How to remove salt from putrescine dihydrochloride?

Quote: Originally posted by Metacelsus

Treatment with sodium hydroxide should work fine. When you attempted it before, what procedure did you follow, specifically?

The pH effect you got is simply the trimming/buffer effect.
Putrescine is 1,4-diamino-butane... it display two basic groups per molecules
H2N-CH2-CH2-CH2-CH2-NH2 + HCl <--==> ClH3N-CH2-CH2-CH2-CH2-NH2 (or H2N-CH2-CH2-CH2-CH2-NH2.HCl) (monohydrochloride)
ClH3N-CH2-CH2-CH2-CH2-NH2 + HCl <--==> ClH3N-CH2-CH2-CH2-CH2-NH3Cl (or H2N-CH2-CH2-CH2-CH2-NH2.2 HCl - dihydrochloride)

The buffer effect is expressed when you have a free base and its salt together into solution (or a free acid and its salt together into solution); it expresses when the concentration ratio salt/base or salt/acid ranks from 1/10 to 10/1; usually the pH is "blocked" arround the value of the pKa (thus + or - 1 with regard to the 1/10 (0,1) to 10/1 (10) ratio).

Here NH2-CH2-CH2-CH2-CH2-NH2 is the free base of NH2-CH2-CH2-CH2-CH2-NH2.HCl
NH2-CH2-CH2-CH2-CH2-NH2.HCl is the free base of NH2-CH2-CH2-CH2-CH2-NH2.2 HCl

conversely
NH2-CH2-CH2-CH2-CH2-NH2.2 HCl is the acidic form of NH2-CH2-CH2-CH2-CH2-NH2.HCl

So you must have a trimming effect/buffer effect for both pKa's of the diaminobutane...
==> The second one should be (I don't have the precise value but it must be 3 to 4 pKa units lower than the first one) arround 6 (+/-1 that is pH 5-7);
==> The first one should be arround 10,8 (+/-1 thus pH 11,8-9,8... what you observed)

Note that pH-meters/ metry is usually done into water alone... into a mix of water/ethanol or ethanol alone the measures may provide strange readings.

NaOH is quite soluble into ethanol...
I suspect your procedure calls for addition of saturated NaOH/ethanol solution to a saturated diaminobutane dihydrochloride/ethanol; in principle when stoechiometric amounts are used, one should get the free base in solution into ethanol and a precipitate of solid NaCl (plus a little water formed into the neutralization process).

***********
To me it would be best (although stinky... putrescine smell like dead meat/zombie (just like cadaverine (diaminopentane; hence their special alchemist names):
Do this into an expandable recipient/reactor (NaOH will ruin any glassware upon heating; the glass will be corroded and become opaque/white); the distillation device must be hermetically closeable (except if you wish to get all dead meat eater arround and smell like the morgue/mortuary.
1°) Add DAB (diaminobutane) dihydrochloride to warm water (about 1g/10 ml)
2°) Add excess saturated NaOH/H2O solution and mix the two (it should warm up a little since it is a neutralization and this produces a lot of heat tempered a little by the initial water
3°) Distil... only DAB and water will pass over (no need of a multiple step/plate distillator... only one plate (a tube) is sufficient (like an alchemistry horn / retort)... water, NaOH and NaCl will remain into the initial flask (aside with Na silicate from dissolving the glassware).

Enjoy


[Edited on 19-9-2017 by PHILOU Zrealone]

Quote: Originally posted by Elemental Phosphorus

Putrescine dihydrochloride should be readily soluble in water, no? I don't see why ethanol should be necesary, the procedure you say you think you should use (without ethanol) seems fine. Perhaps gentle heat might help in forming the freebase amine.

Quote: Originally posted by PHILOU Zrealone

The pH effect you got is simply the trimming/buffer effect. Putrescine is 1,4-diamino-butane... it display two basic groups per molecules H2N-CH2-CH2-CH2-CH2-NH2 + HCl <--==> ClH3N-CH2-CH2-CH2-CH2-NH2 (or H2N-CH2-CH2-CH2-CH2-NH2.HCl) (monohydrochloride) ClH3N-CH2-CH2-CH2-CH2-NH2 + HCl <--==> ClH3N-CH2-CH2-CH2-CH2-NH3Cl (or H2N-CH2-CH2-CH2-CH2-NH2.2 HCl - dihydrochloride) The buffer effect is expressed when you have a free base and its salt together into solution (or a free acid and its salt together into solution); it expresses when the concentration ratio salt/base or salt/acid ranks from 1/10 to 10/1; usually the pH is "blocked" arround the value of the pKa (thus + or - 1 with regard to the 1/10 (0,1) to 10/1 (10) ratio). Here NH2-CH2-CH2-CH2-CH2-NH2 is the free base of NH2-CH2-CH2-CH2-CH2-NH2.HCl NH2-CH2-CH2-CH2-CH2-NH2.HCl is the free base of NH2-CH2-CH2-CH2-CH2-NH2.2 HCl conversely NH2-CH2-CH2-CH2-CH2-NH2.2 HCl is the acidic form of NH2-CH2-CH2-CH2-CH2-NH2.HCl So you must have a trimming effect/buffer effect for both pKa's of the diaminobutane... ==> The second one should be (I don't have the precise value but it must be 3 to 4 pKa units lower than the first one) arround 6 (+/-1 that is pH 5-7); ==> The first one should be arround 10,8 (+/-1 thus pH 11,8-9,8... what you observed) Note that pH-meters/ metry is usually done into water alone... into a mix of water/ethanol or ethanol alone the measures may provide strange readings. NaOH is quite soluble into ethanol... I suspect your procedure calls for addition of saturated NaOH/ethanol solution to a saturated diaminobutane dihydrochloride/ethanol; in principle when stoechiometric amounts are used, one should get the free base in solution into ethanol and a precipitate of solid NaCl (plus a little water formed into the neutralization process). *********** To me it would be best (although stinky... putrescine smell like dead meat/zombie (just like cadaverine (diaminopentane; hence their special alchemist names): Do this into an expandable recipient/reactor (NaOH will ruin any glassware upon heating; the glass will be corroded and become opaque/white); the distillation device must be hermetically closeable (except if you wish to get all dead meat eater arround and smell like the morgue/mortuary. 1°) Add DAB (diaminobutane) dihydrochloride to warm water (about 1g/10 ml) 2°) Add excess saturated NaOH/H2O solution and mix the two (it should warm up a little since it is a neutralization and this produces a lot of heat tempered a little by the initial water 3°) Distil... only DAB and water will pass over (no need of a multiple step/plate distillator... only one plate (a tube) is sufficient (like an alchemistry horn / retort)... water, NaOH and NaCl will remain into the initial flask (aside with Na silicate from dissolving the glassware). Enjoy [Edited on 19-9-2017 by PHILOU Zrealone]

Very good, thank you. I will try your suggestions.

The problem with pH hitting a wall was just NaOH and water - no diaminobutane. Is there a method to create the 'excess saturated NaOH solution'? A specific formula?

I am somewhat familiar with distilation apparatus, but not with a closed or 'hermetically' sealed type. How is this made, or what is it called? I am most curious how it copes with changing volume of distillation.

EDIT: Is the sealed distillation just as simple as this? I would expect it to develop pressure if the erlenmeyer and all junctions were airtight, no?




Would not #9 need to lead to some type of expansion chamber capable of expanding to meet the changing volume? If so, what is suitable as an expansion chamber for this purpose?







[Edited on 19-9-2017 by Freddyhampt]

@Freddyhampt,

You got it

It can be hermetical if you have a cold trap as the end recipient; then no pressure build up can occure (assuming you have enough cooling fluid)... with an efficient cooling the all system can't display any overpressure since any vapour forming is condensing into the cold trap... the pressure into the system remains thus close to constant.

Exces means what it means...
==> over the stoechiometric amount...
If you know how much DBA dihydrochloride you put into your reactor in grams; then you know the number of moles of DBADHC and because of the 1/2 ratio for neutralization (1 DBA.2HCl needs 2 NaOH); then you find by conventional stoechiometric calculations how much g of NaOH you would need... any quantity above this is exces... since NaOH is the cheap reactant... you can work on a 1,5 to 2 fold exces.

[Edited on 19-9-2017 by PHILOU Zrealone]

Quote: Originally posted by DraconicAcid

Have number nine lead to a trap with some acid in it, to catch any zombie juice trying to escape. And put crushed ice and salt into 16, to keep it from evaporating.

Quote: Originally posted by PHILOU Zrealone

@Freddyhampt, You got it It can be hermetical if you have a cold trap as the end recipient; then no pressure build up can occure (assuming you have enough cooling fluid)... with an efficient cooling the all system can't display any overpressure since any vapour forming is condensing into the cold trap... the pressure into the system remains thus close to constant. Exces means what it means... ==> over the stoechiometric amount... If you know how much DBA dihydrochloride you put into your reactor in grams; then you know the number of moles of DBADHC and because of the 1/2 ratio for neutralization (1 DBA.2HCl needs 2 NaOH); then you find by conventional stoechiometric calculations how much g of NaOH you would need... any quantity above this is exces... since NaOH is the cheap reactant... you can work on a 1,5 to 2 fold exces. [Edited on 19-9-2017 by PHILOU Zrealone]

Quote: Originally posted by PHILOU Zrealone

The distillation step allows you to leave the salt behind because non volatile. If your reactants were cold enough... the volatility is less... so should the smell... mild heating should reveal if free DAB base is present or not. If the pH changed from 7 to 13 then your NaOH is efficient and still active; so you should have smell at ambiant temperature, unless very dilluted solution or if the DABDHC is not DABDHC but something else? Edit: Last option... you are imune to the smell of putrescine and cadaverine... I think it is possible that a genetical modification of the smell receptors may induce such effect... rare but possible... ==> Ask other people to smell ;o) [Edited on 27-9-2017 by PHILOU Zrealone]

Quote: Originally posted by Freddyhampt

Okay thank you. Will try this and report back the results.

Quote: Originally posted by Melgar

Quote: Originally posted by Freddyhampt   Okay thank you. Will try this and report back the results. Are you sure that you have what you think you have? Where did you get it? What you did is essentially a test for this compound, and if it actually existed in significant quantities, you'd DEFINITELY be aware of it by now.