Phthalic Acid → 2-Isopropylamino-4-methylbenzonitrile

Temperature

55 °C

To a stirred mixture of 264 g. of 2-amino-4methylbenzonitrile, 504 g. of phthalic acid and 2.32 liters of reagent grade acetone is added 80 g. of sodium borohydride portionwise over 40 minutes at a temperature of 18°-30° C. The resulting solution is stirred for 30 minutes during which the temperature rises from 29°-30° C. to 35° C. and then dropped to 34° C. The resulting solution is then heated from 34° C. to 53° C. over a period of 30 minutes and their maintained at 55° C. for one hour. The mixture is cooled to 37° C., 500 ml. of water added followed by addition of 417 g. of 50% aqueous sodium hydroxide, after which the temperature is allowed to rise to 56° C. to maintain the solution. An additional 92 ml. of water is added and the acetone and aqueous salt layers separated at 45°-50° C. The acetone layer is concentrated in vacuo to obtain a brown oil and salt solution which is diluted with 800 ml. of heptane and the aqueous and heptane layers separated. The heptane layer is dried, filtered and cooled to 10° C. to obtain the major portion of the desired 2-isopropylamino-4-methylbenzonitrile, m.p. 55°-57° C. Additional product is also recovered from the mother liquor and phthalic acid is recovered to a high degree from aqueous salt layer above referred after dilution with a total of 4.5 liters of water, filtering and acidifying with sulfuric acid (other aqueous alkaline solutions obtained in the work up being combined with said aqueous salt layer).

1. additionTo a stirred mixture of 264 g
2. customrises from 29°-30° C. to 35° C.
3. additiondropped to 34° C
4. temperatureThe resulting solution is then heated from 34° C. to 53° C. over a period of 30 minutes
5. temperatureThe mixture is cooled to 37° C.
6. additionfollowed by addition of 417 g
7. customto rise to 56° C.
8. temperatureto maintain the solution
9. customthe acetone and aqueous salt layers separated at 45°-50° C
10. concentrationThe acetone layer is concentrated in vacuo
11. customto obtain a brown oil and salt solution which
12. additionis diluted with 800 ml
13. customof heptane and the aqueous and heptane layers separated
14. dry with materialThe heptane layer is dried
15. filtrationfiltered
16. temperaturecooled to 10° C.

ORD record

ord-8b26a3966c76447eb835a8b10722f15b

Source dataset

uspto-grants-1987_06

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US04670600