American Journal of Chemistry 2012, 2(4): 186-190 DOI: 10.5923/j.chemistry.20120204.02 Cationic Surfactants from Arginine: Synthesis and Physicochemical Properties Pravin U. Singare 1 , Jyoti D. Mhatre 2,* 1 Department of Chemistry, Bhavan’s College, Munshi Nagar, Andheri (West), 4000058, Mumbai 2 Department of Chemistry, Shri. Jagdishprasad Jhabarmal Tibrewala University, Jhunjhunu, 333001, Rajasthan Abstract The present invention concerns the preparation of cationic surfactants derived from the condensation of an acid chloride, preferably a fatty acid with a number of carbon atoms 8, 9 and 14 with esterified amino acids, preferably basic-type amino acids, like (L)-arginine. The method comprises a first step in which the esterification of the amino acid with an alcohol is performed and a second step for the condensation with a chloride of fatty acid, using Schotten Baumann conditions. These surfactants constitute a novel class of chemicals of low toxicity with excellent surface properties and considerable antimicrobial activity. As in a conventional series of surfactants with different chain lengths, changes in the chain result in changes in the physicochemical properties. Excellent antimicrobial activity is observed for the homologue of 14 carbon atoms. Keywords Cationic Surfactants, N Α -Acyl, Arginine, Schotten Baumann 1. Introduction Arginine based cationic surfactants are amphiphilic compounds that possess excellent self-assembling properties, a low toxicity profile, high biodegradability and a broad antimicrobial activity, which make them candidates of choice as preservative and antiseptics in pharmaceutical, food and dermatological formulations[1-5]. The value of amino acids as raw materials for the preparation of surfactants was recognized as soon as they were discovered some 50 years ago. Initially they were used as preservatives for medical and cosmetic applications and were subsequently found to be active against various disease-causing bacteria, tumors and viruses. There is a large variety of amino acid/peptide structures and the fatty acid chains can vary in their structures, length and number, which explains their wide structural diversity and different physicochemical and biological properties[6]. In the last two decades, a group of scientists has published a number of papers addressing the synthesis and properties of biocompatible cationic amino acid based surfactants of different structures[7-10]. These surfactants show a low toxicity profile and an antimicrobial activity similar to those of conventional cationic surfactants. Lipoaminoacids derived from L-Arginine are a recently described family of nontoxic and biodegradable cationic surfactants with * Corresponding author: jyoti.mhatre27july@gmail.com (Jyoti D. Mhatre) Published online at http://journal.sapub.org/chemistry Copyright © 2012 Scientific & Academic Publishing. All Rights Reserved antimicrobial properties[1,3]. Arginine based surfactants constitute a promising alternative to other antimicrobial surfactants with high intrinsic toxicity and questioned biodegradability such as quaternary ammonium halides[11-12]. The antimicrobial activity of the argnine-based cationic surfactants is directly associated with the presence of the cationic charge of the protonated guanidine group of this amino acid[13]. Amino acid based surfactants have some distinctive structural features as shown by general chemical formula of N α - acyl arginine derivatives, the surfactants object of this study (Fig. 1). (A) The special properties exhibited by these type of compounds are due to the strong hydrogen bonding of the amide bond located between the hydrophilic (amino acid residue) and hydrophobic part of the molecule. (B) Presence of asymmetric carbon atom in the molecule making formation of the chiral aggregates[14]. In this paper, the main part of the systematic study whose aim deals with the influence of terminal fatty acid chain on the properties of N α - acyl arginine esters is reported. N α - acyl arginine derivatives that contain basic amino acid (Arginine) as terminal amino acid have been prepared by peptide synthesis methods. These compounds have been synthesized as ethyl esters and their fundamental surfactant properties and antimicrobial activities have been evaluated. The properties of these compounds have been compared to the properties of the cationic monomer derivative methyl ester of N α - lauroyl arginine and the amphoteric monomer derivative N α - lauroyl arginine reported earlier. In this work, three arginine-derivative surfactants, ethyl