Synthesis and physicochemical properties of non-ionic and cationic - PowerPoint PPT Presentation

Synthesis and physicochemical properties of non-ionic and cationic surfactants derived from methionine Nausheen Joondan Anousha Radhan Sabina Jhaumeer Laulloo Prakashanand Caumul Department of Chemistry Faculty of science University of Mauritius

Surfactants Key ingredients in detergents and cosmetics Good antibacterial activity Good foaming ability Cleaning property Benefits O - Na + O S O O Sodium dodecyl sulfate (SDS) N + Br - Cetyltrimethylammonium bromide (CTAB) Drawbacks Antimicrobial resistance Toxic Non-biodegradable Petroleum based chemicals

Amino acid based surfactants  Consists of an amino acid head group linked to a long fatty acid/alcohol chain  Can be used as alternative to conventional surfactants Biodegradable Use of renewable raw Environment friendly materials for their Advantages synthesis Non-toxic

Examples of amino acid surfactants reported O R' n O O I - N n N R O Proline-based surfactants Aromatic amino acid-based quaternary n= 15 ammonium surfactants n= 7, 9, 11, 13, 15 R= R'= H; n= 9, 11, 13, 15 O R=OH, R'= H; n= 9, 11, 13, 15 R= R'= OH; n= 9, 11, 13, 15 R' n O Cl - NH 3 R Aromatic amino acid surfactants R=R’= H, n=7-19 R=OH, R’=H, n=7-21 R= R’=OH,’ n=7-13 Joondan, N., Jhaumeer-Laulloo, S., Caumul, P., 201 4. Microbiol. Res. 1 69, 675-685 Joondan, N., Caumul, P., Akerman, M., Jhaumeer-Laulloo, S., 201 5 Bioorg. Chem. 58, 1 1 7-1 29 Joondan, N., Jhaumeer-Laulloo, S., Caumul, P., 201 5. J. Surfactants Deterg. 1 8, 1 095-1 1 04 Joondan, N., Jhaumeer-Laulloo, S., Caumul, P., Marie, D.E.P., Roy, P., Hosten, E., 201 6. Colloids. Surf. A. Physicochem. Eng. Asp. 51 1 , 1 20-1 34 Joondan, N., Caumul, P., Jhaumeer-Laulloo, S., 201 7. J. Surfactants Deterg. 20, 1 03-1 1 5 Baczko, K., Larpenta C., Lesot, P., 2004. Tetrahedron: Asymmetry, 1 5, 971 –982

Sulfur-based Amino acid surfactants Cysteine Methionine NH 3 Cl - O O HN S N S S 11 H 11 HO O Cl - NH 3 NH 2 O OH H However, there is very N S S N n little report on n H surfactants derived from OH methionine O O CH 3 Cl - N CH 3 O HN C 10 Cl - H 3 N CH 3 H 3 C 10 NH S CH 3 S R R Branco, M.A., Pinheiro, L., Faustino, L., 201 5. Colloids and Surfaces A: Physicochemical and Engineering Aspects, 480, 1 05-1 1 2 Fan, H., Han, F., Liu, Z., Qin, L., Li, Z., Liang, D., Ke, F., Huang, J., Fu, H., 2008. Journal of Colloid and Interface Science, 321 , 227-234 Pinazo, A., Diz, M., Solans, C., Pes, M.A., Erra, P., Infante, M.R., 1 993. Journal of American Oil Chemists’ Society, 70, 37 Yoshimura, T., Sakato, A., Tsuchiya, K., Ohkubo, T., Sakai, H., Abe, M., Esumi, K., 2007. Journal of Colloid and Interface Science, 308, 466-473

Synthesis of methionine O -alkyl esters and their hydrochloride derivatives O O O S S S C n H 2n+1 OH O C n H 2n+1 OH O C n H 2n+1 HCl PTSA NH 3 Cl - Refluxing toluene/ 48 hr NH 2 NH 2 1a: n= 8; 1b: n=10; 1c: n=12 2a: n= 8; 2b: n=10; 2c: n=12 Chain length Methionine % Yield Methionine ester % Yield esters hydrochloride 8 1a 81 2a 70 10 1b 66 2b 62 12 1c 54 2c 50

1 H NM R spectrum 4.117 4.114 4.090 4.062 3.578 3.558 3.545 3.526 2.630 2.599 2.571 2.083 2.027 2.006 1.995 1.975 1.818 1.790 1.785 1.762 1.758 1.730 1.614 1.586 1.559 1.278 1.247 0.880 0.855 0.827 h O f d S e O h g c a NH 2 b i b a g d f c, i e f 4.0 3.5 3.0 2.5 2.0 1.5 1.0 ppm 1.92 1.05 1.93 3.00 0.99 1.01 4.45 10.55 3.15

13 C NM R spectrum O g d S f e O i c h a NH 2 b CDCl3 h a f d g i e

IR spectra O S O NH 2 Ester peak

Synthesized compounds Non-ionic surfactant Cationic surfactant Methionine ester Methionine ester hydrochloride O O S S O O NH 2 Cl - NH 3 O O S S O O Cl - NH 3 NH 2 O O S S O O Cl - NH 3 NH 2

Physicochemical properties Critical micelle concentration Conductivity measurements Pyrene fluorescence measurements O O S S OC n H 2n+1 OC n H 2n+1 Cl - NH 3 NH 2

Comparing the CMC of the methionine esters with their ester hydrochloride derivatives Chain Methionine CMC Methionine CMC length esters (mM) ester (mM) hydrochloride 8 1a 1.28 2a 4.74 10 1b 0.63 2b 3.42 12 1c 0.25 2c 2.31 • In both series, the CMC was found to decrease with increasing chain length of the surfactants. • The CMC of the methionine esters were lower than their corresponding ester hydrochloride derivatives. • The ester hydrochlorides have less tendency to micellise due to repulsion between their cationic head groups

Physicochemical properties The Krafft T emperature (T K ) The minimum temperature at which surfactant can form micelles in aqueous solution Obtained from the plot of conductivity of surfactant solution (above CMC) versus temperature

Effect of chain length on the Krafft temperature. Methionine ester hydrochloride Tk ( ° C) 2a 23 2b 25 2c 29 CTAB (cetyl trimethylammonium bromide) 22 The ester hydrochloride derivatives showed an increase in the Krafft temperature with increasing chain length showing that the surfactants with longer chain length has a tendency to micellise at a much higher temperature

Conclusion  The methionine esters with varying chain lengths as well as their hydrochloride derivatives were successfully synthesized.  The CMC of the methionine esters and their hydrochloride derivatives were found to decrease with chain length, as observed for previously reported surfactants.  The methionine ester hydrochloride derivatives have a less tendency to micellise compared to their non-ionic ester derivatives due to the repulsion caused by their cationic head groups.  An increase in chain length of the methionine ester hydrochloride caused an increase in the Krafft temperature of the surfactants, suggesting that the methionine surfactants with longer chain length micellise at higher temperatures