

Halogenated benzenes and halides also exhibit good predictive correlations. The rate constants increase as ELUMO does. The dataset for the benzene class is composed of benzene, chlorobenzene, and toluene ... 

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