Diphenylmethane, substituted

The first three of a series of papers by Ridd and co-workers on Inductive and Field effects in Aromatic Substitution have appeared. Results of studies of the nitration of 4-phenylp5nidine and of 4-benzylpyridine in aqueous sulphuric acid were reported and use of the usual criteria (para 8.2) showed that in each case the conjugate acid was the species undergoing nitration. The values of where fm refers to the corresponding homocyclic compound (biphenyl or diphenylmethane) when plotted against r, the distance between the... 

For uniformity with the stmctures given in the Colourindex the ammonium radical (9) is used for the amino-substituted xanthenes and the keto form for the hydroxy derivatives. The xanthene dyes may be classified into two main groups diphenylmethane derivatives, called pyronines, and triphenylmethane derivatives (eg, (4)), which are mainly phthaleins made from phthaUc anhydride condensations. A third much smaller group of rosamines (9-phenylxanthenes) is prepared from substituted ben2aldehydes. The phthaleins may be further subdivided into the following fluoresceins (hydroxy-substituted) rhodamines (amino-substituted), eg, (6) and mixed hydroxy/amino-substituted. 

Diphenylmethane Base Method. In this method, the central carbon atom is derived from formaldehyde, which condenses with two moles of an arylamine to give a substituted diphenylmethane derivative. The methane base is oxidized with lead dioxide or manganese dioxide to the benzhydrol derivative. The reactive hydrols condense fairly easily with arylamines, sulfonated arylamines, and sulfonated naphthalenes. The resulting leuco base is oxidized in the presence of acid (Fig. 4). 

In a variation of this method, isolation of the ben2hydrol derivative is not required. The methane base undergoes oxidative condensation in the presence of acid with the same or a different arylamine direcdy to the dye. New fuchsine [3248-91 -7] Cl Basic Violet 2 (16), is prepared by condensation of two moles of o-toluidine with formaldehyde in nitrobenzene in the presence of iron salts to give the corresponding substituted diphenylmethane base. This base is also not isolated, but undergoes an oxidative condensation with another mole of o-toluidine to produce the dye. 

Very recently equilibrium ion-pair acidities of substituted diphenylmethanes have been measured in cyclohexylamine188. The meta series gives a normal Hammett plot (p = 9.69)... 

The effect of solvent upon k2 has been reported , and it was concluded that the activated complex is not sufficiently polar to be called ionic . The oxidations of toluene and triphenylmethane exhibit primary kinetic deuterium isotope effects of 2.4 and ca. 4 respectively. No isotopic mixing occurred during formation of the Etard complex from a mixture of normal and deuterated o-nitrotoluene . The chromyl chloride oxidation of a series of substituted diphenylmethanes revealed that electron-withdrawing substituents slow reaction while electronreleasing groups have the opposite effect, the values ofp andp being —2.28 + 0.08 and —2.20 + 0.07 respectively . ... 

It can be seen that primary and secondary R02 radicals disproportionate with the participation of the a-C—H bond. This explains why the substitution of D in the a-position for H retards the recombination of R02 [/tn//tD =1.9 for ethylbenzene, h/ d = 2.1 for styrene, and h/ d=1-37 for diphenylmethane [179]). Because of this, R02 radicals of unsaturated compounds with a double bond in the a-position to the peroxyl free valence disproportionate more rapidly than structurally analogous aliphatic peroxyl radicals (at 300 K, 2kt = 2x 107 and 3.8 x 106 L mol-1 s-1 for R02 radicals of cyclohexene and cyclohexane, respectively [180]). Among the products of secondary peroxyl radicals disproportionation, carbonyl compound and alcohol were found in a ratio of 1 1 at room temperature (in experiments with ethylbenzene [181], tetralin [103], and cyclohexane [182-184],... 

This procedure illustrates a process which is general for 1,1-diphenyl substituted hydrocarbons. Diphenylmethane has been alkylated3 with benzyl chloride, benzhydryl chloride, a-phenyl-ethyl chloride, /3-phenylethyl chloride, isopropyl chloride, 2-ethylbutyl bromide, and re-octyl bromide in yields of 99, 96, 97, 88, 86, 96, and 99%, respectively. 

Methyl substituted diphenylmethanes are present in trace amounts in the reaction product with ZSM-5 catalyst, and in larger quantities with ZSM-4 catalyst. 

C. F. Correia, R. M. Borges dos Santos, S. G. Estacio, J. P. Telo, B. J. Costa Cabral, J. A. Martinho Simoes. Reaction of para-Hydroxyl-substituted Diphenylmethanes with tert-Butoxy Radical. Chem. Phys. Chem. 2004, 5, 1217-1221. 

The substituted diphenylmethane dye, auramine O, is weakly fluorescent in fluid solvents but highly fluorescent in viscous or rigid media. It was originally used to probe the viscosity of viscous polymeric samples. Such a strong dependence on solvent viscosity can be explained in the same way as for triphenylmethane dyes. 

TABLE 21. Equilibrium acidity of nitro-substituted diphenylmethanes in 30% H2O-70% DMSO at 25 °C... 

Attempts at correlation analysis for X—C—H acidity have been made for a long time. Bowden and colleagues192 examined the problem in 1970 for the pKa values of 9-X-fluorenes and related series. For a limited selection of substituents X in 9-X-fluorenes, a correlation with Taft s a values for X was found89. A more general correlation, albeit with considerable scatter, was found with AM, a parameter based on LCAO-MO calculations. Several dinitro-substituted diphenylmethanes fitted the line quite well and 2-nitrofluorene fitted passably 9-cyanofluorene also fitted quite well, but malononitrile deviated strongly. 

Electron-rich olefins with substituents Y = phenyl, vinyl, amino, or alkoxy can be coupled by anodic oxidation to tail-tail dimers being either deprotonated to dienes and/or substituted a to Y, depending on Y and the reaction conditions (Eq. 6). Alkyl substituted arenes can be dehydrodimer-ized to diphenyls or diphenylmethanes depending on the kind of substitution (Eq. 7). 

Representative couplings of aromatic hydrocarbons are summarized in Table 10. Alkyl-substituted aromatic hydrocarbons can be coupled to diphenyls and/or diphenylmethanes depending on their substitution pattern (Table 10, numbers 1-6). Reactions occur according to Scheme 9, paths (a) and (c). 

Laseter, J.L. Lawler, G.C. Griffin, G.W. Influence of Methyl Substitution on Mass Spectra of Diphenylmethanes. Analytical Applications. Anal. Lett. 1973, 6, 735-744. 

Figure 2. Competing cydization and radical substitution pathways in pyrolysis of sdica-immobilized diphenylmethane.

A few alkyl- and aralkyl-substituted aromatic hydrocarbons find limited use in perfumery. Examples include /i-cymene [99-87-6], which is a component of many essential oils and when pure has a weak, citrus odor, as well as diphenylmethane [101-81-5] which has an odor like geranium ... 

Various dehydrating agents—concentrated sulphuric acid, zinc chloride, phosphorus pentoxide—can be used. Sulphuric acid, although perhaps the most convenient, has the disadvantage that it tends to sulphonate the aromatic substances employed. At a low temperature, however, diphenylmethane can be obtained from benzyl alcohol and benzene. At 140° phosphorus pentoxide condenses benzene and diphenylcarbinol to triphenylmethane (see B., 7,1204). Not only substituted benzyl alcohols, but even mandelic acid can be brought within the scope of the reaction, while in place of benzefte its nitro, amino or phenolic derivatives may be used. 

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