| Title: PROCESS FOR PREPARATION OF NON-CONJUGATED DIOLEFINS Inventor(s):
G. Summers, F. Hamilton
Disclosure 168 U.S. Patent 5,245,098
The monomer 5-methyl-1,4-hexadiene (5-MHD), uncontaminated with 4-methyl-1-4-hexadiene
(4-MHD), or other hydrocarbons, is obtained by reacting 1-chloro-2-methylpropene with
allylmagnesium bromide in equimolar amounts under gentle reflux at atmospheric pressure in
an organic solvent medium (diethyl ether) and in the presence of a catalytic amount of a
dichloro-[1,2-bis(dimethylphosphino) ethane] nickel (II) in an inert atmosphere. The allyl
magnesium bromide is added dropwise with stirring with a mixture of
1-chloro-2-methylpropene and catalyst in the solvent at room temperature. The solvent is
separated from the product by distillation, giving substantially pure product. Absence of
other hydrocarbons is either the crude product or the pure product maybe shown by 1H NMR,
13C NMR and GC analysis.
Other nonconjugated diolefins can be prepared in an analogous manner using an alkenyl
halide and an alkenyl Grignard reagent which upon cross coupling will give the desired
nonconjugated diene.
The patented process yields vulcanized rubber having outstanding biocompatibility and
very high flex resistance, excellent ozone resistance, good compression resistance and
high damping. Because of its outstanding biocompatibility and flex resistance, this rubber
has become the elastomer of choice in biomedical devices.
Specific advantages of methodology include simple procedures, mild reaction conditions
(atmospheric pressure in diethyl ether at reflux), high yields (50-90%), easy recovery of
product in high purity without contamination by structural isomers.
Applications are established in the use of artificial heart diaphragms and compliance
chambers (cycles 31,000,000 times in a year), spinal discs, finger joints. Other possible
applications include artificial toe joints, sphincters, and inner sole of shoes where high
flex properties are required. |
