CH3CH2CH2CH2

CH3CH2CH2CH2 is the n-butyl group, a four-carbon straight-chain alkyl substituent derived from butane by removing one hydrogen from the terminal carbon. When attached to a parent molecule, the group is commonly written as -CH2-CH2-CH2-CH3, indicating the point of attachment at the end of the chain. The substituent has the systematic name butan-1-yl and a formula of C4H9.

In chemical nomenclature, CH3CH2CH2CH2- specifically denotes the primary, linear n-butyl substituent. It is one of several possible C4H9 substituents, as butane can yield other isomeric groups such as sec-butyl (butan-2-yl), isobutyl (2-methylpropyl), and tert-butyl (2-methylprop-2-yl).

Applications of the n-butyl group appear across organic synthesis and materials chemistry. It serves as a building block for larger molecules, a leaving or protecting group in reactions, and is present in various esters and ethers. In polymer science, butyl-containing monomers such as n-butyl acrylate are used to tailor properties like hydrophobicity and flexibility in polymers and coatings.

Conceptually, CH3CH2CH2CH2- represents a hydrocarbon-derived substituent with relatively low polarity and notable hydrophobic character. Handling considerations align with other hydrocarbon fragments: flammability and vapor pressure require standard laboratory safety practices and appropriate storage. The term “butyl” reflects the broader family name derived from butane.