Acetic Acid → Isoprene Butadiene Isoprene

HRID 1781951Notes

Reaction equation

HRID 1781951 reaction equation
O1[CH2:5][CH2:4][CH2:3][CH2:2]1.[CH2:6]=[CH:7][C:8](=[CH2:10])[CH3:9].C([Li])CCC.C=CC=C.C(O)(=O)C>C1CCCCC1>[CH2:6]=[CH:7][C:8](=[CH2:9])[CH3:10].[CH2:2]=[CH:3][CH:4]=[CH2:5].[CH2:6]=[CH:7][C:8](=[CH2:9])[CH3:10]

Participants

7

Reactant 5

HCID 176Acetic AcidHCID 6557Isoprene3×HCID 78451,3-Butadiene2×HCID 8028TetrahydrofuranHCID 178418339Butyllithium2×

Product 1

HCID 86746155Isoprene Butadiene Isoprene

Reagents, catalysts & solvents 1

HCID 8078CyclohexaneSolvent

Conditions

Temperature
50 °C

Procedure

Three hundred milliliters (mL) of purified, dried cyclohexane was introduced into a six-hundred milliliter stirred glass reactor. Air was removed from the reactor under vacuum and replaced by dry nitrogen. The reactor was equipped with an air driven stirrer, a pressure gauge, thermocouple, top face inlet valve, dip tube feeder with valve, heating mantle and variable controller and combination nitrogen-vacuum inlet with valve. Three milliliters of a 0.1M solution of dipyridyl in cyclohexane, 7.3 mL (90 mmol) of tetrahydrofuran freshly distilled from benzophenone ketyl, and 1.8 mL (18 mmol) of purified isoprene were injected into the reactor. The temperature of the reactor and its contents was raised to 50° C. The solution was then titrated by the addition of 1.6M butyllithium until a persistent red color was obtained. Following this, 3.75 mL of 1.6M butyllithium was injected into the reactor in order to initiate polymerization of the isoprene. The reaction was allowed to run for one hour, after which 47.5 g of purified butadiene was pressured into the reactor at a rate such that the reaction temperature did not exceed 70° C. After one hour, the reactor pressure had returned to its initial level and the formation of the second block of the copolymer was completed. Isoprene (1.8 mL, 18 mmol) was again injected into the reaction to allow the formation of the third and final block of the triblock polymer. After one hour, 0.35 mL of acetic acid (4.5 mmol) was injected into the reactor to quench the triblock living anion. The color of the reaction mixture changed from a dark amber to colorless immediately. The mixture was cooled to room temperature and filtered through alumina/Celite. An anti-oxidant Irganox 1076 from Ciba-Geigy (100 ppm based on dry polymer) was added and solvent was removed under reduced pressure to yield a triblock polymer of about 8400 molecular weight as a clear, colorless, viscous fluid. Infrared analysis (FTIR) showed the butadiene center block to possess 55% 1,2- and 45% 1,4-microstructure.

Workup

  1. customThree hundred milliliters (mL) of purified
  2. additiondried cyclohexane was introduced into a six-hundred milliliter
  3. customAir was removed from the reactor under vacuum
  4. customThe reactor was equipped with an air
  5. temperaturea pressure gauge, thermocouple, top face inlet valve, dip tube feeder with valve, heating mantle
  6. customwas obtained
  7. customdid not exceed 70° C
  8. waitAfter one hour
  9. waitAfter one hour
  10. customto quench the
  11. temperatureThe mixture was cooled to room temperature
  12. filtrationfiltered through alumina/Celite
  13. additionAn anti-oxidant Irganox 1076 from Ciba-Geigy (100 ppm based on dry polymer) was added
  14. customsolvent was removed under reduced pressure
  15. customto yield a triblock polymer of about 8400 molecular weight as a clear, colorless, viscous fluid

Sources & evidence

ORD record
ord-44988dfca7bd41258d4d28be93b8e091
Source dataset
uspto-grants-1997_05
Patent number
US05633415

Reaction notes

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