Gryn
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EDTA to EDA? Naphazoline Synthesis
Hey there, newbie here! I hope it's fine for me to get straight to asking stuff!
We have a special synthesis project for class. It has a certain restriction though: Only use the chemicals available in the lab
Now, one of the syntheses that we're trying to do is Naphazoline HCl, through this pathway:
napthalene + formaldehyde, HCl > 1-naphthyl-methyl chloride + KCN > 1-naphthyl acetonitrile + EDA + (HCl) > Naphazoline HCl
Problem is, we don't have ethylenediamine (EDA), and we're not allowed to just buy some.
We do have EDTA though! Our professor said something about treating EDTA with soda lime to degrade it to EDA, but he wasn't sure about it.
Anyone have any ideas, recommendations, and sources for this synthesis, particularly obtaining and separating EDA from EDTA? Thanks much!
NaOH solves all of my cleaning problems, don't tell my profs~
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hissingnoise
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| Quote: |
We do have EDTA though! Our professor said something about treating EDTA with soda lime to degrade it to EDA, but he wasn't sure about it.
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Hi Newbie, and welcome.
Would that the diamine were that easy to procure ─ us HE hobbyists would have an easy route to EDNA and MMAN...
It's likely that the disodium salt would be the product.
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CuReUS
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Quote: Originally posted by Gryn  | | Our professor said something about treating EDTA with soda lime to degrade it to EDA, but he wasn't sure about it. |
here is the ref - Indian Journal of Chemistry, Section A: Inorganic, Physical, Theoretical and Analytical, , vol. 25, # 7 p. 666 - 668
Alternatively,you could use ethanolamine instead of EDA -https://link.springer.com/article/10.1007/BF00898385
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DavidJR
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Do you have 1,2-dichloroethane or 1,2-dibromoethane? Reacting either of these with aqueous ammonia could give ethylenediamine.
Use a large excess of ammonia and strong stirring to minimise secondary/tertiary/quaternary amine products.
[Edited on 15-4-2019 by DavidJR]
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hissingnoise
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That reaction, I believe, requires pressure at temps of 160 ─ 180°C ─ I doubt it will proceed very far at NTP?
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Gryn
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| Quote: | | Alternatively,you could use ethanolamine instead of EDA -https://link.springer.com/article/10.1007/BF00898385 |
We do have ethanolamine, thanks for the sources! Can't really read German on the second one, but it's surprisingly navigable
| Quote: | | Do you have 1,2-dichloroethane or 1,2-dibromoethane? |
Unfortunately, we don't  However, I think we can synthesize DBE, then use your
method. Do you happen to have a source for this (just for the sake of justifying it to the judges later)
| Quote: | | Would that the diamine were that easy to procure ─ us HE hobbyists would have an easy route to EDNA and MMAN... |
It's really interesting to see how what I thought would be a small problem, is actually a roadblock for many other things. That kinda makes this more
exciting...
And thanks for the welcome!
[Edited on 4-15-2019 by Gryn]
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Gryn
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Update!
Going through the German paper, this is what I've managed to piece together:
| Quote: | Eine Lösung von 9,20g Zinkchlorid in 11,00g ⍺-Naphthylessigsäurenitril, die sich in einem Bad von
190 bis 200 deg befand, wurde im Laufe von 1 Stde. unter Rühren mit 4,20 g
Monoäthanolamin versetzt. Nachdem 1 weitere Stde. bei gleicher Temp.
gehalten worden war, wurde das erkaltete reaktionsgemisch zerkleinert
und mit 5,50 g fester NaOH und Alkohol wie im Versuch 3 aufgearbeitet.
Wir erhielten nach Destillation bei 1 Torr und 160 bis 180 deg C (Luftbad) 1,30 g
(9%) Imidazolin... |
What I get from that is:
- Put 9.20g zinc chloride in 11.00g 1-napthaleneacetonitrile, in a bath at
190 to 200 deg C and stir for an hour.
- Add 4.20g MEA, and let that stir for an hour.
- The cooled reaction mixture was crushed(?)
and worked up with 5.50 g of solid NaOH and alcohol as in Experiment 3.
- Distillation at 1 Torr and 160 to 180 deg C (air bath)
- Expected yield: 1.30 g (9%) naphazoline(?)
And the other one seems to give a better yield:
| Quote: | In einer Lösung von 16,30g
Zinkchlorid in 20,00 g α-Naphthylessigsäurenitril wurden 12,80 g Ammonchlorid suspendiert. Zu dieser Mischung, die sich in einem Bad von 200 bis 210
deg C befand, wurden in 45 Min. unter Rühren 8,50 g Monoäthanolamin
eingetropft. Nach 2stündigem Erhitzen auf gleiche Temp. wurde unter
Zusatz von 19,20g fester NaOH wie im Versuch 3 weitergearbeitet. Die
Destillation (1 Torr, 160 bis 180 deg C Luftbad) ergab 7,56 g (30%) 2-[Naphthyl-
( l')-methyl]-imidazolin... |
What I get from that is:
- Put 16.30g ZnCl and 20.00g 1-naphthaleneacetonitrile together
- Suspend that in 12.80g NH4Cl
- Heat that to 200-210 deg C for 45 mins.
- Add 8.50g MEA with stirring, heat for 2 hrs.
- Same workup, but with 19.20g NaOH
- Distill at 1 Torr, 160-180 deg C air bath
- Expected yield: 7.56 g (30%) of naphazoline(?)
These procedures seem reasonable, except for the last part. A 1 Torr vacuum distillation?
Also, I overlooked that it's possible to make EDA from ethanolamine, but apparently it needs sophisticated catalysts to prevent side products
But regardless, the MEA pathway seems to be the most promising ('cuz at least there's some source to show for it). Question is, did I interpret that
right?
[Edited on 4-15-2019 by Gryn]
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DavidJR
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Do you have a source for that?
And I assume that will be for the industrial route using 1,2-dichloroethane. Remember that 1,2-dibromoethane is going to be more reactive.
From Ullmann's:
| Quote: |
Production. 1,2-Diaminoethane is mainly produced by treating ethylene dichloride (EDC) with aqueous or liquid ammonia at about 100C in the liquid
phase [236]. This so-called EDC process has been modified frequently [237]; the reactant ratio, product recycle, pH, reactor geometry, temperature,
and pressure control the product mix. Byproducts include the higher oligomers diethylenetriamine (DETA), triethylenetetramine (TETA), and
tetraethylenenpentamine (TEPA). An unavoidable coproduct of the EDC process is the amine hydrochloride, which must be neutralized with caustic soda,
lime, or other bases to form, e.g., sodium or calcium chloride. Ethylenediamine is either extracted or distilled from the aqueous stream after
neutralization. If deemed necessary, the higher amines can be recycled to optimize EDA production and vice versa. About two-thirds of the installed
ethylenediamine capacity still relies on the EDC process.
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(See https://onlinelibrary.wiley.com/doi/abs/10.1002/14356007.a02...)
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Metacelsus
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| Quote: Originally posted by Gryn | Hey there, newbie here! I hope it's fine for me to get straight to asking stuff!
We have a special synthesis project for class. It has a certain restriction though: Only use the chemicals available in the lab
Now, one of the syntheses that we're trying to do is Naphazoline HCl, through this pathway:
napthalene + formaldehyde, HCl > 1-naphthyl-methyl chloride
|
Be very careful with this Blanc chloromethylation. Bis(chloromethyl) ether will be produced as a byproduct, and this is highly carcinogenic. Make sure
to not expose yourself to the reaction mixture or crude product, and have a plan for proper waste disposal.
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draculic acid69
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Your trying to synth cleareyes? Why just buy it
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Pumukli
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Just for the record, 1,2-dibromoethane is also a nasty one! Check the MSDS first!
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hissingnoise
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Actually, these days, you need look no further than Wiki... lol
Isn't the internet great?
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karlos³
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| Quote: Originally posted by Gryn | Update!
And the other one seems to give a better yield:
| Quote: | In einer Lösung von 16,30g
Zinkchlorid in 20,00 g α-Naphthylessigsäurenitril wurden 12,80 g Ammonchlorid suspendiert. Zu dieser Mischung, die sich in einem Bad von 200 bis 210
deg C befand, wurden in 45 Min. unter Rühren 8,50 g Monoäthanolamin
eingetropft. Nach 2stündigem Erhitzen auf gleiche Temp. wurde unter
Zusatz von 19,20g fester NaOH wie im Versuch 3 weitergearbeitet. Die
Destillation (1 Torr, 160 bis 180 deg C Luftbad) ergab 7,56 g (30%) 2-[Naphthyl-
( l')-methyl]-imidazolin... |
What I get from that is:
- Put 16.30g ZnCl and 20.00g 1-naphthaleneacetonitrile together
- Suspend that in 12.80g NH4Cl
- Heat that to 200-210 deg C for 45 mins.
- Add 8.50g MEA with stirring, heat for 2 hrs.
- Same workup, but with 19.20g NaOH
- Distill at 1 Torr, 160-180 deg C air bath
- Expected yield: 7.56 g (30%) of naphazoline(?)
[Edited on 4-15-2019 by Gryn] |
I was asked to look over that, and only thing I have to correct is, that the mixture is not heated for 45min, but while being in a bath at 200-210°,
the ethanolamine is dripped into there over 45min and not just added.
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Gryn
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| Quote: Originally posted by karlos³ |
I was asked to look over that, and only thing I have to correct is, that the mixture is not heated for 45min, but while being in a bath at 200-210°,
the ethanolamine is dripped into there over 45min and not just added. |
Thanks for that, I'll make sure to note that down
Also, thanks to the others for warning me about the hazards! We have made safety and disposal protocols with these in mind
NaOH solves all of my cleaning problems, don't tell my profs~
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Gryn
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Ok, so this is what me and my team came up with. Would this work? Had to compromise some of the steps cuz we dont have access to vacuum
distillation...
Alternative Blanc chloromethylation of naphthalene
A mixture of 226 g (2 moles) of naphthalene, 297.3 g (3 moles) of 37 wt.% formaldehyde, 260 mL glacial acetic acid, 362 mL of concentrated
hydrochloric acid, and 165 mL of 85 wt.% phosphoric acid, will be heated at about 80-85°C for 6 hours with vigorous stirring.
The crude mixture will be washed with 2 L of cold water (5-15°C), followed by 500 mL cold 10% K2CO3, and then with 500 mL cold water, always keeping
the oily layer1. 200 mL of ether will be added and the ethereal solution will be dried with 10 g anhydrous K2CO3 with agitation for 1 hour. The
ethereal layer will be separated, and dried over 20 g K2CO3 for 8-10 hours. Once the ethereal layer is separated, 50 mL dry benzene will be added2.
First, the ether, benzene, and benzene-water azeotrope will be distilled off by heating the mixture to above 80.1°C. Unreacted naphthalene will then
be separated from the mixture by filtering the mixture while it is below 80°C, but above 32°C3 (NCBI, n.d.). The remaining mixture will then be
cooled, and the solid 1-napthyl-methyl chloride will be collected. The expected yield is 74-77%, 195-204 g (Grummitt & Buck, 1944).
Confirmatory test(s): Silver Nitrate Test and Sodium Iodide in Acetone Test (Shriner et al., 2004, pp. 320-325)
Detects: Alkyl halides, 1-naphthyl-methyl chloride
Melting point: 32°C (NCBI, n.d.)
RFIS:
1 The water and K2CO3 washings should be done carefully to wash away water-soluble impurities and acids (Grummitt & Buck, 1944).
2 K2CO3 is a drying agent. Dry benzene will form an azeotrope with water. Drying is essential to avoid resinification of the product (Grummitt &
Buck, 1944).
3 Naphthalene and 1-naphthyl-methyl chloride have different melting temperatures (80°C vs 32°C), allowing for separation (NCBI, n.d.).
Kolbe nitrile synthesis of 1-naphthyl-acetonitrile
(Assuming yield of 195 g, 1.10 mol), 58.22 g of NaCN will be weighed and suspended in 250 mL DMSO with rapid stirring maintained at 80°C. When the
temperature quickly rises, it will be maintained at 140 +/- 5°C by cooling when necessary. After the addition of 1-naphthyl-methyl chloride, the
temperature will drop, and the reaction will be completed.
This reaction mixture will be diluted to 1000 mL with distilled water, and will be extracted thrice with 150 mL ether per extraction, and the extract
will be tested for cyanide before proceeding to the next step4. The extract will be washed with 6M HCl5, then with water. The washed ethereal solution
will then be dried over calcium chloride6. The dried ethereal solution will then be distilled to remove the ether and separate 1-napthyl-acetonitrile.
The expected yield is 93%, 171.06 g (Friedman & Shechter, 1960).
Confirmatory test(s): Nitrile Hydrolysis to Carboxylic Acid (Shriner et al., 2004, pp. 427-428)
Detects: Nitriles, 1-napthyl-acetonitrile
Melting point: 32.5°C (NCBI, n.d.)
RFIS:
4 Allows the product to be separated from water-soluble impurities, especially NaCN. Increasing the volume lowers the concentration of these
impurities, and allows the product to be concentrated in ether. A small portion of the extract will be tested for the formation of Prussian blue
indicative of the presence of cyanide (Hyde, 1975). If positive, more ether extractions will be performed.
5 HCl is used to hydrolyze the isocyanide byproducts (Friedman & Shechter, 1960).
6 Prevents loss of product through hydrolysis during the distillation step.
Condensation with ethanolamine and formation of HCl salt
(Assuming yield is 171.06 g, 1.02 mol), 1-naphthyl-acetonitrile and 143.1 g (1.05 mol) of ZnCl2 will be mixed in a sand bath at 190-200°C. To this,
65.36 g (1.07 mol) of monoethanolamine will be added slowly, over an hour, and with constant stirring. The reaction product will then be broken up,
which will be followed with the addition of 85.6 g (2.14 mol) NaOH and absolute ethanol7. The precipitated zinc hydroxide will be separated, and the
ethanol will be distilled off. The remaining mixture will then be filtered, followed by 1-2 cold water washes, to separate the solid naphazoline8. The
expected yield is 9%, 12.88 g (Kubiczek & Neugebauer, 1949).
The solid product will then be dissolved in sufficient ether. An HCl gas generator will then be set-up, which is simply a 3 or 2-necked flask with 50
mL concentrated H2SO4, with one of the necks hosed to bubble gas through the ethereal amine solution. 30 mL concentrated HCl will then be added to the
H2SO4 flask dropwise, until no more precipitate forms. The naphazoline HCl precipitate will be separated through filtration, and washed with more
ether (Shriner et al., 2004, p. 389).
Confirmatory test(s): Hinsberg Test (for secondary amines) and Quaternary Ammonium Salt Formation with Methyl Iodide (for tertiary amines) (Shriner et
al., 2004, pp. 386-388).
Detects: The secondary and tertiary amines in the imidazole group, naphazoline
Melting point: 255-260°C (NCBI, n.d.)
Figure 7. NMR spectrum of naphazoline HCl (Chemical Book, 2017).
RFIS:
7 NaOH is used to precipitate Zn(OH)2, which is insoluble in ethanol. The product is soluble in ethanol.
8 Ethanolamine is a liquid beyond 10.5 °C, while naphazoline remains a solid up to 260°C. Furthermore, ethanolamine is more soluble in water than
naphazoline (NCBI, n.d.)
NaOH solves all of my cleaning problems, don't tell my profs~
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CuReUS
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what happened to the 30% route ?
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Metacelsus
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For the workup in the first reaction, what's the point of the distillation with benzene? I think your drying step should remove all the water. Just
evaporate the ether. (And if you do decide to do the azeotropic distillation, substituting toluene for benzene would be a good idea.)
Also, I'm pretty sure the filtration step to remove unreacted naphthalene wouldn't work, because your naphthalene would dissolve in the melted
product. But that doesn't matter, since any unreacted naphthalene wouldn't interfere in subsequent reactions. I would not bother removing it until the
final step with the HCl salt.
Your other steps look OK, but be careful about waste disposal. Cyanide in DMSO isn't a very good thing to spill.
Also, I would definitely test the reactions on smaller scales first. A 2 mole reaction going wrong is a lot worse than a 20 millimole
reaction going wrong. How much of the final product do you think you actually need?
[Edited on 2019-4-28 by Metacelsus]
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Gryn
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| Quote: Originally posted by Metacelsus | For the workup in the first reaction, what's the point of the distillation with benzene? I think your drying step should remove all the water. Just
evaporate the ether. (And if you do decide to do the azeotropic distillation, substituting toluene for benzene would be a good idea.)
Also, I'm pretty sure the filtration step to remove unreacted naphthalene wouldn't work, because your naphthalene would dissolve in the melted
product. But that doesn't matter, since any unreacted naphthalene wouldn't interfere in subsequent reactions. I would not bother removing it until the
final step with the HCl salt.
Your other steps look OK, but be careful about waste disposal. Cyanide in DMSO isn't a very good thing to spill.
Also, I would definitely test the reactions on smaller scales first. A 2 mole reaction going wrong is a lot worse than a 20 millimole
reaction going wrong. How much of the final product do you think you actually need?
[Edited on 2019-4-28 by Metacelsus] |
The reference I used recommended performing azeotropic distillation along with the other drying methods just to be sure, so I put it in there in case
the drying is not enough. It's kind of optional though, and we'll definitely take your suggestion of toluene over benzene
We only need enough to show in a presentation, and some to perform tests on, so not a lot. I just used the size in the first reference, then used the
expected yield for that to adjust the next steps. We will definitely be doing this on a smaller scale in the actual thing (though this is actually the
backup synthesis if our main synthesis doesn't work.)
| Quote: | | what happened to the 30% route ? |
I completely forgot that NH4Cl is fairly easy to make, cuz we just ran out. Its definitely substitutable. Thanks for pointing that out!
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clearly_not_atara
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There are some reports on oxidative decarboxylation with persulfate and catalytic Ag+. If this rxn tolerates the amines, it should convert the
-CH2-COOH groups into -CH2OH, which can then be hydrolyzed to release CH2O.
Simple decarboxylation of EDTA on the other hand will yield TMEDA, not ethylenediamine, so soda-lime is out I’m afraid.
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Gryn
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Update on the synthesis! The first one failed, so we proceeded to Naphazoline. We're currently on the first part, but we made good progress
Our prof insisted on some changes, so ill be highlighting them:
Blanc chloromethylation of naphthalene
A mixture of 12.8 g (0.1 moles) of naphthalene dissolved in sufficient chloroform, 8.1 g (0.1 moles) of 37 wt.% formaldehyde,
[GAA was removed], 9.9 g of concentrated hydrochloric acid, and 1.7 g (found a patent that claimed 0.05-0.2 mol worked best, so we
averaged it to 0.125 mol) of ZnCl2 [instead of phosphoric acid], will be heated at about 80-85°C [although due to the use of
chloroform we only reached around 70°C] for 6 hours with vigorous stirring [we weren't able to use the stirring hot plate due to some
annoying reasons, so we just allowed the boiling of the chloroform to mix it up, and some swirling every 30 mins.].
The crude mixture will be washed with 50 mL of cold water (5-15°C), followed by 25 mL cold 10% K2CO3, and then with 25 mL cold water, always keeping
the oily layer(1). 50 mL of ether will be added [skipped the agitation with K2CO3 due to time constraints. We assume the separations and the last
drying should be enough to remove the water at this smaller scale]. The ethereal layer will be separated, and dried over 20 g K2CO3 for 8-10
hours [we're currently here!]. [the azeotropic distillation with benzene/toluene will be skipped, its not very practical at this scale
and a bit hard to do](2).
First, the ether, [azeotropic distillation skipped] will be distilled off by heating the mixture to above 34.6°C. [as
pointed out, the filtration might not really work. I wonder if it's possible to separate them by allowing naphthalene to sublimate, or through
crystallization (just in case the prof really wants a clean intermediate for some reason)]. The remaining mixture will then be cooled, and the
solid 1-napthyl-methyl chloride will be collected. The expected yield is 74-77%, 195-204 g (Grummitt & Buck, 1944) [this yield probably isn't
applicable now though, with the change of procedure and all].
So far, we got a clear, yellow liquid in ether, now currently stored in K2CO3 to dry
Test Results
Confirmatory test(s): Silver Nitrate Test and Sodium Iodide in Acetone Test (Shriner et al., 2004, pp. 320-325)
Detects: Alkyl halides, 1-naphthyl-methyl chloride
Results:
- NaI test presented a white precipitate (likely NaCl), indicative of the presence of an alkyl chloride.
- AgNO3 test presented a precipitate insoluble in HNO3 (possibly silver chloride), indicative of the presence of an alkyl halide.
Melting point: 32°C (NCBI, n.d.) [not yet done]
RFIS:
1 The water and K2CO3 washings should be done carefully to wash away water-soluble impurities and acids (Grummitt & Buck, 1944).
2 K2CO3 is a drying agent. Dry benzene will form an azeotrope with water. Drying is essential to avoid resinification of the product (Grummitt &
Buck, 1944).
3 Naphthalene and 1-naphthyl-methyl chloride have different melting temperatures (80°C vs 32°C), allowing for separation (NCBI, n.d.).
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Metacelsus
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Thin-layer chromatography (if you can do it) would be a good way to monitor the reaction progress.
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Gryn
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We actually tried TLC to track the progress of our plan A (Dapsone) synthesis. Didn't go so well. We also don't have the reference chemicals, nor the
time to figure out the mobile phase
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Gryn
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Update!
We dried down the product, and it solidified as a waxy substance?
We tried to do the melt and separate method, but it wasn’t playing nice (high chance it would just solidify in the funnel), so we skipped that part
it melts at ~60, and I’m not sure why. I wonder if this is the resin that wound form with water, since it has been pretty humid here. would this
affect the next steps?
NaOH solves all of my cleaning problems, don't tell my profs~
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