Toluene → 3-Amino-4-n-butoxy-3-cyclobutene-1,2-dione

Preparation C: In a 5-Liter flask equipped with stirrer and nitrogen inlet/outlet tubes was placed 1,2-dihydroxy-1-cyclobutene-3,4-dione (400.0 g, 3.506 moles), 1-butanol (1.2 L) and toluene (800 mL). The mixture was stirred and heated under reflux with a Dean-Stark water trap until water stopped passing over (136 mL water collected, about 5.5 hours). The clear reaction mixture was heated under reflux for a further one hour, then cooled under nitrogen to 0°-5° C. The cooled stirred solution was treated dropwise at such a rate that the reaction remains at or below 10° C. (2.5 hours required) with a solution containing 14M ammonium hydroxide (240 mL, 3.37 moles), 1-butanol (960 mL) and methanol (40 mL). Stirring was continued at ambient temperature for 2 hours, then the mixture was cooled to 0°-5° C. for 1.5 hours and filtered. The product was washed with toluene (800 mL) and dried to give 492.4 g (88.0%) of the title compound; mp=165°-168° C.

1. customPreparation C
2. customIn a 5-Liter flask equipped with stirrer and nitrogen inlet/outlet tubes
3. temperatureheated
4. customstopped passing over (136 mL water collected, about 5.5 hours)
5. temperatureThe clear reaction mixture was heated
6. temperatureunder reflux for a further one hour
7. temperaturecooled under nitrogen to 0°-5° C
8. stirringThe cooled stirred solution
9. additionwas treated dropwise at such a rate that the reaction
10. custombelow 10° C. (2.5 hours required)
11. stirringStirring
12. temperaturethe mixture was cooled to 0°-5° C. for 1.5 hours
13. filtrationfiltered
14. washThe product was washed with toluene (800 mL)
15. customdried

ORD record

ord-340c66a836ec4a27ab25b3d23a0bd156

Source dataset

uspto-grants-1990_05

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US04927968