Dispersive liquid–liquid microextraction applied to isolation and concentration of alkylphenols and their short-chained ethoxylates in water samples

Dispersive liquid–liquid microextraction (DLLME) coupled with high-performance liquid chromatography with fluorescence detector was applied for the determination of alkylphenols and their short-chained ethoxylates in water samples. Development of DLLME procedure included optimisation of some important parameters such as kind and volume of extracting and dispersing solvents. Under optimised conditions 50 μL of trichloroethylene in 1.5 mL of acetone were rapidly injected into 5 mL of a water sample. After centrifuging the organic phase containing the analytes was taken for evaporation with a gentle nitrogen purge and reconstituted to 50 μL of acetonitrile. The aliquot of this solution was analysed with the use of HPLC. For octylphenol (OP) and octylphenol ethoxylates (OPEOs) linearity was satisfactory in the range 8–1000 μg L⁻¹ and for nonylphenol (NP) and nonylphenol ethoxylates (NPEOs) linearity was in the range from 50 to about 3000 μg L⁻¹. Limit of quantitation was 0.1 μg L⁻¹ for OP and OPEOs and 0.3 μg L⁻¹ for NP and NPEOs. Satisfactory recoveries between 66 and 79% were obtained for environmental samples. The results showed that DLLME is a simple, rapid and sensitive analytical method for the preconcentration of trace amounts of alkylphenols and their ethoxylates in environmental water samples.     

Micellization of a cationic gemini surfactant in aqueous solutions with different alkanols and alkanediols as additives: Effect of nonpolar chain and position of hydroxyl groups

The gemini surfactant N-N′bis(dimethyldodecyl)-1,4-butanediammonium dibromide (12-4-12) was synthesized and its critical micelle concentrations (CMCs) and degree of counterion dissociation (α) in aqueous solutions in the presence of alkanols viz ethanol, isomeric butyl alcohols, 1-hexanol and alkanediols (ethanediol, 1,4-butanediol, 1,2-hexanediol, 2,5-hexanediol 1,6-hexanediol, and 1,8-octanediol) determined from electrical conductivity are reported. While ethanol, ethanediol, 1,4-butanediol showed an increase in CMC, a decrease was seen for isomeric butyl alcohols, 1-hexanol, isomeric hexanediols and 1,8-octanediol. For butyl alcohols the CMC decrease showed the trend 1° >2° > 3°; in C₆ diols, 1,2-hexanediol exerted more decrease as compared to 2,5-hexanediol and 1,6-hexanediol.The results are explained on the basis of the structure and hydrophobicity of alcohols that determine their effect as cosolvent or cosurfactant (partitioning in micelles). Two-dimensional nuclear overhauser enhancement spectroscopy (2D-NOESY) was used to examine the location for 1-butanol and 1,4-butanediol in micellar systems as representative additives from alkanols and alkanediols showing CMC decreasing and increasing effect respectively.     

Solubility of benzilic acid in select organic solvents at 298.15 K

Experimental solubilities are reported for benzilic acid dissolved in ethanol, 1-propanol, 1-butanol, 1-pentanol, 1-hexanol, 1-heptanol, 2-propanol, 2-butanol, 2-methyl-1-propanol, diethyl ether and methyl tert-butyl ether at 298.15?K. Results of these measurements reveal that the observed solubilities in the nine alcohol solvents fall within a fairly narrow mole fraction range of each other. Benzilic acid is also very soluble in the two ether solvents studied.     

Effective oxidation of alcohols by Iron(III)-Schiff base-triphenylphosphine complexes

Iron(III)-Schiff base-triphenylphosphine complexes catalyze the oxidation of alcohols to their corresponding carbonyl compounds in presence of hydrogen peroxide in good yields.     

Efficient tetrahydropyranyl and tetrahydrofuranyl protection/deprotection of alcohols and phenols with Al(OTf)3 as catalyst

A simple and efficient method for the conversion of alcohols and phenols into their corresponding THP and THF ethers at room temperature has been developed using 1 mol % aluminium triflate as catalyst. The deprotection reaction in the presence of methanol using Al(OTf)₃ was equally successful and could be performed at ambient temperature in high yields.     

Air-stable iron catalyst for the Oppenauer-type oxidation of alcohols

An alcohol oxidation process using an air-stable iron tricarbonyl compound structurally similar to Shvo’s diruthenium bridging hydride was developed. Secondary benzylic and allylic alcohols are oxidized in high yields, and evidence for an Oppenauer-type mechanism is presented.     

Performance of amperometric alcohol electrodes prepared by plasma polymerization technique

A single-layer alcohol electrode was prepared by plasma polymerization technique. Ethylenediamine was used to incorporate amino groups on tract-etched polycarbonate membranes in glow discharge reactor. In order to determine the plasma polymerization parameters (discharged power, monomer flow rate, exposure time) on membrane permeability, hydrogen peroxide was used as tracer. The single-layer alcohol electrode that was produced by 0.6% (w/v) of alcohol oxidase (AOx) solution on the polycarbonate membrane, which was modified at 30 W, 20 ml/min monomer flow rate and 15 min exposure time, was selected for optimum performance. Sensitivity, linearity and response time of that particular layer were 5.6 nA/mM, 2 mM and 50 s, respectively. The performance of the amperometric alcohol electrode was tested on commercial alcoholic beverages.     

Analysis of ethyl glucuronide and ethyl sulfate using aqueous normal‐phase chromatography with mass spectrometry

The use of aqueous normal‐phase chromatography is explored as a possible format for the analysis of the forensically significant compounds ethyl glucuronide and ethyl sulfate. Standard solutions of the two compounds are used to verify the retention capabilities of two stationary phases (diamond hydride and undecanoic acid). These results are then compared to data obtained on hair extracts to determine if any matrix effects exist with respect to both retention and peak shape. The undecanoic stationary phase is used for the establishment of calibration curves for quantitative analysis. These curves are utilized to determine the concentration of ethyl glucuronide in several hair samples tested.     

Selective oxidation of alcohols over nickel zirconium phosphate

Nickel zirconium phosphate nanoparticles were found to function as efficient catalysts for the selec-tive oxidation of a wide range of alcohols to their corresponding ketones and aldehydes using H2O2 as an oxidizing agent and without any organic solvents, phase transfer catalysts, or additives. The steric and electronic properties of various substrates had significant influence on the reaction con-ditions required to achieve acetylation. The results showed that this method can be applied for the chemoselective oxidation of benzyl alcohols in the presence of aliphatic alcohols. The catalyst used in the current study was characterized by ICP-OES, XRD, NH3-TPD, Py-FTIR, N2 adsorp-tion-desorption, SEM and TEM. These analyses revealed that the interlayer distance in the catalyst increased from 0.75 to 0.98 nm when Ni2+ was intercalated between the layers, whereas the crystal-linity of the material was reduced. The nanocatalyst could also be recovered and reused at least seven times without any discernible decrease in its catalytic activity. This new method for the oxi-dation of alcohols has several key advantages, including mild and environmentally friendly reaction conditions, short reaction time, excellent yields and a facile work-up.