Volume 47, Issue 4

Alkylmonoglycosides with different alkyl chain lengths (APG 8 , APG 9 , APG 10 and APG 14 ) were prepared by Fisher reaction of glucose with fatty alcohols. Excess alcohol was used to increase the possibility of producing alkyl monoglycosides products. Mass spectrometry with chemical ionization was used to confirm their structures as alkyl monoglycosides. Accordingly, the obtained signals at m/z = 293, 307, 321 and 377 corresponds to their protonated molecules. The base lines which are the most intensive signals in each spectrum at m/z = 145, 127, 141 and 197 represent the most abundant ions and define the pathway of their fragmentation mechanism. The mass 145 for APG 8 is generated from the parent ion by elimination of the mass ROH followed by H 2 O. For this compound cleavage occurs at the C–O bond next to the glucose ring, while fragmentation of alkyl monoglycosides with carbon number 9, 10 and 14 occurs at the O–R bond releasing the alkyl cation R of the aglucone moiety (C n H 2n+1 ) along with large fragment ions characteristic of the glucose moiety.

In the present paper analysis of alkylphenols and their short-chained ethoxylates was presented. The analytes were determined in sediments from Lake Malta as well as in water incoming to and outgoing from the lake. Sonication-assisted extraction was used for isolation of the analytes from the sediment samples. Solid-phase extraction with polytetrafluoroethylene sorbent was used for both clean-up of extracts and isolation of analytes from the water samples. Alkylphenols and their ethoxylates were quantitatively analysed with the use of HPLC with fluorescence detection. The analytes were determined in the sediment samples at relatively low concentrations with the maximum concentration of 168 μg kg −1 for nonylphenol monoethoxylate, which can be ascribed to periodic removal of sediments from Lake Malta. Maximum concentration in water samples was noted for nonylphenol at 0.56 μg L −1 . No octylphenol nor its ethoxylates were found in the water samples.

1,1,1-triethoxycarbonyl-3-[2-(F-alkyl)-ethyl]propanes and 1,1,q,q-tetraalkoxycarbonyl-1,q-di-[2-(F-alkyl)-ethyl]alcanes were prepared from 2-(F-alkyl)-ethyl iodides in a one-step procedure involving a Solid-Liquid Phase Transfer Catalysis.

Amphipatic compounds with connecting group between two lipophilic groups were prepared by phosphorylating a long chain alcohol (hexadecanol) with pyrophosphoric acid to prepare hexadecyl phosphate. Then the resulting hexadecyl phosphate was used to prepare bisphosphate surfactants with terminal dibromo alkanes viz. 1,4-dibromo butane or 1,6-dibromo hexane or 1,8-dibromo octane using acetonitrile as solvent. The structure of synthesized products were verified by modern analytical techniques viz. FT-IR, and 1 H-NMR. The disodium salts of bisphosphate surfactants were obtained by neutralization of free acid with sodium hydroxide. The performance properties viz. foaming, wetting, emulsifying ability and anionic content of synthesized surfactants were also evaluated. The synthesized bisphosphate surfactant with 1,6-dibromo hexane possessed maximum anionic content and showed good water solubility, foaming, wetting, and emulsifying ability compared to conventional analogs.

The interest in biosurfactant has increased considerably due to their large potential for industrial applications. Rhamnolipid is a simplest class of biosurfactants with well defined structure. The main obstacle in commercialization of biosurfactant especially rhamnolipids is the higher cost of the production. Glycerol is readily available from commercial fat-splitting process in the form of sweet water (up to 20% w/v) at very low cost. Two natural strains of Pseudomonas aeruginosa (ATCC 10145 and ATCC 9027) were compared for rhamnolipid production. The neotype strain of Pseudomonas aeruginosa (ATCC 10145) was found to produce more amounts of rhamnolipids than Pseudomonas aeruginosa (ATCC 9027) on glucose and glycerol as carbon source. The microbial growth (0.94 g/L) and formation of rhamnolipids (2.75 g/L) was maximum at 5% (w/v) glycerol concentration by Pseudomonas aeruginosa (ATCC 10145). The fermentation was monitored for 8 days on shake flask and magnetically stirred batch culture. In magnetically stirred batch culture, microbial growth was 0.69 g/L and 2.73 g/L of rhamnolipid was formed. Sweet water was also used as a source of glycerol.

Three novel dialkyl disulfonate gemini surfactants (C n -6-C n , n = 6, 8, 12; n is carbon number of hydrophobic chain) were synthesized from cyanuric chloride, aliphatic amine and taurine. The chemical structures of the prepared compounds were confirmed by 1 H NMR, 13 C NMR, IR spectra and ESI-MS. Their critical micelle concentrations (CMC) in the aqueous solutions at 25°C were determined by surface-tension method. With the increasing length of the hydrophobic carbon chain, the values of their CMC decreased. The surface tension measurements of C n -6-C n give low CMC, great efficiency in lowering the surface tension, and strong adsorption at air–water interface. In addition, adsorption and micellization behavior of C n -6-C n were estimated by the parameter of pC 20 , the minimum average area per surfactant molecule (A min ).

A new thin layer chromatographic system comprising of silica gel impregnated with 0.1% aqueous solution (below CMC) of nonionic surfactant Brij-35 as stationary phase and 0.1% aqueous solution (below CMC) of cationic surfactant (cetrimide) as eluent has been found most suitable for the separation of closely related amino acids (phenylalanine and tyrosine) from their mixture. Effect of substitution of Brij-35 by cetrimide and sodium cholate has been examined to assess the impact of charge of impregnant on the chromatographic behavior of analytes. The changes brought about by the impregnation in the structure and homogeneity of silica gel have been studied by scanning electron microscopy (SEM) and fourier transform infra-red spectroscopy (FTIR) techniques. Optimizations of concentration of Brij-35 and cetrimide in the stationary and mobile phases respectively and the effect of bed height on the separation have also been examined. Chromatographic parameters like ΔR F , separation factor (α) and resolution (R S ) were calculated for the separation of tyrosine from phenylalanine and separation mechanism have been proposed. The limits of detection for phenylalanine and tyrosine were found to be 0.25 and 0.23 μg respectively. The proposed method studied is simple, rapid and free from the use of volatile organic solvents.

The conductance results showed that uranyl soaps behave as weak electrolyte in dilute solution of N,N-dimethylformamide (DMF) at various temperatures below the critical micelle concentration, indicating that Debye–Hückel–Onsager's equation is not applicable to these soaps solutions. The value of critical micelle concentration decreases with increasing chain length of the soap and increasing temperature. The results were used to evaluate various thermodynamic parameters for both dissociation and association processes and may be satisfactorily explained in the light of phase separation model. The results show that the dissociation process of these soaps was found to be endothermic while micellization is exothermic in nature.

A metal(II) ion (Cu 2+ )-induced vesicle phase was prepared from a mixture of n-undecylamine and CuCl 2 in aqueous solution. Cu 2+ -ligand coordination with n-undecylamine results in the formation of molecular bilayers because Cu 2+ can firmly bind to the amine groups of n-undecylamine which reduced the area of the head-group. In this system, no counterions in aqueous solution exist because of the Cu 2+ -ligand coordination, and the bilayer membranes are not shielded by salts. The vesicles were determined by transmission electron microscopy (TEM) images and dynamic light scattering (DLS) measurements.