Leaving-group ability

The relationship between leaving group ability and ba sicity IS explored in more de tail in Section 8 14... 

The relative leaving-group abilities of R 0 and are strongly correlated with the... 

The acid-catalyzed hydrolysis of imidazolides can also be accelerated by protonation of N-3, which increases the leaving-group ability of the ring. Accumulation of additional... 

Preparation of fluorine-containing sulfides has been achieved mainly by the reacuon of sulfenyl chlorides (RSCl), which may react with a vanety of nucleophiles The method is based on the electrophilicity of sulfur and on the leaving-group ability of chlorine... 

Dithiocarbamatc 16 has been used to prepare low dispersity PMAA ( Mw 1 Mn-1.2).52 Photopolymerization of S in the presence of dithiocarbamate 16 also displays some living characteristics (molecular weights that increase with conversion, ability to make block copolymer). However, 17 appears to behave as a conventional initiator in S polymerization.53 The difference in behavior was attributed to the relatively poor leaving group ability of the 2-carboxyprop-2-yI radical. This hypothesis is supported by MO calculations. Dithiocarbamatc 17 was used to control polymerizations of MMA,54 HEMA54 and NIPAM.5... 

Such arylations are characterized by a general order of leaving group ability in which the bromine is better than chlorine and much more than fluorine. Therefore, such catalytic reactions seem to be well adapted for a synthetic use of aryl bromides. 

Table 10.10 lists some leaving groups in approximate order of ability to leave. The order of leaving-group ability is about the same for SnI and Sn2 reactions. 

Nitro substitution increases the leaving-group ability of ArO groups, and alkyl picrates [2,4,6-R0C6H2(N02)3] react at rates comparable to tosylates Sinnott, M.L. Whiting,... 

Neplyuev, V.M. Bazarova, I.M. Lozinskii, M.O. J. Org. Chem. USSR, 1989, 25, 2011. This paper also includes a sequence of leaving group ability for other Z groups. 

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