Pimelic acid, 290 Table

Tables 4 and 5 show the general structures and mesomorphic characteristics of the homo- and co-polycondensate liquid crystal systems, respectively. Chiral thermotropic polyesters have been studied mainly by Blumstein and Krigbaum, almost simultaneously with, or immediately following, the first report by Strzelecki and co-workers.The latter report described also the preparation and properties of a cholesteryl end-capped polyester based on achiral components 4 -hydroxyphenyl 4-hydroxy benzoate and pimelic acid (Table 5).

Common Names of Dicarboxylic Acids A dicarboxylic acid (also called a diacid) is a compound with two carboxyl groups. The common names of simple dicarboxylic acids are used more frequently than their systematic names. A common mnemonic for these names is Oh my, such good apple pie, standing for oxalic, malonic, succinic, glutaric, adipic, and pimelic acids. The names and physical properties of some dicarboxylic acids are given in Table 20-2. 

Order of thermal stabiUty as determined by differential thermal analysis is sebacic (330°C) > a2elaic = pimelic (320°C) > suberic = adipic = glutaric (290°C) > succinic (255°C) > oxahc (200°C) > malonic (185°C) (19). This order is somewhat different than that in Table 2, and is the result of differences in test conditions. The energy of activation for decarboxylation has been estimated to be 251 kj/mol (60 kcal/mol) for higher members of the series and 126 kJ/mol (30 kcal/mol) for malonic acid (1). 

Extension by three carbon atoms is possible with methyl glutarate [183], by the isoprene unit with ethyl 3-methyl adipate [184], by four carbon atoms with methyl adipate [143], by five carbon atoms with methyl pimelate [185] and by six carbon atoms with methyl suberate [186]. A series of branched -fluorocarboxylic acids were prepared by cross-coupling with oo-fluorocarboxylic acids [187]. For further examples see Tables 6, 7. 

Table 4. Experimental conditions and weight percent of original organic matter converted to oxalic (Q), succinic (C4), pyrotartaric (C5), glutaric (C5), iso-adipic (Q), adipic (C6), pimelic (C7), suberic (Cg), azelaic (C9), and sebacic (Ciq) acids at maximum generation of total dicarboxylic aliphatic acids...

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