نتایج جستجو برای: acrylates
تعداد نتایج: 601 فیلتر نتایج به سال:
A direct and scalable route to γ-keto-α,β-unsaturated esters, useful intermediates in medicinal chemistry and natural products synthesis, is reported. The key step involves the use of Grubbs' second-generation olefin metathesis catalyst for cross-metathesis of alkyl acrylates and 2° allylic alcohols. The metathesis step is followed by oxidation to give the desired products in high yield on scal...
This paper describes recent progress made in the use of high pressure or supercritical fluids to process polymers into three-dimensional tissue engineering scaffolds. Three current examples are highlighted: foaming of acrylates for use in cartilage tissue engineering; plasticization and encapsulation of bioactive species into biodegradable polyesters for bone tissue engineering; and a novel las...
A high-pressure (> 3 MPa) on-chip injector has been developed for microchip applications including HPLC. The mechanical injector is implemented using in situ photopolymerization of fluorinated acrylates inside wet-etched silica microchips. The injector allows reproducible injections as small as 180 pL with < 250 ms duration. The injector operated robustly over 60 days and over 1000 injections. ...
The developmental toxicities of seven acrylates were studied in Sprague-Dawley rats after inhalation exposure for 6 h/day, during days 6 to 20 of gestation. The exposure concentrations were: for acrylic acid, 50, 100, 200, or 300 ppm; for methyl acrylate, 25, 50, or 100 ppm; for ethyl acrylate, 25, 50, 100, or 200 ppm; for butyl acrylate, 100, 200, or 300 ppm; for ethylhexyl acrylate, 50, 75, o...
A 50-year-old healthy man was seen at the outpatient clinic after he had suffered two episodes of skin lesions on his left knee, right wrist, and left ring finger (Fig. 1a,b). A few hours after he had finished his work, these lesions appeared as burning, indurated redness, developing into tense blisters within 24 hr. The lesions healed without scar formation within 10 days. An occupational derm...
Allergy to acrylic plastics is rather frequent among doctors and dental technicians. A rare case of allergy to acrylates in a dental nurse (only one reports can be found in the literature) is presented. The patient reacted to eight chemical compounds of the group under study. UV-cured composites used in conservative dentistry for tooth filling was the source of allergy in the case under report.
Over the past few years, there has been an increase in cases of allergic contact dermatitis caused by acrylates, because of the growing popularity of artificial nails. Pathological reactions to artificial nails typically occur on or around the nail area. Eyelid contact dermatitis due to artificial nails is rarely seen, especially in a nonoccupational setting. The authors report the case of a 45...
On the way towards a new total synthesis of (S)-arogenate, a novel aryl-λ(3)-iodane-mediated oxidative spirocyclization of para-substituted phenol derivatives has been discovered. Starting from easy accessible 2-(4-hydroxybenzamido)acrylates we could construct spirocyclic lactams in up to 52% yield. Under alternative reaction conditions the same precursors underwent an unexpected oxidative spir...
The 1,2-sulfone rearrangement resulting from nucleophilic addition to bis activated vinyl-sulfones has been studied in more detail. Various nucleophiles activated by different types of catalysts (enamine, Brönsted base, thiourea) are able to promote such rearrangement in excellent yields and moderate to excellent enantioselectivities (up to 94% ee). Mechanistic studies have led to a better unde...
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