Org. Synth. 1957, 37, 65
DOI: 10.15227/orgsyn.037.0065
NORBORNYLENE
[2-Norbornene]
Submitted by J. Meinwald and N. J. Hudak
1.
Checked by J. D. Roberts, C. M. Sharts, and W. G. Woods.
1. Procedure
A 1-l. steel bomb is charged with 200 g. (1.5 moles) of dicyclopentadiene (Note 1). The bomb is flushed with ethylene (Note 2) and then filled while shaking to an initial pressure of 800–900 p.s.i. at 25°. Shaking is continued as the bomb is slowly heated (Note 3) to 190–200° and maintained at this temperature for 7 hours (Note 4). At the end of this period, the reaction vessel is cooled and vented, and the crude product is transferred to a simple distillation apparatus (Note 5). A fraction boiling between 93° and 100° is collected, yield 162–202 g. (57–71%, based on dicyclopentadiene) (Note 6). The norbornylene may be redistilled with negligible losses to give a final product, b.p. 94–97°/740 mm., m.p. 44–44.5° (sealed capillary).
2. Notes
1.
The
dicyclopentadiene used by the submitters was supplied by the Enjay Company. No preliminary purification is required.
Technical (85%) dicyclopentadiene has been found by the checkers to give
54–56% yields of
norbornylene without preliminary purification.
2.
C.P. grade ethylene was obtained from the Matheson Company.
3.
To avoid complications due to the exothermic nature of this reaction,
2 a rate of heating of about 50° per hour was adopted (cf.
(Note 6)).
4.
Near 180°, the maximum pressure (about 2350 p.s.i.) is developed.
5.
In spite of the low melting point of
norbornylene, the product has a remarkable tendency to crystallize. Care should therefore be taken to prevent premature solidification of the distillate. A short-path, air-cooled assembly using rather wide-diameter tubing is convenient for this purpose.
6.
The submitters report the same yields using a
3-l. bomb and
3.68 moles of dicyclopentadiene. Larger-scale preparations may necessitate special control procedures.
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3. Discussion
The procedure described above is essentially that of Thomas.
2 Norbornylene has also been prepared by the addition of
ethylene to monomeric
cyclopentadiene3 (
p. 238), by dehydration of
β-norborneol with
phosphorus pentoxide,
4 and by dehydrohalogenation of
norbornyl chloride or bromide using
quinoline.
4,5This preparation is referenced from:
Appendix
Chemical Abstracts Nomenclature (Collective Index Number);
(Registry Number)
β-norborneol
norbornyl chloride or bromide
ethylene (9002-88-4)
Quinoline (91-22-5)
CYCLOPENTADIENE (542-92-7)
dicyclopentadiene (77-73-6)
Norbornylene (498-66-8)
2-Norbornene
phosphorus pentoxide (1314-56-3)
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