| 1. |
- Ahlford, Katrin, et al.
(författare)
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Rhodium-catalyzed asymmetric transfer hydrogenation of alkyl and aryl ketones in aqueous media
- 2008
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Ingår i: Green Chemistry. - : Royal Society of Chemistry (RSC). - 1463-9262 .- 1463-9270. ; 10:8, s. 832-835
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Tidskriftsartikel (refereegranskat)abstract
- A novel lipophilic rhodium catalyst was evaluated in the enantioselective transfer hydrogenation of ketones in water using sodium formate as the hydride donor, and in the presence of sodium docecylsulfonate. Alkyl alkyl ketones were reduced in good yields and in moderate to good enantioselectivities, and the reduction of aryl alkyl ketones proceeded with excellent enantioselectivity (up to 97% ee).
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| 2. |
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| 3. |
- Bohman, Björn, et al.
(författare)
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Vegetables as biocatalysts in stereoselective hydrolysis of labile organic compounds
- 2009
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Ingår i: Green Chemistry. - 1463-9262 .- 1463-9270. ; 11:11, s. 1900-1905
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Tidskriftsartikel (refereegranskat)abstract
- Hydrolysis of labile esters of beta-hydroxyketones has been performed with whole plant tissue from various vegetables. The pheromone 5-hydroxy-4-methyl-3-heptanone (1) was used as the model compound. Hydrolysis of acetates and benzoates of 1 was unsuccessful using normal conditions of ester hydrolysis, both by chemical hydrolysis and by the means of commercial lipases. When, however, whole cells of carrot, celery root, eggplant, parsley root, parsnip and potato were used as reagents, hydrolysis of the acetates was successful. At low conversion the hydrolysis was stereoselective and at total conversion virtually no formation of by-products was observed. The selectivity varied among the eight vegetables that were evaluated. Methods of preparation and substrate-to-plant ratio were examined. Furthermore, acetates and benzoates of three analogous compounds [5-hydroxy-3-heptanone (2), 5-hydroxy-5-methyl-3-heptanone (3) and 5-ethyl-6-hydroxy-4-octanone (4)] were hydrolyzed by potato and sweet potato to various degrees, indicating that the method is general for the mild and stereoselective hydrolysis of secondary beta-alkoxy-and beta-aryloxyketones.
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| 4. |
- Co, Michelle, et al.
(författare)
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Pressurized liquid extraction of betulin and antioxidants from birch bark
- 2009
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Ingår i: Green Chemistry. - : The Royal Society of Chemistry. - 1463-9262 .- 1463-9270. ; 11:5, s. 668-674
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Tidskriftsartikel (refereegranskat)abstract
- Pressurized hot (subcritical) water and ethanol were used to extract betulin and antioxidants from birch bark. Betulin was found to be the major compound (around 26% (w/w)), which was able to be extracted with ethanol (120 degrees C, 50 bar, 15 minutes) but not with water at any of the temperatures tested (40-180 degrees C, 50 bar). The obtained extraction result for betulin is supported by theoretical solvation parameter calculations. Furthermore, high antioxidant activity of the extract was obtained using both ethanol and water as solvent. The antioxidant activity, as determined by a DPPH (2,2-diphenyl-1-picrylhydrazyl) assay, was found to be highest for the water extract of finely ground bark and it markedly increased with elevated extraction temperatures (90-180 degrees C). To elucidate if this was due to increased extraction efficiency or chemical reactions, a set of experiments was performed in which the samples were pre-treated with water at different temperatures before extraction. Results from liquid chromatography showed some differences in molecular composition between samples pre-treated at ambient and 180 degrees C, respectively. However, more detailed studies have to be performed to distinguish between hot-water extraction and reaction kinetics.
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| 5. |
- Enquist, Per-Anders, et al.
(författare)
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Open-air oxidative Heck reactions at room temperature
- 2006
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Ingår i: Green Chemistry. - 1463-9262 .- 1463-9270. ; 8:4, s. 338-343
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Tidskriftsartikel (refereegranskat)abstract
- Palladium(II)-catalyzed oxidative Heck arylation reactions proceed at room temperature with atmospheric air as the sole reoxidant. Using arylboronic acids as arylating agents and inexpensive 2,9-dimethyl-1,10-phenanthroline as the supporting ligand, efficient vinylic substitution reactions were obtained both with electron-poor and electron-rich olefins on a 1–50 mmol scale.
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| 6. |
- Hagström, Anna, et al.
(författare)
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Wax esters produced by solvent-free energy-efficient enzymatic synthesis and their applicability as wood coatings
- 2005
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Ingår i: Green Chemistry. - : Royal Society of Chemistry (RSC). - 1463-9270 .- 1463-9262. ; 7:12, s. 837-843
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Tidskriftsartikel (refereegranskat)abstract
- The study aimed at developing a process for making a wood coating wax based on the principles of green chemistry. The research was conducted within the Swedish interdisciplinary research programme Greenchem. Wax esters are attractive since they are non-hazardous, biodegradable and can be produced in an atom-efficient process from building blocks obtained from renewable resources. Four wax esters were prepared in a solvent-free process using an immobilised lipase as catalyst. When the water was removed during the process from what was initially an equimolar mixture of the starting materials carboxylic acid and alcohol by a stream of dry air passed through the reactor, there was a 95-99% conversion to the ester. The enzymatic process consumed 34% less energy and generated less waste than chemical esterification using a strong acid as catalyst. Two of the esters worked well in the industrial wood coating equipment employed and produced surfaces resistant to water and somewhat less to fat stains.
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| 7. |
- Hidestål, Olle, et al.
(författare)
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A chiral biselectrophile for efficient asymmetric synthesis in water
- 2005
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Ingår i: Green Chemistry. - : Royal Society of Chemistry (RSC). - 1463-9270 .- 1463-9262. ; 7:5, s. 259-261
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Tidskriftsartikel (refereegranskat)abstract
- The development of an efficient asymmetric dihydroxylation of 1,6-dibromodiene afforded a chiral biselectrophilic diol that displayed highly useful reactivity in water, as demonstrated by a three-step, two-pot asymmetric synthesis of a highly functionalized tetrahydrofuran.
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| 8. |
- Hillerström, Anna, et al.
(författare)
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Ibuprofen loading into mesostructured silica using liquid carbon dioxide as a solvent
- 2009
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Ingår i: Green Chemistry. - : Royal Society of Chemistry (RSC). - 1463-9262 .- 1463-9270. ; 11:5, s. 662-667
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Tidskriftsartikel (refereegranskat)abstract
- It has been demonstrated that the pharmaceutical molecule, Ibuprofen, can be loaded into mesoporous silica using liquid (near-critical) carbon dioxide as the solvent, and that the resulting material had a high Ibuprofen content (300 mg Ibuprofen/g SiO2). A high enrichment (300 times) of Ibuprofen in the pores was observed in comparison to the Ibuprofen concentration in the solution. When similar experiments were performed in CO2 (l) mixed with minor amounts (5 mol-%) of other organic cosolvents (cyclohexane, acetone or methanol), a significantly lower loading capacity of Ibuprofen into the mesoporous material was achieved. The drug-loaded mesoporous silica material was analyzed with Thermogravimetric Analysis (TGA), confocal Raman microscopy, X-ray Powder Diffraction (XRPD) and Scanning Electron Microscopy (SEM). It was found that the Ibuprofen loaded into the mesoporous silica host was amorphous and that Ibuprofen was present both at the surface and in the centre of the mesoporous silica particles. Furthermore, the SEM images did not reveal any large flakes of Ibuprofen molecules outside the mesoporous silica particles.
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| 9. |
- Sjöström, Jesper
(författare)
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Green chemistry in perspective - models for GC activities and GC policy and knowledge areas
- 2006
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Ingår i: Green Chemistry. - : Royal Society of Chemistry (RSC). - 1463-9270. ; 8:2, s. 130-137
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Tidskriftsartikel (refereegranskat)abstract
- This article presents two new models that give a perspective on green chemistry (GC). The first model is a classification model of different green chemistry activities, while the second model concerns green chemistry policy and knowledge areas (green chemistry principles, industrial biotechnology and "the green sector"). A broad view of green chemistry is used, where all activities with the aim of greening of chemistry and chemical practice are included. The classification model consists of three main parts: (1) research activities ((a) basic chemical research; (b) chemical engineering), (2) management activities ((a) laboratory practice; (b) production; (c) consumption) and (3) policy activities. This article refers to over seventy publications, covering a broad area of research and type.
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| 10. |
- Svensson, David, et al.
(författare)
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Enzymatic route to alkyl glycosides having oligomeric head groups
- 2009
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Ingår i: Green Chemistry. - : Royal Society of Chemistry (RSC). - 1463-9270 .- 1463-9262. ; 11:8, s. 1222-1226
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Tidskriftsartikel (refereegranskat)abstract
- Cyclodextrin glycosyl transferase (CGTase) from Bacillus macerans was used to catalyse the coupling of alpha-cyclodextrin to alkyl beta-glycosides. The acceptor substrate dodecyl beta-maltoside was thus converted to dodecyl beta-D-maltooctaoside. Further coupling steps and disproportionation reactions occurred, but by optimisation of the reaction time, a yield of 50% of the primary coupling product was obtained. The method worked well for a range of acceptors with different length of the carbohydrate part (1-3 glucose residues) and the hydrocarbon chain (10-14 carbon atoms). With respect to the principles of green chemistry, the method is superior to previously used methods involving protection/deprotection reactions.
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