Styrene → Isoprene

HRID 1578559Notes

Reaction equation

HRID 1578559 reaction equation
[CH2:1]=[CH:2][C:3]1[CH:8]=[CH:7][CH:6]=[CH:5][CH:4]=1.[H][H].C([Al](CC)CC)C>C1CCCCC1.[Ni]>[CH2:1]=[CH:2][C:3]1[CH:8]=[CH:7][CH:6]=[CH:5][CH:4]=1.[CH2:1]=[CH:2][C:3](=[CH2:4])[CH3:8]

Participants

7

Reactant 3

HCID 7501StyreneHCID 16682930Triethylaluminum3×HCID 178418361HCID 178418361, compound

Product 2

HCID 6557IsopreneHCID 7501Styrene

Reagents, catalysts & solvents 2

HCID 935NickelCatalyst2×HCID 8078CyclohexaneSolvent2×

Procedure

A copolymer of styrene and isoprene was prepared by polymerization of a mixture of the two monomers in cyclohexane solution, resulting in a tapered copolymer having 37.5 wt.% styrene. The polymer, in cyclohexane solvent, was then subjected to hydrogenation utilizng a catalyst comprising the reaction product of 2.5 moles of aluminum triethyl per mole of nickel-2-ethylhexoate. The hydrogenation reacton conditions comprised 700 psig hydrogen pressure, 80°C, 18% polymer solids in the solution and 4.0 mmoles nickel per pound of polymer. After 180 minutes hydrogenation time, 93.5% of the olefinic unsaturation had been reduced. At this point, triethyl aluminum (TEA) was added, causing substantially complete interruption of hydrogenation. This was indicated by the fact that after holding for 30 additional minutes, the percent of hydrogenation of olefinic bonds had only increased about 1%. In a parallel run with no supplemental TEA being added, the percentage of olefin reduction is about 97.3% after a total of 210 minutes hydrogenation under the same conditions. In the process according to the invention as described above, one mole of supplemental TEA was added per mole of nickel.

Workup

  1. customresulting in a tapered copolymer
  2. customafter a total of 210 minutes hydrogenation

Sources & evidence

ORD record
ord-f079afb3447a44069e91d5df154a79ba
Source dataset
uspto-grants-1976_02
Patent number
US03937759

Reaction notes

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