Benzaldehyde → Benzylidene-hydrazine

Temperature

0 °C

A 1 L flask equipped with a mechanical stirrer, thermometer, and addition funnel was charged with 250 mL of methanol and cooled to 0° C. Barium oxide (9.8 g, 64 mmol) was added portion-wise with exotherm. The reaction was cooled to 0° C., and hydrazine monohydrate (64.1 g, 1.28 mol) was slowly added. The reaction mixture was stirred for 10 minutes, after which time benzaldehyde (135.8 g, 1.28 mol) was added drop-wise over a 30 minute period. The reaction was then stirred for 1 hour, while maintaining a temperature below 8° C. 1H NMR indicated the absence of ketone and a complete reaction. Ether (200 mL) was added, and the BaO was filtered through a bed of silica gel. The resultant clear filtrate was liberated of methanol on a rotary evaporator at or below room temperature. A large mass of bright yellow solid azine (1H-NMR (300 MHz, CDCl3)δ(ppm): 8.67 (s, 2H), 7.85 (m, 4H), 7.47 (m, 6H)), was removed by filtration, and the filtrate was distilled to provide ca. 12 g of distillate benzylidene-hydrazine. The material was stored under refrigeration. 1H-NMR (300 MHz, CDCl3)δ(ppm): 7.74 (s, 1H), 7.53 (m, 2H), 7.35 (m, 3H), 5.5 (br, 2H).

1. customA 1 L flask equipped with a mechanical stirrer
2. additionthermometer, and addition funnel
3. temperatureThe reaction was cooled to 0° C.
4. stirringThe reaction was then stirred for 1 hour
5. temperaturewhile maintaining a temperature below 8° C
6. customa complete reaction
7. filtrationthe BaO was filtered through a bed of silica gel
8. customThe resultant clear filtrate was liberated of methanol on a rotary evaporator at or below room temperature
9. customA large mass of bright yellow solid azine (1H-NMR (300 MHz, CDCl3)δ(ppm): 8.67 (s, 2H), 7.85 (m, 4H), 7.47 (m, 6H)), was removed by filtration
10. distillationthe filtrate was distilled

ORD record

ord-d3f913c977f74a5eb769d9490399ffb5

Source dataset

uspto-grants-2007_12

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07304162B2