CAS Registry Number

CAS 4635-59-0 — 4-Chlorobutyryl chloride

4-Chlorobutyryl chloride is an acyl chloride reagent widely used in organic synthesis for chlorination, acylation, and the preparation of pharmaceutical intermediates. It serves as a key building block in the manufacture of fine chemicals, agrochemicals, and specialty polymers. CAS 4635-59-0, a clear to pale yellow liquid with a pungent odor, boils at 178–180°C and has a density of ~1.2 g/cm³. It is miscible with organic solvents but reacts violently with water and alcohols. Purity is typically ≥97% by GC, with no signal word classification under GHS. Molekula supplies 4-Chlorobutyryl chloride from research to bulk quantities with full documentation and ISO 9001:2015 traceability.