Thermodynamic properties of aqueous solution of bisquatera theoretical point of view, but they are also very useful in nary ammonium salts, which are derivatives of N , N-bisdidefining the interaction model (1-3).
methyl-1,2-ethanediamine ( bis-C n -BEC ) , of general formula
In this paper we are dealing with bisquaternary ammonium
0 (bis-C n -BEC, where the subscript n stands for the diamine of general formula /C n H 2n /1 OOCCH 2 (CH 3 ) 2 N ᮍnumber of carbon atoms of the alkyl chain bound to the carboxyl CH 2 CH 2 N ᮍ (CH 3 ) 2 CH 2 COOC n H 2n /1 /2Cl 0 (bis-C n -BEC, group) are here reported and compared with those of the corre-
where the subscript n stands for the number of carbon atoms sponding monomers. Dilution enthalpies have been measured by of the alkyl chain bound to the carboxyl group) and, at least means of a flow type microcalorimeter at 313 K, and densities have been measured by means of a vibrating tube densimeter at formally, can be treated as double amphiphilic betaine ester 298 K. Apparent and partial molar quantities have been obtained derivatives (C n -BEC). Betaine ester derivatives, we studied from the experimental data and expressed as a function of molalibefore (6-8), show biological activity and influence desorpties, assuming the infinite dilution as standard state. The changes tion of calcium ion and transport of sulfate anion across the in enthalpy and in volume upon micellization have been evaluated membranes (4, 5). Among others, it was found that the by assuming the pseudo-phase transition model. From the calcumicelles formed by C n -BEC are hydrated at the depth of lated enthalpy changes at 313 K and that previously reported at -CH 2 COO-group and those of N-alkyltriemethylammonium 298 K, the changes in heat capacity for micellization has been at the depth of two methylene groups (7). For that reason C nevaluated. The data suggest the hypothesis that the alkyl chain in BEC in respect to micellar properties are equivalent to the the dimers are already partially associated in solution. Moreover, respective N-alkyltrimethylammonium chlorides with chains the trends of the cmc as a function of the chain length for monolonger by two methylene groups (6, 8). It has been also shown mers and dimers suggest that the association of the chains probably leaves out the first three methylene groups of the alkyl chains that bis-C n -BEC influences desorption of calcium from lipobound to the carboxylic groups. The packing parameter, P, gives somes membranes (5) and induces haemolysis of pig red blood 0.37 for bis-C 10 -BEC, and the formation of rod-like micelles is cells. In this respect their effectiveness is greater than that of therefore suggested.