CALCULATION OF HYDROPHILIC-LIPOPHILIC BALANCE FOR THE SYSTEM OF 2,3-SUBSTITUTED-5,6-DIHYDRO-3H-[1,3]THIAZOLO[3,2-b][1,2,4]TRIAZOL-7-IUM

Abstract

Cationic surfactants are widely used in industry, medicine, and in studies of a number of physicochemical processes. Analysis of the literature data indicates the high biological activity of cationic surfactants, particularly antimicrobial, antifungal, and in general biocidal. Currently, QSPR methods are increasingly used; they allow the prediction of properties based on the compound's molecular structure. One of the important parameters of cationic surfactants is the ratio of polar (positively charged "head") and non-polar (long hydrocarbon "tail") parts of their molecules. This ratio is called hydrophilic-lipophilic balance (HLB). In 1949, Griffin and Davis developed HLB scales of colloidal surfactants, according to which the HLB parameter can take values in the range from 1 (the substance is insoluble in water but soluble in nonpolar liquids) to 40 (the substance is soluble in water and insoluble in nonpolar liquids) conventional units. Given the complexity of the experimental determination of HLB, mathematical additive models for its calculation were developed.
 In our previous studies, methods for the synthesis of cationic 1,2,4-triazolium systems, including cationic surfactants based on 1,3-thiazolo-1,2,4-triazole condensed nucleus, were developed. Thus, 2,3-substituted-5,6-dihydro-3H-[1,3]thiazolo[3,2-b][1,2,4]triazol-7-ium were selected as model objects in this study.
 The construction of model compounds was performed in the Avogadro program with subsequent optimization of the geometry using the force field MMFF94. The HLB index was calculated by three methods: Griffin, Davis, and the ratio of polar and nonpolar areas on the isosurface of the molecule using the software package Vega ZZ.
 Simple approach for calculating HLB based on the number of carbon atoms in long alkyl substituents have been established. HLB values are the largest when calculating the ratio of polar and non-polar parts of the molecule. The calculated values of HLB vary in a wide range, which allows referring the investigated systems to emulsifiers "oil/water" (for short alkyl chains C1–C4), wetting agents (for short alkyl chains C1–C5), emulsifiers "water/oil" (for alkyl chains C5–C20), antifoams (for alkyl chains C18–C20).