ABSTRACT
Most of the carbon-based compounds currently manufactured by the chemical industry are derived from petroleum. The rising cost and dwindling supply of oil have been focusing attention on possible routes to making chemicals, fuels, and solvents from biomass instead. In this context, many recent studies have assessed the relative merits of applying different dedicated crops to chemical production. Here, we highlight the opportunities for diverting existing residual biomass--the by-products of present agricultural and food-processing streams--to this end.
Subject(s)
Biomass , Carbohydrates/chemistry , Proteins/chemistry , Waste Products , Biofuels , Crops, Agricultural , Food , Lignin/chemistry , Plant Proteins/chemistryABSTRACT
Several intermediates and different reaction paths were identified for the acid catalysed conversion of fructose to 5-(hydroxymethyl)-2-furaldehyde (HMF) in different solvents. The structural information combined with results of isotopic-labelling experiments allowed the determination of the irreversibility of the three steps from the fructofuranosyl oxocarbenium ion to HMF as well as the analogous pyranose route.
Subject(s)
Fructose/chemistry , Furaldehyde/analogs & derivatives , Catalysis , Desiccation , Furaldehyde/chemistry , Sulfuric Acids/chemistryABSTRACT
The reaction of sodium perfluoro-tert-butoxide with benzylic carbon-bromide bond(s) leads to the formation of (nonafluoro-tert-butoxy)methyl ponytail(s), which can enhance the fluorous solubility and partition of aromatics and heterocycles.
ABSTRACT
The application of fluorous phosphine-modified catalysts for the hydroformylation of olefins is reviewed.
ABSTRACT
The application of fluorous phosphine-modified catalysts for the hydrogenation of olefins is reviewed.
Subject(s)
Fluorocarbons/chemistry , Alkenes/chemistry , Catalysis , Hydrogenation , Rhodium/chemistryABSTRACT
Use of imidazolium ionic liquids as solvents for organic transformations with tetravalent cerium salts as oxidizing agents was evaluated. Good solubility was found for ammonium hexanitratocerate(IV) (ceric ammonium nitrate, CAN) and cerium(IV) triflate in 1-alkyl-3-methylimidazolium triflate ionic liquids. Oxidation of benzyl alcohol to benzaldehyde in 1-ethyl-3-methylimidazolium triflate was studied by in-situ FTIR spectroscopy and 13C NMR spectroscopy on carbon-13-labeled benzyl alcohol. Careful control of the reaction conditions is necessary because ammonium hexanitratocerate(IV) dissolved in an ionic liquid can transform benzyl alcohol not only into benzaldehyde but also into benzyl nitrate or benzoic acid. The selectivity of the reaction of cerium(IV) triflate with benzyl alcohol in dry ionic liquids depends on the degree of hydration of cerium(IV) triflate: anhydrous cerium(IV) triflate transforms benzyl alcohol into dibenzyl ether, whereas hydrated cerium(IV) triflate affords benzaldehyde as the main reaction product. Reactions of ammonium hexanitratocerate(IV) with organic substrates other than benzyl alcohol have been explored. 1,4-Hydroquinone is quantitatively transformed into 1,4-quinone. Anisole and naphthalene are nitrated. For the cerium-mediated oxidation reactions in ionic liquids, high reaction temperatures are an advantage because under these conditions smaller amounts of byproducts are formed.
ABSTRACT
A modular synthetic protocol was developed for the preparation of fluorous trialkylphosphines with a different number of methylene spacers and various lengths of the fluorous ponytails P[(CH(2))(A)R(FX)][(CH(2))(B)R(FY)][(CH(2))(C)R(FZ)] (A, B, C = 3 and 4; X, Y, Z = 4, 6, and 8). [reaction: see text]
ABSTRACT
A high-yield synthesis was developed for the preparation of 2,2'-bipyrimidine (1) using the Ullmann coupling of 2-iodopyrimidine. The new procedure was also used for the preparation of 4,4',6,6'-tetramethyl-2,2'-bipyrimidine (2) and 5,5'-dibromo-2,2'-bipyrimidine (3).
