Abstract

Background: Exact information about micellar feature of Cu (II) Soaps play a vital role in its selection in specific phenomena such as foaming, wetting, detergency, emulsification, etc. and also in their use as herbicides, fungicides, pesticides and insecticides. Copper soaps having a tendency of complex formation with the compounds containing donor atoms like N, O, Br, S, etc. It is well known that benzothiazoles are derivatives of anilines and play significant role in biological activities and having sufficient industrial and analytical applications.

Objective: Coherence of biological activities of copper soaps and benzothiazole stimulated our interest to extend the studies in their cumulative form as complexes. It is anticipated that it will generate new hopes in the pharmacological activities. Critical micelle concentration, revelation of the nature and size of micelles formed and surface active properties have been investigated in the proximity of mixed solvents having wide difference in degree of polarity.

Methods: Copper soap complex solutions in polar and non-polar solvent (methanol and benzene) mixtures have been chosen for the surface tension studies. Their micellar and colloidal behaviour have been analysed and these results confirm that CMC values depend upon composition of solvent mixture and are found to decrease with increase in chain length of copper surfactant (caprylate, caprate and laurate) in the referred molecule taken for study.

Results: The results of surface tensions have been explained on the basis of Szyszkowski’s empirical equation and it is observed that X, Y and (-XlnY) lead to the confirmation of fact that the change in the behaviour of copper surfactant complex occurs differently at two different compositions (40% & 80%) of methanol-benzene mixture. The results reveals that the numerical value of X for all the complexes in 40% and 80% methanol-benzene mixture below CMC are higher than above CMC. The area covered by 1 g. mole of the complex decreases gradually from 40% methanol to 80% methanol. The values of parachor of the complex solution increase with increase in the mole fraction and volume percent of methanol below CMC and decrease above CMC. The plots of parachor against the mole fraction of the copper surfactant complex are characterized by an intersection of two straight-lines at the CMC of copper surfactant complex.

Conclusion: Hammic and Andrew’s equations has been successfully applied to explain the behaviour of copper surfactant complex in two different compositions of methanolbenzene mixtures.

Keywords: 2-Amino-6-methyl benzothiazole, benzene, caprate, caprylate, CMC, empirical applications, laurate, methanol, surfactants.

Graphical Abstract