1,4-Dibromobenzene → 3,3'-[1,4-Phenylenebis(oxy)]dianiline

Temperature

117 °C

A 250 mL, 3-necked, round bottom flask fitted with a mechanical stirrer, a still head, a condenser with a nitrogen inlet on the take-off adapter, and a thermometer was charged with 150 mL of pyridine and 21.8 g (0.20 mole) of m-aminophenol. After the m-aminophenol dissolved, 10.8 g (0.20 mole) of sodium methoxide was added. Methanol, formed in this reaction, was distilled off. When the still head temperature reached 110° C., the still head was replaced with a reflux condenser, and 23.6 g (0.10 mole) of p-dibromobenzene and 0.1 g of cuprous chloride were added. The mixture was heated at reflux at 117° C. for 3 hours; 25 mL of DMAc was added to help dissolve sodium m-aminophenoxide formed in the first step. Refluxing was continued for 19 additional hours; the reaction mixture was then cooled to room temperature, filtered to remove inorganic salts, and poured into water. The resulting aqueous solution was extracted with three 300 mL portions of methylene chloride; the extract was dried over magnesium sulfate, decolorized with active carbon, and filtered through diatomaceous earth. Methylene chloride was vacuum-evaporated, and the liquid residue was poured into stirred concentrated hydrochloric acid. The precipitated dihydrochloride of 1,4-bis(3-aminophenoxy)benzene was filtered, washed with concentrated hydrochloric acid, and dried. It then was dissolved in a minimum amount of water containing a small amout of ascorbic acid as antioxidant. The solution was decolorized with activated carbon, filtered through diatomaceous earth, and neutralized with concentrated ammonium hydroxide. The precipitated product was separated by filtration and vacuum-dried overnight at 65° C. The dry diamine weighed 12.4 g (42% yield). Recrystallization from 35 mL of butanol gave 8.6 g of product melting at 98°-99° C., which was distilled bulb-to-bulb to give 6.5 g of colorless 1,4-bis(3,5-aminophenoxy)benzene melting at 99°-100° C.

1. customA 250 mL, 3-necked, round bottom flask fitted with a mechanical stirrer
2. distillationwas distilled off
3. customreached 110° C.
4. customthe still head was replaced with a reflux condenser
5. temperatureThe mixture was heated
6. customformed in the first step
7. temperatureRefluxing
8. temperaturethe reaction mixture was then cooled to room temperature
9. filtrationfiltered
10. customto remove inorganic salts
11. additionpoured into water
12. extractionThe resulting aqueous solution was extracted with three 300 mL portions of methylene chloride
13. dry with materialthe extract was dried over magnesium sulfate
14. filtrationfiltered through diatomaceous earth
15. customMethylene chloride was vacuum-evaporated
16. additionthe liquid residue was poured
17. filtrationThe precipitated dihydrochloride of 1,4-bis(3-aminophenoxy)benzene was filtered
18. washwashed with concentrated hydrochloric acid
19. customdried
20. dissolutionIt then was dissolved in a minimum amount of water containing a small amout of ascorbic acid as antioxidant
21. filtrationfiltered through diatomaceous earth
22. customThe precipitated product was separated by filtration
23. customvacuum-dried overnight at 65° C
24. customRecrystallization from 35 mL of butanol

ORD record

ord-ab9ee9260f1a429d96661568c10105ad

Source dataset

uspto-grants-1984_11

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US04485140