Cours de surfactants

Surfactant SurfaceActive agent (compound) Surfaceor Interface: The border between two materials • extremity thin layer = very small amount (nano world) • controlled by surface tension (surface free energy) Determine the l ooksof materials some properties for example Iron Gold plating Looks Gold Strong as Iron Modification of just surface make the material more worthful Surfactant Molecular Structure ofSurfactant Lipophile (Alkyl chain) no affinity Hydrophile Polarized group repulsive to H2O connected with covalent bond attractive to H2O strange structure versatile function Molecular Assembly of Surfactant (decrease surface tension) air Lipophile (Alkyl chain) repulsive to H2O Hydrophile attractive to H2O pushed out from H2O surface absorbtion Balance dissolved into H2O water aggregation in H 2O Micelle Hydrophile-Lipophile Balance HLB Surface Properties of Surfactant Surface tension - concentration Solubility - temperature of H2O solution of H2O solution cmc concentration (mol/L) • Critical Micelle Concentration(cmc, mol/L) = minimum concentration of surfactant for formation of micelle • Surface Tension at cmc (γcmc, mN/m) Over cmc, surface tension was kept constant value (mol/L) solubility γc mc (mN/m) surface tension 72 mN/m (pure H2O) Kp • Krafft point (Kp, temperature (°C) °C) Solubility at Kp goes up to cmc Surface Properties of Surfactant Incre ase Lipophilicity de cre ase Hydrophilicity (lengthene alkyl chain) • cmc: smaller for down sizing = good for cost& environment • γc mc: lower high ability of lowering surface tension • Kp: lower temp wide range of temp for use ◎ smalle r lowe r highe r (below Kp, micelle was not formed) Same HLB will suggest same surface properties such as cmc Next Generation of Surfactant connected Novel Structure Fascinating surface propeties with spacer by covalent bond Lipophile Spacer • smaller cmc + γ • lower cmc Hydrophile Conventional ( + type) same HLB ??? Ge mini • lower Kp Dimeric + type Excellent properties Structural Factor of Gemini • Alkyl chain length (Lipophilicity) • Kind of hydrophile (Hydrophilicity) • Symmetry (same or different length of lipophiles) Spacer connecting • Stereochemistry at connecting point (syn- /anti- isomer, optical isomer) point Hydrophile • Spacer length • Kind of spacer Ge mini Lipophile Chemical Structure vs Surface Properties Relationship Synthetic Strategy of Gemini Strategy 1; Connection of Conventional Strategy 2; Synthetic Block Lipophile (spacer) Functional group for connecting Hydrophile Conventional Gemini • Malonic Gemini Synthetic block Gemini • Tartaric Gemini ã Gemsurfđ Synthetic Strategy for Malonic Gemini Malonate H H H Base CnH2n+1 Br C C EtO C C OEt EtO C C OEt Alkylation O O O O enolate H H R–Br Lipophile R Malonic ester synthesis Br-(CH 2) n-Br Spacer Malonic Gemini R EtO2C C (CH 2)n C CO2Et CO2Et H CnH2n+1 C EtO C C OEt O O CO2Et R hydrolysis R C (CH2)n C R decarboxylation CO2H HO 2C CO2H CO2H 2/4 Gemini R HC (CH2)n CH HO 2C CO2H 2/2 Gemini feature • No hetero atom at connecting point • Several length of lipophile and space are available in large scale Preparetion of Malonic Gemini H H H R i, NaOEt (fresh prepared) in EtOH C C EtO C C OEt EtO C C OEt ii, R-Br O O O O Diethyl malonate R ii, Br-(CH2)s-Br 60-70 % yields R EtO2C C (CH2)s C CO2Et CO2Et i, NaH in THF R aq-KOH in EtOH R C (CH2)n C CO2H HO 2C CO2H CO2H CO2Et 50-80 % yields 2/4 Gemini > 85 % yields R AcOH, reflux R HC (CH 2)n CH HO 2C CO2H 2/2 Gemini 65-95 % yields R- = CnH2n+1- Synthetic Strategy for Tartaric Gemini Tartaric acid HO HO2C Lipophile O-Alkylation RO- OH CO2H Ammonium + –CH2 N Me3 X Interconversion Carboxylate + * * –CO2 Na Polyethylene glycol –CO(OCH2CH2 )n-OH Hydrophile optically active Gemini feature • L-, D-, and meso-Tartaric acid is commercially available • Cationic, anionic, and nonionic Gemini were prepared R- = C nH2n+1- Preparetion of Tartaric Gemini O O HO C-NMe2 R-Br, LiOH•H2O in DMSO at 60°C RO C-NMe2 HO C-NMe2 O ca 90 % yields RO C-NMe2 O Tetramethyltartaramide LiAlH4 in THF RO CH2NMe2 RO CH2NMe2 BuOH, p-TsOH RO at 120°C RO CO2Bu in CH3CN aq-KOH in EtOH CO2Bu H-(OCH 2CH2)3-OH, p-TsOH at 120°C CH3Br RO CH2N+ Me3 Š 2Br CH2N+ Me3 RO CO2H RO CO2H RO cationic Gemini anionic Gemini RO CO(OCH2CH2)3-OH RO CO(OCH2CH2)3-OH nonionic Gemini R- = CnH2n+1- ® Synthetic Strategy for Gemsurf O O Esterification R-OH / H + (– H2O) O Tetrahydrophthalic anhydride O R-O C Oxidation KMnO R-O C O not isolated O RŠO C CO2H CO2H RŠO C O Ge msurf® >80% overall yield R- = C nH2n+1- feature • steps and one-pot synthesis • Unexpensive starting materials and reagents Large scale preparation Commercially available Gemini Relationship between structure / surface properties Significant factor • Diastereo-isomerism : Big difference between meso-vs dl- isomer • Structural difference near connecting point Less effective factor • Optical-isomerism : Few difference between L-vs D- isomer • Equal length of lipophile (symmetry) : Gemsurf with12+12, 14+10, and 16+8 alkyl chains are almost same properties • Space length : small differences Strong influence of intramolecular lipophile interaction (hydrohobic) ... Lipophilicity de cre ase Hydrophilicity (lengthene alkyl chain) • cmc: smaller for down sizing = good for cost& environment • γc mc: lower high ability of lowering surface tension • Kp: lower temp wide... covalent bond attractive to H2O strange structure versatile function Molecular Assembly of Surfactant (decrease surface tension) air Lipophile (Alkyl chain) repulsive to H2O Hydrophile attractive to... Gemini R EtO2C C (CH 2)n C CO2Et CO2Et H CnH2n+1 C EtO C C OEt O O CO2Et R hydrolysis R C (CH2)n C R decarboxylation CO2H HO 2C CO2H CO2H 2/4 Gemini R HC (CH2)n CH HO 2C CO2H 2/2 Gemini feature • No