Green Synthesis, Characterization, and Properties of Acyl Lysine, Serine, Threonine, and Methionine Derived from Three Types of Natural Oils

Abstract

The development of environmentally benign products has been the subject of growing interest in the field of surfactant chemistry. Acyl amino acid surfactants bearing lysine, serine, threonine, and methionine residues were synthesized using natural oils extracted from coconut, palm kernel, and soybean as acyl donors. The chemical structures were confirmed by high‐performance liquid chromatography (HPLC/MS) and infrared (IR) spectra. Their surface activities, ion‐specific effects, detergency, and foam properties were studied systematically. The critical micelle concentration (CMC) values depend significantly on amino acid and oil types and follow the orders: (i) Lys > Thr ≈ Ser > Met and (ii) Coconut ≈ Palm kernel > Soybean oil. Interestingly, the ion‐specific effects showing that the γCMC value decreases with increasing counterion size and hydrophobicity were observed, and the results were consistent with the famous Hofmeister series. The detergency ability of acyl amino acid surfactants is better than multiple traditional surfactants in distilled water. Although the detergency ability of our products for oil‐soiled swatches decreased significantly in hard water, this problem was solved by the C‐Lys‐Na/AES mixed system showing excellent synergistic effects. Excellent foamability and foam stability were achieved for acyl threonine and serine bearing hydroxyl groups on their headgroups, suggesting that the packing of these surfactants at the air–water interface was assisted by hydrogen bonding.

Experimental and theoretical study of adsorption of synthesized amino acid core derived surfactants at an air/water interface

“…Amino acid surfactants are biodegradable compounds with promising adsorption properties competitive to typical surface-active substances. 2,5,32 Although their ability to reduce solution surface tension is presented in many papers, 5,9,[32][33][34] there is an acute lack of reported attempts for the robust theoretical description of the adsorption process by means of a model, allowing extraction of useful physicochemical parameters of the studied compounds. Our studies aim to fill this gap.…”

“…The type of proteinogenic amino acids chosen for the synthesis determines the final product polarity, adsorption features, surface activity and acid-base behavior. 2,[7][8][9] The search for environment-friendly surfactants requires their thorough characterization, including the determination of molecular structure and surface activity. This paper presents the analysis of the adsorption behavior of five AASs based on alanine, valine, leucine, proline, and phenylalanine, with an amide bond connecting the polar head-group (originating from natural amino acids) and a hydrophobic tail (originating from lauric acid, a natural fatty acid).…”

“…The type of proteinogenic amino acids chosen for the synthesis determines the final product polarity, adsorption features, surface activity and acid–base behavior. 2,7–9…”

Influence of inorganic and organic electrolytes on the micellization of synthesized γ‐alkyl (C12 and C14) aspartate

“…CMC values of SGDdA and SGTdA are reported in Table 2, based on the tensiometry and conductivity data plotted in Figure 1a and b, respectively. The results clearly show that CMC decreases slightly with an increase in the alkyl chain length (from 7.0 mM to 6.3 mM via conductivity), which reflects the increased hydrophobicity of SGTDA (Wang et al, 2019). In addition, only a minor difference exists between CMC values obtained by tensiometry and conductometry.…”

Synergism and properties of binary mixtures based on an arginine dodecyl ester surfactant

“…Green amphiphiles made from sugar and amino acids are widely used in the surfactant industry because of their mild and safe properties and ecologically beneficial properties. 1,2 Amino acid surfactants (AASs) contain a large amino acid head and fatty alkyl chain, with widely varying structures 3,4 in addition to differing physicochemical properties. Therefore, AASs are used in cosmetics, household, drug delivery, and personal care products.…”