n-butylamine condensations

IndoleAmine · Dreamreader Deluxe

Nice - I was just about to calculate your yield by myself.. Very Happy

(tips: next time better tell the weight of the compounds you used instead of ml's, since the same volume at different temperatures means different amounts in fact, and you didn't include any temp. reading with the amount in ml, so I had to assume you measured out the amounts at 15°C room temp....)

Besides that: good job!

Last thing: better crystallize out as much p2np as will precipitate before concentrating the post-rxn solution, because more solvent during Xtalization leads to cleaner product, generally. If you remove all solvent before cooling things in the freezer, you will have more impurities trapped inside your p2np, and probably will want to recrystallize it one more time afterwards, compared to crystallizing directly from the rxn mixture with much solvent present to catch the impurities...

i_a

icecool · Insistent Chemist

That is absolutely true SWIM got a lot darker crystals as SWIM did before.
But after drying the crystals are a lot lighter.
And there were so much P2NP crystals they didn't quite fit in the buchner filter so there was some liquid left from the crystals that were lying on top.
Now that liquid has been soacked into the newspaper it is drying on.
I guess some crystals will dissolve in there and then it will evaporate where are the crystals gone then(inside the newspaper?).
How can you prevent this.
SWIM did spray very little ice cold IPA over the crystals and it really improved color.
The temperature in the room where SWIM was working is 19*C.
But thanks for the info I'll try to remember it next time.

IndoleAmine · Dreamreader Deluxe

Filter the whole mass in several portions, and press the crystals together in the buchner with a small glass beaker to pack them tightly, then rinse with ice-cold IPA until they don't get lighter in color anymore, then let air suck through them for at least 10 minutes.

Also, you could try drying on a normal eating dish instead of paper...

(time to reXztalize this time! Wink

)

brain · Linguist Extraordinaire

i add litle more BzCHO ! and used silicagel ! and the yeld was :91% ... when refluxed 50C for 8h, added litle toluene ... can someone try it to compare with my results? i dont have time at the moment...

its wird-but getting the water out in situ-ca yelded so much???? i was suprised-expected 60-70 max !

IndoleAmine · Dreamreader Deluxe

That sounds pretty good!

The reaction proceeds through an intermediate 1-phenyl-2-nitropropan-1-ol, which is dehydrated and forms H2O and 1-phenyl-2-nitropropene, so it can very well be that you have >90% yield.

When using more benzaldehyde than nitroethane, you should calculate the molar yield based on the amnt. of nitroethane used, not based on benzaldehyde (because nitroethane is the limiting reagent then).

i_a

brain · Linguist Extraordinaire

nitroethan is to precious to giw it "too much" -because :you will get beter yelds but use more nitroethane-it will be thesame,

i will try mix it all together, and left it on 3-4 weaks.maybe add some toluene?

icecool · Insistent Chemist

SWIM will compare to you SWIM is going to vacuum filtrate second crop of P2NP crystals in an hour or so and then calculate how much P2NP in total the reaction yielded.
This was with more n-butylamine then needed and buffered with GAA.
Okay SWIM weighed the second crop and it weighs: 3,19g

Before SWIM got 46,83g g from the first crop so in total SWIM got from 42,5ml BzCHO: 50,02g of P2NP.
That means 73,26% yield.
Still not bad at all for the second time. Smile

Bumblebee · Thu Apr 28, 2005 5:02 am

I love the n-butylamine condensations i made so far.
It´s funtastic!
I wonder if it can done also with Piperonal (3,4-methylenedioxybenzaldehyde)?
the recipes i seen, didn´t use n-butylamine, and the reaction time was between 3 and 21 days.
Is it possible that the condensation of Piperonal with Nitroethane to mdp-2-np can be done in the same fast manner as it is done here with plain Benzaldehyde?

icecool · Insistent Chemist

I did some calculations, and came to this conclusion for 2,5-dimethoxybenzaldehyde on doing a knoevenagel reaction on it:

2,5-diMeOBzCHO
0,060 mol = 9,97g

MeNO2
0,065 mol = 3,97g = 3,54ml

n-butylamine
0,015 mol = 1,10g = 1,48ml

I first calculated the molair ratio in which they react with each other, started with benzaldehyde+nitroethane reaction.
Any comments on these ratio's?

So in short
Dissolved in 20ml toluene:
9,97g 2,5-diMeOBzCHO
3,54ml MeNO2
1,48ml n-butylamine

Reflux this until dark orange (should one use a dean&stark trap here insted?)

I also calculated for a smaller amount the ratio's from indole amine's synthese which had a very high yield of 93%.

10g 2,5-diMeOBzCHO
4,4g MeNO2 = 3,93ml MeNO2
1,08g EDDA = 0,05 mol = 3,66 g n-butylamine = 4,95 ml n-butylamine

48ml IPA

I guess n-butylamine is a stronger base then EDDA since when using equimolar amine you will use more amine then nitromethane...
Indole amine uses more MeNO2 which will indeed most likely improve the yield although 1,1 equimolar nitromethane to 2,5-DiMeOBzCHO is 3,5ml but that doesn't matter on such a small scale to use a bit more. I would stick with the 1,5ml n-butylamine could even be less then that I guess.
So the improved synthese would be then:

10g 2,5-diMeOBzCHO
3,93ml MeNO2
1,00ml n-butylamine
48ml toluene.

sony · Sun May 01, 2005 1:06 am

IndoleAmine · Dreamreader Deluxe

What about 3,4,5-triMeO-nitroethene? Can it be made with n-BuAm catalyst too, and if - which conditions exactly?

icecool · Insistent Chemist

Are my calculations right?

sony · Tue May 03, 2005 6:03 am

IndoleAmine · Dreamreader Deluxe

Yes..
I'm familiar with reflux in 2x excess nitromethane with CH3NH3COOCH3, and know this thread - but now the pdf is available too, it wasn't when I asked afew posts above... Cool

(thx for your help!)

brain · Linguist Extraordinaire

can i condensate the indole-3-carboxaldehyde with nitroethane in presents of n-buyhylamine [not amonium acetate] ? what then will be proportions?