Reactions with 2-Alkyl Groups

The particular acidity of the protons of pyridine a- and 7-alkyl groups is echoed by quinoline-2- and 4-alkyl groups and by alkyl at the isoquinoline 1-position, but to a much lesser extent by alkyl at isoquinoline C-3. Condensation reactions with alkyl groups at these activated positions can be achieved in either basic or acidic media the key nucleophilic species in the latter cases is probably an enamine, or enamide, and in the former, a side-chain carbanion. ... 

Reaction with Alkyl Halide. The active methylene group of an Al-acylamino-malonic acid ester or Ai-acylamino cyanoacetic acid ester condenses readily with primary alkyl hahdes. 

Thus, reduction of the Mannich reaction product (65) from acetophenone leads to alcohol 66. Replacement of the hydroxyl group by chlorine (67) followed by displacement of halogen with the anion from o-cresol affords the ether 68. Removal of one of the methyl groups on nitrogen by means of the von Braun reaction or its modem equivalent (reaction with alkyl chloroformate followed by saponification) leads to racemic 69 which is then resolved with L-(+)-mandelic acid to give the levorotary antidepressant tomoxetine (69) [16]. 

With most common monomers, the rate of the reverse reaction (depropagation) is negligible at typical polymerization temperatures. However, monomers with alkyl groups in the a-position have lower ceiling temperatures than monosubstituted monomers (Table 4.10). For MMA at temperatures <100 °C, the value of is <0.01 (Figure 4.4). AMS has a ceiling temperature of <30 °C and is not readily polymerizable by radical methods. This monomer can, however, be copolymerized successfully (Section 7.3.1.4). 

Lucchi , who studied the oxidation of substituted benzaldehyde derivatives found that chlorine atoms in the meta and para position accelerate the reaction and alkyl groups retard the oxidation. A Hammett plot of Lucchi s data yields a good straight line with the slope p = 1.06. These data suggest that the reaction proceeds by way of the chromic ester of hydrated benzaldehyde as intermediate, viz. 

Allylic stannanes are an important class of compounds that undergo substitution reactions with alkyl radicals. The chain is propagated by elimination of the trialkyl -stannyl radical.315 The radical source must have some functional group that can be abstracted by trialkylstannyl radicals. In addition to halides, both thiono esters316 and selenides317 are reactive. 

In practice, fragmentation of exactly this kind is observed under basic conditions, to give 18 in 45% isolated yield along with less than 10% /767>. (With alkyl groups other than the methyl substituent the ratio of 2- to 3-cyclopentenyl isomers can rise to 40 60.)67). The reactivity functions in EROS evaluate these products quite highly. The enthalpy of reaction is also realistic at —2.5 kcal/mol for both products. This value is more favorable than those for the other possible products suggested. 

Many organoarsenic compounds are prepared by reactions of AsC13 with alkyl group transfer agents such as Grignard reagents, lithium alkyls, or aluminum alkyls. Typical reactions include... 

In addition to homolytic decomposition, hydroperoxyl groups of polymer are decomposed in reactions with alkyl radicals (see Chapter 4). Such induced decomposition of POOH groups... 

In addition to this reaction, quinones and other alkyl radical acceptors retard polymer oxidation by the reaction with alkyl radicals (see earlier). As a result, effectiveness of these inhibitors increases with the formation of hydroperoxide groups in PP. In addition, the inhibiting capacity of these antioxidants grows with hydroperoxide accumulation. The results illustrating the efficiency of the antioxidants with cyclic chain termination mechanisms in PP containing hydroperoxide groups is presented in Table 19.12. The polyatomic phenols producing quinones also possess the ability to terminate several chains. 

Silylated iminophosphines (15) react with alkyl halides to give the iminophos-phoranes (16).8 Similar reactions with Main-group IV and VII halides give the heterocycles (17) via the intermediate 1,2-addition products (18), which can be isolated in the case of germanium. 

The rate of the base-catalysed condensation of carbonyl compounds with alkyl groups activated by Jt-deficient aromatic systems is enhanced by the addition of quaternary ammonium salts. For example, 2-methylbenzoxazole, 2-methylbenzo-thiazole and 4-nitrotoluene react with a range of substituted benzaldehydes to produce the corresponding 2-styryl derivatives (62-80%) at room temperature over 1 -2 hours [61, 62]. The intermediate alcohol can also be isolated after a short reaction time. 

Friedeb Crafts reaction Anisole undergoes Friedel-Crafts reaction, i.e., the all rl and acyl groups are introduced at ortho and para positions by reaction with alkyl halide and acyl halide in the presence of anhydrous alurntnlurn chloride (a Lewis acid) as catalyst. 

Production of iminoboranes by a hot tube procedure is obviously restricted to those reactants that can be transported into the gas phase without decomposition. Owing to this restriction the reactions according to Eqs. (3) and (4) cannot be applied to reactants with alkyl groups larger than C4H9 or with aryl groups. 

The electrophilic reactivity of lithium carbenoids (reaction b) becomes evident from their reaction with alkyl lithium compounds. A, probably metal-supported, nucleophilic substitution occurs, and the leaving group X is replaced by the alkyl group R with inversion of the configuration . This reaction, typical of metal carbenoids, is not restricted to the vinylidene substitution pattern, but occurs in alkyl and cycloalkyl lithium carbenoids as well ". With respect to the a-heteroatom X, the carbenoid character is... 

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