Heterogeneous catalysis offers a sustainable toolbox for the synthesis of a wide variety of biomass-derived amines.

Short amines, such as ethanolamines and ethylenediamines, are important compounds in today's bulk and fine chemicals industry. Unfortunately, current industrial manufacture of these chemicals relies on fossil resources and requires rigorous safety measures when handling explosive or toxic intermediates. Inspired by the elegant working mechanism of aldolase enzymes, a novel heterogeneously catalyzed process-reductive aminolysis-was developed for the efficient production of short amines from carbohydrates at low temperature. High-value bio-based amines containing a bio-derived C2 carbon backbone were synthesized in one step with yields up to 87 C%, in the absence of a solvent and at a temperature below 405 K. A wide variety of available primary and secondary alkyl- and alkanolamines can be reacted with the carbohydrate to form the corresponding C2-diamine. The presented reductive aminolysis is therefore a promising strategy for sustainable synthesis of short, acyclic, bio-based amines.

Reductive amination of glycolaldehyde (GA), the smallest sugar molecule and obtainable from biomass, creates a versatile platform for ethylamine products, potentially replacing current pathways via toxic ethylene oxide and dichloroethane. Given the high reactivity of α-OH carbonyls, the main challenge was control of selectivity in a cascade of parallel and consecutive reactions during reductive amination. The type of solvent and catalyst, preferably methanol and Pd, respectively, are key enabling parameters to achieve high product yields. A kinetic study on product intermediates accompanied with detailed product analysis (MS and NMR) suggested a general mechanistic scheme and validation with density functional theory calculations provided a rational understanding of the solvent effect in terms of energetics and kinetics. Primary alkanolamines (AA) such as 2-(dimethylamino)-ethanol are preferred products, and large excess of the amine reagent is not required to reach almost quantitative yields. Interestingly substoichiometric amine-to-GA ratio allows for high yield of higher (consecutive) AAs such as N-methyldiethanolamine (MDEA) and triethanolamine, for which a peculiar cyclic 5-membered oxazolidinic precursor was analyzed (e.g., for reaction with monomethylamine to MDEA). The shift to diamine-selective (DA) reactions is possible by switching to a two-step one-pot approach. With ethylene glycol as a preferred solvent, high yield of an unsaturated C 2 -enediamine precursor is obtained under an inert atmosphere, followed by its metal-catalyzed hydrogenation at elevated temperature to the final DA product such as N,N,N′,N′-tetramethylethylene-diamine. A conceptual model of the catalytic reductive amination routes that allows production of a variety of ethylamines with up to +90 C % yield is thus presented. The successful preparation and sensory assessment of a GA-based diester quat in fabric softener formulations demonstrates the viability of a full bio-based and drop-in production route for high-value chemicals, directly from GA as a platform molecule.

A catalytic reductive aminolysis of reducing monosaccharides into short ethylene diamines (or C 2 diamines) was recently communicated by our group (Pelckmans et al.

Short amines,s uch as ethanolamines and ethylenediamines,a re important compounds in todaysb ulk and fine chemicals industry.U nfortunately,c urrent industrial manufacture of these chemicals relies on fossil resources and requires rigorous safety measures when handling explosive or toxici ntermediates.I nspired by the elegant working mechanism of aldolase enzymes,anovel heterogeneously catalyzed process-reductive aminolysis-was developed for the efficient production of short amines from carbohydrates at low temperature.H igh-value bio-based amines containing ab ioderived C2 carbon backbone were synthesized in one step with yields up to 87 C%, in the absence of as olvent and at at emperature below4 05 K. Aw ide variety of available primary and secondary alkyl-and alkanolamines can be reacted with the carbohydrate to form the corresponding C2diamine.T he presented reductive aminolysis is therefore apromising strategy for sustainable synthesis of short, acyclic, bio-based amines. Scheme 1. Twopossible bio-based routes to C2-amines from glucose.