• Study Resource
  • Explore Categories
    • Arts & Humanities
    • Business
    • Engineering & Technology
    • Foreign Language
    • History
    • Math
    • Science
    • Social Science

    Top subcategories

    • Advanced Math
    • Algebra
    • Basic Math
    • Calculus
    • Geometry
    • Linear Algebra
    • Pre-Algebra
    • Pre-Calculus
    • Statistics And Probability
    • Trigonometry
    • other →

    Top subcategories

    • Astronomy
    • Astrophysics
    • Biology
    • Chemistry
    • Earth Science
    • Environmental Science
    • Health Science
    • Physics
    • other →

    Top subcategories

    • Anthropology
    • Law
    • Political Science
    • Psychology
    • Sociology
    • other →

    Top subcategories

    • Accounting
    • Economics
    • Finance
    • Management
    • other →

    Top subcategories

    • Aerospace Engineering
    • Bioengineering
    • Chemical Engineering
    • Civil Engineering
    • Computer Science
    • Electrical Engineering
    • Industrial Engineering
    • Mechanical Engineering
    • Web Design
    • other →

    Top subcategories

    • Architecture
    • Communications
    • English
    • Gender Studies
    • Music
    • Performing Arts
    • Philosophy
    • Religious Studies
    • Writing
    • other →

    Top subcategories

    • Ancient History
    • European History
    • US History
    • World History
    • other →

    Top subcategories

    • Croatian
    • Czech
    • Finnish
    • Greek
    • Hindi
    • Japanese
    • Korean
    • Persian
    • Swedish
    • Turkish
    • other →
 
Profile Documents Logout
Upload
Metal Complexes Containing Natural and Artificial Radioactive
Metal Complexes Containing Natural and Artificial Radioactive

... analog of Hf. In contrast to lanthanides, the actinides display a wide collection of oxidation states. As An3+ ions they are analogs of the related Ln3+ ions, but as An4+ they resemble both Hf(IV) and Ce(IV) compounds. Actinides form various Anm+ (m = 2–4) and AnO2m+ (m = 1, 2) ions containing only ...
Table of Contents Pages Unit 1- Matter and Change 1
Table of Contents Pages Unit 1- Matter and Change 1

... Matter is anything that takes up __________________ and has mass. ______________ is the measure of the amount of matter that an object contains. Virtually all of the matter around us consists of mixtures. A mixture can be defined as something that has _____________________ composition. Soda is a mix ...
AS Chemistry Teacher Handbook
AS Chemistry Teacher Handbook

... exists when a pair of electrons is shared and that, if both electrons are contributed by the same atom, this is co-ordinate bonding. ...
General Concepts of Chemical Equilibrium
General Concepts of Chemical Equilibrium

... common ion is usually a product ion which means that reactants concentration will increase on the expense of products. Let us look at the following example: ...
Thermodynamics: Entropy and Free Energy
Thermodynamics: Entropy and Free Energy

LABORATORY MANUAL FOR CHEMISTRY 102
LABORATORY MANUAL FOR CHEMISTRY 102

... Temperature The presence of a catalyst Surface area in a heterogeneous reaction ...
Table of Contents
Table of Contents

... which the composition is _______________________, there are no chunks or layers. Salt water, ___________________ ___________________ and dust free air (mixture of nitrogen, oxygen, argon, carbon dioxide, water vapor and other gases) are examples of homogeneous mixtures. Brass (solid mixture of coppe ...
formula writing and nomenclature of inorganic - Parkway C-2
formula writing and nomenclature of inorganic - Parkway C-2

... +1, while each chlorine atom has gained one electron and is assigned an oxidation number of -1. The two ions are held together as a result of their opposite charges in what is called an ionic bond. As a second example, consider the formation of water from hydrogen and oxygen: 2 H2 + O2 → 2 H2O In th ...
Synthesis and Structural Studies of Calcium and Magnesium
Synthesis and Structural Studies of Calcium and Magnesium

... calcium solids lie in the large metal diameters, the absence of energetically available dorbital to direct metal geometry, as well as the overall weakness of the metal-ligand bonds. A significant part of this project was concerned with the development of suitable reaction conditions to obtain X-ray ...
Ch16 - WordPress.com
Ch16 - WordPress.com

... An equilibrium mixture consists of the gases N2O4 and NO2: N2O4(g)  2NO2(g) The volume of the container was increased at constant temperature and a new equilbrium was established. Predict how each of the following quantities would change at the new equilibrium compared with the initial equilibrium: ...
Chemistry
Chemistry

... behind methods and Vogel’s Quantitative Chemical Analysis provides clear introductions to all the key analytical methods including those involving advanced computerised equipment available in many analytical laboratories. The editors have built further on the work of Dr Vogel, modernising the approa ...
Formic acid oxidation reaction on a PdxNiy bimetallic nanoparticle
Formic acid oxidation reaction on a PdxNiy bimetallic nanoparticle

Document
Document

... Solve: ...
Chapter
Chapter

... Solve: ...
M.Sc. Part-I Chemistry - North Maharashtra University
M.Sc. Part-I Chemistry - North Maharashtra University

... 1) Determination of the dissociation constant of acetic acid in DMSO, DMF, acetone and dioxane by titrating it with KOH. ...
Chapter 14 (Kinetics) – Slides and Practice
Chapter 14 (Kinetics) – Slides and Practice

... Solve: ...
Chapter 8 "Ionic versus Covalent Bonding"
Chapter 8 "Ionic versus Covalent Bonding"

... constant k is equal to 2.31 × 10−28 J·m.This value of k includes the charge of a single electron (1.6022 × 10−19 C) for each ion. The equation can also be written using the charge of each ion, expressed in coulombs (C), incorporated in the constant. In this case, the proportionality constant, k, equ ...
Ch16
Ch16

... An equilibrium mixture consists of the gases N2O4 and NO2: N2O4(g)  2NO2(g) The volume of the container was increased at constant temperature and a new equilbrium was established. Predict how each of the following quantities would change at the new equilibrium compared with the initial equilibrium: ...
Chem13-14PrecipABNeut
Chem13-14PrecipABNeut

Formatting Blackline Masters
Formatting Blackline Masters

... The atomic radius is ½ the distance between the centers of neighboring atoms. It is the size of the atom due to the size of the electron cloud. Group trends The atomic radii of the main group elements (s & p sublevels) generally increases down a group. The outermost electrons occupy energy levels th ...
chemical and isotopic evidence for the in situ origin of marine humic
chemical and isotopic evidence for the in situ origin of marine humic

... not be rclatcd to the organic matter from the water but may have been introduced from the sediment. The amount of sulfur that WC found is lower than that reported by Swanson (Lmpublishcd) for three samples from the basins off southern California. This is particularly true of the Santa Barbara sampIc ...
National German Competition
National German Competition

... Similar to magnesium in Grignard reactions the metals copper and zinc as the main components of brass are often used in specific organic reactions. Each metal has its own specific reaction possibility e.g. copper organic compounds are efficient at forming new C-C bonds. ...
Student Study Guide Chemistry 534
Student Study Guide Chemistry 534

... function in the upper atmosphere by preventing harmful ultraviolet radiation from reaching the Earth. Air conditioning increase our comfort in hot climatic conditions and one of the gases that has been used for cooling is freon (a chlorinated fluorocarbon or CFC). This gas is effective for cooling b ...
KCET – CHEMISTRY – 2016 - Medicine.careers360.com
KCET – CHEMISTRY – 2016 - Medicine.careers360.com

... 16. Benezene carbaldehyde is reacted with concentrated NaOH solution to give the products A and B. The product A can be used food preservative and the product B is an aromatic hydroxyl compound where OH group is linked to sp3 hydridised carbon atom next to Benzene ring. The products A and B respect ...
CHAPTER 18
CHAPTER 18

< 1 ... 13 14 15 16 17 18 19 20 21 ... 185 >

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.
  • studyres.com © 2026
  • DMCA
  • Privacy
  • Terms
  • Report