Comparison of Activity and Selectivity of Weakly Basic Anion-Exchange Catalysts for the Aldolization of Butyraldehyde with Formaldehyde

Abstract

Aldols are important intermediates in the production of polyols, which are raw material for lubricants, surface coatings, and synthetic resins. The activities and selectivities of gel-type and macroporous anion-exchange resin catalysts in the aldolization of butyraldehyde with formaldehyde in an aqueous environment were investigated at 60 °C. The experiments were carried out batchwise in a stirred glass reactor, and the reaction products were analyzed with high performance liquid chromatography. Two main products were observed, 2-ethyl-3-hydroxy-2-hydroxy-methylpropanal (trimethylolpropane aldol) and 2-ethylpropenal (ethylacrolein). The product ratio was strongly dependent on the catalyst. The selectivity with respect to trimethylolpropane aldol varied within the range 2.7-7.3 for the catalysts investigated. Systematic kinetic experiments were carried out at 50-70 °C with the gel-type resin catalyst displaying the highest aldol selectivity. A kinetic model based on molecular mechanisms was able to describe the product distribution.

Self- and Cross-Aldol Condensation of Propanal Catalyzed by Anion-Exchange Resins in Aqueous Media

“…Possible Reaction Pathway during Self-and Cross-Aldol Condensation of Propanal and Formaldehyde in Aqueous Medium (mono-ol). 13 However, as in the present system, the final reaction pH was around 5, this possibility was ruled out. On the other hand, hydration and/or hemiacetalization of 3 could take place in the acidic aqueous medium.…”

“…Resulting alcohol, vinyl, hemi-acetal, and acetal products appeared at the chemical shift region of 3.0À7.0 ppm. 13 C NMR spectrum showed multiple peaks in the 80À110 ppm region, also indicating hydration and/or hemiacetalization of aldehyde, but the hydration could also take place on the βcarbon of R,β-unsaturated aldehyde such as 3 and 7.…”

“…12 Butyraldehyde was aldolized with formaldehyde at 40À80 °C over an anion-exchange resin catalyst in aqueous and methanolic solutions to form two main products: 2-ethyl-3-hydroxy-2-hydroxymethylpropanal (trimethylolpropane aldol) and 2-ethylpropenal (ethylacrolein). 13,14 Inspite of the great interest in applying more environmentally friendly approaches for new CÀC bond formation from propanal, there is little information available on the aldol condensation reaction in aqueous media. Under aqueous conditions, the aldol condensation should be more complicated due to additional reactions such as hydration and acetalization of aldol products.…”

The selective sorption of solvents on sulphonic acid polymer catalyst in binary mixtures

“…There is a growing interest in the application of functionalised polymers (resins) as catalytic materials as well as catalysts in various reactions, e.g., hydrogenation [1][2][3][4], esterification [5][6][7], aldolisation [8] and etherification. A specific feature of polymers, in contrary to conventional oxide supports, is that as a polymer material is brought into contact with a liquid, it does not only adsorb the liquid, but swells as well.…”

The Aldol Reaction under High‐Intensity Ultrasound: A Novel Approach to an Old Reaction

“…Recently, the focus has shifted to the use of transition metal catalysts (Rh, Ni, V), [6] to solventfree reactions mediated by magnesium hydrogen sulfate, [7] to supported reagents [8] and anion-exchange resins. [9] Aldols are raw materials for the production of lubricants, surface coatings and synthetic resins; [10] moreover, they are important intermediates in the synthesis of polyols. [11] In the present work, we applied high-intensity ultrasound (HIU) to base-catalyzed AR in water to prepare a wide range of aldols and polyols, mainly from acetophenones as starting materials.…”