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H. R. HUDSON ET AL.
further at 80–908C (0.5 h). The mixture was cooled, diluted with ether,
and filtered to remove sodium bromide and excess of sodium cyanide.
Ether was removed under reduced pressure and the residue was distilled
to give DMSO followed by 1,6-di-([14C]-cyano)hexane (5.69 g,
0.04184 mol, 86.0 mCi), b.p. 1208C at 0.5 mm Hg, showing a single
peak on glc.
Preparation of 1,8-diamino-1,8-[14C]2-octane (4)
The dinitrile (5.69 g, 0.04184 mol) was dissolved in absolute ethanol
(170 ml) and placed in a 1 l Baskerville and Lindsay stainless-steel stirred
autoclave together with Raney nickel (5 ml of wet solid after ethanol
washing). The autoclave contents were cooled to 08C, liquid ammonia
(25 ml) was added, and the system was then sealed, purged with
hydrogen and pressurized to 36 atm at room temperature. The
temperature was raised to 1108C (41 atm) for 4 h with stirring. Stirring
was continued while the contents cooled overnight. After separation of
the clear solution from the nickel, which was washed with more ethanol,
the solvent was removed under reduced pressure with gentle heating to a
final maximum of 508C to leave the carbon-14 labelled diamine (4.66 g,
77.3% yield, 66.5 mCi), showing a single peak on glc.z
Reforming reaction
Raney nickel (1.0 ml of wet solid after washing with ethanol, followed
by anhydrous ether) was added to the diamine (4.35 g), in a three-
necked 50 ml flask under dry nitrogen. The flask was fitted with a reflux
condenser and gas inlet tube and a magnetic stirrer was introduced.
Ether was removed in a stream of nitrogen and the mixture was heated
in an oil bath until molten (ca. 508C). The temperature was then raised
progressively, with vigorous stirring, during four short periods of time
as indicated below. After each period of heating the mixture was cooled
rapidly to below 1008C and, as the nickel settled, a small sample (ca.
0.06–0.09 g) was removed by pipette, weighed, dissolved in ethanol (4 or
5 ml) and analyzed by glc.
zRadioactive contamination was found to adhere tenaciously to the stainless-steel inner surface of
the autoclave. Unless it is intended to reserve an autoclave spcifically for this and similar
hydrogenations of radioactive material, it is recommended that a process of reduction that can be
carried out at lower pressure in glass equipment should be used for this stage of the synthesis.
Copyright # 2001 John Wiley & Sons, Ltd.
J Labelled Cpd Radiopharm 2001; 44: 541–547