chemistry

Electrochemistry - Index Home > Physical & Theoretical Chemistry > Electrochemistry ELECTROCHEMISTRY Balancing Oxidation - Reduction reactions by the Oxidation Number Method Oxidation Numbers: Assigning oxidation numbers to atoms in a chemical compound - Examples Oxidation – Reduction (Redox) Reactions – Balancing Redox Reactions   Electrochemistry is the study of the relationship between electricity and chemical reactions. It is primarily concerned with two processes that involve oxidation-reduction reactions : the generation of an electric current from a chemical reaction and the opposite process, the use of a current to produce chemical change . At the heart of electrochemistry are the oxidation-reduction reactions. These reactions power batteries that in turn are used in cars, calculators, laptops and in our portable electr

Carbocations Home > Organic Chemistry > Carbocations CARBOCATIONS Carbocations: Factors affecting their Stability Carbocations and factors affecting instability Carbocation Rearrangements: 1,2-H and 1,2-alkyl Shifts Carbocation Rearrangements and Change in Ring Size   A species containing a positively charged carbon atom is called a carbocation (Fig. I.1) . For many years these species were called " carbonium ions ". In the early seventies George Olah proposed that the name "carbonium ion" should be reserved for pentacoordinated positive ions and that carbocations should be named " carbenium ions ". Carbocations and their reactivity play an important role in chemistry since these species are intermediates in several kinds of reactions. The more stable ones have been prepared in solution and in som

Nucleophilic Substitution Reactions Home > Organic Chemistry > Nucleophilic Substitution Reactions NUCLEOPHILIC SUBSTITUTION REACTIONS Organic Chemistry| SN1 and SN2 Nucleophilic Substitution Nucleophilic Substitution: Nucleophiles in SN2 & SN1 Reactions Nucleophilic Substitution: SN2 & SN1 Reactions and Stereochemistry SN1 and SN2 reactions. When do they take place at a saturated carbon atom? Solvent Effects and SN2 and SN1 reactions: Nucleophilic Substitution The SN2 reaction: Substitution Nucleophilic Bimolecular   Nucleophilic Substitution reactions occur when an electron rich species the nucleophile reacts at an electrophilic saturated carbon C atom attached to an electronegative group, the leaving group , that can be displaced as shown bel

Carbanions Home > Organic Chemistry > Carbanions CARBANIONS Keto-Enol Tautomerism – Enolization – Reactions and Mechanism The chemistry of enolate ions – Reactions with alkyl halides   Carbanions are species with a complete octet around the carbon atom. A general formula of a carbanion is of the form:     By definition, every carbanion possesses an unshared pair of electrons and is therefore a base. When a carbanion accepts a proton, it is converted to its conjugate acid . The stability of a carbanion is directly related to the strength of its conjugate acid. The weaker the acid, the greater the base strength and the lower the stability of the carbanion - the greater the reactivity of the carbanion . Less stable carbanions tend to react rapidly with proton donors and hence exist as carbanions for short time. Carba

Liquid Chromatography Home > Analytical Chemistry > Liquid Chromatography LIQUID CHROMATOGRAPHY Basic Liquid Chromatography Advantages of Liquid Chromatography (LC) vs. Gas Chromatography (GC) Gradient Elution in Liquid Chromatography Identifying Compounds by LC/HPLC - Qualitative Analysis by LC / HPLC Ion-Exchange Chromatography (IEC) - Liquid Chromatography Separation Modes     Liquid Chromatography (LC): Columns in LC/HPLC – Bonded Phase Columns (C18) Liquid Chromatography / HPLC Separation Modes: Steric Exclusion Chromatograply (SEC) Liquid Chromatography: Column Theory, Chromatographic Resolution, Column Efficiency     Normal phase liquid chromatography (LC) / HPLC? Selection & Optimization of operating parameters in Liquid Chromatography (LC) Selection of the LC or HPLC