4-Vinylpyridine

4-Vinylpyridine (4-VP) is an organic compound with the formula CH2CHC5H4N. It is a derivative of pyridine with a vinyl group in the 4-position. It is a colorless liquid, although impure samples are often brown. It is a monomeric precursor to specialty polymers. 4-Vinylpyridine is prepared by the condensation of 4-methylpyridine and formaldehyde.

4-VP is sometimes used in biochemistry to alkylate protein cysteine residues. When compared to other alkylation agents, such as iodoacetamide, acrylamide, and N-ethylmaleimide, 4-VP is less reactive, meaning the completion rate of cysteine alkylation is lower, but it also yields fewer side reactions. For some uses, such as during mass spectrometry measurements, 4-VP might be better because it is basic and can thus be protonated, adding net charge.