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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.
One way to get around this is to turn the aldehyde into a silyl enol ether using trimethylsilyl chloride and a base, such as triethylamine, and then perform the aldol condensation. Here this tactic is employed in the condensation of acetaldehyde and benzaldehyde. A Lewis acid, such as TiCl 4, must be used in order to promote condensation. [4]
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 ...
In the classic example, benzaldehyde is converted to benzoin (PhCH(OH)C(O)Ph). [3] The benzoin condensation was first reported in 1832 by Justus von Liebig and Friedrich Wöhler during their research on bitter almond oil. [4] The catalytic version of the reaction involving cyanide was developed by Nikolay Zinin in the late 1830s. [5] [6 ...
An enantioselective aldol addition product can be obtained in asymmetric synthesis by reaction of benzaldehyde with nitromethane and the a catalyst system consisting of zinc triflate as a Lewis acid, diisopropylethylamine (DIPEA), and N-methylephedrine (NME) as and as a chiral ligand. [16] A diastereoselective variation of this reaction is ...
Benzaldehyde (C 6 H 5 CHO) is an organic compound consisting of a benzene ring with a formyl substituent. It is among the simplest aromatic aldehydes and one of the most industrially useful. It is a colorless liquid with a characteristic almond -like odor , and is commonly used in cherry -flavored sodas . [ 5 ]
Aldol condensation product; top right. Intramolecular aldol condensation is between two aldehyde groups or ketone groups in the same molecule. Five- or six-membered α, β-unsaturated ketone or aldehydes are formed as products. This reaction is an important approach to the formation of carbon-carbon bonds in organic molecules containing ring ...
Aldol condensation with either propionaldehyde or acetaldehyde, followed by hydrogenation, gives the fragrance compounds lilial and bourgeonal, respectively. References [ edit ]