Электролитическое восстановление нитростиролов.
Этот способ был предоставлен Уемурой, пчелой-исследователем, живущим в Германии. Он, однако же, так и не был опробован до сих пор, хотя в старой литературе, до того, как был открыт алюмогидрид лития, этот способ восстановления нитростиролов был самым предпочитаемым, если не единственным.
Основная трудность для юного химика в электролитических реакциях вообще - это нахождение мембраны. Мембрана представляет из себя некоторый сосуд, который не позволяет смешиваться двум жидкостям - на аноде и на катоде, но всё же пропускает через себя электрический ток (который переносится сквозь неё ионами воды).
В качестве кухонной мембраны предлагались и телячьи кишки, и презервативы, и пористые горшки для цветов - ни одна из них не работала. Ещё один предложенный вариант - сделать мембрану из смеси гипса с серебрянкой (пропорции??) и затем растворить алюминий щёлочью, создав тем самым необходимую пористость. Но он не был испробован.
В общем, конкурс на мембраны до сих пор открыт.
Сама же процедура следующая:
A) Equipment for electrolytic reduction
An anode cell (Z) - a porous cell of Haldenwanger porcellain - was placed
in a filter assembly of 500 ccm (F) volume. The anode had measurements of
75mm x 160mm with a 70mm wide glazed edge that prevented the drawing-up and
smearing of the liquid to be reduced.
To the anode cell was added a solution of 25ccm concentrated sulfuric acid
in 175ccm water. The anode used was lead or carbon rod and was enclosed in
a tightly wound, glass spiral cooler. The water in this was conducted to the
outer container to help cool the inner tube. By regulating the cooling water
it was possible to keep the whole reduction solutionfor the first six hours
at 20 degrees Celsius. In the last hours the temperature was allowed to rise
to 40 degrees Celsius, to get a nearly quantitative course of the reduction.
The outer container contained a cathode (K) - a lead sheet (200mm x 90mm x
2mm), which before each experiment was coated electrolytically using diluted
sulfuric acid, with lead superoxide.
B) Reduction
A solution of 30g 3,4,5-trimethoxy-beta-nitrostyrene in 100ccm glacial acetic acid
and 100ccm ethanol was mixed with 50ccm concentrated hydrochloric acid and
added to the cathode container. The anode cell was filled with dilute sulfuric
acid to the outer level of the cathode cell. Now a current of 5 to 6 amps was
passed through the equipment for 12 hours, so that the current density was
about 3 amps.
After the finished reduction, the contents of the cathode cell was filtered and
dried under vacuum. The remainder was then dissolved in 300ccm water. Any
remaining unchanged nitrostyrene was removed by twice shaking it out with ethyl
acetate. The ester in the solution was then removed by shaking out once with
diethyl ether.
The liquid thus obtained of chloride of mescaline was then put in a separating
funnel which had ether added. The amine was freed with a cold concentrated
solution of 100g technical sodium hydroxide. The solution obtained, after
extracting four times with ether, was dried with calcium carbonate and the
amine precipitated with dry hydrochloric acid gas.
After twice dissolving in absolute, dry, non-denatured alcohol, completely pure
mescalin hydrochlorid*xH2O was obtained as white leafs with a melting point of
184 degrees Celsius and a yield of 24g (77.3%)