Note: Descriptions are shown in the official language in which they were submitted.
i3~
Manufacture of Norbornene
The present invention relates to the manufacture
of norbornene i.e. bicyclo(2,2,1)-2-heptene, by the reaction
of ethylene with c~clopentadiene and/or dicyclopentadiene in
an inert hydrocarbon solvent.
Norbornene may be polymerized to give tough trans~
parent materials. In addition norbornene i5 capable of
being copolymerized with ethylene to give polymers that have
potential in a variety of appli~ations including moul~ed ancl
extruded articles and film. The polyethylene and elastomer
businesses, to which such copolymers relate, is very compet-
itive and it is therefore important that the methods used to
obtain any comonomers be efficient and economic.
Processes for the manufacture of norbornene are
known. A vapour phase process in which dicyclopentadiene is
reacted with ethylene at elevated ternperature and pressure
is disclosed in U.S. Patent 3 007 977 of A.B. Hill et al,
which issued 1961 November 07. The use of excess olefin in
2C a vapour phase process is disclosed in U.S. Patent 3 763 253
of M.S. Wing et al, which issued 1973 October 02. The manu-
facture of norbornene from ethylene and cyclopentadiene or
dicyclopentadiene in the presence of an inert solvent is
disclosed in U.S. Patent 3 766 283 of N.~. Lorette, which
issued 1973 October 16. The solvents used are high boiling
inert solvents having a boiling point greater than about
100C, examples of which are stated to be commercial
aromatic hydrocarbons such as xylene, diisopropylbenzenes,
toluene, ethyl methyl benzenes, trimethyl benzenes, naphtha
and the like. Such processes are capable of improvement,
especially with respect to the conversion obtained and the
selectivity of the reaction in producing norbornene.
~n improved process for the manufacture of norbor-
nene from ethylene and cyclopentadiene and/or dicyclopenta-
diene has now been found.
~s3c~
Accordingly the present invention provides a proc-
ess for the manufacture of norbornene comprising the steps
of:
(a~ feeding ethylene, a diene selected from the
group consisting of cyclopentadiene and dicyclopentadiene,
and mixtures thereof, and inert aliphatic hydrocarbon sol-
vent into a reactor;
(b) maintaining the ratio of ethylene:diene at
least 3:1 on a molar basis, a reactor temperature of at
least 200~C, a reactor pressure of at least 5 MPa and a
residence time in the reactor of at least 5 minutes; and
(c) separating the norbornene so formed from
inert solvent and unreacted diene.
In a preferred embodiment of the process of the
present invention, the ethylene and diene are each fed to
the reactor in inert solvent.
In the process of the present invention, ethylene,
diene and inert solvent are each fed to a reactor. The
diene may be cyclopentadiene or dicyclopentadiene~ or
mixtures thereof. DicyclopentaAiene is preferred because of
its stability, relative to cyclopentadiene, and to facili-
tate separation of the products of the reaction. Both the
ethylene and the diene are preferably admixed with solvent
prior to being fed to the reactor, with additiona] solvent
optionally being fed to the reactor.
Reactors suitable for carrying out a process of
the type described herein are known in the art and include
tubular reactors and stirred reactors. The latter are
preferred.
The solvent used in the process of the present
invention is an inert aliphatic hydrocarbon solvent. As
used herein, aliphatic hydrocarbon solvent means linear,
branched and cyclic aliphatic hydrocarbon solven-ts,
examples of which are pentane, hexane, heptane and cyclo-
hexane. Mixtures of such solvents may be used. The prefer-
~lS3~
red solvent is heptane.
The reaction i5 carried out at a temperature of at
least 200C and preferably 200-300C. In preferred embodi-
ments the temperature is 240 to 300C, and especially 2S0 to
290C. The reaction pressure should be maintained at at
least 5 MPa, especially 5-60 MPa and preferably in the range
15 to 25 MPa. The residence or hold-up time in the reactor
should be maintained at at least 5 minutes, especially in
the range of 5 to 30 minutes and preferably in the range of
6 to 18 minutes. It will, however, be understood by those
skilled in the art that relatively high reaction temperatur-
es, high reaction pressures and long hold-up times many not
be desirable on ecomonic grounds and the increased possibil-
ity of the formation of by-products.
The ethylene and diene are fed to the reactor such
that the ratio of ethylene to diene, on a molar basis, is at
least 3:1. Preferred ratios of ethylene to diene are in the
r~nge 4:1 to 30:1, especially 8:1 to 20:1.
The norbornene produced in the reactor may be
separated from inert solvent and any unreacted ethylene
and/or diene by techniques known in the art. In particular
the norbornene may be separated hy distillation. Unreacted
ethylene and diene, and the inert solvent are preferably
recycled to the reactor, although a small portion of the
recycled material may be bled off or otherwise separated so
as to control impurity levels in the reactor, as in known in
the art.
Norbornene may be copolymerized with ethylene to
form high molecular weight polymers that may be used in the
packaging and other plastics industries.
The invention is illustra-ted by the following
examples.
Example I
A solution of n-hep-tane containing 26-27%, by
weight, of ethylene was pumped at a rate of 14.4 mL/min.
1~2~3~9~
into a stirred autoclave. The autoclave was a~proximately
cylindrical with a diameter of 8.9 cm and a length of 7.0
cm, the volume being 475 cm3. The reactor was stirred at
700-900 rpm. A solution of dicyclopentadiene in n-heptane
S (1:1 by volume) was admixed at a rate of 2.6 mL/min. with
the ethylene solution just prior to the reactor. An addi
tional 3.6 mL/min. of n-hep~ane was fed directly to the
reactor. The molar ratio of ethylene:dicyclopentadiene was,
therefore, 9.66:1. The residence time in the reactor was
16.7 minutes.
The reactor was maintained at a temperature of
200C and under a pressure of 12.5 MPa.
The effluent from the reactor was mc~nitored using
an on-line gas chromatograph. It was found that the conver-
sion to products was 52.0~ and t~at the yield to norbornene
in the product was 99%; yield to norbornene is defined as
product less detected by-products.
Example II
The procedure of Example I was repeated using
different reaction conditions. Further experimental details
and the results obtained are given in Table I, together with
the results for Example I (Run 1).
Example III
The procedure of Example I was repeated using a
reactor with an inside diameter of 6.2 cm and a length of
4.9 cm, the volume being 150 cm3. Further experimental
details and the results obtained are given in Table II as
Runs 16-22.
Example IV
The procedure of Example III was repeated using
cyclohexane as solvent instead of n-heptane. Further
experimental details and the results obtained are given in
Table II as Runs 23-24.
9~
Table I
DCP- Residence
Initial Te~p. Press. Time Conver- Yield
Run (Wt.%) E/DCP* (~C) MPa (min.) sion~%) ~%)
l 8.72 9.66 200 12.516.7 52.0 99.0
2 9.25 9.18 200 12.523.0 58.5 94.6
3 10.95 9.18 200 12.527.4 62.4 99.6
4 10.50 9.66 200 12.520.2 55.0 94.5
5 18.00 4.66 200 12.523.0 5g.4 96.9
6 13.68 6.26 200 12.623.0 56.6 g9.0
7 9.25 9.38 200 17.523.0 69.1 85.1
8 9.25 9.38 200 25.023.0 74.4 82.4
9 9.25 9.38 200 27.523.0 78.8 66.7
10 13.68 6.26 200 27.523.0 74.3 76.3
11 19.6g 4.67 200 27.523.0 73.3 61.5
12 9.25 9.38 250 25.018.3 99.0 89.3
13 9.25 9.38 300 25.018.0 99.0 73.3
14 9.25 9.38 300 25.09.0 99.0 81.4
15 9.25 9.38 300 25.06.0 99.0 85.1
Table II
DCP- ~esidence
Initial Tenp. Press. Time Conver- Yield
Run (Wt.~) E/DCP* (C) MPa (min.) si~n(%) (%)_
16 6.98 16.4 250 20 8.66 98.8 99
17 6.98 16.4 250 20 5.77 97.8 99
18 6.98 16.4 275 20 8.59 99.6 99
19 6.36 20.5 280 20 7.81 99.6 99
20 9.69 10.2 300 20 4.27 99.3 99
21 6.98 16.38 300 20 5.70 99.7 99
22 9.72 10.24 300 20 7.50 99.6 99
23 5.63 16.73 280 20 7.73 99.7 99
24 6.18 15.75 300 20 5.63 99.6 99
DCP = dicyclcpentadiene
E = ethylene
DCP-Initial is the initial concentration of dicyclopentadiene
*E/DCP = ratio of ethylene:dicyclcpentadiene on a mDlar basis
