Dialkyl Succinates and Adipates as Alternative Plasticizers—Even More Efficient Synthesis

Abstract

As a result of strict regulations of phthalate plasticizers, alternative non-phthalate forms are desired and increasingly used. This work presents a synthetic method for alternative plasticizers (dialkyl succinates and adipates) via esterification of succinic and adipic acid with alcohols: butan-1-ol and 2-ethylhexan-1-ol. Ionic liquids were synthesized by the reaction of triethylamine with over-equimolar (1:2.7) amounts of sulfuric(VI) acid, which were used as an acidic catalyst and solvent. The two-phase liquid–liquid system was formed during the reaction due to immiscibility of the esters with the ionic liquid. This phenomenon is a driving force of this process, shifting the equilibrium toward the product formation. As a result, dialkyl succinates and adipates were obtained in high yields (99%) and selectivities (>99%), under mild reaction conditions at 70–80 °C and using a 4:1 molar ratio of alcohol to acid and 15 mol% of catalyst. The catalyst was recycled 10 times without any loss of activity. This alternative method is highly competitive: it involves a simple procedure for product isolation as well as a high yield and purity of the resulting esters. These advantages make this method sustainable and promising for industrial applications.

Characterization of Nematicidal Activity and Nematode-Toxic Metabolites of a Soilborne Brevundimonas bullata Isolate

“…The M. incognita-toxic substance identified in the current study, 2-ethylhexan-1-ol, is a conventional basic chemical material that particularly serves as an important raw material for synthesizing esters or natural esters in the chemical engineering field. For example, it is widely used as an adjuvant for material synthesis and separation of metal ions (such as Cd 2+ ) from complex solutions [52,53] or was widely used in food, medicine, cosmetics, and other chemical industries, with only one report with regard to the investigation of the physiological function of this substance in murine cells, which was found to be involved in peroxisome proliferation in both rat and mouse hepatocytes [54]. Only one report was found on nematicidal activity against the nematode [40].…”

Water‐Doped Brønsted Acidic Protic Ionic Liquids for Enhanced Tributyl Citrate Synthesis in a Two‐Phase Esterification System

“…The procedure and specific physicochemical characterization of the presented ILs have been described in our previous works. [58][59][60]62,65,66]…”

“…Their low vapour pressures, high thermal stability, and the ability to dissolve a variety of organic compounds are desirable for catalytic applications. [54][55][56][57] Special focus is directed towards Brønsted acidic ionic liquids with high catalytic activity and low cost which additionally provide facile product separation from the post-reaction mixture, as demonstrated in esterification reactions [58][59][60][61][62] Some Brønsted acidic ILs benefit from specific phase behaviour that in certain reaction media allow them to form a separate water-absorbing phase, facilitating both shifting the reaction equilibrium toward product formation as well as product purification. Such a unique two-phases reaction system contributes to the design of greener and environmentfriendly methodologies, where additional unit operations dedi-cated to product purification are reduced.…”

Conversion of Adipic Acid to Bis-2-ethylhexyl Adipate Overcoming Equilibrium Constraints: A Laboratory Experiment

“…They are usually prepared by a standard esterification protocol employing a huge excess of alcohol or removing water in order to shift the equilibrium toward the desired ester. Bis-2-ethylhexyl adipate ( 3 ), one of the most commonly used adipates, has also been recently prepared with a biocatalytic route under vacuum in order to remove water produced by the esterification or with acidic ionic liquid catalysis …”

“…Bis-2-ethylhexyl adipate (3), one of the most commonly used adipates, has also been recently prepared with a biocatalytic route 5 under vacuum in order to remove water produced by the esterification or with acidic ionic liquid catalysis. 6 The master's degree program in industrial chemistry at Universitàdegli Studi di Milano includes a practical session to carry out the synthesis of industrially relevant compounds. Under this program, the industrial synthesis of adipate 3 (Scheme 1) was chosen to be adapted to facilities commonly available in an academic laboratory.…”