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An organolithium reagent is an organometallic compound with a direct bond between a carbon and a lithium atom. As the electropositive nature of lithium puts most of the charge density of the bond on the carbon atom, effectively creating a carbanion, organolithium compounds are extremely powerful bases and nucleophiles. An organometallic compound is partially characterized by the presence of one or more metal-carbon bonds, in which the carbon involved would, apart from the metal-carbon bond, be otherwise considered a part of an organic compound. ...
Covalently bonded hydrogen and carbon in a molecule of methane. ...
Charge density is the amount of electric charge per unit volume. ...
A carbanion is an anion in which carbon has an unshared pair of electrons and bears a negative charge usually with three substituents for a total of eight valence electrons. ...
A base is: in mathematics: A number that is raised to a power, or base of an exponential function. ...
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Production Organolithium reagents are industrially prepared by the reaction of an organohalogen with lithium metal, i.e. R-X + 2 Li → R-Li + LiX. A side reaction of this synthesis, especially with alkyl iodides, is the Wurtz reaction, in which an R-Li species reacts with an R-X species forming an R-R coupled product. This side reaction can be almost completely avoided by using alkyl chlorides or bromides. General Name, Symbol, Number lithium, Li, 3 Chemical series alkali metals Group, Period, Block 1, 2, s Appearance silvery white/gray Atomic mass 6. ...
The Wurzt reaction after Charles Adolphe Wurtz is a coupling reaction in organic chemistry and organometallic chemistry where by two alkyl halides are reacted with sodium: 2 R-X + Na → R-R + 2NaX This reaction involves the radical species R.. References A. Wurtz, Ann. ...
A second method is the reaction of an alkyl halide with a radical anion lithium salt, such as lithium naphthalide. These radical anions can be prepared by the reduction of an aromatic system with metallic lithium. As the reduction of alkyl halides is much faster with radical anions than it is with direct reaction with lithium metal, this reactions enables a number of more exotic organolithium compounds to be prepared. Radical is derived from the Latin word radix, which means root. In various fields of endeavor, it can mean: Sciences in chemistry, either an atom or molecule with at least one unpaired electron, or a group of atoms, charged or uncharged, that act as a single entity in reaction. ...
An anion is an ion with negative charge. ...
A third method involves the metal-halogen exchange between an organic halide compound and an organolithium species. As this is an equilibrium reaction, the equilibrium lies towards the most electronegative organometallic compound, which stabilizes the carbanion the best. This method is usually used with halide compounds that are generally unreactive towards metallic lithium, such as aryl-, vinyl- and ethynyl halides. The only prerequisite is the halide compound is substantially more electronegative than butyllithium. Chemical equilibrium is the state in which a chemical reaction proceeds at the same rate as its reverse reaction; the rates of the forward and reverse reactions are equal, and the concentration of the reactants and products stop changing. ...
A fourth method is another exchange, this time between an organolithium compound and another organometallic compound. This is again an equilibrium reaction, where the most electropositive metal (lithium) will end up attached to the most electronegative organic group. An example is the synthesis of vinyllithium out of tetravinyltin and phenyllithium. Vinyllithium is very difficult to prepare with other methods.
A fifth method is the deprotonation of organic compound with an organolithium species. This is comparable to a common acid-base reaction. An acid-base reaction is a chemical reaction between an acid and a base. ...
Reactivity and uses Organolithium compounds are strongly polarised by the electropositive character of lithium. They are therefore highly reactive nucleophiles and react with almost all types of electrophiles. They are comparable to Grignard reagents, but are much more reactive. Due to this reactivity they are incompatible with water, oxygen, and carbon dioxide, and must be handled under a protective atmosphere, preferably argon. In chemistry, a nucleophile (literally nucleus lover) is a reagent which is attracted to centres of positive charge. ...
In chemistry, an electrophile (literally electron-lover) is a reagent attracted to electrons that participates in a chemical reaction by accepting an electron pair in order to bond to a nucleophile. ...
A Grignard Reagent is an alkyl- or aryl- magnesium halide. ...
Water (from the Old English word wæter; c. ...
General Name, Symbol, Number oxygen, O, 8 Chemical series Chalcogens Group, Period, Block 16, 2, p Appearance colorless Atomic mass 15. ...
Carbon dioxide is an atmospheric gas comprised of one carbon and two oxygen atoms. ...
General Name, Symbol, Number argon, Ar, 18 Chemical series noble gases Group, Period, Block 18, 3, p Appearance colorless Atomic mass 39. ...
The main use of organolithium compounds is as a very strong base. Organolithium compounds can deprotonate almost all hydrogen-containing compounds, with the exception of alkanes. They are mainly used to synthesize other organolithium compounds. A deprotonation is complete if the acidic compound is 2 pKA units stronger than the lithium species.
Due to the extreme basicity of organolithium compounds, they are not commonly used for nucleophilic addition reactions, even though this can be a side reaction when using n-butyllithium. Grignard reagents are an alternative in addition reactions, with less problems with deprotonation. A Grignard Reagent is an alkyl- or aryl- magnesium halide. ...
The most commonly used organolithium reagents are methyllithium, n-butyllithium, and t-butyllithium. As alkyl groups are weakly electron donating, the instability of the organolithium compound increases with the number of alkyl substituents on the charge-bearing carbon atom. This makes t-butyllithium, or tert-butyllithium, the single strongest base that is commercially available, with a pKa greater than 85. An organolithium reagent is a carbon nucleophile similar to a Grignard reagent. ...
An acid-base reaction is a chemical reaction between an acid and a base. ...
In chemistry and biochemistry, acid dissociation constant, the acidity constant, or the acid-ionization constant () is a specific type of equilibrium constant that indicates the extent of dissociation of hydrogen ions from an acid. ...
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