Methyl group, 753 table

The PMBs, when treated with electrophilic reagents, show much higher reaction rates than the five lower molecular weight homologues (benzene, toluene, (9-, m- and -xylene), because the benzene nucleus is highly activated by the attached methyl groups (Table 2). The PMBs have reaction rates for electrophilic substitution ranging from 7.6 times faster (sulfonylation of durene) to ca 607,000 times faster (nuclear chlorination of durene) than benzene. With rare exception, the PMBs react faster than toluene and the three isomeric dimethylbenzenes (xylenes). 

This indicator functions well giving a sharp colour change and is also resistant to oxidative decomposition. The transition potential may be modified by ring substitution with nitro or methyl groups (Table 5.5). 

Methyl magnesium halides react with most steroid ketones with a very pronounced preference for formation of the tertiary alcohol with an equatorial methyl group (Table 15). Methyl... 

In this case the stereocontrol is due to the chirality of the active center. However, it was found that isospecific addition of propylene occurs when the alkyl group attached to metal is more bulky than the methyl group (Table 5). Insertion of CjHe into the Ti—bond is not stereospecific and results in the formation of an equimolar mixture of threo- and erithro-isomers ... 

The value of the contact shift for the exo and endo protons can be derived indirectly from the calculated contact shift for the methyl groups in 1,1 -dimethyluranocene. Assuming a geometry factor for the methyl group (Table XIV) as 1/6(A + 2C + 2E + G)... 

The extent of enclosure of the ester functionality by the wall components of tetrathiacuppedophanes can be judged by the diamagnetic shielding experienced by the methyl groups. Table 1 lists chemical shift values of the methyl protons of the methyl ester in various tetrathiacuppedophanes. Included in parenthesis is the extent of shielding, i.e. Ad = tester (cuppedophane)-5ester (m-terphenyl). 

Best results were obtained when the active manganese was added to the neat benzyl bromide. The reaction was completed within 10 min at rt without a catalyst [39]. Several other benzyl halides produced good to excellent yields of homocoupling products, which showed a wide tolerance of functional groups such as nitrile, ester, nitro, chloro, bromo, methoxy, and methyl groups (Table 8.16). 

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