Tri-substituted aromatics

Fig-C. Possible numbering systems if tri-substituted aromatic ring. 

A.9 TRI-SUBSTITUTED AROMATIC COMBINATIONS USING DONOR AND ACCEPTOR GROUPS... 

C. Nucleophilic Attack on Other Atoms.—Amidoximes have been shown to react with tris(dimethylamino)phosphine by displacing dimethylamine to give the phosphine oxides (52), but some N-substituted aromatic amidoximes give derivatives of (53). ... 

Competitive consecutive reactions are combinations of parallel and series reactions that include processes such as multiple halogenation and nitration reactions. For example, when a nitrating mixture of HN03 and H2S04 acts on an aromatic compound like benzene, N02 groups substitute for hydrogen atoms in the ring to form mono-, di-, and tri-substituted nitro compounds. 

Cg aromatics. The schematic in Figure 14.10 shows how the saturated species can interconvert, including formation of mono-, di- and tri-substituted alkylcyclopen-tanes. The trimethylcyclopentanes are intermediates that can be invoked for isomerization among the different xylenes. 

Various aldehydes 184 and alcohols have been shown to be competent in the redox esterification of unsaturated aldehydes in the presence of the achiral mesityl triazo-lium pre-catalyst 186. Both aromatic and aliphatic enals participate in yields up to 99% (Table 13). Tri-substituted enals work well (entry 3), as do enals with additional olefins present in the substrate (entries 4 and 7). The nucleophile scope includes primary and secondary alcohols as well as phenols and allylic alcohols. Intramolecular esterification may also occur with the formation of a bicyclic lactone (entry 8). 

The spectra are clearer in substituted compounds, especially in para-and poly-substituted aromatic systems. In the former case sign determination is feasible and McFarlane has obtained the values for some typical compounds as shown in Table XXII the data (without signs) for the tris(4-fluorophenyl)phosphine oxide are also included. 

In addition to the Bisphenol-A backbone epoxy resins, epoxies with substituted aromatic backbones and in the tri- and tetra- functional forms have been produced. Structure-property relationships exist so that an epoxy backbone chemistry can be selected for the desired end product property. Properties such as oxygen permeability, moisture vapor transmission and glass transition temperature have been related to the backbone structure of epoxy resins5). Whatever the backbone structure, resins containing only the pure monomeric form can be produced but usually a mixture of different molecular weight species are present with their distribution being dictated by the end-use of the resin. 

Other addition compounds of Hg2(N03)2 with aromatic amines97 contain two molecules of the N ligand and one molecule of Hg2(N03)2 with 4-fluoroaniline four molecules of the ligand are coordinated.97 Similar results have been obtained with Hg2(N03)2 or Hg2(C104)2 and mono-, di- and tri-substituted anilines, pyridines and l,4-diazabicyclo[2.2.2]octane.101,102 Coordination compounds are also formed with aminopyridine, trichloroacetaminopyridine and aminochloropyridine.103 The X-ray structure determination of the coordination compound between Hg2(C104)2 and 3-aminopyridinium perchlorate revealed the structure (12).103... 

Tris (triphenylphosphine) nickel, tris (tri-p-tolylphosphine) nickel, and bis (1,3-diphenylphosphinepropane) nickel proved to be good catalysts, the first being slightly more effective. The tricyclohexylphosphine complex was a very poor catalyst, and bis (cyclooctadiene) nickel did not catalyze cyanation. Cyanation of several substituted aromatic halides in the presence of Ni[P(C6H5)3]3 prepared by reducing dichlorobis (triphenylphosphine) nickel (II) 2 with a powdered manganese iron (80 20) alloy (Reaction 3) is reported in Table II. 

Di- and tri-substituted enamines of aldehydes have been generated under mild conditions (1 h, 0°C, 1.2 equiv. of amine).278 Although easily isolable, they can be conveniently employed in situ. The reaction is chemoselective (ketones present are not affected), it tolerates sensitive groups such as acetals and silyl ethers, and it works for both aliphatic and aromatic aldehydes. 

The formation of di- and tri-alkyl aromatics and b henyls from their aromatic precursor is a consecutive reaction, in A hich first the mono-substituted aromatic conopound is formed which subsequently reacts to form the di-alkyl compund. This was observed in the shape selective ethylation of bphenyl [91] isopropjdation of naphthalene [92] over H-Mordenite and the isopropylation of napthalene over HY [63], Therefore, if a dialkyl-isomer is the desired product, the reaction conditions (reaction time/readence time, partial pressures and tenperature) have to be optimized to obtain the the maximum yield of this de ed product. With shape selective catalysts the formation of poly-substituted aromatic compounds can be suppressed because they are not able to diffuse out of the channels of the zeolites [63]. 

The chemistry of resol formation has many similarities to that of novolacs. However, because conditions utilize a phenol to formaldehyde ratio less than 1, mono-, di-, and tri-substitutions to the aromatic ring occur. Additionally, the aqueous medium is basic. Hence,... 

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