Methylene group

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Methylene group refers to a specific grouping of atoms within organic chemistry consisting of one carbon atom bonded to two hydrogen atoms. This group is represented by the formula =CH2, where the carbon atom is double bonded to another carbon atom, making it a fundamental building block in the structure of many organic compounds. The methylene group plays a crucial role in the chemistry of hydrocarbons, polymers, and various other organic molecules.

Structure and Bonding

The methylene group features a carbon atom double bonded to two hydrogen atoms. This configuration gives the group a linear shape, with bond angles close to 120 degrees, characteristic of sp2 hybridization. In organic compounds, the methylene group can act as a bridge connecting two other carbon atoms, or it can be a terminal group, affecting the compound's physical and chemical properties.

Reactivity

Due to its double bond, the methylene group is highly reactive. It can undergo addition reactions, where the double bond is broken, and new atoms or groups are added to the carbon. This reactivity is exploited in various chemical syntheses, such as hydrogenation, halogenation, and hydroxylation, to modify or build complex organic molecules.

Occurrence

Methylene groups are ubiquitous in organic chemistry. They are found in simple molecules, like ethylene (ethene), as well as in complex molecules such as vitamins, hormones, and polymers. In biological systems, methylene groups are part of fatty acids, amino acids, and the backbone of DNA and RNA, underscoring their importance in life's molecular foundation.

Importance in Organic Synthesis

In organic synthesis, the methylene group is a pivotal intermediate. It can be introduced into molecules through various reactions, including the Wittig reaction, which is widely used to construct carbon-carbon double bonds. The versatility of the methylene group allows chemists to build a wide array of organic compounds, from simple hydrocarbons to complex molecules like pharmaceuticals and polymers.

Environmental Impact

Methylene groups, particularly when present in volatile organic compounds (VOCs), can have environmental and health impacts. Compounds containing methylene groups can contribute to air pollution, forming ground-level ozone and participating in chemical reactions that lead to the production of secondary pollutants.

See Also

• Organic chemistry
• Hydrocarbon
• Polymer
• Wittig reaction