Reaction Scale Calculator

Switch reaction

Press / to jump here from anywhere. Type to search all 3374 reactions.

Claisen-Schmidt aldol: benzaldehyde + acetone → benzalacetone

Ph–CHO + CH3–C(=O)–CH3 → Ph–CH=CH–C(=O)–CH3 + H2O

Textbook aldol condensation. Acetone's α-carbon (deprotonated by aqueous NaOH) attacks benzaldehyde, then β-elimination dehydrates the aldol intermediate to give the E-enone benzalacetone (4-phenyl-3-buten-2-one). The 5-fold acetone excess is a kinetic control measure — without it, double-condensation to dibenzylideneacetone (DBA) competes.

Conditions: Dissolve NaOH (0.2 equiv) in 95 % EtOH/H2O (~3 mL per mmol benzaldehyde). Cool to 0–10 °C in an ice bath. Add benzaldehyde (1.0 equiv) followed by acetone (5.0 equiv) over 5 min with stirring. Warm to RT and stir 2–4 h until pale-yellow solid crystallises. Filter; wash crystals with cold water; recrystallise from ethanol. Yellow needles, mp 41–42 °C. Quench excess base with dilute HCl if filtrate is needed for analysis.

Expected yield

70–85 %

Expected duration

2–4 h at RT after 0–10 °C addition

Mechanism reference ↗