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The mechanism for base-catalyzed aldol condensation can be seen in the image below. A mechanism for aldol condensation in basic conditions, which occurs via enolate intermediates and E1CB elimination. The process begins when a free hydroxide (strong base) strips the highly acidic proton at the alpha carbon of the aldehyde.
After which it may undergo dehydration to give a unsaturated carbonyl compound, the aldol condensation product. The scheme shows a simple mechanism for the base-catalyzed aldol reaction of an aldehyde with itself. Base-catalyzed aldol reaction. Simple mechanism for base-catalyzed aldol reaction of an aldehyde with itself. Base-catalyzed dehydration
In its simplest implementation, base induces conversion of an aldehyde or a ketone to the aldol product. One example involves the aldol condensation of propionaldehyde: 2 CH 3 CH 2 CHO → CH 3 CH 2 CH(OH)CH(CH 3)CHO. Featuring the RCH(OH)CHR'C(O)R" grouping, the product is an aldol. In this case . Such reactions are called aldol aldol ...
The Perkin reaction is an organic reaction developed by English chemist William Henry Perkin in 1868 that is used to make cinnamic acids.It gives an α,β-unsaturated aromatic acid or α-substituted β-aryl acrylic acid by the aldol condensation of an aromatic aldehyde and an acid anhydride, in the presence of an alkali salt of the acid.
Similar to many other organic bases, DBN could be employed for dehydrohalogenation reactions, base-catalyzed rearrangement reactions, as well as Aldol condensation. [3] Several examples are shown below: Elimination: [2] Epimerization of penicillin derivatives, catalyzed by DBN: [4] Aldol condensation: [5]
Robinson annulation is one notable example of a wider class of chemical transformations termed Tandem Michael-aldol reactions, that sequentially combine Michael addition and aldol reaction into a single reaction. As is the case with Robinson annulation, Michael addition usually happens first to tether the two reactants together, then aldol ...
Many variations of condensation reactions exist. Common examples include the aldol condensation and the Knoevenagel condensation, which both form water as a by-product, as well as the Claisen condensation and the Dieckman condensation (intramolecular Claisen condensation), which form alcohols as by-products. [5]
The Hajos–Parrish–Eder–Sauer–Wiechert and Barbas-List [1] reactions in organic chemistry are a family of proline-catalysed asymmetric aldol reactions.. In the 1970s, two research groups discovered (and published) almost simultaneously their discoveries of two related intramolecular reactions: Zoltan Hajos and David Parrish at Hoffmann-La Roche [2] [3] and Rudolf Wiechert et al at ...