But-2-enoyl Chloride , Crotonoyl Chloride

But-2-enoyl chloride,also known as crotonoyl chloride,is a clear,colorless to pale yellow liquid with a pungent odor.It boils at 120–123°C at atmospheric pressure and has a density of 1.091 g/mL at 25°C.The refractive index is 1.459,and its flash point is 95°F(35°C),classifying it as a flammable liquid.It is recommended to store it below+30°C.This acid chloride is highly reactive with water and alcohols,undergoing vigorous hydrolysis or esterification.It must be handled under anhydrous conditions in a well-ventilated area,away from open flames and moisture.

But-2-enoyl chloride(CAS No.10487-71-5)is an unsaturated acid chloride,specifically the acyl chloride derivative of crotonic acid.The presence of theα,β-unsaturated carbonyl system(conjugated with a carbon-carbon double bond)makes it a valuable Michael acceptor and a highly reactive acylating agent in organic synthesis.

1.Acylating Agent for Friedel-Crafts Reactions
Used to introduce the crotonoyl group into electron-rich arenes via Friedel-Crafts acylation.The resulting aryl ketones are key intermediates for synthesizing chalcones and other flavonoids with potential biological activity.

2.Monomer for Functional Polymer Synthesis
Undergoes radical polymerization or copolymerization with styrene to yield polymers with pendant unsaturated ketone groups.These reactive side chains can be further modified via thiol-ene"click"chemistry to create cross-linked hydrogels for controlled drug release.

3.Precursor for Heterocyclic Synthesis
Reacts with nucleophilic dinucleophiles like hydrazines or amidines to directly form five-and six-membered nitrogen heterocycles(e.g.,pyrazoles,pyrimidines)in a single step,streamlining the synthesis of agrochemical and pharmaceutical scaffolds.

4.Surface Modifier for Nanoparticles
Employed to functionalize the surface of hydroxylated silica or iron oxide nanoparticles.The acid chloride group reacts with surface-OH groups,covalently attaching the unsaturated chain,which can later be used to graft polymer brushes via surface-initiated polymerization.