n-Alkyl a-and fl-glucopyranosides, a-D-mannopyranosides and fi-D-galactopyranosides with alkyl chains having from 8 to 12 carbon atoms were synthesized and their surface properties--such as static surface tension (7), critical micelle concentration (CMC), occu, pation area of molecule, dynamic surface tension and foaming properties, biodegradability and antimicrobial activities -were evaluated. Alkyl glycosides containing C8 to C 12 carbon chains showed surface activities and critical micelle concentrations. D-Glucoside, Dmannoside and D-galactoside having the same alkyl chain showed similar surface tension lowering at CMC (Ycmc) and occupation area of the molecule at the surface. Among the alkyl glucosides, a-anomers were less hydrophilic than fl-anomers. All alkyl glycosides tested in this study were readily biodegraded by activated sludge of a municipal sewage plant compared to those of ethoxylated nonionic alcohols. The difference of the hydrophilic glycopyranoside group in biodegradability was not seen clearly, n-Alkyl glycosides containing C8 to C12 alkyl chains showed a broad spectrum of increasing antimicrobial activity, n-Dodecyl a-D-mannopyranoside was the most effective, the order of antimicrobial activity being mannopyranoside > glucopyranoside > galactopyranoside group. Members of this class of compounds exhibit the physicochemical and biological properties needed both for a wide range of applications and for environmental acceptance.

Gemini-type cationic surfactants containing carbonate linkages as biodegradable and chemically recyclable segments, consisting of two long-chain alkyl groups, two quaternary ammonium groups and a linker moiety, were designed and synthesized as novel green and sustainable cationics with improved physicochemical and biological activities. The gemini-type cationics containing a carbonate linkage showed lower critical micelle concentration values compared to the corresponding singletype cationics. Also, the gemini-type cationics containing a carbonate linkage in the linker moiety showed strong antimicrobial activities. The biodegradability of the gemini-type cationics was significantly improved when a carbonate linkage was introduced into the linker moiety. The maximum biochemical oxygen demand-biodegradability of the gemini-type cationics containing a carbonate linkage in the linker moiety exceeded 70% after a 28-day incubation. Furthermore, the gemini-type cationics containing both a carbonate linkage and an n-dodecyl group showed a chemical recyclability using a lipase (E.C. 3.1.1.3).

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Novel gemini-type cationics containing carbonate linkages as biodegradable and chemically recyclable segments were designed and synthesized by a green process. The carbonate linkages were introduced into only the hydrophobic moiety or in both the hydrophobic and linker moieties of gemini-type cationics. They showed higher surface activities, such as a low critical micelle concentration value, a surface tension lowering, and a high adsorption efficiency, when compared to the corresponding single-type cationics. Also, the gemini-type cationics containing carbonate linkages in both the hydrophobic and the linker moieties showed stronger antimicrobial activities when compared to those only in the hydrophobic moiety. It was found that some gemini-type cationics containing carbonate linkages showed higher biodegradability compared to the conventional gemini-type cationics. The biodegradability of the gemini-type cationics decreased when a carbonate linkage was introduced into the hydrophobic moiety rather than the linker moiety. However, some gemini-type cationics containing carbonate linkages both in the hydrophobic and linker moieties showed ready biodegradability. The gemini-type cationics containing carbonate linkages in the hydrophobic moiety showed chemical recyclability by a lipase (E.C. 3.1.1.3).

Novel biodegradable and chemically recyclable carbonate-type cationic surfactants consisting of a long chain alkyl group and a quaternary ammonium propyl group were designed and synthesized as a green surfactant. These carbonate-type cationics showed better surface activities in an aqueous solution when compared to the conventional cationics. Novel cationics containing both the carbonate linkage and n-dodecyl group showed strong antimicrobial properties, enzymatic degradabilities for chemical recycling and rapid biodegradabilities by activated sludge.