1 / 6

MANNICH REACTION

MANNICH REACTION. ketone. formaldehyde. excess. . pH 6-8. -. Cl. -. . iminium salt. A variety of R groups may be used. Mannich Base “Schiff’s Base”. Aldehydes other than formaldehyde may be used. The reaction works best with methyl ketones.

shing
Download Presentation

MANNICH REACTION

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. MANNICH REACTION ketone formaldehyde excess .. pH 6-8 - Cl - .. iminium salt A variety of R groups may be used Mannich Base “Schiff’s Base” Aldehydes other than formaldehyde may be used. The reaction works best with methyl ketones. Et2NH - HCl is generally used in excess, hence the chloride counter ion. Other secondary amines sometimes work in place of diethylamine.

  2. Activated phenols will also give a reaction similar to the Mannich Condensation. + + - .. Mannich Base resonance structures AROMATIC SUBSTITUTION + This is essentially an electrophilic aromatic substitution reaction – a hydrogen on the ring is replaced by the Mannich Base which is an electrophile. Phenols with activating substituents (methoxy, hydroxy, amino) can give this reaction.

  3. + : : _ .. + .. HNEt2 Mannich Base B: H+

  4. PICTET-SPENGLER REACTION condensation occurs at biological pH values H3O+/D + a tetrahydroisoquinoline ring Mannich Base if cyclization does not occur sponttaneously This is a general method for the synthesis of tetrahydroisoquinoline rings.

  5. BISCHLER-NAPIERALSKI REACTION amide H3PO4 or P2O5 via - H2O synthesis of the initial amide Intermediate loses water Synthesis of a dihydroisoquinoline An acid anhydride may be used instead of an acid chloride to synthesize the amide.

  6. ester-amide (urethane) .. .. H3PO4 or P2O5 H+ H+ ethyl chloroformate synthesis of the initial urethane

More Related