T-butylbenzene

The photoisomerization of aromatic rings has also been studied using 1,3,5-tri-t-butylbenzene. The composition of the photostationary state is shown below ... 

Detailed kinetic studies of the decomposition of platinum(II) dineophyls show (Figure 3.60) the exclusive formation of t-butylbenzene and an internally metallated platinum complex (3,3-dimethylplatininadan). 

Finally, rates of mercuration have been measured using mercuric trifluoro-acetate in trifluoroacetic acid at 25 °C450. The kinetics were pure second-order, with no reaction of the salt with the solvent and no isomerisation of the reaction products rate coefficients (10 k2) are as follows benzene, 2.85 toluene, 28.2 ethylbenzene, 24.4 i-propylbenzene, 21.1 t-butylbenzene, 17.2 fluorobenzene, 0.818 chlorobenzene, 0.134 bromobenzene, 0.113. The results follow the pattern noted above in that the reaction rates are much higher (e.g. for benzene, 690,000 times faster than for mercuration with mercuric acetate in acetic acid) yet the p factor is larger (-5.7) if the pattern is followed fully, one could expect a larger... 

The column used was a Pecosphere 3 mm in diameter and 3 cm long carrying a Cl8 stationary phase. The mobile phase was a mixture of methanol (75%) and water (25%) at a flow rate of 2 ml/min. The solutes were 1 benzene, 2 toluene, 3 ethyl benzene, 4 isopropyl benzene, 5 t-butylbenzene, 6 anthracene, and 7 sodium chloride. 

The Ag-silica-alumina material is furthermore suited to assist in sterically hindered aromatic brominations. As an example we converted 1,3,5-tri-t-butylbenzene into 2,4,6-tri-t-butylbromobenzene. When using an acidic zeolite and Br2 de-alkylation prevails and 3,5-di-t-butylbromobenzene is formed (ref. 29). 

B. Reactions.—(/) Nucleophilic Attack at Phosphorus. A reinvestigation of the reaction between phosphorus trichloride and t-butylbenzene in the presence of aluminium chloride has shown that the product after hydrolysis is the substituted phosphinic acid (11), and not the expected phosphonic acid (12). Bis(A-alkylamino)phosphines have been reported to attack chlorodiphenyl phosphine with nitrogen, in the presence of a base, to give bis-(A-alkyl-A-diphenylphosphinoamino)phenylphosphines (13). In (13), the terminal phosphorus atoms are more reactive than the central one towards sulphur and towards alkyl halides. 

Fig. 3-1. Separation of racemic 3,5-dinitrobenzamido leucine AW-diallylamide on silica and polymer-based chiral stationary phases. Conditions column size 150 x 4.6 mm i.d. mobile phase 20 % hexane in dichloromethane flowrate 1 mL min-1 injection 7 pg. Peaks shown are l,3,5-tri-te/t.-butylbenzene (1), -enantiomer (2) -enantiomer (2 ). (Reprinted with permission from ref. [8]. Copyright 1997 American Chemical Society.)...

Synonym (l,l-dimethylethyl)benzene, 2-methyl-2-phenylpropane, trimethylphenylmethane, pseudobutylbenzene, t-butylbenzene... 

Finally, we ask, if the reactive triads in Schemes 1 and 19 are common to both electrophilic and charge-transfer nitration, why is the nucleophilic pathway (k 2) apparently not pertinent to the electrophilic activation of toluene and anisole One obvious answer is that the electrophilic nitration of these less reactive [class (ii)] arenes proceeds via a different mechanism, in which N02 is directly transferred from V-nitropyridinium ion in a single step, without the intermediacy of the reactive triad, since such an activation process relates to the more conventional view of electrophilic aromatic substitution. However, the concerted mechanism for toluene, anisole, mesitylene, t-butylbenzene, etc., does not readily accommodate the three unique facets that relate charge-transfer directly to electrophilic nitration, viz., the lutidine syndrome, the added N02 effect, and the TFA neutralization (of Py). Accordingly, let us return to Schemes 10 and 19, and inquire into the nature of thermal (adiabatic) electron transfer in (87) vis-a-vis the (vertical) charge-transfer in (62). 

Juri and Bartsch (1979) have studied the coupling of 4-t-butylbenzene-diazonium tetrafluoroborate with N,N-dimethylaniline in 1,2-dichloroethane solution. The addition of one equivalent (based on diazonium salt) of 18-crown-6 caused the rate constant to drop by a factor of 10, indicating that complexed diazonium is less reactive than the free cation. Benzenediazonium tetrafluoroborate complexes of crown ethers are photochemically more stable than the free salt. The decomposition into fluorobenzene and boron trifluoride is strongly inhibited but no explanation has been given (Bartsch et al., 1977). 

Cyclization of diethyl N-[cyclohepta(6)pyrrrol-2-yl]aminomethylene-malonates (1676), by heating in xylene, t-butylbenzene, or tetralin at reflux temperature, gave cyclohepta[4,5]pyrrolo[l, 2-a]pyrimidine-3-carboxyl-ates (1677) in 46-90% yields (87BCJ1053). Cyclization were also carried out in a mixture of phosphoryl chloride and polyphosphoric acid. While compound 1676 (R = COOEt) gave 1677 (R = COOEt) in 95% yield, the unsubstituted 1676 (R = H) afforded a mixture of 1677 (R = H) and 4-hydroxycyclohepta[4,5]pyrrolo[2,3-b]pyridine-3-carboxylate (1678) in 7% and 48% yields, respectively. The nitrogen bridgehead compound (1677, R = H) could not be transformed into pyridine derivative (1678). 

Ogimachi et al. (1955) also investigated in more detail the steric effect on the equilibrium constants of the complex formation of ICl with various benzene derivatives. The basicity decreases greatly on substitution of bulky groups, e.g. the t-butyl group. This effect is particularly pronounced for 1,3,5-tri-t-butylbenzene. 

Alkyltetralin from alkyltetrahn, linear alkylbenzene NaY t-Butylbenzene [1.2]... 

Acid-catalyzed reactions of aromatics with monoolefins result in nuclear alkylation. But the base-catalyzed reactions of aromatics with olefins do not result in nuclear alkylation as long as benzylic hydrogens are available. This is true even with aromatics, such as cumene, which have deactivated benzylic hydrogens resulting in facile metalation of the ring. Apparently phenyl carbanions do not readily add to olefins. Pines and Mark (20) found that in the presence of sodium and promoters only small yields of alkylate were produced at 300° in reactions of benzene with ethylene and isobutylene and of t-butylbenzene with ethylene. With potassium, larger yields may be obtained at 190° (24)-... 

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