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Chapter 12
Chapter 12

... butanoate. The salad dressing is preserved with BHT, which is an example of an arene. John orders fish, but he sends it back. The smell of the amine called trimethylamine let him know that it was spoiled. The number of natural and synthetic organic, or carbon-based, compounds runs into the millions. ...
UNIVERSITI MALAYSIA SABAH
UNIVERSITI MALAYSIA SABAH

... NH3(aq) + H2O <=> NH4+ + OHis only 1.8 X 10-5. This means that it mostly exists as NH3(aq) in water. Ammonia is one of the most used chemical in industry. It is mostly used in the production of fertilizers (ammonium sulphate and ammonium nitrate); manufacture of explosives, plastics, pulp & paper, t ...
Reaction Rates/Chemical Kinetics
Reaction Rates/Chemical Kinetics

chemistry
chemistry

... known, while graphite is a very soft substance. Diamond has a rigid network of bonded atoms. Graphite has atoms bonded in thin layers that are held together by weak forces. Recent experiments have produced new forms of solid carbon called fullerenes. One fullerene, C60, is a spherical, cagelike mole ...
Basic Chemical Concepts I
Basic Chemical Concepts I

Atomic Structure
Atomic Structure

... The statements (i) “In filling a group of orbitals of equal energy it is energetically preferable to assign electrons to empty orbitals rather than pair them into a particular orbital. (ii) When two electrons are placed in two different orbitals, energy is lower if the espins are parallel” are valid ...
Effect of Potassium on Sol-Gel Cerium and Lanthanum Oxide
Effect of Potassium on Sol-Gel Cerium and Lanthanum Oxide

... to burn this particulate material [7] [9]. The catalyst deposited in the ceramic filters could oxidize the soot, reducing its emission into the atmosphere. However, the temperatures at which the gases emitted into the atmosphere are cooled between 300˚C and 400˚C, coal is burned at temperatures that ...
Basic Chemical Concepts I
Basic Chemical Concepts I

Combustion
Combustion

... A combustion reaction always involves oxygen as one of the reactants. Often the other reactant in a combustion reaction is a hydrocarbon. Hydrocarbons are organic compounds that are made up of hydrogen and carbon atoms (General formula of a hydrocarbon: CxHy). The combustion of hydrocarbons can be ...
Oxidation numbers
Oxidation numbers

... a reaction, we go through these steps: 1 Write down the chemical equation for the reaction. 2 Go through and work out the oxidation numbers for every element in the equation. 3 Look for an element that has increased its oxidation number from one side of the equation to the other - it has been oxidis ...
Rutile titanium dioxide nanoparticles and ordered acicular
Rutile titanium dioxide nanoparticles and ordered acicular

... The resulting reaction mixture was then cooled to room temperature and transferred to a different container where the particles formed were allowed to settle for a few hours. After essentially all of the particles were observed to have settled to ...
Chemical Reactions and Solution Stoichiometry
Chemical Reactions and Solution Stoichiometry

... Notice that in Interactive Figure 4.2.1 the water molecules orient themselves so that the oxygen atoms are near the Na+ cations and the hydrogen atoms are near the Cl− anions. This is due to the polar nature of water, a result of uneven electron distribution in water molecules. ( Flashforward to Se ...
 College  Grossmont    115 
 College  Grossmont    115 

... It is understood that the last digit in any measurement is the estimated digit. Sometimes the last digit is called the “doubtful digit” or “unreliable digit”. Scientists communicate the level of uncertainty by the use of significant figures. A mass of 2.9 g contains two significant figures; a mass o ...
Periodic Table and the Atom Answers
Periodic Table and the Atom Answers

... 7) How do you increase or decrease the pH of pure water? Answer: By adding a few drops of alkali to pure water, it's pH increases; and by adding a few drops of an acid decreases the pH of pure water. 8) What are indicators? Answer: Indicators are chemicals that show whether the given solution is aci ...
Exemplar Paper
Exemplar Paper

... DO NOT WRITE ON THIS PAGE ...
1b-Redox FIB notes and practice
1b-Redox FIB notes and practice

... In general, all chemical reactions can be assigned to one of two classes. In oxidation-reduction reactions electrons are transferred from one reacting species to another. In all other reactions electrons are not transferred. A majority of the reactions presented prior to this unit do not involve ele ...
Determination of the Molar Volume of H2(g) and of O2(g)
Determination of the Molar Volume of H2(g) and of O2(g)

Review Unit 8 Test (Chp 15,17)
Review Unit 8 Test (Chp 15,17)

... increases until it becomes the same as the reverse reaction rate at equilibrium. stays constant before and after equilibrium is reached. A is half true, but “decreases”, decreases to become a constant nonzero rate at equilibrium. not “increases.” decreases to become zero at equilibrium. Greater pres ...
Question Bank - Edudel.nic.in
Question Bank - Edudel.nic.in

... The metal calcium (atomic mass = 40 gm mol–1] crystallises in a fcc unit cell with a = 0.556 nm. Calculate the density of the metal if (i) It contains 0.2% Frenkel defect. (ii) It contains 0.1% schottky defect. [Ans. : (i) 1.5463 g/cm3; (ii) 1.5448g/cm3] ...
CHEMICAL REACTIONS
CHEMICAL REACTIONS

... NIE from Reactants • Write NIE for any reaction (or no rx) that occurs when (aq) solutions of NaCl(aq) + AgNO3(aq) are mixed ...
Spring 2005
Spring 2005

... 14. (3 pts) What is the oxidation number (charge) on C in H2C2O4? Explain your reasoning. 15. (8 pts) How many atoms of nitrogen are there in 15.3 mg of Ba(NO3)2? 16. (8 pts) What is the mass percent of oxygen in KMnO4? 17. (8 pts) The balanced reaction of muriatic acid with lime is 2 HCl + CaO ! Ca ...
Organic Chemistry
Organic Chemistry

... Disulfides are important compounds that are widely used in both biological and chemical processes. They were used as reagents to stabilize polypeptide secondary structure in peptide and protein synthesis.[1] Moreover, disulfides are important reagents for vulcanization in rubbers and elastomers.[2] ...
Chemical Reactions
Chemical Reactions

... • The problem with word equations is they do not actually show the number of atoms or molecules of each substance… formulas would have to be written out for this to happen. (Absent? We looked at examples of these in class) ...
Chapter 4 Chemical Quantities and Aqueous Reactions
Chapter 4 Chemical Quantities and Aqueous Reactions

... Things Don’t Always Go as Planned! • many things can happen during the course of an experiment that cause the loss of product • the amount of product that is made in a reaction is called the actual yield generally less than the theoretical yield, never more! ...
the Main-Group Metals - McQuarrie General Chemistry
the Main-Group Metals - McQuarrie General Chemistry

... group, differs in many respects from that of the rest of the group. Boron is a semimetal, and the other members of the series are metals, with the metallic character of the elements increasing as we descend the group in the periodic table. Boron has a metallic luster but behaves more like the semime ...
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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.
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