C4H5

C4H5 is a molecular formula that can represent several different chemical compounds, all of which contain four carbon atoms and five hydrogen atoms. These compounds are unsaturated hydrocarbons, meaning they contain at least one carbon-carbon double or triple bond. The presence of these multiple bonds accounts for the lower hydrogen-to-carbon ratio compared to a saturated alkane like butane (C4H10).

One common isomer with the formula C4H5 is but-1-yne, also known as 1-butyne. This molecule is an alkyne, characterized by a carbon-carbon triple bond at the first position. Another isomer is but-2-yne, or 2-butyne, where the triple bond is located between the second and third carbon atoms. Both but-1-yne and but-2-yne are gases at room temperature and have distinct chemical properties due to the reactivity of the triple bond.

Other C4H5 isomers exist, including various cyclic compounds and alkenes with a more complex arrangement of double bonds. For instance, cyclobutyne, a strained cyclic alkyne, would also fit this formula, though it is highly unstable. The specific arrangement of atoms, or isomerism, dictates the physical and chemical behavior of the molecule, including its boiling point, melting point, and reactivity in chemical reactions. Identifying the exact isomer requires further structural information beyond just the molecular formula.