n-butylamine condensations

IndoleAmine · Dreamreader Deluxe

You see, they are brighter when you crystallize from toluene - right?
And become more yellow again when you do wash with hot water? Then they become a bit more impure again, I would guess. You could compare melting points, very pure p2np can have a mp as high as 71-72°C, and impure only 64-65°C...

To make filtering from toluene easier: just crush up the needles in the ice-cold toluene BEFORE filtering, then rinse with ice-cold IPA after filtering off the toluene, to remove toluene traces (maybe wait for 30-60 minutes after rinsing, before you spread the P2NP out to dry; the air that is sucked through the crystals dries them almost completely if you wait long enough).

But if you're satisfied with your results, then why bother. And if you purify your final product properly, well.....

i_a

brain · Linguist Extraordinaire

the melting points-off course i did ! the difference in both cases was about 0,6-0,7C between the samples

i used these 'beauty' :

IndoleAmine · Dreamreader Deluxe

the difference isn't very big, that's right. Beautiful apparatus, nothing to be ashamed of! Many bees do well with a test tube, sawflower oil and a thermometer, so this is quite professional.

May I ask what the melting point was exactly?

i_a

brain · Linguist Extraordinaire

test was made 2 times (for compare results):

1)
-the start maretial (orange-yellow) mp~62°C (couldnt feel the momen -start melting and when the every crystal is meldet)
-recrystalizated from toluene mp.70,1-70,8°C (start to melt-every crystal is melted)
-from "hot h2o wash" mp.69,2-69,5°C(start to melt-every crystal is melted)

2)
-the start maretial (orange-yellow) mp~62°C (couldnt feel the momen -start melting and when the every crystal is meldet)
-recrystalizated from toluene mp.70,0-70,8°C (start to melt-every crystal is melted)
-from "hot h2o wash" mp.69,1-69,3°C(start to melt-every crystal is melted)

[when water wash-on bottom of baker forms reddish oil-can by pufyfied-by recrystalizaton-to give some more p2np]

IndoleAmine · Dreamreader Deluxe

Hm - really only slight loss in purity, sounds ok for reduction.

But why don't you just wash the toluene with brine solution, dry it, distill to 1/2 its volume and crystallize from toluene, since you have the p2np dissolvend in it anyway?

It gives you cleaner product (although small difference only), and you should have some pride and try to make all reagents as clean as you can - this gives better results, generally.

70-71°C is good BTW - highest I had was 73°C from 3x IPA reXtal, and that was probably overkill - I did it just because I wanted to know how pure it can get... Very Happy

i_a

brain · Linguist Extraordinaire

hm, that amounts are giwing better yelds from : nitroetha+beznaldehyde(n-butylamine)... it condens at room temperature.. to give crystals (3-4 weeks) orange-yellow... it dont contain toluene! Smile

i its better for me to wash it with (acid-water, water, hot water) than recrystalize it from toluene (getting rid of toluene from crystals isn't easy).... i recrystlaize from toluene only red oil-whih is small amount-to give some more p2np-for some different synthesis Smile

-only when using rotor wap. the toluene can be totaly separated(its my own rotar-wap, get it for free from my "friend"):

IndoleAmine · Dreamreader Deluxe

Oh - then it is maybe simpler to wash with water of course...

(thought you were using dean-stark/toluene at reflux for 5h, gives superior yields normally, especially with such large batches. Don't know how I came to this thought...)

And to keep up with the good tradition of pimpin' along - thats mine....

(I guess now THATS what is usually called dicksizing.... Laughing

)

i_a

icecool · Insistent Chemist

Damn how do you guys get those rotavaps?
Did you steal them from school, or really bought one for 9000 euro?
Or built your own?

IndoleAmine · Dreamreader Deluxe

You could try to get a used one.... Wink

i_a

brain · Linguist Extraordinaire

yes!

mine is used to Smile

my friend bought a new one and give me old rot.vap. Smile

i had problem with taking it to me... it weight 45 kg Wink

icecool · Insistent Chemist

Didn't know these things were that heavy.
What vacuum do you use for it?
Aspirator or really good expensive vacuum pump?
And would it improve things when making P2NP by adding GAA to buffer the n-butylamine?
Now SWIM got 13,7 purified P2NP out of 17ml benzaldehyde...

IndoleAmine · Dreamreader Deluxe

icecool · Insistent Chemist

Would the equal molarity as the n-butylamine be the best?
Like 1 mol n-butylamine with 1 mol GAA...?

IndoleAmine · Dreamreader Deluxe

Yep. This converts all base to butylammonium acetate, and creates almost neutral conditions, which is favorable IIRC.

icecool · Insistent Chemist

Next time SWIM'll dry all the chemicals with anhydrous MgSO4, to get better yields.
But first SWIM needs to get rid of the P2NP.