A novel hydrogen-bonded silica-supported acidic ionic liquid: An efficient, recyclable and selective heterogeneous catalyst for the synthesis of diesters

Abstract

In this study, two novel acidic ionic liquids, including a hydroxyl functionalized diacidic ionic liquid [HFDAIL] and a sulfonated diacidic ionic liquid [SFDAIL], were prepared and immobilized on the surface of silica nanoparticles (SNPs) via hydrogen bonding. The materials were characterized by FT-IR, NMR, SEM, nitrogen physisorption measurement, TGA and acid-base titration. The catalytic activity of the prepared catalysts was investigated in the synthesis of phthalate, maleate and succinate diesters under solventfree conditions. It was found that nanosilica@[HFDAIL] with higher availability of acidic sites and higher hydrophilicity was more efficient compared to the nanosilica@[SFDAIL]. Notably, nanosilica@[HFDAIL] catalyst has also demonstrated excellent selectivity for the diester product while the monoester product was predominant in the case of nanosilica@[SFDAIL] even after prolonged reaction time or higher catalyst loading. In addition, the nanosilica@[HFDAIL] catalyst could be separated by simple filtration and reused several times without any significant loss of catalytic performance, but a remarkable decrease in activity was observed for nanosilica@[SFDAIL] in the next runs.

Organocatalyst Promoted Efficient Synthesis of Carboxylic Acid Esters and its Application as Plasticizer for Polyvinyl Chloride

“…Conventionally aluminum oxide (Al 2 O 3 ) and tetra‐n‐butyl titanate (Ti(OBu) 4 ) [16] are used as esterification catalysts for the synthesis of DOP and dibutyl phthalate [18] . Recently, the diester of phthalic acid has been synthesized by using a hydroxyl functionalized diacidic ionic liquid [HFDAIL] and sulfonated diacidic ionic liquid [SFDAIL] immobilized on the surface of silica nanoparticles (SNP) via hydrogen bonding [19] …”

“…[18] Recently, the diester of phthalic acid has been synthesized by using a hydroxyl functionalized diacidic ionic liquid [HFDAIL] and sulfonated diacidic ionic liquid [SFDAIL] immobilized on the surface of silica nanoparticles (SNP) via hydrogen bonding. [19] The diester of phthalic acid (7) has been synthesized using phthalic acid (0.3 mol) and n-butanol/2-ethyl-1-hexanol (1.09 mol) in the presence of 3 mol% triphenylphosphonium triflate catalyst (3). The resulting product (8 a-b) was synthesized with high purity and good yield (93 % and 67 %, respectively).…”

Synthesis of Fuel Additives via Esterification of Succinic Acid over a Sustainable Catalyst Comprising 12-Tungstophosphoric Acid Anchored to Zeolite HY

“…Tremendously, succinic acid esters (mono and di) are flashed in the industrial sector due to their well-known potential applications as fuel substituents, bio-based solvents, plasticizers, food preservatives, medicines, and cosmetics . According to the literature, there have been multiple successful attempts to synthesize dibutyl succinate over heterogeneous catalysts such as supported ionic liquids, , acid-activated clay, , resins, immobilized enzymes, and polyoxometalate-based catalysts. ,− Polyoxometalates (POMs) are composed of early transition metal oxoanions linked by a common oxygen atom. Among all, Keggin POMs having the general formula [XM 12 O 40 ] n − , where X belongs to the heteroatom [P­(V), Si­(VI), or B­(III)], M is the addenda atom [Mo­(VI), W­(VI), or V­(V)], and O represents oxygen, are widely acknowledged from the viewpoint of structural stability as well as acidity.…”

“…Tremendously, succinic acid esters (mono and di) are flashed in the industrial sector due to their well-known potential applications as fuel substituents, bio-based solvents, plasticizers, food preservatives, medicines, and cosmetics. 6 According to the literature, there have been multiple successful attempts to synthesize dibutyl succinate over heterogeneous catalysts such as supported ionic liquids, 7,8 acid-activated clay, 9,10 resins, 11 immobilized enzymes, 12 and polyoxometalate-based catalysts. 8,13−18 Polyoxometalates (POMs) are composed of early transition metal oxoanions linked by a common oxygen atom.…”