Aldonamide‐type gemini surfactants: Synthesis, structural analysis, and biological properties

A new group of nonionics, so‐called sugar surfactants having a gemini structure, N,N′‐bisalkyl‐N,N′‐bis[(3‐gluconylamido)propyl]ethylenediamines [bis(CnGA): Cn=n‐C8H17, n‐C12H25], N,N′‐bisdodecyl‐N,N′‐bis[(3‐glucoheptonylamido)propyl]ethylenediamine [bis(C12GH)], and N,N′‐bisalkyl‐N,N′‐bis[(3‐lactobionylamido)propyl]ethylenediamines [bis(CnLA): Cn=n‐C8H17, n‐C12H25], were prepared in a convenient four‐step procedure from easily accessible reagents. Their structure and purity were confirmed by means of elemental analysis, electrospray ionization MS (ESI‐MS), and NMR spectra—1H, 13C, 1H−13C COSY, and distortionless enhancement by polarization transfer. All tested surfactants were practically nontoxic to gram‐negative bacteria and fungi, but they inhibited the growth of some gram‐positive bacteria. From the results of the Closed Bottle test (OECD Guideline 301D) for biodegradability measurements, it was concluded that the tested aldonamide gemini structures are biodegraded by environmental microorganisms to 16–55% of the initial levels by day 28, the extent depending on both the aldonamide type and the alkyl chain length. Consequently, N,N′‐bisalkyl‐N,N′‐bis[(3‐aldonylamido)propyl]ethylenediamines are a surfactant class having low ecotoxicity and fulfilling requirements desired from an ecological standpoint.