Weermann degradation mechanism of Hydroxy-Carbonsäureamide
At first the carbonic acid amide (1) reacts with the sodium hypochlorite. After the separation of water and chloride an amine with a free bond is built 2. The intermediate (3) is generated by rearrangement. In the next step a hydrolysis takes place. Water is added at the carbon-atom with the number '1'. A hydroxylic group is generated. The last step is that an acidic amide is separated and the aldehyde (4) is generated.
Degradation of α,β-unsaturated carbonic acid amides
Additionally the Weerman degradation could be executed with α,β-unsaturated carbonic acid amides. For example, acrylamide.
General reaction scheme
During the degradation of α,β-unsaturated amides, the carbon chain shortens about one carbon-atom, too.[2]
Weermann degradation general unsattuered carbonic acid amides
The reaction is very slow at room temperature, therefore the reaction mixture is heated up to 60–65 °C.
At first the carbonic acid amide (1) reacts with the sodium hypochlorite. After separate water and chloride an amine with a free bond is built 2. The intermediate (3) is generated by rearrangement. At this point two different mechanisms are possible. In the mechanism above two methanol molecules reacts with the intermediate. So is the compound (4) generated. After this carbon dioxide, water, ammonium and methanol are separated in different steps. At least it is protonated into an aldehyde (5).
Weermann degradation 2nd unsattuered
Until the intermediate (3) the mechanism is the same like above. Then only one methanol-atom is added 4. With a protonation water, methanol and carbon dioxide are separated. An ammonium ion (5) is generated. During the hydrolysis a hydroxylic group is built 6. An aldehyde (7) is generated by separating an ammonium ion.
Applications
One study demonstrated the direct oxidation of glucose to arabinose by the same sodium hypochlorite, skipping the aldonic acid and aldoamide steps.[4][5] For example, the general degradation of D-gluconamide into D-arabinose:
Sugar example
On top of that, the Weerman test could be used to show whether a hydroxylic group is beside the amido group. This reaction is only important in a historical sense because it is slow yielding and thus rarely used.
^Weerman, R. A. (3 September 2010). "Sur une synthèse d'aldéhydes et de l'indol". Recueil des Travaux Chimiques des Pays-Bas et de la Belgique. 29 (1–2): 18–21. doi:10.1002/recl.19100290104.
^ abcdeWang, Zerong (2009). Comprehensive organic name reactions and reagents. Hoboken, N.J.: John Wiley. pp. 2946–2950. ISBN978-0-471-70450-8.
^Arcus, C. L.; Greenwood, D. B. (1953). "398. The Hofmann reaction with α- and β-hydroxy-amides: reactions of the intermediate isocyanates". Journal of the Chemical Society (Resumed): 1937–1940. doi:10.1039/JR9530001937.
^editor, Martha Windholz, editor ; Susan Budavari, associate editor ; Lorraine Y. Stroumtsos, assistant editor ; Margaret Noether Fertig, assistant (1976). The Merck index : an encyclopedia of chemicals and drugs (9th ed.). Rahway, N.J.: Merck. pp. ONR-92. ISBN0-911910-26-3. {{cite book}}: |last1= has generic name (help)CS1 maint: multiple names: authors list (link)
^Weerman, R. A. (3 September 2010). "L'action de l'hypochlorite de sodium sur les amides d'α-hydroxy-acides et de polyhydroxy-acides, ayant un groupe hydroxyle à la place α. Nouvelle méthode de dégradation des sucres". Recueil des Travaux Chimiques des Pays-Bas et de la Belgique. 37 (1): 16–22. doi:10.1002/recl.19180370103.
