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Fig. 2.24.
Chromatogram of PGA and PGB in alprostadil.
2
1
Peaks: A = excess derivatizing reagent; B = methyl
testosterone (I.S.); C = PGA ; D = PGB . [Reproduced
1
1
from ref. 102, p 284, Fig. 2.].
0.5 g (1.9 mmol) triphenylphosphine and 2 ml dry carbon tetrachloride were placed in a 15 ml vial. The
vial was sealed with a Teflon-lined screwcap and kept at 80 °C for 5 min. Cloudiness appears when the
reaction is complete. After cooling to room temperature, the vial contents were mixed with 0.5 g (4.1
mmol) of p-methoxyaniline dissolved in 8 ml of dry ethyl acetate. The vial was heated at 80 °C for 1 h.
An insoluble oil appears at this point but, because it is insoluble, it has no effect on chromatography. If
the reaction temperature is raised to 140 °C, the first step can be completed in 2 min and the second step
in 20 min. HPLC conditions and separation (Fig. 2.25): The chromatograph has a UV detector that was
operated at 254 nm. The flow rate of the chromatographic solvent was 1.0 ml/min. A 1/4-in. o.d. by 30
cm µ-Bondapak C18 column (Waters Associates) was used. The column's plate number was 3000
measured with p-methoxylauranilide and a solvent of 83% acetonitrile and 17% water. In all runs, 2 µ1
of the solution containing the anilides was injected with a 10-µl syringe. The gradient elution program
was begun immediately upon sample injection. However, the used injector has a 2 ml solvent loop
between the pumped solvent and the point of injection. Therefore, 2 ml of programmed solvent must be
pumped before it reaches the point of injection (approximately the head of the column). The gradient
curve in Fig. 2.25 plots the solvent composition at the head of the column and show this 2 ml lag.

2.3.3—
Hydrazines

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