Catalytic, Enantioselective Alkylation of r
... not been nearly as well studied nor as successful.2 R-Imino esters are almost unstudied in Lewis acid-catalyzed reactions,3 but are especially attractive imine substrates for the efficient syntheses of natural product precursors,4 pharmaceutically active compounds,5 and nonnatural amino acids;6 the ...
... not been nearly as well studied nor as successful.2 R-Imino esters are almost unstudied in Lewis acid-catalyzed reactions,3 but are especially attractive imine substrates for the efficient syntheses of natural product precursors,4 pharmaceutically active compounds,5 and nonnatural amino acids;6 the ...
Introduction to enzymes
... 2. Kinetics alone will not give a chemical mechanism but combined with chemical and structural data mechanisms can be elucidated. 3. Kinetics help understand the enzymes role in metabolic pathways. 4. Under “proper” conditions rates are proportional to enzyme concentrations and these can be determin ...
... 2. Kinetics alone will not give a chemical mechanism but combined with chemical and structural data mechanisms can be elucidated. 3. Kinetics help understand the enzymes role in metabolic pathways. 4. Under “proper” conditions rates are proportional to enzyme concentrations and these can be determin ...
Types of Chemical Reactions
... occur in various systems. Memorizing the equations for so many chemical reactions would be difficult. It is more useful and realistic to classify reactions according to various similarities and regularities. ...
... occur in various systems. Memorizing the equations for so many chemical reactions would be difficult. It is more useful and realistic to classify reactions according to various similarities and regularities. ...
Final Exam Practice-2017
... b) There are too many electrons in this diagram. The lone pair on carbon should be removed. c) There are too many electrons in this diagram. The lone pair of electrons on carbon should make a double bond with hydrogen. d) There are too many electrons in this diagram. The lone pair on carbon should i ...
... b) There are too many electrons in this diagram. The lone pair on carbon should be removed. c) There are too many electrons in this diagram. The lone pair of electrons on carbon should make a double bond with hydrogen. d) There are too many electrons in this diagram. The lone pair on carbon should i ...
Chapter 7
... Energy in Chemical Reactions Heat and other natural processes in a system always tend toward less usable energy and greater disorder… This is known as the second law of thermodynamics When you eat something, only about 55% of energy is actually used…the rest is converted into heat and “lost” to you ...
... Energy in Chemical Reactions Heat and other natural processes in a system always tend toward less usable energy and greater disorder… This is known as the second law of thermodynamics When you eat something, only about 55% of energy is actually used…the rest is converted into heat and “lost” to you ...
Organometallic Compounds and Catalysis: Synthesis
... palladium salt; 3) Ziegler Natta Process, olefins are polymerized using an organoaluminumtitanium catalyst to form stereoregular polymers; and 4) Fischer-Tropsch Reactions, the reductive polymerization of CO to form straightchain hydrocarbons, olefins and alcohols. The role inorganic chemists often ...
... palladium salt; 3) Ziegler Natta Process, olefins are polymerized using an organoaluminumtitanium catalyst to form stereoregular polymers; and 4) Fischer-Tropsch Reactions, the reductive polymerization of CO to form straightchain hydrocarbons, olefins and alcohols. The role inorganic chemists often ...
Year 10 Chemistry Exam June 2011 Multiple Choice Section A
... 1. An aqueous solution is obtained when: a. a substance dissolves in any liquid b. a substance is dissolved in water c. when a substance is mixed with water and doesn’t dissolve d. water is removed from a substance 2. The graph shows the relative amount of chemical substances which can be taken up b ...
... 1. An aqueous solution is obtained when: a. a substance dissolves in any liquid b. a substance is dissolved in water c. when a substance is mixed with water and doesn’t dissolve d. water is removed from a substance 2. The graph shows the relative amount of chemical substances which can be taken up b ...
review sheet
... 9. What substance will decrease the surface tension of water?______________________ 10. A highly volatile substance will have _______ intermolecular forces. 11. What type of intermolecular force will be the strongest in polar molecules?________________Nonpolar molecules?_______________ 12.Adding he ...
... 9. What substance will decrease the surface tension of water?______________________ 10. A highly volatile substance will have _______ intermolecular forces. 11. What type of intermolecular force will be the strongest in polar molecules?________________Nonpolar molecules?_______________ 12.Adding he ...
Stoichiometry and Balanced Reactions Chemical Accounting
... Write and balance the chemical equation for the process. Determine molar masses of substances involved in the calculation. Use the coefficients of the balanced equation to convert the moles of the given substance to the moles of the desired substance. Use the molar mass to convert the moles of the d ...
... Write and balance the chemical equation for the process. Determine molar masses of substances involved in the calculation. Use the coefficients of the balanced equation to convert the moles of the given substance to the moles of the desired substance. Use the molar mass to convert the moles of the d ...
halogen compounds organic chemistry
... (FeCl3, FeBr3, AlCl3) in the dark, at ordinary temperatures (310-320 K). The Lewis acid acts as a catalyst or a halogen carrier, as its function is to carry the chlorine to the aromatic hydrocarbon. In actual practice, iron filings in the presence of chlorine commonly used. The chlorine reacts with ...
... (FeCl3, FeBr3, AlCl3) in the dark, at ordinary temperatures (310-320 K). The Lewis acid acts as a catalyst or a halogen carrier, as its function is to carry the chlorine to the aromatic hydrocarbon. In actual practice, iron filings in the presence of chlorine commonly used. The chlorine reacts with ...
activity series
... It is most important for a chemist to be able to write correctly balanced equations and to interpret equations written by others. It is also very helpful if he/she knows how to predict the products of certain specific types of reactions. ...
... It is most important for a chemist to be able to write correctly balanced equations and to interpret equations written by others. It is also very helpful if he/she knows how to predict the products of certain specific types of reactions. ...
Unit 5 Practice Problems (with answers at end) - H
... 7. To produce the original "water gas" mixture, carbon (in a combustible form known as coke) is reacted with steam: ...
... 7. To produce the original "water gas" mixture, carbon (in a combustible form known as coke) is reacted with steam: ...
Chemistry 116: General Chemistry
... The reaction is faster at higher temperatures. The reaction has only one type of reactant. The rate remains constant when the reactant concentration is doubled. The reaction slows down as time goes on. The half life remains constant as time goes on. ...
... The reaction is faster at higher temperatures. The reaction has only one type of reactant. The rate remains constant when the reactant concentration is doubled. The reaction slows down as time goes on. The half life remains constant as time goes on. ...
Single Replacement Reactions
... with excess water and inform the instructor. Wear safety goggles and closed toed shoes throughout the entirety of the lab procedure.*** b. Label five test tubes - each with the name of one of the metals (zinc, aluminum, copper, iron and magnesium) if this has not been done already. c. Following your ...
... with excess water and inform the instructor. Wear safety goggles and closed toed shoes throughout the entirety of the lab procedure.*** b. Label five test tubes - each with the name of one of the metals (zinc, aluminum, copper, iron and magnesium) if this has not been done already. c. Following your ...
Bifunctional Asymmetric Catalysis: Cooperative Lewis Acid/Base
... transition state involves InIII coordination to the substrate and the chiral additive, while the N-oxide initiates the InIII-assisted transfer of the allyl group (Figure 8). Nelson et al. have reported several remarkable lithium-assisted reactions of cinchona alkaloid ketene enolates. In 2004, the a ...
... transition state involves InIII coordination to the substrate and the chiral additive, while the N-oxide initiates the InIII-assisted transfer of the allyl group (Figure 8). Nelson et al. have reported several remarkable lithium-assisted reactions of cinchona alkaloid ketene enolates. In 2004, the a ...
Final Exam Review – Free Response Section Name: 1. A sample of
... If it is a single displacement reaction, use the activity series to determine if it will occur. If it will not occur, write “no reaction.” If it is a double displacement, use the solubility rules to determine if it will occur. If it will not occur, write “no reaction.” If it will occur, write the ba ...
... If it is a single displacement reaction, use the activity series to determine if it will occur. If it will not occur, write “no reaction.” If it is a double displacement, use the solubility rules to determine if it will occur. If it will not occur, write “no reaction.” If it will occur, write the ba ...
Cooperative Lewis Acid/Base Systems
... providing access to disubstituted β-lactones, through a putative metal-organized six-member transition-state complex (Scheme 7A).31 More recently, Nelson proposed a similar transition-state argument for the lithium/cinchona alkaloid cocatalyzed reaction of ketenes and N-thioacyl imines (Scheme 7B). ...
... providing access to disubstituted β-lactones, through a putative metal-organized six-member transition-state complex (Scheme 7A).31 More recently, Nelson proposed a similar transition-state argument for the lithium/cinchona alkaloid cocatalyzed reaction of ketenes and N-thioacyl imines (Scheme 7B). ...
Chemical Reactions
... 2. The relative masses of the reactants and products of a chemical reaction can be determined from the reaction’s coefficients. 3. The reverse reaction for a chemical equation has the same relative amounts of substances as the forward reaction. ...
... 2. The relative masses of the reactants and products of a chemical reaction can be determined from the reaction’s coefficients. 3. The reverse reaction for a chemical equation has the same relative amounts of substances as the forward reaction. ...
Final Exam Practice 2016 (MC)
... b) There are too many electrons in this diagram. The lone pair on carbon should be removed. c) There are too many electrons in this diagram. The lone pair of electrons on carbon should make a double bond with hydrogen. d) There are too many electrons in this diagram. The lone pair on carbon should i ...
... b) There are too many electrons in this diagram. The lone pair on carbon should be removed. c) There are too many electrons in this diagram. The lone pair of electrons on carbon should make a double bond with hydrogen. d) There are too many electrons in this diagram. The lone pair on carbon should i ...
Lewis acid catalysis
In Lewis acid catalysis of organic reactions, a metal-based Lewis acid acts as an electron pair acceptor to increase the reactivity of a substrate. Common Lewis acid catalysts are based on main group metals such as aluminum, boron, silicon, and tin, as well as many early (titanium, zirconium) and late (iron, copper, zinc) d-block metals. The metal atom forms an adduct with a lone-pair bearing electronegative atom in the substrate, such as oxygen (both sp2 or sp3), nitrogen, sulfur, and halogens. The complexation has partial charge-transfer character and makes the lone-pair donor effectively more electronegative, activating the substrate toward nucleophilic attack, heterolytic bond cleavage, or cycloaddition with 1,3-dienes and 1,3-dipoles.Many classical reactions involving carbon–carbon or carbon–heteroatom bond formation can be catalyzed by Lewis acids. Examples include the Friedel-Crafts reaction, the aldol reaction, and various pericyclic processes that proceed slowly at room temperature, such as the Diels-Alder reaction and the ene reaction. In addition to accelerating the reactions, Lewis acid catalysts are able to impose regioselectivity and stereoselectivity in many cases.Early developments in Lewis acid reagents focused on easily available compounds such as TiCl4, BF3, SnCl4, and AlCl3. The relative strengths of these (and other) Lewis acids may be estimated from NMR spectroscopy by the Childs method or the Gutmann-Beckett method. Over the years, versatile catalysts bearing ligands designed for specific applications have facilitated improvement in both reactivity and selectivity of Lewis acid-catalyzed reactions. More recently, Lewis acid catalysts with chiral ligands have become an important class of tools for asymmetric catalysis.Challenges in the development of Lewis acid catalysis include inefficient catalyst turnover (caused by catalyst affinity for the product) and the frequent requirement of two-point binding for stereoselectivity, which often necessitates the use of auxiliary groups.