To the resulting colorless solution of
glutaraldehyde are added, in order, 350 ml. of water,
50 g. (0.74 mole) of commercial methylamine hydrochloride dissolved in 500 ml. of water,
83 g. (0.57 mole) of acetonedicarboxylic acid (Note
3) dissolved in 830 ml. of water, and a solution of
88 g. (0.25 mole) of disodium hydrogen phosphate dodecahydrate and
7.3 g. (0.18 mole) of sodium hydroxide dissolved in 200 ml. of water by heating.
Carbon dioxide is evolved, and the pH of the solution, initially 2.5, increases to 4.5 after the mixture has been stirred under
nitrogen for 24 hours. Concentrated
hydrochloric acid (33 ml.) is added, and the solution is heated on the
steam bath for 1 hour to complete the decarboxylation (Note
4). After the solution has been cooled to room temperature,
75 g. of sodium hydroxide in 100 ml. of water is added (Note
5), and the basic mixture is extracted with eight
250-ml. portions of methylene chloride (Note
6). The combined
methylene chloride extracts are dried over
sodium sulfate, concentrated to about 500 ml. (Note
7), and filtered through a layer of 400 g. of alumina (Note
8) packed in a 50-mm. column. The column is eluted with
methylene chloride until about 1.5 l. of eluate has been collected. The eluate is concentrated under reduced pressure to yield crystalline but yellow
pseudopelletierine. The solid is sublimed at 40° and 0.3 mm. to yield
47–55.5 g. (
61–73%) of crude, nearly colorless
pseudopelletierine (Note
9). The product is dissolved in
100 ml. of boiling pentane, 3 ml. of water is added, and the mixture is boiled until the aqueous layer disappears. After thorough chilling in a
refrigerator, the crystals which separate are collected on a filter and washed well with ice-cold
pentane. Evaporation of the combined filtrate and washings to 20 ml., followed by filtration and washing, yields a second crop of almost equally pure material. The combined
pseudopelletierine hemihydrate weighs
47–55 g. and melts at
47–48.5°. Sublimation of the hemihydrate as described above removes the water of hydration and yields
44–52 g. (
58–68%) of pure, colorless
pseudopelletierine, m.p.
63–64° (
sealed tube). Anhydrous material which has been prepared in this manner does not decompose on storage under dry conditions.