Dear Amine, and others, there it is. I have not contacted the person who gave me the hints on this, but I assume he would not object. If he agrees, I will of course include his name later on. One word of caution, this still not finished, but, I have this fellow word it works, I have seen the amine on top, fishy smell, got it after the A/B, etc, looks right.
Reduction with Zinc Dust / Al ( by Wolfx )
- Setup:
- Place a 2 l BF over a stirrer, with a fitting funnel on top and
also a thermometer. Don't let the thermometer to hit the spin-
ning bar. Cool the BF with ice. During the zinc addition and
after, do not let temperature to exceed 30 C.
Reagents :
- 2,5-dimethoxynitrostyrene ( 20 g )
- Zinc dust ( 100 g )
- MeOH ( 200 ml )
- HCl 31 % ( 300 ml )
Procedure :
- Add 200 ml MeOH to the BF. Slowly add 300 ml 31 % HCl. Watch the
temperature, let it cool down to under 30 C.
- Add all of the 2,5-dimethoxynitrostyrene all at once. It should
dissolve easily, everything then a nice uniform orange color.
- Start dropping in the zinc dust in small ammounts. It will foam
a bit, but soon stops, foaming decreases. Watch the temperature
at every zinc dust addition. Don't let it go over 30 C. Should
take one hour or more.
- After addition complete, drip inside BF a small ammount of MeOH
to wash orange foamed in sides of BF. Glass will look clear now.
- Stir for a total reaction time of 7 h, including zinc addition.
At the end, the orange color is completely gone, there is a clear
watery liquid with some zinc at the bottom. Color yellow-gray,
clear, transparent.
- Filter out zinc. Should now have some 700 ml of a clear yellow
liquid, looks like white wine.
- Workup :
- Setup for distillation, distill out HCl and most of the MeOH.
- Dissolve 200 g NaOH in 600 ml water. It will heat up, let it cool
down to RT or close.
- With cooling, stirring, slowly drip in the filtrate in small
increments. Newly formed Zn(OH)2 will make solution thick milk
white. Keep stirring.
- After all filtrate added in, add some 150 ml of toluene and stir
for a few minutes. Place in fridge ( optional ) and wait one hour
or so. Now, most of the Zn(OH)2 on bottom. Carefully decant the
top water + toluene layer. Filter out any Zn(OH)2 carried over.
- Separate the toluene, it will be on top of the water layer. Wash
the toluene if you feel like.
- Now, gas it or back extract with dilute HCl and dry on low heat.
- Should have now 2C-H.HCl.
- Comments :
- This is a modification of the Leminger reduction, hints on the
reduction procedure and workup given to me as private com-
munication.
- Previous post has been edited. Changed title, added reagent ammounts, also added distilling out HCl + MeOH before dripping in NaOH. Have not tried workup whithout distilling out the HCl + MeOH first, but it should work, I think there is NaOH enough. In the original Leminger paper it is not done.