KTFO
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MeNH2.HCl help
New her and just looking for some help. Sorry for the long post
If one had a large amount of methylamine hydrochloride what would be the best way to proceed to gas? A friend of mine was thanking about
using a 2 neck RB flask with a 600m (or about 24 inches ) column filled with colure change DRIERITE attached with tubing to a dry ice condenser which
would be filled with of course dry ice and acetone. The condenser would be sit on top of a RB flask also which hopefully would catch pure methylamine.
In the first flask he was thinking of having a saturated solution of NaOH, attached to the other neck would be a pressure equalizing funnel filled
with a saturated solution of MeNH2.HCl. He was hoping this will work so that he can use a stir bar in the flask, and not have a rock hard toxic cake
to dig out. He just don’t know if this will be too much water.
Also if any body can give info on this procedure found on rhodium it seems like it would be the best way? Will it work on honey?
General procedure: 10 mmol of Ketone, titanium(IV)isopropoxide (5.9 ml, 20 mmol), methylamine hydrochloride (1.35 g, 20 mmol) and triethylamine (2.79
ml, 20 mmol) in absolute Ethanole (15 ml) was stirred in a capped flask at room temp. for 8-10 h. Sodium borohydride (0.57 g, 15 mmol) was added and
the mixture stirred for additional 7-8 h at room temp. The reaction was quenched by pouring into aq. ammonia (30 ml, 2M), resulting inorganic
precipitate filtered off, organic layer separated, A/B extraction, drying. Yield of primary amine after isolation purification for acetophenone was 86
% of N-methyl-phenethylamine.
Will it be the same as this with just the addition of Titanium(IV)isopropoxide and triethylamine
Any help will be appreciated
1) PREPARATION
Dissolve 300g methylaminegas in chilled 3000g methanol (-20°C). Cool the mixture to +5. Start the mixer (anticlockwise so no air is mixed in) and add
the1000g MDP-2-P.
Notes: Make 300g MeNH2-gas by reacting MeNH2.HCl with NaOH. Or dissolve the methylaminegas in methanol, using an upside down laying (45 degree's)
gastank with (fluid) methylaminegas in it, no pressure regulator on it. Attach a thick black synthetic rubber hose to the valve, open that valve
slowly ,while the hose is down at the bottom of your first jerrycan with icecold Methanol,which stands on a big flat digital balance. Surround the
hose with a wet towel. Add slowly 300g gas in the jerrycan. Be aware of a popping sound when the gas implodes when it enters the Methanol. Don't let
suck back, close the valve everytime suddenly.
2) REACTION
Start adding NaBH4, one teaspoon ca. every 5 minutes, H2-gas bubbling has to disappear before adding again, temp. should be between 8-10 deg. (Wash
down with methanol). Adding of the NaBH4 will take 2-7 hours. With mixer on let it sit for 2 days. (4 hours will do for people that are in a
hurry,loss 10-20%).
NOTES: When the reaction vessel is opened it should be covered by a wet towel, so the methylamine-gas can be absorped by the water. (1 L water absorps
1000 L NH3.) An airlock might be sufficient for that goal too. Do not airtight the flask, let a thin tubing out the window,wrapped at the end with a
WET towel!.
3) WORK-UP I
Leave the mixer on. Add 8 L clean H2O with 8 mL 33% HCl. Liquid will be greenish brown, pH=10,5 (11 is better than 10). !!When green soap starts to
form: you added far too much HCl. Freebase will sink to the bottom of the vessel. Tap of, till clear water is coming out of the valve.
Add 200 mL DCM to the reactionvessel and mix for 10 min. Stop the mixer and wait 30 minutes. The DCM with the rest of the freebase will sink to the
bottom. Tap off. Combine the two There will be app. 1750 mL of base fluid + DCM.
Notes:You can again basify the water with conc NaOH sol. to pH =13-14 and tap off the last oil.
The 8 mL 33% HCL (1%) is added to the water to make sure any unreacted NaBH4 is neutralised.
4) WORK-UP II
A vac.distillation setup is prepared. First the methanol, DCM, water and other lowboiloing stuff are removed, then at 165 C the clean freebase comes
over. App. 1.0 L.
Notes: Step 1. The water and other lowboiling stuff comes over at 130 C. Remove when nothing more comes! Step2. Set on 165 C. At first around
140-145°C you see the first little drops of oil condensate and at 160-165 C and 20-18 mbar it starts Running!.
To distill of the water, methanol and other low boiling stuff from the reaction mixture, the use of an aspirator is sufficient! To get the freebase
out the use of a decent vacuum pump is recommended.
5) CRYSTALLIZATION
Mix the base 1:4 with clean,cold(-10 to -20 C) acetone and bubble through with a Stainless steel pipe 8 mm x 1 meter with HCl-gas 99%. SLOWLY! After
ca. 5 min a thick, white crystal mass will form. Check frequently with pH-meter or paper,until pH=7 -6,5. If the mix get to hot, place back in big
freezer to cool and proceed with next cold batch. Be very carefull not to go under pH=7 to 6,5, because then your powder will solute again and you
must add base again until pH comes up again to 7. So keep always at least 200 mL base ready in case of mistakes ! Dry the acetone/powder mix in a
Buechner-funnel with aspirator vacuum. Dry again on glassplates on the floor under airconditioner or slow blowing fan's in a dry room.
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leu
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There's a very good procedure in Organic Syntheses for generating gaseous methylamine, and there's this article from JACS 61
2457-9 (1939) which was posted on a few other sites already 
Attachment: kenner.zip (54kB)
This file has been downloaded 731 times
Chemistry is our Covalent Bond
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leu
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This paper, JACS 54 1442-5 (1932) titled the Heats of Solution of Gaseous Methylamine illustrates the gas generation
apparatus used to obtain the data in the previous paper 
Attachment: felsing.zip (53kB)
This file has been downloaded 674 times
Chemistry is our Covalent Bond
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