Butyl group, 753 table

Kinetic data are available for the nitration of a series of p-alkylphenyl trimethylammonium ions over a range of acidities in sulphuric acid. - The following table shows how p-methyl and p-tert-h xty augment the reactivity of the position ortho to them. Comparison with table 9.1 shows how very much more powerfully both the methyl and the tert-butyl group assist substitution into these strongly deactivated cations than they do at the o-positions in toluene and ferf-butylbenzene. Analysis of these results, and comparison with those for chlorination and bromination, shows that even in these highly deactivated cations, as in the nitration of alkylbenzenes ( 9.1.1), the alkyl groups still release electrons in the inductive order. In view of the comparisons just... 

Semiempirical molecular orbital PM 3 calculations of the parent thiepin (Table 4) differ from the data of 2,7-di-fe/7-butylthiepin concerning the bow angle, probably reflecting the strong influence of the /erf-butyl groups.29... 

The organolanthanide initiators allowed stereospecific polymerization of ethyl, isopropyl, and t-butyl methacrylates (Table 3). The rate of polymerization and the syndiotacticity decreased with increasing bulkiness of the alkyl group in... 

Lack of reactivity towards SN2 reactions at nitrogen would in itself account for low mutagenic activity. However, the tert-butyl groups on 31c f and 32a,b are well removed from the reactive nitrogen and, as well, SN2 reactions of mutagens 31c e with A-methylaniline in methanol at 303 °C occur with relatively similar rate constants to that of unsubstituted 28a, and of mono tert-butylated systems 28i and 31 a,b (Table 18). 

No fluorescence is observed at room temperature from TIN in non-polar solvents such as cyclohexane. In these solvents only the intramolecularly hydrogen-bonded form, which can undergo rapid ESIPT upon excitation, is present. The t-Bu-STIN derivative (see Table II) is very weakly fluorescent in all of the solvents examined. This is attributable to the protection of the intramolecular hydrogen bond from the solvent by the tertiary butyl group which is adjacent to the labile proton. 

Several of the entries in Table A5.6 also represent many of the efforts by Breslow s group to improve substrates for cleavage by /3-CD. The adamantylpropiolate ester [15a] exhibits a healthy acceleration of 2150, which is raised to 14000 by flexible capping and to 15 000 by judicious placement of a t-butyl group (Breslow et al., 1980) KTS values for these... 

Murray and colleagues199 developed some 2,5-diketopiperazines as new chiral auxiliaries and examined their asymmetric induction in the Diels-Alder reactions of their A-acryloyl derivatives with several dienes. Some of their results with dienophile 320 have been summarized in Table 19 (equation 89). When the benzyl group on 320 was substituted by an isopropyl or /-butyl group, the diastereofacial selectivity dropped dramatically. It was proposed that tv-tt stacking between the phenyl group and the electron-poor double bond provided a more selective shielding of one face of the double bond in this special case. 

Adolph and Cichra prepared a number of cyclic nitramines from the nitrolysis of tert-butyl protected Mannich products (Table 5.5). Nitrolysis of the fert-butyl groups was achieved with mixed acid, pure nitric acid or a mixture of nitric acid in acetic anhydride depending on the substrate. Pure nitric acid was found to affect the nitrolysis of both the ferr-butyl groups of (97), (Table 5.5, Entry 4) whereas the use of mixed acid led to the isolation of the product where only one of the ferf-butyl groups had undergone nitrolysis. Some of the cyclic nitramine products... 

The results presented here correspond to a series of tin-modified platinum catalysts prepared by SOMC/M techniques, which have the characteristics shown in entries 1, 6, 7 and 13 in Table 6.4. Figure 6.10 shows the variation of crotonaldehyde conversion as a function of time for two successive reaction cycles. A characteristic of these catalytic systems is their stability-only a slight flattening is observed for the Pt/Si02 catalyst. The presence of tin seems to improve this stability. Completely reproducible behavior is observed for both cycles, which is an important result mainly for the PtSn-OM system, which contains butyl groups anchored to the surface. 

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