Chemistry Letters Vol. 41, No. 8 (August, 2012) Design Concept for High-LUMO-level Fullerene Electron-acceptors for Organic Solar Cells by Yutaka Matsuo on pg 754 Department of Chemistry, School of Science, The University of Tokyo This review article describes design concept, synthesis, and features of fullerene derivatives having high lowest unoccupied molecular orbital (LUMO) levels to… Continue reading Design Concept for High-LUMO-level Fullerene Electron-acceptors for Organic Solar Cells
Category: ORGANIC CHEMISTRY
Development of Heterogeneous Catalysts for the Conversion of Levulinic Acid to γ-Valerolactone
http://onlinelibrary.wiley.com/doi/10.1002/cssc.201200111/abstract Biomass-derived γ-valerolactone (GVL) can be used for manufacturing food, chemicals, and fuels. Numerous hydrogenation catalysts have been developed for the GVL synthesis, with heterogeneous systems arguably the most viable. We discuss current heterogeneous systems, with emphasis on catalyst innovation and development of integrated biomass processing. William R. H. Wright, Regina Palkovits Development of Heterogeneous… Continue reading Development of Heterogeneous Catalysts for the Conversion of Levulinic Acid to γ-Valerolactone
Chiloglottone –Australian orchid uses a single simple diketone to attract wasps that pollinate it
The Australian orchid Chiloglottis trapeziformis' very existence hinges upon there being some truth to the old adage that love is blind. Unlike other flowers, which lure pollinators with nectar, C. trapeziformis attracts its pollinator, the thynnine wasp Neozeleboria cryptoides, by producing the same pheromone that the insects use to attract the opposite sex–a practice… Continue reading Chiloglottone –Australian orchid uses a single simple diketone to attract wasps that pollinate it
2′-Hydroxychalcone to Flavanone: Asymmetric Catalysis
http://onlinelibrary.wiley.com/doi/10.1002/ejoc.201200838/abstract Asymmetric Ion-Pairing Catalysis of the Reversible Cyclization of 2′-Hydroxychalcone to Flavanone: Asymmetric Catalysis of an Equilibrating Reaction Lukas Hintermann and Claudia Dittmer The cyclization of nonactivated 2′-hydroxychalcones to flavanones has been realized for the first time with asymmetric induction. In spite of the reversibility of the reactions, this ion-pairing catalysis reaches intrinsic enantioselectivities… Continue reading 2′-Hydroxychalcone to Flavanone: Asymmetric Catalysis
COLOURFUL MECHANISMS-ACADEMIC HELP
Epoxidation OZONOLYSIS oxidations DIELS ALDER RXN We noted earlier that addition reactions of alkenes often exhibited STEREOSPEFICITY, in that the reagent elements in some cases added syn and in other cases anti to the the plane of the double bond. Both reactants in the Diels-Alder reaction may demonstrate stereoisomerism, and when they do it is… Continue reading COLOURFUL MECHANISMS-ACADEMIC HELP
Cram’s rule
The Cram’s rule of asymmetric induction developed by Donald J. Cram in 1952, is an early concept relating to the prediction of stereochemistry in certain acyclic systems. In full the rule is: In certain non-catalytic reactions that diastereomer will predominate, which could be formed by the approach of the entering group from the least hindered side… Continue reading Cram’s rule
CUBANE SYNTHESIS
CubaneCubane (C8H8) is a synthetic hydrocarbon molecule that consists of eight carbon atoms arranged at the corners of a cube, with one hydrogen atom attached to each carbon atom. A solid crystalline substance, cubane is one of the Platonic hydrocarbons. It was first synthesized in 1964 by Philip Eaton, a professor of chemistry at the… Continue reading CUBANE SYNTHESIS
Efficient levoglucosenone production
Levoglucosenone Levoglucosenone is a highly dehydrated sugar that has been used in the preparation of chiral synthons such as (–)-y-multistriatin and (+)-Prelog—Djerassi lactonic acid. Negative-form is a pyrolysis product of cellulose and cellulose-containing materials including pulp and paper waste products. Known as a pyrolytic product of cellulose, which is very useful as a chiral source… Continue reading Efficient levoglucosenone production
Isolation of Optically Pure (S)-(+)-Ibuprofen
Isolation of Optically Pure (S)-(+)-Ibuprofen In this laboratory exercise we will isolate (S)-(+)-Ibuprofen from a racemic mixture of both enantiomers of this compound. This will be accomplished by treating the racemic mixture of Ibuprofen with (S)-(-)-alpha-Phenethylamine, whose molecules are themselves chiral, to form (S,S) and (R,S) Ibuprofen/Phenethylamine diastereomeric salts. Because the (S,S) salt is much… Continue reading Isolation of Optically Pure (S)-(+)-Ibuprofen
Resolution-Racemization-Recycle.
In one of its steps the racemic alcohol 1 is dissolved in a mixture of toluene and methanol to which solution is added optically active (S)-mandelic acid 3. The alcohol (S)-enantiomer forms an insoluble diastereomeric salt with the mandelic acid and can be filtered from the solution. Simple deprotonation with sodium hydroxide liberates free (S)-alcohol. In the meanwhile the (R)-alcohol remains in solution unaffected and is recycled back… Continue reading Resolution-Racemization-Recycle.