Formaldehyde → Dihydrobenzoxazine

Temperatur

30 °C

To a suitably equipped glass resin reactor equipped with stirrer is charged 450 parts phenol, 450 parts toluene and 595 parts of 50% formalin. A uniform toluene-water dispersion is maintained with agitation. The temperature of the reaction mixture is adjusted to 25° C. and maintained below 30° C. while 144 parts of ethylene diamine are added slowly. The reaction mixture is stirred for 2 hours at 30° C. after the amine addition is complete. The reaction mixture is heated to 46° C. under reduced pressure and refluxed for 3 hours. After 3 hours the distillate is passed through an oil water separator in the distillate return line. The toluene is continuously returned to the reactor while the water is removed. Azeotropic water removal is continued while the batch temperature is increased to 69° C. and the pressure is gradually reduced to about 5.0 kPa. The reaction mixture is essentially water free. It is cooled while 150 parts of 2-butoxyethanol are added and mixed in. The clear pale yellow solution is filtered. The product had the following composition and properties: Percent closed dihydrobenzoxazine 66%; equivalent wt. 224; solids 55.2%; Brookfield viscosity 12 cps @25° C.

1. customTo a suitably equipped glass resin reactor equipped with stirrer
2. customis adjusted to 25° C.
3. additionare added slowly
4. temperatureThe reaction mixture is heated to 46° C. under reduced pressure
5. temperaturerefluxed for 3 hours
6. customis removed
7. customAzeotropic water removal
8. temperatureis increased to 69° C.
9. temperatureIt is cooled while 150 parts of 2-butoxyethanol
10. additionare added
11. additionmixed in
12. filtrationThe clear pale yellow solution is filtered
13. customPercent closed dihydrobenzoxazine 66%
14. custom25° C.

ORD-Eintrag

ord-8290867759304b4283dc21f6519606f7

Quelldatensatz

uspto-grants-1985_02

DOI

10.6084/m9.figshare.5104873.v1

Patentnummer

US04501864