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Carbocations, continued reactivity

Carbocations are highly reactive species that can be used for C-C bond formation. One driver for using continuous micro chemical processing is to employ also unstable cations, which are not amenable to batch synthesis because they decompose before they can actually be used [66, 67]. [Pg.444]

The tertiary carbocation can now act as an electrophile and attack the alkene to form another tertiary carbocation of similar stability and reactivity to the first. So the polymerization continues. [Pg.1462]

The more stable a cation is, the less reactive it is and, conversely, the less stable a cation is, the more reactive it is. This means that, although a methyl cation is very reactive if it forms, this higher energy carbocation has a higher activation barrier to formation, relative to a more stable ion such as a tertiary carbocation. As noted, this information leads to the conclusion that it is easier to form a tertiary cation by ionization of a tertiary halide than it is to form a secondary carbocation by ionization of a secondary halide. Continuing the trend, it should be very difficult to form a primary cation from a primary halide such as 1-bromopentane (72) and very difficult indeed to form a methyl carbocation from iodomethane or bromomethane. [Pg.531]

Useful reviews include preparation, reactivity, and spectroscopic identification of carbocations and the use of pico- and nano-second pulse radiolysis for observing both monomer and polymer cations. Theoretical discussions on the use of Mayo plots in cationic polymerizations have appeared. Morawetz derived an expression for M /M for a system involving instant and complete initiation with termination but no transfer and showed why this is normally less than the most probable distribution of M /M = 2. Heublein et continued... [Pg.6]

Cationic Poiymerization Electophilic Addition in the Absence of a Reactive Nucleophile. In the presence of catalytic amounts of acidic materials (protic as well as nonprotic) lacking nucleophilic counterions, the attack of the electron-rich alkene on the electrophile appears to occur with the formation of a carbocation as expected but, as a nucleophilic anion is missing, another alkene attacks the carbocation (Table 6.1, entry 19). The result is the formation of a new carbocation, larger than the original by one alkene unit (Scheme 6.32 R H).The process continues until termination is effected (e.g., by proton loss). [Pg.340]


See other pages where Carbocations, continued reactivity is mentioned: [Pg.225]    [Pg.861]    [Pg.94]    [Pg.595]    [Pg.166]    [Pg.697]    [Pg.482]    [Pg.23]    [Pg.231]    [Pg.719]    [Pg.427]    [Pg.245]    [Pg.672]    [Pg.427]    [Pg.601]    [Pg.160]    [Pg.169]    [Pg.239]    [Pg.119]    [Pg.595]    [Pg.10]    [Pg.697]    [Pg.368]   
See also in sourсe #XX -- [ Pg.99 , Pg.309 ]




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Carbocations reactivity

Carbocations, continued

Reactivity (continued

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