Sciencemadness Discussion Board

Preparation of 5-dimethoxy-phenylethylamine

Cookie Monster - 12-6-2021 at 07:15

C.2, the preparation of 5-dimethoxy-phenylethylamine

Patent CN101311162B

" The reflux water-dividing device is being housed, add alpha-amino group-2 in the 1000ml three-necked bottle of thermometer and magnetic stirring apparatus, 5-dimethoxy-acetophenone (19.5g, 0.1mol), potassium hydroxide (33.6g, 0.6mol), glycol ether (240ml) and concentration are 80% hydrazine hydrate (38ml, about 0.6mol), stirring and refluxing is divided the water reaction, until the water of telling above theoretical amount, continue again to reflux 2 hours, have about 18 hours altogether, reaction finishes, reaction mixture is poured in the frozen water after being cooled to room temperature, and mixed solution extracts with ethyl acetate (100ml * 3), separatory, the ethyl acetate layer anhydrous sodium sulfate drying, carry out underpressure distillation after the removal of solvent under reduced pressure, collect 155-157 ℃/533Pa cut, promptly 2,5-dimethoxy-phenylethylamine (12.2g), yield 67.4%.1H?NMR(CDCl 3,500MHz)δ:2.81(2H,t),2.95(2H,m),3.71-3.74(6H,s),6.48-6.61(3H,m)。m/z:182.190(M+H)+。 "

If the available hydrazine is 40%, can it be used instead of hydrazine-80% by multiplying by 2 (x2) the amount added to the mixture or is there a risk of generating an unwanted hydrate?

Note: OCR is poor with Chinese language


Antigua - 12-6-2021 at 08:00

You didn't really read the document, did you?
This is just a Wolff-Kischner reaction you showed us here, the real starting material is 2,5-dimethoxy-alpha-amino-acetophenone. And the answer to your question is... no and yes. Wolff-Kischner reactions are performed with as little water as possible as the water removal is the driving force for the reaction. Maybe you should read about Clemmensen reduction, it seems more convenient here if you don't have access to 80% hydrazine.

zed - 13-6-2021 at 00:56

Maybe this procedure works. Dunno!

40% Hydrazine can be concentrated. Look it up.

clearly_not_atara - 13-6-2021 at 03:29

Sounds like a mistranslation. The rxn product should be dimethoxyphenylethane...

karlos³ - 13-6-2021 at 04:04

Quote: Originally posted by clearly_not_atara  
Sounds like a mistranslation. The rxn product should be dimethoxyphenylethane...

Or maybe the "a-amino" in front of the acetophenone was lost in translation?
Because it says phenethylamine twice, once in the headline and in the text.

Cookie Monster - 13-6-2021 at 15:23

is 2,5-dimethoxy-phenylethylamine
OCR messes up the text with scissors.:D