doc_367
... The problems encountered by homogeneous catalysts can be overcome by immobilizing them on a suitable matrix. The immobilization of homogeneous catalysts leads to higher thermal and chemical stabilities. The product selectivity and substrate specificity is increased to a greater extent by sterric cro ...
... The problems encountered by homogeneous catalysts can be overcome by immobilizing them on a suitable matrix. The immobilization of homogeneous catalysts leads to higher thermal and chemical stabilities. The product selectivity and substrate specificity is increased to a greater extent by sterric cro ...
Stable gold(III) catalysts by oxidative addition of a carbon
... Lewis-acid-catalysed 1,4-additions to a,b-unsaturated aldehydes remain challenging because 1,2-additions generally predominate32–34. Yamamoto and colleagues have reported a unique strategy for Lewis-acid-promoted 1,4-addition to a a,b-unsaturated aldehyde using aluminium reagents with sterically dem ...
... Lewis-acid-catalysed 1,4-additions to a,b-unsaturated aldehydes remain challenging because 1,2-additions generally predominate32–34. Yamamoto and colleagues have reported a unique strategy for Lewis-acid-promoted 1,4-addition to a a,b-unsaturated aldehyde using aluminium reagents with sterically dem ...
Chapter 17: Aldehydes and Ketones: Nucleophilic Addition to the
... The Wittig reaction gives C=C in a defined location, based on the location of the carbonyl group (C=O) CH3 ...
... The Wittig reaction gives C=C in a defined location, based on the location of the carbonyl group (C=O) CH3 ...
cycloadditions with singlet oxygen
... electron-rich olefin was farther from the directing hydroxyl group and a decreased selectivity was observed. When the methoxy group was placed in the ortho position, the selectivity was increased because singlet oxygen bonded to the electron-rich olefin first and was closer to the directing hydroxyl ...
... electron-rich olefin was farther from the directing hydroxyl group and a decreased selectivity was observed. When the methoxy group was placed in the ortho position, the selectivity was increased because singlet oxygen bonded to the electron-rich olefin first and was closer to the directing hydroxyl ...
1P18 IR spectroscopic investigation on intermolecular proton
... although their neutral CH bonds are normally aprotic.[1] These findings raise the question which is more acidic in cationic states, OH (and NH) or CH. To compare acidities of cationic CH and OH bonds, we have studied an ionization-induced proton transfer of ethylene glycol and propanediol, both of w ...
... although their neutral CH bonds are normally aprotic.[1] These findings raise the question which is more acidic in cationic states, OH (and NH) or CH. To compare acidities of cationic CH and OH bonds, we have studied an ionization-induced proton transfer of ethylene glycol and propanediol, both of w ...
CHEM 212B, Organic Chemistry - City College of San Francisco
... d. Readings from the textbook and instructor-generated handouts e. Problems from the textbook and instructor-generated problem sets B. Evaluation 1. Graded laboratory reports which include data, observations, calculations and interpretation of lab results. 2. Graded computer assignments for molecula ...
... d. Readings from the textbook and instructor-generated handouts e. Problems from the textbook and instructor-generated problem sets B. Evaluation 1. Graded laboratory reports which include data, observations, calculations and interpretation of lab results. 2. Graded computer assignments for molecula ...
Faculteit der Natuurwetenschappen, Wiskunde en Informatica
... A new approach towards the right-hand side of Solanoeclepin A (figure 3) is under investigation. The key step in the synthesis of the tricyclic core of the natural product is a [2+2] photocycloaddition. A challenging part of this approach is to obtain enantiomerically pure β-hydroxy-ketones (17, fig ...
... A new approach towards the right-hand side of Solanoeclepin A (figure 3) is under investigation. The key step in the synthesis of the tricyclic core of the natural product is a [2+2] photocycloaddition. A challenging part of this approach is to obtain enantiomerically pure β-hydroxy-ketones (17, fig ...
Elimination Reactions
... The previous example demonstrates a common problem in synthetic chemistry – the problem of competing reactions which lead to numerous products. In the previous example, our base (H2O) was also nucleophilic. What if we used a base that was a poor nucleophile? Below are some examples of strong bases w ...
... The previous example demonstrates a common problem in synthetic chemistry – the problem of competing reactions which lead to numerous products. In the previous example, our base (H2O) was also nucleophilic. What if we used a base that was a poor nucleophile? Below are some examples of strong bases w ...
Molecules 2002
... Thus, 4 was easily prepared from the condensation of four equivalents of 1-(hydroxymethyl)-3,5dimethylpyrazole with one equivalent of p-phenylenediamine under gentle conditions (room temperature, atmospheric pressure, 4-7 days), using anhydrous acetonitrile as solvent. The yield was good (67%) and t ...
... Thus, 4 was easily prepared from the condensation of four equivalents of 1-(hydroxymethyl)-3,5dimethylpyrazole with one equivalent of p-phenylenediamine under gentle conditions (room temperature, atmospheric pressure, 4-7 days), using anhydrous acetonitrile as solvent. The yield was good (67%) and t ...
Elimination Reactions
... The previous example demonstrates a common problem in synthetic chemistry – the problem of competing reactions which lead to numerous products. In the previous example, our base (H2O) was also nucleophilic. What if we used a base that was a poor nucleophile? Below are some examples of strong bases w ...
... The previous example demonstrates a common problem in synthetic chemistry – the problem of competing reactions which lead to numerous products. In the previous example, our base (H2O) was also nucleophilic. What if we used a base that was a poor nucleophile? Below are some examples of strong bases w ...
Chapter 7: Recent advances in enzyme technology
... This represents a fairly complex relationship but a few generalisations may be made. If the product (C) is less polar than either reactant (A or B) then the yield generally increases with the relative concentration of the organic phase () to reach a plateau. If the reverse occurs, then there will b ...
... This represents a fairly complex relationship but a few generalisations may be made. If the product (C) is less polar than either reactant (A or B) then the yield generally increases with the relative concentration of the organic phase () to reach a plateau. If the reverse occurs, then there will b ...
Chemistry
... 2. Explain the difference between 10, 20 and 30 alkyl halides, with suitable examples. 3. Allyl halides are more reactive than alkyl halides. Why? 4. What are the reagents required prepare alkyl halide from the following (i) alcohol (ii) alkene (iv) alkanes 5. Explain the reactions used to convert b ...
... 2. Explain the difference between 10, 20 and 30 alkyl halides, with suitable examples. 3. Allyl halides are more reactive than alkyl halides. Why? 4. What are the reagents required prepare alkyl halide from the following (i) alcohol (ii) alkene (iv) alkanes 5. Explain the reactions used to convert b ...
Chapter 17: Organic Chemistry
... Recycling is simplified by using codes found on plastic items: ...
... Recycling is simplified by using codes found on plastic items: ...
Chapter 20: Carboxylic Acids
... reaction is quantitative and very easy…but diazomethane has a tendency to explode…. ...
... reaction is quantitative and very easy…but diazomethane has a tendency to explode…. ...
Chapter 20 Coordination chemistry: reactions of complexes
... The ligand trans to the amido or hydroxo group is frequently the one lost Additional evidence 1. Base catalyzed exchange of hydrogen from the amine groups takes place under the same conditions. 2. The isotope ratio (18O/16O) in the product in 18O-enriched water is the same as that in the water regar ...
... The ligand trans to the amido or hydroxo group is frequently the one lost Additional evidence 1. Base catalyzed exchange of hydrogen from the amine groups takes place under the same conditions. 2. The isotope ratio (18O/16O) in the product in 18O-enriched water is the same as that in the water regar ...
Scheme I a la 2a 3a d ~ ~`~ .~ff 3 4a 5a
... obtained using this procedure. 9. A solution of 2d (28.0 g, 99.5 mmol) and triethylamine (28 mL, 199 mmol) in CH2C12 (330 mL) at -3°C was treated over 2.5h with methane sulfonyl chloride (8.5 mL) in CH2C12(8.5 mL). The resulting brown slurry was stirred for an additional 2.5h. All volatiles were rem ...
... obtained using this procedure. 9. A solution of 2d (28.0 g, 99.5 mmol) and triethylamine (28 mL, 199 mmol) in CH2C12 (330 mL) at -3°C was treated over 2.5h with methane sulfonyl chloride (8.5 mL) in CH2C12(8.5 mL). The resulting brown slurry was stirred for an additional 2.5h. All volatiles were rem ...
chapter 4 review_package
... 9. Given the following balanced equations, solve the stoichiometric problems (PLO-D5) a. Ammonia combines with oxygen gas in the following reaction: 4 NH3 + 5O2 → 6H2O + 4NO i. How many moles of NH3 are needed to combine with 3.57 moles of O2 gas? ...
... 9. Given the following balanced equations, solve the stoichiometric problems (PLO-D5) a. Ammonia combines with oxygen gas in the following reaction: 4 NH3 + 5O2 → 6H2O + 4NO i. How many moles of NH3 are needed to combine with 3.57 moles of O2 gas? ...
Ring-closing metathesis
Ring-closing metathesis, or RCM, is a widely used variation of olefin metathesis in organic chemistry for the synthesis of various unsaturated rings via the intramolecular metathesis of two terminal alkenes, which forms the cycloalkene as the E- or Z- isomers and volatile ethylene.The most commonly synthesized ring sizes are between 5-7 atoms; however, reported syntheses include 45- up to 90- membered macroheterocycles. These reactions are metal-catalyzed and proceed through a metallacyclobutane intermediate. It was first published by Dider Villemin in 1980 describing the synthesis of an Exaltolide precursor, and later become popularized by Robert H. Grubbs and Richard R. Schrock, who shared the Nobel Prize in Chemistry, along with Yves Chauvin, in 2005 for their combined work in olefin metathesis. RCM is a favorite among organic chemists due to its synthetic utility in the formation of rings, which were previously difficult to access efficiently, and broad substrate scope. Since the only major by-product is ethylene, these reactions may also be considered atom economic, an increasingly important concern in the development of green chemistry.There are several reviews published on ring-closing metathesis.