Addition to aromatic compounds

I 5 Anodic Reactions of Alkanes, Alkenes, and Aromatic Compounds Tab. 15 Anodic addition to aromatic compounds... 

Laboratory PIDs have a better selectivity due to the lower energy lamps (typically 10.2 eV) used in laboratory instruments. In addition to aromatic compounds, the laboratory PIDs respond to unsaturated and oxygenated compounds, such as cyclohexene, trichloroethylene (TCE), methyl tertiary butyl ether (MTBE), and many others. 

Addition of OH to olefinic and aromatic compounds is also very rapid usually k = 109-1010 M -1 s"1. Despite the high rates, a reasonable correlation with Hammett s substitutent constants was obtained for the series of substituted benzenes and demonstrated the electrophilic behaviour of OH in its addition to aromatic compounds (Neta and Dorfman, 1968). 

For toluene, and other aromatics, there are several possible sites of attack for the OH radical. Some sites are less sterically hindered than others or are favored because of stabilizations resulting from group interactions. Andino et al. (1996) have performed ab initio calculations to determine the most energetically favored structures resulting from OH addition to aromatic compounds. For toluene the most favored structure is that resulting from OH addition at the ortho position 9... 

Organosodium compounds are prepared from sodium and other organometaUic compounds or active methylene compounds by reaction with organic haUdes, cleavage of ethers, or addition to unsaturated compounds. Some aromatic vinyl compounds and aHyUc compounds also give sodium derivatives. 

As with the reduction of aldehydes and ketones (16-23), the addition of organometallic compounds to these substrates can be carried out enantioselectively and diastereoselectively. Chiral secondary alcohols have been obtained with high ee values by addition to aromatic aldehydes of Grignard and organolithium compounds in the presence of optically active amino alcohols as ligands. ... 

Since aromatic substitutions, aliphatic substitutions, additions and conjugate additions to carbonyl compounds, cycloadditions, and ring expansion reactions catalyzed by Fe salts have recently been summarized [17], this section will focus on reactions in which iron salts produce a critical activation on unsaturated functional groups provided by the Lewis-acid character of these salts. 

Nucleophilic Additions to Carbonyl Compounds Saponification of hindered aromatic esters... 

Anionic phosphorus has been used as well in a number of recent reports of additions to carbonyl compounds. Addition of dialkyl phosphite to aromatic aldehydes in the presence of catalytic amounts of La-BINOL and dilithium (R)-binaphthoxide occurs enantioselec-... 

Scheme 32 Addition of the methylthiogroup and nucleophiles to aromatic compounds.

In addition to those compounds which contain hetero-atoms having lone electron pairs and which are therefore characterized as bases , there exist analogous interactions with molecules which do not possess any lone pairs. It is however known from the chemistry of unsaturated compounds, particularly of aromatics, that solutions of such compounds. 

The photochemical addition of tetranitromethane to aromatic compounds under conditions of excitation of the [ArH C(N02)4l charge-transfer complex by light matching the wavelength of the charge-transfer band results in a recombination within [ArH+, NOj, C(N02)3 ] triad. The destiny of triad depends on the nature of the solvent (Sankararaman et al. 1987, Sankararaman and Kochi 1991). In dissociating solvents, radical substitution is predominant, leading to nitro products and trinitromethane ... 

HO -Addition to Monocyclic Aromatic Compounds and Biphenyls. The rate constants for HO addition to aromatic rings are simply calculated by using the rate constant for the unsubstituted compound and the Hammett-cr+ constants. Thus, kHO, (Ar) for addition to a substituted benzene ring can be estimated by ... 

In the photolysis of vitreous matrices containing some additives of aromatic compounds, as well as in the radiolysis of vitreous matrices both with and without these additives, it is frequently possible to observe a luminescence after the irradiation is over [49U57, 123 125]. As a rule, the luminescence lasts for a long time and its intensity varies with time according to the Debye-Edwards law [49]... 

Thus, the hydrodesulfurization process is a very complex sequence of reactions due, no doubt, to the complexity of the feedstock. Furthermore, the fact that feedstocks usually contain nitrogen and oxygen compounds (in addition to metal compounds) increases the complexity of the reactions that occur as part of the hydrodesulfurization process. The nitrogen compounds that may be present are typified by pyridine derivatives, quinoline derivatives, carbazole derivatives, indole derivatives, and pyrrole derivatives. Oxygen may be present as phenols (Ar-OH, where Ar is an aromatic moiety) and carboxylic acids (-C02H). The most common metals to occur in petroleum are nickel (Ni) and vanadium (V) (Reynolds, 1997). 

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