The following sections of this BookRags Literature Study Guide is offprint from Gale's For Students Series: Presenting Analysis, Context, and Criticism on Commonly Studied Works: Introduction, Author Biography, Plot Summary, Characters, Themes, Style, Historical Context, Critical Overview, Criticism and Critical Essays, Media Adaptations, Topics for Further Study, Compare & Contrast, What Do I Read Next?, For Further Study, and Sources.
(c)1998-2002; (c)2002 by Gale. Gale is an imprint of The Gale Group, Inc., a division of Thomson Learning, Inc. Gale and Design and Thomson Learning are trademarks used herein under license.
The following sections, if they exist, are offprint from Beacham's Encyclopedia of Popular Fiction: "Social Concerns", "Thematic Overview", "Techniques", "Literary Precedents", "Key Questions", "Related Titles", "Adaptations", "Related Web Sites". (c)1994-2005, by Walton Beacham.
The following sections, if they exist, are offprint from Beacham's Guide to Literature for Young Adults: "About the Author", "Overview", "Setting", "Literary Qualities", "Social Sensitivity", "Topics for Discussion", "Ideas for Reports and Papers". (c)1994-2005, by Walton Beacham.
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Organolithiums are a type of organometallic compound in which the carbon of an organic group is directly bonded to a lithium atom. The term is also sometimes used for compounds in which a nitrogen or other non-metallic atom of an organic group is directly bonded to a lithium atom. Organolithiums are critical to the preparation of many important pharmaceuticals, agricultural compounds, and specialty organic chemicals.
Organolithiums were first identified in 1917 as products from the reaction of lithium metal and organomercury compounds. A simpler preparation discovered in 1930, reaction of an organic halide with lithium metal, made possible their current widespread use.
Organolithium-initiated polymerization of isoprene was discovered in 1957. When carried out in hydrocarbon solvent, this reaction produces a synthetic rubber similar to natural rubber. This discovery led to the first large scale application of organolithiums. They are now used in the preparation of polymers such as styrene-butadiene-styrene (SBS) rubber. SBS rubber is a common component of tire treads and rubber-soled shoes.
Organolithiums undergo similar chemical reactions to those of Grignard reagents, another important class of organometallic compounds. However, organolithiums are generally more reactive and hence more useful. Most organolithiums react vigorously with air and water. The more reactive burn spontaneously in air. To avoid such reactions, the compounds and their solutions must be handled under a protective atmosphere of nitrogen or argon.
Organolithiums have physical properties similar to organic compounds. Organolithiums made from nonconjugated hydrocarbons are colorless liquids or low-melting, white, crystalline solids. Compounds with conjugated hydrocarbon groups are often colored. Most organolithiums are soluble in hydrocarbon solvents, which are cheaper than the ether solvents required by Grignard reagents. Although commonly represented as monomers, organolithiums tend to form oligomers of two to six (or more) monomer units. The degree of association depends on the organic group, solvent, concentration, and temperature.