03-15-04 15:54
No 495277
Hi! I made some MeNH2.HCl yesterday and i want to use it with NaBH4 in LabTop's RedAmin. I have read some posts about making the gas, e.g. reacting with NaOH, but did not found a detailled discription. How much Methylamine.HCl (g) do i need for 1g MeNH2-gas and how much NaOH(% ???). So, i decided to throw in x gramm of MeNH2.HCl into an 500ml Erlenmeyer with hoseadapter on top, hose with attached glaspipette leading into MeOH (-20 C). Then add some (?) NaOH and hopefully gas will go into MeOH... will this work??? Thanx in advance.
(Hive Bee)
03-16-04 02:48
No 495397
You need a molar equiv amount of NaOH and MeNH2.HCl as its a simple acid base reaction.
Best way would be to attach a dropping funnel of a conc NaOH solution to a 3 way adaptor, ontop of a rbf with your MeNH2.HCl (make it into a conc solution if its not at the moment) other top arm on the 3-way to a cone tube adaptor, to a vacuum bubbler of your MeOH.
When you drop in the NaOH and it reacts forming NaCl and water + MeNH2 gas it will be drawn away through your bubbler by the vacuum. That way you wont have to wait for enough to react to form push through pressure.
-ApprenticeCook
(Hive Bee)
03-19-04 21:06
No 496175
i have no vacuum bubbler, but this should not be the problem. thanx for your help, greetings.
(Wonderful Personality)
03-19-04 21:32
No 496178
Nonsense. You need a LARGE excess of NaOH as the reaction of NaOH and methylamine.HCl produces water and you want the shit anhydrous, yes? So you use an large excess of NaOH for to suck up the formed water, go to Rhodiums page there is a writeup om this.
(Hive Bee)
03-20-04 06:20
No 496259
Drip saturated NaOH solution(around 50% that is) onto MeNH2.HCl til no more amounts gas evolves and.When dripping always stir or agitate that MeNH2.HCl or whoosh.And watch out for suckback,add NaOH slowly,cub always gets few suckbacks(methanol gets sucked into apparatus but only tiny amount if you notice it immediatly).It's not rocket science.
EDIT:Forgot to add,methanol needs to be cooled constantly cuz dissolution is exothermic and don't use beaker to gas your methanol,use RBF or something with narrow neck so most of your gas won't fly away.In warm methanol and in open beaker,gas doesn't really want to dissolve and flies away...
(Wonderful Personality)
03-20-04 16:51
No 496331
../rhodium /10pc-me
This works quite similar for methylamine.HCl. Dissolve the methylamine salt in a minimal amount of ALCOHOL (the same you use to catch the amine in, it hasnt even to be bonedry) and drop it slowly onto a LARGE excess of NaOH. The NaOH neutralizes the salt (HCl) and sucks up the water formed when the salt is neutralized:
MeAm.HCl + NaOH = MeAm + H2O + NaCl
You get quite dry methylamine gas, all the other named methods produce quite WET methylamine gas as there is no dry NaOH present for to scavenge the water.
(Hive Bee)
08-13-04 13:13
No 525239
SWIM tried this method, while trying to control the flow of meam gas, he did a stupid mistake and shut off the outflow tube, and seconds later he heard some fizzing sound and his rbf had broken a small hole..... what could have happened to "break" the glass?
oops i did it again
(Hive Bee)
08-14-04 12:57
No 525391
pressure buildup inside the flask when you shutoff the outlet tube.
-AC
Its just my opinion, but no-one listens to me anyway, and rightly so...