Abstract
A series of new phosphate type of amphoterics having a 2-hydroxypropyl group and ether bond, 2- [N- (3-alkoxy-2-hydroxypropyl) -N, N-dimethylammonio] ethyl hydrogen phosphates [alkyl (R) : decyl, dodecyl and tetradecyl], were synthesized. Their interfacial properties, such as surface tension, cmc (critical micelle concentration), occupied area/molecule at the air/water interface and changes in free energy of micellization, and antimicrobial activity were investigated. The results indicated that the cmcs were very low and that the phosphobetaine moiety, ether bound and 2-hydroxypropyl group caused improvement of their surface active properties by increasing their hydrophobicity. The MICs (Minimum Inhibitory Concentration) of these homologues were high for gramnegative and gram-positive bacteria. However, in the case of fungi, they decreased linearly with increase in carbon number of the long chaine-alkyl group. Those of 2- [N- (3-tetradecyloxy-2-hydroxypropyl) -N, N-dimethylammonio] ethyl hydrogen phosphate against fungi were lower than those of chlorhexidine digluconate.
