Amphiphilic Long-chain Citric Acid Ethers

Abstract

The etherification of the hydroxyl group of citric acid with saturated and unsaturated long-chain alkyl groups is described. This is a new approach to polydentate acids which may serve as ligands for metal or metal oxide nanoparticles. For this purpose we developed a synthetic route to long-chain ω-unsaturated alcohols and their triflate derivatives.

A Citric Acid-Derived Ligand for Modular Functionalization of Metal Oxide Surfaces via “Click” Chemistry

“…Subjecting 1 to various basic ester saponification conditions resulted in competitive elimination of propargyl alcohol to give aconitic acid (not shown). This result differs from the report by Meissner and Jutzi of the base-catalyzed hydrolysis of the methyl esters of a variety of O -alkyltrimethyl citrate derivatives in 71–80% yield, a difference that is likely due to the better leaving-group ability of the propargyl alkoxide of 1 used here relative to that of the straight-chain alkyl alkoxides (Δp K a ≈ 2) investigated by them. Methyl ester hydrolysis of 1 under acidic conditions yielded O -propargyl citric acid ( 2 ), which was found to be stable to decomposition at room temperature over the course of a week in both highly acidic (pH = 1) and basic (pH = 14) aqueous solution.…”

“…This material was synthesized in a procedure analogous to that developed by Meissner and Jutzi. 30 A nitrogen-purged flame-dried round-bottom flask submerged in a water bath at room temperature was charged with NaH (1.67 g, 60% dispersion in mineral oil, 41.8 mmol) and Et 2 O (20 mL). To this stirred suspension trimethyl citrate (10.3 g, 43.9 mmol) was added slowly in three portions over the course of 5 min with hydrogen gas evolution, after which the reaction mixture was stirred for 20 min.…”

“…This material was synthesized in a procedure analogous to that developed by Meissner and Jutzi . A nitrogen-purged flame-dried round-bottom flask submerged in a water bath at room temperature was charged with NaH (1.67 g, 60% dispersion in mineral oil, 41.8 mmol) and Et 2 O (20 mL).…”

“…Citric acid, a tridentate carboxylic acid, has been widely used as a stabilizing ligand for many types of nanoparticles because the citrate ion provides good surface binding, imparts water solubility to the resulting nanoparticles and reduces aggregation. , Indeed, citrate has been shown to be effective with many materials including gold , and other metals, numerous metal oxides including iron oxides, − ZnO, , and TiO 2 , , and silicates and aluminosilicates . Despite this, there are very few reports of the synthesis of citric acid derivatives, likely due in part to harsh reaction conditions and competitive elimination side reactions in the direct functionalization of the free hydroxyl group of citric acid. − This has restricted the development of more versatile multidentate ligands, and to our knowledge no functionalized derivative of citric acid has been studied in the context of nanoparticle functionalization.…”

Covalent Deposition of Zwitterionic Polymer and Citric Acid by Click Chemistry-Enabled Layer-by-Layer Assembly for Improving the Blood Compatibility of Polysulfone Membrane

“…The polymer multilayer deposited PSf-N 3 membrane was denoted as PSf- n , where n represents the number of the clicked layers. For the PSf- n membranes with the outermost layer of azide -PSBMA, the anticoagulant alkynyl -citric acid − (the synthesis consisted of three reactions as shown in the Supporting Information) was then deposited by click chemistry at room temperature for 2 h, and the dipping solution consisted of alkynyl -citric acid (5 mg/mL, 9 mL), copper­(II) sulfate (0.72 mg/L, 3 mL), and sodium ascorbate (1.76 mg/mL, 3 mL). The citric acid-grafted PSf- n membrane was denoted as PSf- n -CA.…”