Search Results (2)

Allyl ethers bearing free hydroxyl groups of CH₂=CH-CH-O-A-OH type (hydroxyalkyl allyl ethers, allyloxyalcohols) are valuable chemicals in many environmentally friendly industrial applications. The development of technologically attractive methods for their production is necessary. The two pathways (L-L PTC and non-catalytic solvent-free conditions) were optimized for the highly selective and yield synthesis of 4-allyloxybutan-1-ol. Improvements in the PTC method (50% NaOH(aq), the equimolar ratio of NaOH to diol, cyclohexane as solvent) with a new highly selective and effective PT catalyst, i.e., Me(n-Oct)₃N⁺Br⁻ (0.3 mol%), resulted in 88% yield and 98% selectivity of 4-allyloxybutan-1-ol with minimal formation of allyl chloride hydrolysis by-products (<1%). In turn, application of non-catalytic solvent-free conditions and the change in the key substrate with an excess of diol and use of solid NaOH solely led to a mono-O-allylation product with an excellent yield of 99% in a relatively short reaction time (3.5 h), with trace amounts of by-products (<0.1%). This sustainable method is perfectly suitable for the synthesis on a larger scale (3 moles of the key substrate) and for the full O-allylation process. Full article

The 1-propenyl ethers bearing free hydroxyl groups of CH₃CH=CH–O–A–OH type (hydroxyalkyl 1-propenyl ethers, 1-propenyloxyalcohols) are the most desired as the reactive diluents for photopolymerizable systems with enhanced reactivity or intermediates for the synthesis of hybrid monomers for special applications. The ruthenium complexes-catalyzed isomerization of allyl ethers under solvent-free conditions is an atom-economical and environmentally sustainable method for their production. Here, the reaction conditions and limitations for the highly productive and selective synthesis of model 4-(1-propenyloxy)butan-1-ol have been investigated. The minimal loading of ruthenium pre-catalysts needed for completion of reaction within reasonable times was priority assumption. It was found that [RuClH(CO)(PPh₃)₃] or [RuCl₂(PPh₃)₃] exhibited extremely high catalytic activity under optimized non-oxidative reaction conditions. The key effect of reaction temperature on the activation pre-catalyst and the exothermal effects of isomerization was discovered. The practically quantitative yields of 4-(1-propenyloxy)butan-1-ol were achieved with using of very low loading of [Ru] (5 ppm) and Bu₃N (to maintain reaction chemoselectivity) at the temperature of 120 °C for only 0.5 h. Consequently, the attained TON (turnover number) and TOF (turnover frequency) values of ca. 198,000 and 390,000 h⁻¹ were unprecedentedly high and industrial attractive. On the other hand, the direct recycling of ruthenium catalyst is not a reasonable method for improving catalyst productivity. Full article