Sciencemadness Discussion Board

Preparation of Diethyl Sulfate

Magpie - 7-12-2017 at 08:28

December 7, 2017

A. Introduction

This preparation follows the method of Lynn and Shoemaker (ref1).

2C2H5OH + H2SO4 --→ (C2H5)2SO4 + 2H2O

Na2SO4 is added to the pot as a dehydrating agent.

B. Reagents
90g anhydrous Na2SO4
50g 95% ethanol
104.5g conc sulfuric acid
Na2CO3

C. Equipment

2-neck 1-L rbf (the “pot”)
distillation tapered glassware
hotplate
thermocouple (or suitable thermometer)
vacuum pump (or aspirator)
p-e funnel
oil bath
separatory funnel

D. Procedure

a. Reaction/Distillation

Caution: Diethyl sulfate is reputed to be poisonous when vapors are inhaled or the liquid is absorbed through the skin. Provide adequate ventilation and wear gloves.

1. Setup the equipment for simple distillation using the 1-L rbf as pot.
2. Add 90g anhydrous Na2SO4 to the pot.
3. Pour 50g of the 95% ethanol in a beaker and cool in an ice bath.
4. Slowly add 104.5g of conc H2SO4 to the ethanol while cooling in the ice bath.
5. To the side neck of the pot attach the p-e funnel.
6. Pour the ethanol/acid mix into the p-e funnel.
7. In the center neck of the pot affix the thermocouple, or thermometer (See Note 1 below.)
8. Place the apparatus under full vacuum (≤ 45 mmHg).
9. Heat the oil bath to about 180°C. The goal is to bring the pot to 155°-165°C. (See Note 2 below.)
10. Add the ethanol/acid mix at 120-150 drops/minute. Distillate will collect at 2-3 drops/s.
11. Add all of the ethanol/acid dropwise. Distill until no more distillate accumulates.

diethyl sulfate preparation.JPG - 149kB
Photo 1: equipment set-up

utilities for diethyl sulfate preparation.JPG - 193kB
Photo 2: utilities

b. Separating, Washing, & Drying
1. Separate the distillate using a separatory funnel into diethyl sulfate and ethanol. The density of diethyl sulfate is 1.17 so it will be the bottom layer.
2. Wash the diethyl sulfate with dilute Na2CO3.
3. Separate and wash the diethyl sulfate twice with water.
4. Separate, saving the diethyl sulfate and discarding the wash water. See note 3.
5. Place the ~30 mL of diethyl sulfate in a flask and add a scoop of anhydrous Na2SO4. Cap and set aside to dry.
6. Filter the diethyl sulfate and weigh for yield.

E. Results

My yield was 32.7g. Lynn & Shoemaker obtained 32.6g. %yield on ethanol is 41.1%.

F. Discussion

My first attempt to make diethyl sulfate was a miserable failure (see above, in a separate thread) due to inadequate equipment. More importantly, I may have mixed up the diethyl sulfate layer with the dilute Na2CO3 layer during the washing step.

G. References
1. “The Laboratory Preparation of Diethyl Sulfate,” by EV Lynn & HA Shoemaker, January 3, 1924,
[Contribution from the Research Laboratory, Eastman Kodak Co, No. 199], Seattle, WA. See photos of paper here:






Notes
1. If a thermometer is used assure that it can be read in the 155°-165°C range.
2. My pot temperature never came up to 155°C until the very end of the distillation. This was due to clumping of the Na2SO4.
3. Distinguishing the diethyl sulfate layer from the dilute Na2CO3 layer can be tricky. Use the drop sink/float test. Density of diethyl sulfate is 1.17.

Comments, questions, and suggestions are welcomed.



[Edited on 7-12-2017 by Magpie]

[Edited on 7-12-2017 by Magpie]

Lynn & Shoemaker diethyl sulfate paper.JPG - 159kB Lynn & Shoemaker diethyl sulfate paper, p.2.JPG - 126kB

[Edited on 7-12-2017 by Magpie]

[Edited on 7-12-2017 by Magpie]

DJF90 - 7-12-2017 at 11:40

Nice work Magpie. If you have the paper perhaps you could attach it to your post for convenience (although I think I am familiar with it). What is your %th yield?

Magpie - 7-12-2017 at 13:09

Quote: Originally posted by DJF90  
Nice work Magpie. If you have the paper perhaps you could attach it to your post for convenience (although I think I am familiar with it). What is your %th yield?


Thanks, Dan. I added the paper and the %yield to the original post on edit. I don't have a scanner. Hope you can read the paper.

DJF90 - 8-12-2017 at 03:17

Magpie, the reference for the paper is JACS 1924 46 (4) pp. 999 to 1001. I've attached it as a .pdf for convenience.

Attachment: ja01669a023.pdf (65kB)
This file has been downloaded 235 times


PHILOU Zrealone - 8-12-2017 at 14:11

Nice write up and very important for OTC preparation of sulfuric ether (diethyl ether) :):D

Just some side notes...
Side products coud be:
==> CH3-CH2-O-SO2-OH thus a partial sulfuric ester
==> CH2=CH2 (ethene) and H2SO4/H2O if the heating is slightly too high.

[Edited on 8-12-2017 by PHILOU Zrealone]

Magpie - 10-12-2017 at 08:28

Quote: Originally posted by PHILOU Zrealone  
Nice write up and very important for OTC preparation of sulfuric ether (diethyl ether) :):D

Just some side notes...
Side products coud be:
==> CH3-CH2-O-SO2-OH thus a partial sulfuric ester
==> CH2=CH2 (ethene) and H2SO4/H2O if the heating is slightly too high.

[Edited on 8-12-2017 by PHILOU Zrealone]


Thank you PHILOU. In review I feel that I did not know my true temperature because the Na2SO4 clumped around the thermometer bulb. When I get my stepper motor mixer operating I will repeat this synthesis. I have Ba(OH)2 on order and will also do an assay of the product. I urge caution to others who may wish to repeat this synthesis until I can report my assay results.

Do you happen to know the temperature range in which CH3-CH2-O-SO2-OH is produced?

kmno4 - 23-12-2017 at 13:40

Quote:
Na2SO4 is added to the pot as a dehydrating agent.

Of course, Na2SO4 cannot serve as dehydrating agent in this case, because all its hydrates are stable only below 40 C.
It must be a component in this reaction, generating (in situ) some salts.
This procedure works, but not because Na2SO4 can dehydrate anything under given conditions.

Edit:
Literature reseach gives interesting information about given reaction, it is said that hydrogen ethyl sulfate reacts with Na2SO4 under vacuum and heating, giving diethyl sulfate and double salt Na2SO4•NaHSO4.
So indeed, it has nothing to do with dehydration :P

[Edited on 27-12-2017 by kmno4]

Magpie - 12-1-2018 at 21:02

On December 7, 2017 I attempted to make phenetol using the procedure in Brewster. This method uses phenol and diethyl sulfate. The synthesis was a failure, casting doubt on whether or not I had actually made diethyl sulfate.

I was hoping I could find the error and make a correction in my procedure for diethyl sulfate but I have not had a chance to get to this in the alloted time of one month.

Therefore, I will pursue this further when I get my overhead stirrer repaired, soon I hope.

happyfooddance - 12-1-2018 at 21:10

The smell is pretty tell-tale... Some say peppermint, I say candy shop... But it is hard to mistake. You didn't re-distill it, did you?

Edit: I know it's a known occupational carcinogen and one shouldn't go around breathing large amounts of it, but does one occasionally produce small amounts of it when making other things, such as ether for example. I don't imagine it is as bad a thing as some people fear, like benzene in my opinion. I try to breathe as little as possible, but somewhat enjoy it.

[Edited on 1-13-2018 by happyfooddance]

Magpie - 13-1-2018 at 06:27

I did not redistill it. I have an excellent sense of smell and smelled only a trace of peppermint.

The synthesis of phenetole was a failure. I will try to make the DS again.

PirateDocBrown - 13-1-2018 at 11:15

I'm thinking addition of a Dean-Stark type apparatus here could improve yield, by returning the unreacted ethanol to the boiling flask, and allowing continuous removal of the product as it condenses.

happyfooddance - 13-1-2018 at 11:19

Quote: Originally posted by PirateDocBrown  
I'm thinking addition of a Dean-Stark type apparatus here could improve yield, by returning the unreacted ethanol to the boiling flask, and allowing continuous removal of the product as it condenses.


It would be hard or maybe impossible to keep the ethanol condensing and not the product, as the b.p. of ethanol is about 120°C below that of diethyl sulfate.

Magpie - 7-9-2018 at 06:56

Preparation of Diethyl Sulfate (DS) 9/6/18

As before this prep followed the method of Lynn & Shoemaker (Kodak, 1924). 92.6g of anhydrous Na2SO4 was placed in a 2-neck 1000ml RBF located in a silicone oil bath. The bath was heated sufficiently high (180° - 230°C) to keep the salt at 155°- 165°C. A mixture of 63ml of Everclear (95% ethanol) and 57ml of 98% H2SO4 was added at 2d/s. A vacuum distillate of ethanol/diethyl sulfate was collected in a receiver flask. It smelled faintly of peppermint.

The two phases were separated using a 125ml separatory funnel. The DS was washed with dilute aqueous Na2CO3, then twice w/water. Anhydrous Na2SO4 was added to the DS to dry it. The filtered DS weighed 11.4g. Lynn and Shoemaker obtained 32.6g for a 41.1% yield.

Questions, comments, and suggestions are welcomed.

distilling diethyl sulfate - ethanol.JPG - 2MB salt temperature.JPG - 2.3MB

More on next post

Magpie - 7-9-2018 at 07:04

continuation of last post. Toggle picture to turn.

vacuum in 2-neck rbf.JPG - 1.7MB DS product - lower layer.JPG - 2MB

Pumukli - 7-9-2018 at 21:35

Hello Magpie,

Congrats for your synth and setup!

The low yield bothers me a lot though. You usually do much better. :-) (Just pulling your leg, you actually have much more diethylsulfate than me.)

Anyway, don't you think that preheating the dehydrating salt to that high temp caused a lot of ethanol to "flash distill" at the moment of dripping in instead of going into reaction?

This particular synth is a hard one obviously. You either make ethylene around 130 C or diethylether around 160 C. If you are lucky you might end up with some diethylsulfate too. :-) The great guys at Orgsyn were probably very proud of their 41%.

You have so many labware gadgets and such. Would it be possible to distill the "product" into a Dean-Stark - like something and recirculate the upper layer continuously? (I know there is vacuum so a proper Dean-Stark may not work.)

Maybe a catalyst of some sort? As I read Al-sulfate promotes ethylene formation instead of diethylether. (Or vica-versa, I'm not sure.) Maybe another inorganic sulfate would prefer diethylsulfate. Just thinking.

[Edited on 8-9-2018 by Pumukli]

As KMnO4 pointed out, Na2SO4 is a catalyst and not simply a dehydrating agent. So maybe another salt may work better.

Someone already suggested the Dean-Stark too. It seems I could not add any original ideas in this case.

[Edited on 8-9-2018 by Pumukli]

Magpie - 8-9-2018 at 08:14

Thank you Pumulki. After 16 years of collecting I do have all the gadgets I want. Give me a sketch of how you would set up a Dean Stark recycle of ethanol to the pot. (ethyl)2SO4 density is 1.18.

I, too, am very disappointed in the yield. Why do the boys at OrgSyn always get such good yields? Actually this is a Kodak procedure, however. Thanks for your thoughtful suggestions.

I'm going to do this synthesis again today. I will be paying especial attention to the salt temperature.

I had to troubleshoot my thermocouple. It was the damn wire. It just reads 2°C high now. Using a thermometer would be impractical due to the fogging in the distillation adapter. If I had another TC I could control the oil bath temperature better using a PID controller. The drip rate is also hard to control.

Magpie - 8-9-2018 at 14:06

Incorporating the changes just discussed the run today was made with a revised apparatus. A peristaltic pump was set up to recycle unused ethanol and PID control was used on the oil bath temperature. Also the long 24/40 condenser was used along with a 3-neck 1000ml RBF.

Et2SO4 revised apparatus.JPG - 2MB

This run was aborted because no apparent diethyl sulfate (DS) was being made. This is attributed to the salt temperature being too high (~180°C). Also the pump did not work as it needed to be primed first. I had to use a thermometer rather than a TC and could not see the salt temperature due to fogging in the distillation adapter.

Another run will be made once I have:

1. Obtained a longer TC
2. Verified the pump is working.






[Edited on 8-9-2018 by Magpie]

JJay - 8-9-2018 at 17:16

Very interesting setup, Magpie. I was also wondering about the yield. Is it possible that your vacuum is too strong? I'm not exactly sure what the "filter pump" they used in the article was, but I had thought that a water aspirator was usually used for making diethyl sulfate.

Magpie - 8-9-2018 at 18:10

Yes, if the use of the peristaltic pump proves out it could be quite useful. I paid $150 for a glassblower to make a separator that could have been replaced with this pump.

In my notes the vacuum specified is ≤45mmHg.

JJay - 8-9-2018 at 20:00

If I'm reading the manometer correctly, it says 4 mm Hg. That could cause the reaction temperature to be a lot lower than if it were 20-30 mm Hg. I've never done this, of course, but if the reaction is finicky, and I have every reason to think it would be, I would think that applying a vacuum of less than 10% of what your notes specified might make a big difference.



[Edited on 9-9-2018 by JJay]

Magpie - 9-9-2018 at 02:07

My notes say "less than or equal to" 45mmHg. I think my inability to control the salt temperature using the thermometer is the culprit. I have an 18"TC on order.

JJay - 9-9-2018 at 03:32

That seems reasonable. It could be hard to monitor the rate of the reaction as well.

This chart is from "On the Vapor Pressure of Sulfuric Acid" by Ayers et al. The vapor pressure of 98% sulfuric acid is about 1.3 mm Hg at 180 c and closer to .4 mm Hg at 160 C. I don't think it's a huge problem, but I don't think it's insignificant.



Untitled.png - 25kB

(Oh and the initial reaction between ethanol and sulfuric acid approaches equilibrium in about 10 minutes at 70 C and in a few hours at room temperature. Source: https://cdn-pubs.acs.org/doi/10.1021/ja02248a014)


[Edited on 9-9-2018 by JJay]

Magpie - 5-10-2018 at 20:09

I tried this synthesis again keeping the temperature of the salt on the low side. I got not diethyl sulfate (DS), only alcohol. I am going to give up on this synthesis using ethanol and sulfuric acid.

I will now attempt to produce ethylene in usable quantity using ethanol and aluminum oxide in a tube furnace. The ethylene can then be reacted with sulfuric acid to form the DS.

S.C. Wack - 6-10-2018 at 08:47

Quote: Originally posted by kmno4  
it is said that hydrogen ethyl sulfate reacts with Na2SO4 under vacuum and heating, giving diethyl sulfate and double salt Na2SO4•NaHSO4


I have to wonder if the overall reaction isn't Na2SO4 + 2EtHSO4 -> 2NaHSO4 + Et2SO4

as Kuh (US1411215 etc) said

Na2SO4 + EtHSO4 -> NaHSO4 + NaEtSO4
EtHSO4 + NaEtSO4 -> Et2SO4 + NaHSO4

[Edited on 6-10-2018 by S.C. Wack]

Magpie - 6-10-2018 at 13:54

Here's the data and results from the 3 Et2SO4 runs I have made:



time-temp graph 1.JPG - 2MB time-temp graph 2.JPG - 1.8MB time-temp graph 3.JPG - 1.9MB

There does not seem to be any significant difference between the runs in comparing the temperatures to the Lynn & Shoemaker recommended range.

I tested the density of the Et2SO4 I made on the first run: it is 1.15 g/ml. Book value is 1.18.

Magpie - 29-12-2018 at 12:54

I recently attempted to make diethyl sulfate (DES) by sparging ethene into con H2SO4 held at 97°C. The gas was sparging profusely into the acid using a fritted tube. Sparging continued until the ethene was gone, about 4 hrs. Much char was produced and no hint of DES.

An article in the Canadian Journal of Chemical Engineering, 1991) indicates that the pressure in the vessel must be between 20-30 bar. My sparging was done at ~6" of acid hydrostatic pressure.

Since I can make ethene efficiently I wanted to make this method work. But I would have to buy a pump capable of 20-30 bar plus make a pressure vessel, etc, so I will abandon this approach for now.

I have great hopes for a method that first makes ethyl hydrogen sulfate. I will try this next.


kmno4 - 5-1-2019 at 18:14

The simplest method for making DES seems reaction of EtOH and H2SO4, without any additives. It must work, but (from available literature) reaction has to meet some important conditions.
The yield sholud be somewhere between 20% and 40%, at least I think so. I am going to try this, but currently I have no time for experiments, even such simple ones :(

Pumukli - 6-1-2019 at 09:30

Magpie,

I came across the following article a few minutes ago:

On the production of the sulphates of the alcohol-radicals from the nitrites by the action of sulphurous acid
Ernest T. Chapman, J. Chem. Soc., 1870, 23, 415
DOI: 10.1039/JS8702300415

It suggests that ethylnitrite and SO2 or its concentrated solution in water yield DES.
The article is an ancient one, a bit confusing with its old nomenclature and such but seems interesting.


Magpie - 6-1-2019 at 11:30

kmno4: I have use this method with yields of 0-14.4%.

Pumulki: Thanks for the procedure. I may try it eventually. My next try will be using the procedure in patent GB 581,115. It is extremely simple and promises good yields.

[Edited on 7-1-2019 by Magpie]

kmno4 - 6-1-2019 at 14:40

Quote:
kmno4: I have use this method with yields of 0-8%.

"This method" means nothing. Your method may not be my method.Besides, cited patent exploits reaction of H2SO4 and EtOH without any additional substance (but stream of air and heating). So, you did not try every method :P

Magpie - 6-1-2019 at 16:49

The method I am referring to is in the first post of this thread.

lordcookies24 - 6-1-2019 at 17:36

Impressive as always

Pumukli - 7-1-2019 at 12:31

Magpie, I fished out this one:

"Solution of Ethylen in Sulphuric Acid
By Buttlerow and Gorgainow (Deut. Chem. Ges. Ber., VI, 196).
Strong sulphuric acid at 160-170 C perfectly absorbs ethylene. In Berthelot's well known experiment the absorbtion may be due to the heat developed by friction."

Source: Organic chemistry
J. Chem. Soc., 1873, 26, 743
DOI: 10.1039/JS8732600743

It is just the abstract, but that Berichte article may be worth a look up. Also, the once well-known Berthelot method may be referenced in that article, who knows?


Magpie - 7-1-2019 at 15:39

I tried sparging ethylene into con sulfuric acid but at 100°C. The patent I listed above said the reactor pressure must be 20-30 bar. My pressure was atmospheric.

I will look for that reference the next time I am at the library.

I don't think that making diethyl sulfate can be all that easy. Usually if it is easy it is given in Vogel.

Pumukli - 7-1-2019 at 22:46

I tried to save you a journey to the library and downloaded that Berichte article - because all issuses of this journal can be searched online. :-)

Unfortunately the referenced article is just a "correspondence from St. Petersburg" - which is just an abstract in German. As I can tell it does not say a word more than the cited English version, except that "strong sulphuric acid" is "concentrated".

No reference to the original (russian) article nor to the mentioned Berthelot's method of absorbtion. :-(


kmno4 - 4-3-2019 at 07:27

Still no time for experiments .... but not for some little literature.
Here is very interesting article, with many important things for interested in Et2SO4 preparations.

Attachment: estr.pdf (99kB)
This file has been downloaded 70 times


kmno4 - 14-3-2019 at 11:05

My preliminary experiment with 98% EtOH and 96% H2SO4 gave 0% of Et2SO4. It seems that H2O is very harmful for this esterification and must be removed. Added Na2SO4 extracts practically H2SO4 only, added heptane as extractant, it extracts nothing.
I have just ordered some "H2O remover" to test some concept, we will see.....

S.C. Wack - 14-3-2019 at 13:09

Preparation of Neutral Ethyl Sulphate. By A. Villiers (Compt. rend., 90, 1291—1292).—This ether can be prepared by distilling in a vacuum a mixture of sulphuric acid and alcohol. 200 grams of absolute alcohol distilled very slowly in this manner with twice their volume of concentrated sulphuric acid, yielded from 25 to 30 grams of the neutral ether; the end of the operation is indicated by the frothing of the contents of the retort, and by an increase of the internal pressure. The distillate separates into two layers, the lower of which consists of the pure ether. There is no advantage in using fuming sulphuric acid, or in substituting ordinary ether for alcohol. The boiling point of ethyl sulphate under a pressure of 45 mm. is 120.5°, which falls regularly 2.5° as the pressure diminishes 5 mm. It solidifies at about —24.5°, and when treated with warm baryta-water it gives the theoretical quantity of barium ethyl sulphate and alcohol.

JCS 38, 797 (1880)

[Edited on 15-3-2019 by S.C. Wack]

kmno4 - 15-3-2019 at 11:36

Yes, I have seen the article from Comptes Rendus, I think I have seen most of articles about preparation of Et2SO4 :P
My goal is not to use vacuum and/or oleum, the ethyl precursor must be EtOH, the yiel must be better than 50% counting on EtOH. I thought about Na2S2O7 (prepared from Na2S2O8, checked), but after calculations I decided not to do this (expected problems with work-up).
Unfortunately Et2SO4 is sensitive to water or H2SO4, they both cause its decomposition....
As I said, I am waiting for "H2O remover" which is able to remove water even in fair acidic conditions (up to 80% H2SO4) and not consuming too much H2SO4 by the way. However, I have never seen this substance to be reported for this purpose, maybe it simply does not work :D
But it is cheap and worth trying.

SWIM - 16-3-2019 at 08:01

Boron trioxide?

kmno4 - 18-3-2019 at 15:02

No, it is not B2O3. Firstly, I would expect borate esters formation in the mixture. Secondly, glassy B2O3 is terribly hard. Not so long time ago, I prepared some B2O3 (from H3BO3) for another project (triphenyl borate).
To my surprise, I was not able to powder it in my porcelain mortar, ha. It scratches glass, so it would damage my equipment, especially under magnetic stirring. Fortunately, for this purpose partly dehydrated H3BO3 (~HBO2) was equally good.

kmno4 - 11-4-2019 at 14:17

I have got this "H2O remover", but in the meantime I came across the patent US3047604 in my collection of papers. I read it years ago and I thought it is classical bullshit patent. However, it is mentioned elsewhere in this forum as giving good results for MeHSO4 formation.
I tried procedure from the patent and to my surprise Na2SO4 removes water from EtOH-H2SO4 mixture rather complelety. It does work, but somehow it still amazes me. It looks like formed EtHSO4 has "hydrophobic" properities and is not hygroscopic at all. Further experiments are in progress, EtHSO4 is merely a halfway point ;)

[Edited on 11-4-2019 by kmno4]

Pumukli - 13-4-2019 at 00:20

At last some good news in this frustrating thread! :-)
Keep up the tiresome work KMnO4!

kmno4 - 16-4-2019 at 00:13

Just for interested in same EtHSO4.
I performed many runs on 15g of EtOH+34g of H2SO4(97%) scale and result are reproducible. Reaction of these substances is not very fast and takes ~2 hours to establish equilibrium (~60% of EtHSO4 is formed). Next, 6,5-7 g of powdered Na2SO4 is added with continuous stirring, the stirring is continued at r.t. for ~ 6 hours or more*.
The mixture is then placed in a cold place (5-15 C) for a few hours, without stirring, to maximalize stability of Na2SO4 hydrates (but this chilling is optional). It is then vacuum filtered, 38(+/- 1)g of amber liquid is obtained after longer time of filtration**.
It is more or less pure EtHSO4, one titration gave 94% its content (assuming it contains EtHSO4 and H2SO4 only). It has weak, not specific odour, there is no EtOH or Et2O scent, it resembles for me chlorobenzene odour, hah. There were no volatile products detected during these operations, the output weights were equal to input ones. Unfortunately, decomposition of EtHSO4 to Et2SO4 (by Na2SO4 also) is really very frustrating: it seems that also Et2SO4 is decomposed by Na2SO4 (at 50-55 C water bath) :o . More details later....

* all oparations performed in closed bottles
** because of high viscosity of the product and large amouts of filtered solids, there are large machanical losses of the liquid, about 2-3 g is always held in filtrate cake - it was impossible to me to recover more liquid :(

[Edited on 16-4-2019 by kmno4]

kmno4 - 24-4-2019 at 23:38

The latest news are not good.
I decided to repeat more closely analysis of the products from Na2SO4 dehydration step. It is because of odd results of further experiments. As usually, it was checked with 15 g of EtOH + 34 g of 97% H2SO4.
1) the liquid remaining after filtering contains slightly more than 20% of H2SO4 (by BaSO4 precipitation)
2) very large amount of NaOH is needed to neutralize a sample of filter cake (0,50 g of NaOH per 1,13 g of wet precipitate)
The most important conclusion - Na2SO4 dehydrates nothing (or almost nothing) and it is converted into NaHSO4 or similar acid salt under these experimental condition. The cited patent is just complete rubbish, as 95% of other old patents.
I had to use about 150 g of benzene dehydrated EtOH (and corresponding amount of H2SO4) to come to this simple conclusion..... It could be deduced from a single experiment, but lazyness and "fitting" weights pushed me on this wishful thinking path.... how stupid of me :mad:

Magpie - 8-5-2019 at 15:03

I was taught that the products of the reaction between ethanol and sulfuric acid depend on the temperature: (1) at 0°C the products are ethyl sulfuric acid, diethyl sulfate, and water, (2) at 140°C the products are diethyl ether and water, and (3) at 170°C the products are ethylene and water. Therefore, one would not want the temperature to reach 140°C if trying to produce diethyl sulfate.

After carefully rereading the procedure of Lynn and Shoemaker I discovered a major error on my part. It is the oil bath that is to be kept at 155-165°C, not the reactants. So I decided to give this procedure another try. I ended up making 3 successive runs over a 3 day period.

1st run. Here I kept the bath temperature at 165°C and tried to get the reactant drip at 120-130 d/min per procedure. I used a p-e funnel stopcock to set the drip rate and could never get it right. Mostly it was way too low. Also my pressure was about 50mmHg instead of the desired 25mmHg. After all the reactants were in I did not see 2 phases in the receiver and once again was very discouraged. But remembering that the procedure said that it takes about 1.5 hours, I continued the heating. Slowly some heavy product began dripping into the receiver, so I continued until this stopped, a total of about 1.5 hrs. There was about 5ml of this heavy product below the ethanol in the receiver. This gave me hope and I decided to make another run the next day.

2nd run. My goal for this run was to scrupulously follow the procedure of Lynn & Shoemaker. I replaced the water aspirator with a vacuum pump. This gave me a little less than 25mmHg pressure. Reasoning that the large headspace of the 1000mL pot might be condensing some of the Et2SO4 before it could reach the condenser I insulated all the glassware up to the condenser with al foil. I kept the bath at 160°C. This run also produced product at what seemed like a better rate. I let the condensate accumulate on top of that for the 1st run. Further encouraged I decided to make a 3rd run.

3rd run. This was done as the 2nd run except I was determined to increase the drip rate to the 120-130d/min. This run was the best as product began accumulating right away and was quite visible as drops falling to the bottom of the receiver through the supernatant ethanol. However, I still did not achieve the control of the drip rate that I wanted.

Combined Product. Today the combined product was neutralized and washed per the procedure. The resulting weight of Et2SO4 was 25.3g. Lynn & Shoemaker claim 32.6g for each run.

Future Run.At some point I will make another run when I figure out how to control the drip rate. Using just a capillary tube and a pinch clamp may work as the system vacuum will draw the feed into the pot. Also I would try using a 500mL pot to make it easier to carry the Et2SO4 vapor to the condenser. Its normal bp is 209°C. At 25mmHg pressure it is likely about 100°C.

Photos. I have 3 photos which I will post when they show up in my e-mail.

[Edited on 8-5-2019 by Magpie]

Magpie - 16-5-2019 at 14:56

I made another Et2SO4 run today. The only change I made was to use 19/22 glassware instead of 24/40. The pot was big enough (500mL) but the condenser was too short, ie, much vapor was sucked into the vacuum pump. Ethanol, I presume. Attached is a picture of the 100mL receiver. The Et2SO4 is the bottom layer.

today's Et2SO4 production.JPG - 100kB

Pumukli - 16-5-2019 at 20:49

Congrats Magpie!

It seems that you really produced something. ;)

Now comes the testing/characterization part to see if you made "the stuff"! If you could ethylate something (e.g a phenol) it would be ta-da!

Magpie - 17-5-2019 at 07:56

Thank you. I have plans to identify this and eventually make phenetole as you have suggested.

Magpie - 18-5-2019 at 17:58

Here are the results of refractive index determinations:

3- run composite of 8-5-19 above: 1.397@25°C
6-9-18 batch of 11.4g: 1.398@25°C

correction to 20°C would be +0.002

literature value @20°C: 1.400


[Edited on 19-5-2019 by Magpie]

[Edited on 19-5-2019 by Magpie]

brubei - 19-5-2019 at 09:42

Nice