Reaktion #493133

Reaktionsgleichung

triethylamine

Malononitrile

3-mercapto-2-butanone

→

2-amino-4,5-dimethylthiophene-3-carbonitrile

Ausbeute 64.2%

Lösungsmittel

Ethanol

ethanol

Ethanol

Reaktionsbedingungen

Aufarbeitung

1. 1
   Sonstigefitted with torian and transfer tubing
2. 2
   Waschenrinse
3. 3
   workup.ADDITIONthe 3-mercaptobutanone solution is added over 1.3 hrs at −1 to −5° C
4. 4
   workup.WAITAfter an hour
5. 5
   EinengenThe reaction is concentrated on the rotovap (40° C. bath) to a slurry of approximately 2.5 L and 3.0 L of heptanes
6. 6
   workup.ADDITIONare added
7. 7
   TemperaturThe slurry is cooled to 5° C. for 30 minutes
8. 8
   Filtrationthe solids collected by filtration
9. 9
   WaschenThe solids are rinsed with 2.5 L of 20% Ethanol in heptanes in 7 portions
10. 10
    SonstigeThe excess solvent is removed on the filter
11. 11
    Sonstigethe wet cake dried in a vacuum oven overnight at 40° C.

Vorschrift

A solution of 3-mercapto-2-butanone (1.00 kg, 9.0 mole, 93.6% assay) in 2.0 L SDA 3C 200 Proof, absolute Ethanol (Ethanol) is prepared in a 5 L 1N RBF fitted with torian and transfer tubing. Malononitrile (588.8 g, 8.9 mole) is dissolved in 5.0 L Ethanol and cooled to 4° C. at which point triethylamine (250 mL, 1.8 mole, 0.2 eq) is added with a 560 mL ethanol rinse. The anionic malononitrile solution is cooled to −2° C. and the 3-mercaptobutanone solution is added over 1.3 hrs at −1 to −5° C. After an hour, the reaction shows less than 0.1% malononitrile. The reaction is concentrated on the rotovap (40° C. bath) to a slurry of approximately 2.5 L and 3.0 L of heptanes are added. The slurry is cooled to 5° C. for 30 minutes and the solids collected by filtration. The solids are rinsed with 2.5 L of 20% Ethanol in heptanes in 7 portions. The excess solvent is removed on the filter, and the wet cake dried in a vacuum oven overnight at 40° C. and full vacuum to give an off white solid as 2-amino-4,5-dimethylthiophene-3-carbonitrile (870 g, 64.1% yield, 99.7% purity shown by HPLC). The filtrates are reconcentrated to an oily slurry which is filtered and rinsed with 0.5 L of 20% Ethanol in heptanes. The second crop of solids is dried separately (47 g, 3.5% yield, 98.6% purity shown by HPLC). NMR (400 MHz, DMSO-d6) δ 1.93 (d, J=1.2 Hz, 3H), 2.07 (d, J=1.2 Hz, 3H), 3.33 (s, 2H). MS 153 (MH+). HPLC Retention Time: approximately 10.9 minute (Phenomenex Luna C18 (2) column, acetonitrile/water with 0.1% AcOH).

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