Дибензилиденацетон

Description

Dibenzylidene acetone (DBA, distyryl ketone) is an unsaturated diketone, a product of the double croton condensation of benzaldehyde with acetone. Belongs to the class of chalcone-like diaryl ketones with a conjugated system of two styryl fragments. The main industrial role of the substance is as a precursor ligand for palladium(0) complexes, primarily Pd2(dba)3 and Pd(dba)2, widely used in cross-couplings (Suzuki, Heck, Buchwald-Hartwig).

Basic Attributes

• CAS No.: 538-58-9
• Chemical formula: C17H14O
• Molecular weight: 234.29
• Exact weight: 234.29
• EU number: 609-096-4
• UNII: N4SH2VDI6Y
• NSC number: 117234/8103
• DSSTox ID: DTXSID0060224
• PSA specifications: 17.1
• XLogP3: 4.1

Physico-chemical characteristics

• Appearance: yellow powder
• Density: 1.1 g/cm3
• Melting point: 113 °C (with decomposition)
• Boiling point: 400.7 °C at 760 mm Hg. Art.
• Flash point: 176.2 °C
• Refractive index: 1.649
• Storage conditions: 0–6 °C
• Stability: stable under normal conditions, incompatible with strong oxidizing agents, flammable

Scope of application

The main area is metal complex catalysis: dibenzylideneacetone serves as a ligand in the synthesis of Pd2(dba)3 and Pd(dba)2, catalysts for cross-coupling reactions in fine organic synthesis and pharmaceutical chemistry. In addition to catalysis, the substance is used as a component of UV filters and sensitizers in photochemistry, a hardener and modifier in compositions based on epoxy resins, and also in pyrotechnics as a component of whistling compositions.

Safety Information

• WGK Germany: 3
• Safety instructions: S22-S24/25
• Hazard Statements: H315 (causes skin irritation)
• Precautions: P261, P264, P271, P280, P302+P352, P304+P340, P305+P351+P338, P312, P321, P332+P313, P337+P313, P362, P403+P233, P405, P501

Storage and transportation conditions

Store at 0–6 °C in a tightly closed container, in a cool, dry place, away from strong oxidizing agents. The substance is flammable, so contact with open flames and sources of sparks is prohibited. When working, use gloves and safety glasses, avoid the formation of dust. Transport in packaging that prevents heating above the melting point and moisture ingress.

Features of the synthesis of catalytic complexes

When dibenzylideneacetone reacts with palladium(II) salts in the presence of a reducing agent, a trimeric complex Pd2(dba)3 is formed, in which two palladium(0) atoms are stabilized by three ligand molecules through coordination along alkene fragments. Such a complex serves as a convenient source of “ligand-free” palladium(0), which is easily released by adding phosphine or N-heterocyclic carbene ligands directly into the reaction mixture, which simplifies the selection of a catalytic system for a specific cross-coupling reaction without prior synthesis of the target catalyst.

The technical delivery conditions provide for monitoring the content of the main substance by high-performance liquid chromatography, since the presence of monocondensation products significantly reduces the yield of the target palladium complexes during the subsequent synthesis of the catalyst.