Reaktion #335849

Reaktionsgleichung

tetrahydrofuran

isoprene

butadiene

isoprene

butadiene

Butyl lithium

acetic acid

isoprene

butadiene

→

Isoprene Butadiene Isoprene

Lösungsmittel

cyclohexane

water

cyclohexane

Reaktionsbedingungen

Aufarbeitung

1. 1
   Sonstige1500 grams of purified
2. 2
   workup.ADDITIONdried cyclohexane (99.5%, Phillips Petroleum) were introduced into a one gallon
3. 3
   SonstigeThe reactor was equipped with a stirrer
4. 4
   Temperaturpressure gauge, thermocouple, top surface inlet, dip tube feeder with valve, variably controlled heater and heat exchange coil
5. 5
   Sonstigedid not exceed 60° C
6. 6
   SonstigeOne hour
7. 7
   workup.WAITAfter one hour
8. 8
   Temperaturthe reaction mixture was cooled
9. 9
   Sonstigedischarged into a vessel
10. 10
    Sonstigeto quench the
11. 11
    FiltrationThe mixture was filtered through alumina/Celite
12. 12
    workup.ADDITIONan anti-oxidant (100 ppm based on dry polymer) was added
13. 13
    Sonstigethe solvent was removed under reduced pressure
14. 14
    Sonstigeto yield a triblock polymer of about 8200 molecular weight as a clear, colorless, viscous fluid

Vorschrift

1500 grams of purified, dried cyclohexane (99.5%, Phillips Petroleum) were introduced into a one gallon stirred stainless steel reactor. The reactor was equipped with a stirrer, pressure gauge, thermocouple, top surface inlet, dip tube feeder with valve, variably controlled heater and heat exchange coil. Following the addition of the solvent, 50 ml (0.614 mol) of tetrahydrofuran freshly distilled from benzophenone ketyl, 43.3 ml (0.433 mol) of purified isoprene and an additional 80 g of cyclohexane were pressured into the reactor. The temperature of the reactor and its contents was raised to 50° C. Butyl lithium (61.2 ml of 1.5M solution, 91.8 mmol) was pressured into the reactor in order to titrate impurities and initiate polymerization of the isoprene. The reaction was allowed to run for one hour, after which 1100 ml of purified butadiene (12.65 mol) were pumped into the reactor at a rate such that the reaction temperature did not exceed 60° C. Cooling water was passed through the heat exchanger during this process to aid in the control of temperature. The butadiene feed was complete within thirty minutes. One hour later, the formation of the second block of the copolymer was complete and isoprene (43.3 ml, 0.433 mol) in 50 g of cyclohexane was again pressured into the reactor to allow for the formation of the third and final block of the triblock polymer. After one hour, the reaction mixture was cooled and discharged into a vessel containing 5.2 ml of acetic acid (90.8 mmol) to quench the triblock living anion. The mixture was filtered through alumina/Celite, an anti-oxidant (100 ppm based on dry polymer) was added and the solvent was removed under reduced pressure to yield a triblock polymer of about 8200 molecular weight as a clear, colorless, viscous fluid. Infra-red analysis (Fourier Transform) showed the butadiene center block to possess 56% (1,2)- and 44% of (1,4)-microstructure.

Quelle