Trivial aryl groups

The names of esters consist of two words that reflect their formation from an alcohol and a carboxylic acid. According to the 1UPAC rule. Ihe alkyl or aryl group of the alcohol is cited first followed by the carboxylate group of the acid with the ending -ate replacing the -ic of the acid. For example. CHiCHiCOOCH, the methyl ester of propanoic acid, is called methyl propanoate (or methyl propionate, if the trivial name, propionic acid, is used for the carboxylic acid). 

As the reaction conditions for the preparation of the masked disilenes are as harsh as those of the Wurtz-type reductive coupling reaction, the introduction of functional groups is not trivial. An elegant way to introduce at least some diversity is via the transformation of amine-functionalized polysilanes [39] to the chloro substituted derivatives. These can be converted to alkyl and aryl groups using the corresponding Grignard compounds (Fig. 9) [35]. 

Available compounds with a 1,2-relationship include many simple ones 78-90 whose trivial names may help you find them in suppliers catalogues. The amino acids 83 are the constituents of proteins and are available with R = alkyl, aryl, and various functionalised groups.14... 

Not surprisingly, three nitro groups have an even greater influence on the reactivity of the halogen and 1-chloro-2,4,6-trinitrobenzene (picryl chloride) is hydrolysed to 2,4,6-trinitrophenol (picric acid) in boiling water. The trivial names tell us that this aryl halide behaves as an acyl halide and the phenol as an acid. 

Andersson and coworkers investigated the role of solvation, dispersion, and steric effects on the enantioselectivity. The authors results agree with the fact that gas-phase B3LYP calculations describe the drop in enantioselectivity of 2,3,4,5,6-pentafluoroacetophenone compared to acetophenone where steric and electrostatic effects are the only major effects, but the approximation is too crude to reproduce quantitatively the extent of enantioselection observed experimentally. In order to extract the isolated contributions of steric effects, the authors correlated the same energetic parameter with respect to an empirical steric parameter called STERIMOL B1 [132]. Their results showed that bulkier alkyl groups tend to decrease the enantioselectivity, which correlates well with the B1 parameter. Based on this observation, it seems that an intrinsic steric factor enhances or depresses the enantioselectivity in the reduction of acetophenone and other n-alkyl aryl ketones. However, a generalized rationalization of this effect is not trivial, and investigation of similar catalysts reveals only a small role for steric effects [105, 109]. 

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