Piperonal or Benzaldehyde From Chloromethyl Intermediate

The benzylchloride compound made in the previous recipe can be converted to piperonal or benzaldehyde using a chemical called hexamine [137 p817, 37 p700, 136]. Hexamine, also known as methenamine or hexamethylenetetramine, is a weird looking chemical that is easily made from formaldehyde but is better off being purchased.

Piperonyl chloride

Piperonal

Piperonyl chloride

Piperonal

In a flask with stirring is added 158g piperonyl chloride or 126g -241 -

benzyl chloride, 140g hexamine and either 500mL 50% aqueous acetic acid or 500mL 60% aqueous ethanol. The solution is re-fluxed for 2 hours, then 200mL 3N HCI is added and refluxing is continued for 15 minutes more. When cool, the solution is extracted with ether, the ether washed 3 times with water, dried through Na2S04 and vacuum distilled to afford piperonal or ben-zaldehyde (yield=70%). The two products are quite fragrant which will give the chemist an idea of the success of the procedure. Did you know that a lot of methylamine is produced as a side product of this reaction? How it can be salvaged Strike has no idea.

Continue reading here: Protocatechualdehyde From Pyrocatechol

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