Purify a sample of oct-1-ene by distillation before use.
The commercial Triogen generator produces 3.1g/hr of ozone at an oxygen flow rate of 1 l/min.
Do not deviate from this flow rate. The O3/ O2
mixture must be passed through a
reversed Drechsel bottle, placed between the generator and the reactor vessel, to
prevent suck-back into the generator.Similarly, after the reactor, the flow should be
passed through an empty Drechsel bottle, to catch entrained liquid, and vented high in the fume
cupboard. All connections should be securely made with pvc tubing. Have your setup
CHECKED BY A DEMONSTRATORbefore proceeding.
The experiment O3be carried out in the fume hood dedicated to the ozonolysis experiment. Keep
the hood fully down while passing oxygen and/or ozone-oxygen mixtures through
your sample.
Weigh accurately 0.03125 mole of the pure 1-octene into a large Dreschel bottle containing glacial
acetic acid (100 ml). Wash in the last traces with a little acetic acid. Immerse the reactor up to the
neck in an ice/water bath and connect into the gas flow system. Turn on the oxygen and adjust the
flow rate (to 1 l/min) beforeswitching on the generator. When everything is ready, get the set-up
checked by a Demonstrator or Technician.
Finally, switch on the generator and pass the O3/O2mixture for 30 min (0.03125 mole of O3).
Switch off the generator and allow the O2flow to purge the system for a few minutes. Switch off
the gas and disconnect the reactor.
Pour the contents of the reactor into a 500 ml round bottom flask containing zinc dust (5 g) and
wash the reactor with a little water. Add the washings to the r.b. flask and leave to stand for at
least one hour, then set the flask up for steam distillation in the adjacent fume hood (a useful
‘short-cut’ set-up for steam distillation can be found in "Experimental Organic Chemistry", by
Harwood and Moody, page p153; 2nd. ed, pp. 157-158). Steam distil as rapidly as possible and
continue until the distillate contains insignificant amounts of carbonyl compound as judged by a
2,4-dinitrophenylhydrazine test.
Cool the distillate in ice-water and treat directly with 2,4-dinitrophenylhydrazine in ethanolic
mineral acid.3After 30 - 60 min, the mixture of derivatives is filtered off, dried and the crude yield
recorded.
chromatography on silica gel (see experiment 3 for details, including warnings on dangers of silica
gel) eluting with dichloromethane - petroleum ether b.p. 40–60ºC. Recrystallise each pure
derivative from methanol and record the yield, m.p., and n.m.r. and i.r. spectra of each.
