Band 41, Heft 2

Oxyethylation of dodecanoic acid was performed in the presence of a conventional alkaline catalyst, a homogeneous alkaline earth metal catalyst and a heterogeneous rare earth metal catalyst, respectively. As the result, three series of products were obtained in a range of average polyaddition degrees from N = 3 up to N = 9. The content of the obtained products was determined analytically by different chromatographic techniques: Size Exclusion Chromatography (SEC) with dual detection, gradient Liquid Adsorption Chromatography (LAC) with evaporative light scattering detection (ELSD), and Liquid Exclusion Adsorption Chromatography (LEAC), a new technique, which allows quantitatively accurate determination of the oligomer distribution of ethoxylates. It was found that the applied catalysts significantly influenced the obtained homologue distributions and the content of di-esters and polyethylene glycols as byproducts. Much more selective ethoxylation is observed in the presence of the multivalent metal catalysts. As the result, the equivalent product series exhibit significant differences of physicochemical properties and surface activity. The new capabilities in analytical determination of the complex mixture of ethoxylated acids and the detected substantial differences in their chemical content can give a new input for more detailed investigation of these products.

Mesoporous silicas MCM-41 with larger and variable pore size were synthesized hydrothermally by using cetyltriethylammonium bromide (CTEAB) which has a larger hydrophilic head-group compared to cetyltrimethylammonium bromide (CTAB) as templating agent. Various factors such as surfactant and silica molar ratio, sodium hydroxide to silica molar ratio, the crystalization time, the amount of H 2 O on the pore structural properties of samples were investigated. The experimental results showed that mesoporous silicas MCM-41 with a different pore diameter in the range of 4–7 nm can be obtained by adjusting surfactant and silica molar ratio. CTEAB is an effective templating agent for large pore diameter (>4 nm) of mesoporous silicas MCM-41. The MCM-41 pore structure properties did not change markedly when the amount of H 2 O increase in the range investigated in the paper.

A series of high purity monoalkyl methylnaphthalene intermediates were prepared by alkylation of β-methylnaphthalene with a series of different chain lengths of n-bromoalkanes. Gas chromatography and gas chromatography-mass spectrometry were used as appropriate methods for this technology. The reaction conditions were optimized. The effect of dosage of catalysts, the molar ratio of β-methyl naphthalene to bromoalkane and of the solvent to β-methyl naphthalene, the reaction time as well as the temperature had also been investigated in detail. The optimal reaction conditions of alkylation have been achieved, and the reaction results were discussed. Based on the optimal reaction conditions, a series of monoalkylmethylnaphthalene intermediates, hexyl-, octyl-, decyl-, dodecyl-, tetra-decyl-methyl-naphthalenes had been prepared.

Phase diagrams were determined at different temperatures for aqueous systems of alkylamines and alkanoic acids in an equimolecular ratio. The number of carbon atoms in the amines was varied from 4 to 12 and in the acids from 2 to 12. The obtained aqueous catanionic surfactant systems exhibit only two one-phase regions, i. e., isotropic liquid and lamellar liquid crystalline phases, while the obtained aqueous systems of ionic surfactant with organic counterion exhibit in addition also isotropic cubic and hexagonal liquid crystalline phases, and dispersions of vesicles. For one of the surfactants the parent acid was fluorinated. Optical microscopy and low-angle X-ray diffraction measurements were performed on selected systems.

In application of pesticide formulations, use of microemulsion systems offer several advantages over conventional systems such as wettable powders, emulsifiable concentrates (EC's), oil in water emulsions (O/W emulsions), water in oil emulsions (W/O emulsions) and aqueous suspension concentrates. Microemulsion systems are preferred for their long-term thermodynamic stability, low viscosity and ultimate economy. Microemulsion system also enables the usage of the least expensive solvent such as water. Formulation of agrochemical microemulsion is not a straightforward process. However, the pseudo ternary plot is a convenient mean of determining the compositions of microemulsion, macroemulsion and solubilized systems. Identification of specific regions in a pseudo ternary plot makes it possible to arrive at economical composition for microemulsion and solubilized systems. Such compositions gave maximum stability with the optimum usage of surfactants. These microemulsion and solubilized systems when diluted with the inexpensive solvent such as water gave macroemulsion and microemulsion respectively, which were stable over an extended period of time. This paper provides the basis for a simple procedure for the preparation of microemulsion systems employing water, oil, surfactant and cosurfactant.