Microwave-enhanced aqueous biphasic dehydration of carbohydrates to 5-hydroxymethylfurfural

We describe herein an efficient microwave-assisted aqueous biphasic dehydration of carbohydrates to 5-hydroxymethylfurfural (HMF). The effects of several alkali metal salts in aqueous phase, organic solvents as an extractive phase and Lewis acids are evaluated on the reaction. Specifically, starting from fructose, the use of bromide salts in aqueous phase and the common organic solvent MeCN or lignocellulose-derived gamma-valerolactone (GVL) as organic extractors are highly beneficial, leading to excellent HMF yields of up to 91% with HCl as a Bronsted acid catalyst. In conjunction with an isomerization catalyst, the method was applicable to glucose as well as various disaccharides and cellulose, affording HMF in notably good yields, particularly with GVL as an extractor and reusable Amberlyst-38(wet) as an acid catalyst. The exceptionally high HMF yields obtained in aqueous solutions is attributed to the combined effect of the biphasic reaction system and the application of microwaves, which ensures short reaction times and minimized by-product formation thereof.Peer reviewe

Transition metal triflate catalyzed conversion of alcohols, ethers and esters to olefins

Herein, we report an efficient transition metal triflate catalyzed approach to convert biomass-based compounds, such as monoterpene alcohols, sugar alcohols, octyl acetate and tea tree oil, to their corresponding olefins in high yields. The reaction proceeds through C-O bond cleavage under solvent-free conditions, where the catalytic activity is determined by the oxophilicity and the Lewis acidity of the metal catalyst. In addition, we demonstrate how the oxygen containing functionality affects the formation of the olefins. Furthermore, the robustness of the used metal triflate catalysts, Fe(OTf)(3) and Hf(OTf)(4), is highlighted by their ability to convert an over 2400-fold excess of 2-octanol to octenes in high isolated yields.Peer reviewe

Prenatal development is linked to bronchial reactivity: epidemiological and animal model evidence

Chronic cardiorespiratory disease is associated with low birthweight suggesting the importance of the developmental environment. Prenatal factors affecting fetal growth are believed important, but the underlying mechanisms are unknown. The influence of developmental programming on bronchial hyperreactivity is investigated in an animal model and evidence for comparable associations is sought in humans. Pregnant Wistar rats were fed either control or protein-restricted diets throughout pregnancy. Bronchoconstrictor responses were recorded from offspring bronchial segments. Morphometric analysis of paraffin-embedded lung sections was conducted. In a human mother-child cohort ultrasound measurements of fetal growth were related to bronchial hyperreactivity, measured at age six years using methacholine. Protein-restricted rats' offspring demonstrated greater bronchoconstriction than controls. Airway structure was not altered. Children with lesser abdominal circumference growth during 11-19 weeks' gestation had greater bronchial hyperreactivity than those with more rapid abdominal growth. Imbalanced maternal nutrition during pregnancy results in offspring bronchial hyperreactivity. Prenatal environmental influences might play a comparable role in humans

Atomic Layer Deposited TiO2 on a Foam-Formed Cellulose Fibre Network - Effect on Hydrophobicity and Physical Properties

Climate change and plastic pollution challenge us to develop alternatives for fossil-based plastics, and cellulose-based materials are excellent candidates for this. Foam forming technology for cellulose fibre products increases process efficiency, widens the raw materials base, and enables low-density structures from fibres. Low-density cellulose-based materials can be used,for example,for packaging, insulation, and construction materials. However, to achieve optimal performance, the resistance against moisture and mechanical compression ought to be enhanced. In this research, the effect of atomic layer deposited (ALD) titanium dioxideon four foam-formed cellulose-based structureswas studied. The hydrophobicity of these materials was analyzed with water contact angle measurements. Moisture content and mechanical properties were tested at high humidity (50% RH and 90% RH) by analyzing moistureuptakeand compression strength. Furthermore, the morphology and microstructures were evaluated with scanning and transmission electron microscopy (SEMandTEM). ALD treatment changedthe hydrophilic materials to hydrophobic with 5 cycles of TiO2forall four substrates. The effect on moisture content was milder but was observed strongest with unrefined and partly refined samples at 50% RH. A clear trend between moisture content and mechanical strength was detected sincethe compression strength increased with decreasing moisture content

Atomic Layer Deposited TiO2 on a Foam-Formed Cellulose Fibre Network - Effect on Hydrophobicity and Physical Properties

Climate change and plastic pollution challenge us to develop alternatives for fossil-based plastics, and cellulose-based materials are excellent candidates for this. Foam forming technology for cellulose fibre products increases process efficiency, widens the raw materials base, and enables low-density structures from fibres. Low-density cellulose-based materials can be used,for example,for packaging, insulation, and construction materials. However, to achieve optimal performance, the resistance against moisture and mechanical compression ought to be enhanced. In this research, the effect of atomic layer deposited (ALD) titanium dioxideon four foam-formed cellulose-based structureswas studied. The hydrophobicity of these materials was analyzed with water contact angle measurements. Moisture content and mechanical properties were tested at high humidity (50% RH and 90% RH) by analyzing moistureuptakeand compression strength. Furthermore, the morphology and microstructures were evaluated with scanning and transmission electron microscopy (SEMandTEM). ALD treatment changedthe hydrophilic materials to hydrophobic with 5 cycles of TiO2forall four substrates. The effect on moisture content was milder but was observed strongest with unrefined and partly refined samples at 50% RH. A clear trend between moisture content and mechanical strength was detected sincethe compression strength increased with decreasing moisture content