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.
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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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The methyl group is the alkyl group with the chemical formula -CH3. The methyl group is sometimes abbreviated to -Me. The methyl group is derived from methane, CH4. The methyl group, along with other alkyl groups is a modifier of the behavior of the functional group of the molecule in which it occurs. Characteristics such as melting point and boiling point generally increase with an increase in molecular mass. A methyl group has a low molecular mass and as such it has a minimal effect on the properties of other molecules of which it is attached to. To illustrate this point: if we consider the boiling points of the first three members of the carboxylic acid homologous series. Methanoic, or formic, acid (HCOOH) has a boiling point of 212oF (100oC), ethanoic, or acetic, acid (CH3COOH) has a boiling point of 244oF (118oC), and propanoic acid (CH3CH2COOH) has a boiling point of 286o F (141oC).
The methyl carbocation, CH3+ is the least stable carbocation.
The addition of a methyl group to a compound is known as methylation. In aliphatic chemistry this is carried out as a substitution of a hydrogen atom in a group. In aromatic chemistry it may involve the substitution of one of the hydrogen atoms in the ring structure, this can be carried out using the Friedel-Crafts reaction.
Methylation is an important reaction in biology. DNA methylation, for example, is an important method for the regulation of gene transcription. Disorders in these methylation pathways, especially relating to the two vitamins (folic acid and S-adenosylmethionine) are associated with human disease. Inadequate dietary folic acid during pregnancy, for example, may increase the risk of birth defects.