Sciencemadness Discussion Board

chloral hydrate synthesis

garage chemist - 11-9-2004 at 09:25

I have searched the board, but it seems that the praparation of this substance has not been discussed yet.

We probably all know the chloral hydrate synthesis from Rhodium's site.

Today I tried it out with 15 ml Ethanol.

I didn't use the apparatus described in the preparation, instead I just bubbled chlorine (from chlorinated lime + HCl) through ethanol in an ice bath. The temperature was kept low.

As the chlorine began bubbling through, the ethanol was coloured green from dissolving chlorine.

The reaction produced some heat, and I hab to add some more ice.

After the chlorine generator didn't produce any more chlorine, the reaction semms to have finished.
I now have some yellow- greenish liquid with a volume slightly larger than at the beginning. It gives off HCl fumes when the flask is opened.

The strange thing is that the liquid doesn't crystallize! In the instructions it said that there should be a large mass of crystals upon cooling.

Does anybody have experience with the synthesis of chloral hydrate?
What is the composition of my liquid?
Is it possible that it wasn't chlorinated long enough or not hot enough?

S.C. Wack - 11-9-2004 at 10:35

Chlorinations in general take a long time. Like 12 hours to weeks. Yields are usually bad based on chlorine used. You need a good scale to tell you when the solution of whatever is no longer absorbing gas.

And specifically for chloral, when the reaction is no longer exothermic, the cooling is replaced by heating to reflux to speed this up. I don't think that the crystals form immediately on completion, it is more of a heavy syrup. This is stirred with conc. H2SO4, distilled, stirred with solid CaCO3, and distilled again.

I'd be surprised that this hasn't been mentioned, with the interest in chloropicrin here.

Hermes_Trismegistus - 11-9-2004 at 11:02

G. Chemist.

I am not familiar with the synthesis of Chloral Hydrate but it does seem to be a great deal more complicated than bubbling chlorine gas through ethyl alchohol.

From a quick read through, the first difficulty I might point out is that the contributing author of the synthesis makes at least one serious boo-boo.
Chloral Hydrate

Smoothe states in "step one" that conditions are required to be anhydrous, and goes on to claim that either drying the etoh is effective towards making it water free, (which it is) or distilling it will also do so, (which it won't).

Smoothe makes no statement about drying the chlorine gas that would result from the "generator" he describes making.

In describing the filling of the gas generator he uses terms like 2" of HCl acid, and 2 tsp of "sani-flush"

Also, if a chemist was to construct the "gas generator" exactly as described, dumping sani-flush powder into hydrochloric acid, he would not have a slow stream of chlorine gas produced, instead he would most likely have a toxic geyser and a pressing need for medical attention.

Smoothe fails entirely to describe the concentrations of reactants, and the length of time required for chlorination of the the ehthyl alchohol.

Smoothe mixes and matches terms and titles for the reactants.

These are all minor issues by themselves but together raise a serious question.

Perhaps Smoothe wrote a fictional lab report?

[Edited on 11-9-2004 by Hermes_Trismegistus]

garage chemist - 11-9-2004 at 11:06

My liquid has a very low viscosity, exactly like the ethanol used at the beginning.

I should better heat the ethanol instead of cooling it, but I would need a reflux condenser for this.

Anyway, what is the composition of my liquid?
Is it a mix of different chlorination stages of Acetaldehyde?

And what does this have to do with chloropicrin? Sorry, but I don't see the relation to it.

Edit: I've been on Rhodiums site and have read his chloral hydrate synthesis before trying it out.

[Edited on 11-9-2004 by garage chemist]

S.C. Wack - 11-9-2004 at 11:20

Who knows what you've got? The reaction produces several products at various points. The sp. gr. of the fully chlorinated mix is supposedly 1.4, btw.

Chloropicrin: Well, this site is about experimenting, isn't it? Although its easier to start with picric acid or MeOH, it has been made by distilling chloral and HNO3 with or without H2SO4. The historic syntheses of chloropicrin haven't been mentioned here before? Perhaps I overestimated the interest in it by remembering a few recent posts.

garage chemist - 11-9-2004 at 11:32

A specific gravity of 1,4 !?
Then my stuff is definately not fully chlorinated.

I'll buy a reflux condenser as soon as I see one on Ebay.
I will have to carry out the reaction in a 500ml rb flask, as this is my only two- neck flask.
So I will have to work in a larger scale, perhaps with 100ml Ethanol.

Chloropicrin from chloral + HNO3 ? Now that's interesting! I didn't know of this reaction before. Do you know about the reaction conditions, and which concentration the HNO3 must have?
But chlorinated organics + oxidisers in anhydrous conditions sounds scary, as it might produce phosgene on overheating.

Mephisto - 11-9-2004 at 12:18

Maybe it helps you to see the equation. At least you see the formed intermediate.
Here.
Taken from "Kleemann And Engels - Pharmaceutical Substances (Syntheses, Patents, Applications, 4th Edition, 2000)"

chemoleo - 11-9-2004 at 13:47

At the bottom of the rhodium synth page it goes on about the dose 'required'. Out of interest, is anyone aware of side effects? Isn't it carcinogenic or something?

Mephisto - 11-9-2004 at 14:33

I don't know possible side-effects but it's not carcinogen. In my post above you can see the LD50. Although it is the first synthetic soporific (it was first synthesized 1832 by Liebig), it is still today among the top 2000 prescribed pharmaceutics [*1]. Because you can get it even today, I don't think it has very negativ side-effects

[*1: Schwabe u. Paffrath, Arzneiverordnungsreport]

Edit: Additional info [*2]
"Doses of 0.5 – 0.75 g rapidly produce deep sleep, which lasts 4 – 8 h, without morning hangover. Standard doses of 0.5 g do not produce REM sleep, but doses of more than 0.8 g generally have a negative influence. Adverse effects are irritation of the mucous membranes and hepato- and nephrotoxicity. Prolonged administration can cause habituation, and physical and psychological addiction."

[*2: Ullmann's Encyclopedia of industrial chemistry]

[Edited on 11-9-2004 by Mephisto]

Chloral Hydrate

MadHatter - 11-9-2004 at 16:57

The classic Mickey Finn over the rocks ! It seems to have the negative
effects from prolonged exposure - like many other drugs.

Mephisto - 12-9-2004 at 03:00

Garage chemist: For your next attempt to synthesize choral hydrate, there might be the following improvements: My suggestions refers to the following text from Ullmann's Encyclopedia:
[color=darkgray]"The chlorination is carried out in hydrochloric acid, which speeds up the reaction, represses condensation and aldehyde-oxidation reactions, and facilitates temperature control. Antimony trichloride is sometimes used as a catalyst. The process can be performed either in batches or continuously. The rate of chlorination decreases as the stepwise chlorination proceeds; thus, the temperature is gradually increased from 0 °C to 90 °C during the process. Chloral is distilled from the reaction mixture as the hydrate. The hydrate is then mixed with concentrated sulfuric acid, the heavier acid layer is drawn off, and chloral is distilled through a fractionating column of moderate height."[/color]

Please make some pictures, if your synthesis is successful.

garage chemist - 12-9-2004 at 04:12

When the ethanol has to be mixed with hydrochloric acid, how can the mix still be anhydrous? And during the chlorination of pure ethanol, HCl gas is produced (half of the reacting Cl2 escapes as HCl!), so I don't see the necessity to add HCl.

I didn't hear about SbCl3 as a catalyst before, if I can get it, i will use some.

I will buy a dimroth condenser and a suitable reaction vessel as soon as possible.

I won't be able to fractionate the chloral though.

Do I have to dry the Cl2 or can I use it directly from the generator?

I don't have a digicam so I can't take pictures, but if I succeed, I will describe my setup in detail.

I just measured the density of my chlorinated mix, and the density is 1,0. :(
The green color has also disappeared.

Dodoman - 12-9-2004 at 04:28

I've tried chloral hydrate synthesis before a few years ago. I used the Rhodium's site prepration as well. I ended up with a clear liquid with a strange smell that when left in air turned into a turbid one. Nothing precipetated as well. So i placed some of the liquid in a test tube and sealed it with a rubber stopping, after a few weeks the rubber turned from red to yellow and the liquid stored remained clear. I know this sounds like a riddle.:cool: I threw the whole thing away.:D

BromicAcid - 12-9-2004 at 06:13

This reaction forms chloral, it's funny how converting it to chloral hydrate is almost an after thought i.e., it's not even a numbered step, thought it refers to it as chloral hydrate even though it hasn't been hydrated yet. We covered chloral hydrate in my organic chemistry class because it is one of the aldehydes that preferably forms a stable hydrate due to the electron withdrawing chlorine atoms on the carbon adjacent to the C=O bond.

The equilibrium constant for hydrate formation when trichloroacetaldehyde is added to water is K = 1.9 x 10^4 so its a pretty assured thing.

My chemistry dictionary [Hawley's] has this to say on the prep of chloral and the subsequent prep on chloral hydrate:

Chloral (Bp 98C)
1) By chlorination of ethyl alcohol, addition of sulfuric acid, and subsequent distillation. or 2) Chlorination of acetaldehyde.

Chloral Hydrate
Derivation: Action of 1/5 of its volume of water on chloral.

Mephisto - 12-9-2004 at 06:19

Quote:
When the ethanol has to be mixed with hydrochloric acid, how can the mix still be anhydrous? And during the chlorination of pure ethanol, HCl gas is produced (half of the reacting Cl2 escapes as HCl!), so I don't see the necessity to add HCl.
In this point I've got more trust in Ullmann's Encyclopedia, than in Smoothe's text. Adding hydrochloric acid to the ethanol will bring some water to the ethanol. But this water is necessary for the crystallisation of solid chloral hydrate. Remember anhydrous chloral is a liquid, the hydrate is solid. So without water in your mixture, your won't get any solid.

Till 1943 chloral hydrate was made in Germany like in Smoothe's text. The German patent DE 734723 proposes the use of alcohol with 1/2 mole water per 1 mole ethanol. There is an example in the patent:
[color=darkgreen]1000 parts per weight denaturised spirit are mixed with 130 ppw water. The mixture is chlorinated at first at 25-30 °C, increasing the temperature till it boils. If the Cl2 won't get absorbed by the liquid, the reaction is complete. The density of the mixture is 1.64 g/cm³ at this point (measured at 23 °C). The mixture should solidify completely.[/color]

garage chemist - 12-9-2004 at 06:39

Thanks Mephisto, that patent text helped me a lot.

So I will mix ethanol with water (not HCl!) like in the text and chlorinate it. And when it solidifies completely upon cooling, I know that it's fully chlorinated.

When I have done it, I'll post the results here.
I won't have time for experimenting for a few weeks (school...) so it may take time.

Mephisto - 12-9-2004 at 07:00

Garage chemist: Good luck for your synthesis.

BTW: I've upload the named patent on axe's ftp "/upload/Mephisto/DE 734723 - chloral hydrate.pdf", you can also find the patent, which was used before DE 734723 there. (both 300 dpi+OCR, German)

[Edited on 12-9-2004 by Mephisto]

Darkfire - 18-9-2004 at 11:58

Chloral hydrate is just a more illegal and complicated version of chlorobutanol, they will both yeild chloroethanol in the body for the desired effects.

CHLORAL HYDRATE

Punk - 26-2-2006 at 01:54

You will have to work out the ratios on your own but heres a quik sample of EXACTLY what happened:

Some bacardi 151 proof rum [yellowish tint] was poured into a beaker along with more than enough iodized table that would disolve in it.

A pair of graphite electrodes were droped in on each side of the beaker then 12volts DC/3amps was ran through them for 15 hours. Durring these 15 hours a decent amount of chlorine gas was emmiting from the anode as massive amounts of hydrogen were bubbling from the cathode. The temperature maxed out at 110'F.

After 15 hours the power supply was turned off and the LED light was still lit. It was discovered that this solution had battery like propertys. Maybe this is how a hydrogen cell works in a car?

After testing the solution with a pool/spa test stip it registerd high on the chlorine, and vary alkaline with a high ph level.

The solution was distilled. A vary dark yellow fluid with some solid white floaties including some dark graphite floaties was left behind and a crystal clear alcohol solution was caught in the collection flask.

Upon CAREFULLY sampling the alcohol over a 45 minute period:
few drops>nothing
few more drops>nothing
halfteaspoon>think im feeling it
another half teaspoon>this is definetly not just alcohol

So about 2 tsp had some really sedating/relaxing+a alcohol buzz effects but no sleep or unconsiousness. Maybe it is just a small amount of cloral hydrate but I think the purity of the alcohol makes it harder to notice. As far as taste goes it tastes like how rubbing alcohol smells. 1 shot would surely have one ready to throw up.

Any thoughts on how to isolate the chloral hydrade as a solid from these 2 solutions?

[Edited on 28-2-2006 by Punk]

a_bab - 3-3-2006 at 05:11

Be carefull as the chloral hydrate is known to screw up the liver. It's also toxic.

Mr. Wizard - 3-3-2006 at 10:58

Did you mean iodized table (salt) that would dissolve in it? Or did you mean an iodine tablet?

I've had similar effects while running current through table salt using carbon electrodes. On some electrodes I could keep a flashlight bulb lit for minutes. I always thought it was due to the hydrogen and chlorine recombining as in a fuel cell. I never tried to maximize the effect by increasing the carbon's gas holding ability. Maybe charcoal briquets, or activated charcoal could be used to maximize the gas holding effect?

The bp of chloral is 98*C so you could distill it. It is supposed to be a fairly pungent oil. Some sources seem to mix up the chloral hydrate and the anhydrous chloral. The smell is supposed to be distinctive and recognizable down to 47 ppb.

Mr. Wizard - 3-3-2006 at 12:17

This got me looking for more information. Chloral is a rather active compound that combines with 'nascent' Hydrogen to form aldehydes, thus it would be destroyed at the negative electrode, and it reacts with alkalis to form chloroform at the other electrode. You may have made a mixture of acetylaldehyde and chloroform.
http://encyclopedia.jrank.org/CHA_CHR/CHLORAL.html
I'd guess it wasn't chloral hydrate.

garage chemist - 3-3-2006 at 14:29

There is absolutely no way that chloral hydrate could have been formed during your experiment.

In order for chloral hydrate to be formed, ethanol must be chlorinated first at 0°C with a strong stream of chlorine and very efficient reflux condenser (acetaldehyde formation is the first step) until chlorine uptake stops (takes about an hour), then at room temperature and then several hours at boiling temperature. Total chlorination time required is 7- 8 hours, most of the time at the boiling point.

Insane amounts of chlorine are needed, and the product is still very impure. Isolation of the chloral is done by adding concentrated sulfuric acid and careful fractionation of the upper phase that separates. The crude chloral is collected between 92 and 98°C, and converted to the hydrate by adding a carefully calculated and measured amount of water.
The crystals that form are dissolved in warm chloroform and precipitated by adding petrolether and cooling.

Your procedure may have yielded some acetaldehyde, and its monochlorinated derivative which will wreak havoc on your liver.

mantis - 3-3-2006 at 14:38

@garage chemist: Have you ever testet this way?

garage chemist - 3-3-2006 at 14:40

No, but there's a synthesis on lambdasyn.
http://www.lambdasyn.com/synfiles/chloralhydrat.htm

mantis - 4-3-2006 at 00:58

Thanks!
I know this synthesis from lambdasyn, but I also read that a lot of people had big problems to syntheticize chloral hydrate. The reason was that they often get a unknown mix of chlorinated substances.

Punk - 4-3-2006 at 23:12

Thanks for the warning before punk poisoned himself, punk will try the latter suggestions and report back in a few days or so.

Punk - 4-3-2006 at 23:18

As far as chloral hydrate destroying the liver it cant be all that bad since doctors prescribe it.


Iodized table salt GC, fumes must have gone to the brain.

Punk - 4-3-2006 at 23:27

What if a cell divider was used to keep the hydrogen out of the reaction? And what about adding a ph buffer to nutralize the sodium hydroxide that is produced?

Another thing is the chlorine produced from this electro setup doesnt smell potent like the lung burning gas created from acid/bleach maybe its not even strong enough to do the job. The electro chlorine smells weak like nearby pool.

[Edited on 5-3-2006 by Punk]

garage chemist - 5-3-2006 at 03:55

Production of chloral hydrate by electrolysis is impossible.

Go to the pool shop and get some HCl and trichloroisocanuric acid or calcium hypochlorite. Then you'll be able to make some serious amounts of chlorine and actually have a chance for success.

Chloral hydrate isn't so bad for the liver, you're right.
But the byproducts in a nonprofessional synthesis are very much.

If you just want a sedative with the effects of chloral hydrate, consider making chlorobutanol (search, there's an excellent thread on this here). It's much easier to make a pure product with this, and it's even a bit more potent than chloral hydrate.

unionised - 5-3-2006 at 13:07

"If you just want a sedative "
Drink the rum.:D

Madandcrazy - 10-4-2006 at 07:45

Hmm, interested.

the way to -(OH)2 by trichloroacetaldehyde, i think a funny name. A hydrate can be too *H2O ;).
Important perhaps for other syntheses when ethanol is reacted with to the =O group and other chemicals to -CH(OH)2.

But how prepared the trichloroacetaldehyde, easy by the treatment of acetaldehyde with Cl2 or HCl, it would surely decompose by strong treatment or the endproduct is chloro or dichloroacetaldehyde.
Maybe is can prepared by trichloromethane and a other chemical or aldehyde ;) and a slight acid.
I don´t know the method of the dehydration or oxidation of trichloroethanol walk fine when it threated with Na2Cr2O7 and H2SO4.


[Edited on 12-4-2006 by Madandcrazy]

Sauron - 3-3-2007 at 03:04

Doesn't Vogel have a prep for chloral? I'm sure I saw it in 3rd edition. I will go have a look.

Can't be worse than Smoothe's BS.

My idea of a chlorine generator is the classical conc HCl dripping onto permanganate (or MNO2) and you can calculate the amounts needed and therefore the reactor size. My modification is to employ a peristaltic pump to feed the acid at a steady controlled rate. Run the Cl2 which will contain some HCl and acid mist through the usual series of wash bottles as described in Vogel, and you have a really good supply of dry Cl2 for larger scale, lengthy chlorinations. The chlorine prep on Rhodium may not look it but they did get the ratios right if you compare to Vogel. (No not Smoothe's.)

Just a guess but I would say that the cooling at the start of chlorination of ethanol is to limit the oxidation to the aldehyde stage, else you make chloroacetic acid (and higher chlorinated acetic acids) instead of chloral. Then once you have achieved at least monochlorination and all ethanol has been oxidized as well, that's when the chlorination needs to be continued to room temperature and finally reflux.

I believe it is also possible to get at chloral from trichloroacetic acid by reduction. I will look into both these issues. I think I kept bumping into chloral preps a couple years ago when I was looking at unsym-dichloromethyl methyl ether.

Also I wonder whether UV would accelerate (catalyze) the chlorination of ethanol, this is after all a free radical chain isn't it? If so, then a radical initiator might also do same. UV being a pain in the butt when you are trying to hold the pot at o C.

As a reagent, chloral is interesting. As a drug of abuse it is way too harsh and toxic to contemplate. You will soon have the liver of a 75 year old alcoholic, there are dermatological complications associated with chloral addiction, and your breath will reek of pool cleaner.

The infamous Mickey Finn was administered in an alcoholic drink, to unsuspecting drunks. A relatively sober victim would notice the stench of chlorine coming off his cocktain and wonder how the bleach got in there. The ethanol and the chloral hydrtate of course potentiate each other and even if the bartender got the dosage right, if the victim is drunk enough he may very well wake up dead. I used to know a club owner on Bourbon Street (New Orleans) who did a stretych in prison for mickey finning a customer, who promptly expired. Bad show, that.

Sauron - 3-3-2007 at 03:40

Well, unfortunately Vogel does not give a detailed procedure for chloral, merely alludes to is preparation (on pp 297-298) as proceeding like a haloform reaction.

He does describe a few reactions of chloral hydrate and give some physical constants.

Merck (12th) is a little more helpful. Monograph 9755 Trichloroacetaldehyde. Apart from half a dozen citations regarding chlorination of thanol which everyone appears to be familiar with, there's also a US patent on preparation from hypochlorous acid and trichloroethylene which may well bear scrutiny.

US 2,759,978 (1956)

which I will now go fetch and attach.

[Edited on 3-3-2007 by Sauron]

Attachment: 2759978[1].pdf (166kB)
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Sauron - 3-3-2007 at 03:54

Preferred conditions are >3 M HOCl (aq) and dry-ice/acetone temperatures, yield 30%

Still, interesting. They require removing elemental chlorine from the hypochlorous acid by blowing air through.

Worth a try?

Cf. Brauer, pp 308-309 procedure 1 for 25% HOCL (aq) from chlorine water (Cl2.6H20) and HgO. Isolation by vacuum distillation into a cold trap. This must be stored under -20 C and I suppose, used directly is best. See also p.299, prepn of Cl2O (hypochlorous anhydride) from HgO and Cl2. This is stored in CCl4. Addition of water gives HOCl.
(p309 procedure 2).

If I did the sums right in my head, a 25% soln of hypochlorous acid is c.5 M and this prep calls for slightly more than 3 M (like, 3.1 M). So, the required concentration is about 15-16%.

Note that the mercury chlorides produced can be conserved/recycled.

Also, there is a review specifically on chloral chemistry:

Chemistry of chloral

Chem. Rev. 75,3, 259 (1975)

which I have requested from References. There's a section on preparations.

[Edited on 3-3-2007 by Sauron]

[Edited on 3-3-2007 by Sauron]

Sauron - 3-3-2007 at 08:23

Ah! Let me gloat. According to this 1975 Chem.Rev. piece, if the ethanol chlorination is begun at 20 C rather than 0 C you obtain not chloral but trichloroacetic acid.

So, the temperature control is specifically to limit oxidation to the aldehyde stage.

Per Org.Syn., chloral hydrate can be reduced (with Al(OEt)3 in EtOH) to trichloroethanol. So I repeat my assertion above in the thread, that trichloroacetic acid ought to be reducible to chloral (trichloroacetaldehyde). I believe we have selective reducing agents that knock carboxylic acids back to aldehydes and stop there and are inert to alpha-halogens.

The Chem.Rev article states that direct chlorination by the element, of ethanol is th best method of preparing chloral. So far I only have the first page but the section on preparations starts there and concludes on next page. It says that this process, using absolute ethanol but with traces of water, and basically unimproved since Leibig in 1832, gives 70-80% yields under best conditions. This is a whole lot better than 30% from tric and HOCl. Unless one has a whole lot of tric to dispose of.

Bad news for the druggies: there's a mutagenicity study referenced in Merck.

Good news for the rest of us: chloral is a versatile reagent and intermediate. It formerly was of great industrial importance fpr manufacture of DDT. See Org.Syn. for about a dozen preps in which it figures.

Also Org.Syn has a prep of bromal, starting from paraldehyde and Br2, with a catalytic amount of sulfur. So, a small amount of S or SCl2 might be of value in the chlorination of ethanol.

And I still suspect that UV (or bright sunlight) would accelerate the chlorination, just as it does for chlorination of acetic acid. Clearly the same mechanism is at work. As long as temperature control is not compomised I'd think there's no downside.

Sauron - 3-3-2007 at 11:57

OK, thanks to @kmno$ I have the Chem.Rev. piece and there's a gold mine in there. Anyone who is interested can now go retrieve it from page 15 in References.

This flatly states that UV does not assist this chlorination; and that 100 C at the endgame is as important as ) C at the start. In fact by stopping the increase in temperature being input at 30 C only monochloroacetaldehyde is obtained and at 60 C only dichloroacetaldehyde. An electrochemical process is succesful and is detailed. It is possible to use acetaldehyde as substrate rather than ethanol but given the cost relative to ethanol this does not seem worthwhile.

@gc, I trust this will be useful for you.

Eclectic - 3-3-2007 at 17:51

AFAIK, this was a fairly routine prep in organic chemistry college lab courses in the early part of the 20th century (along with barbitol). This is before it was assumed that anyone who could be a drug fiend, would be. Check organic lab texts published between 1910 and 1935.

S.C. Wack - 3-3-2007 at 19:00

The only one that I found it in was Systematic Organic Chemistry, which was the source of the 1.4 figure that I posted earlier. Probably unsuitable for students due to the long time it takes to fully chlorinate.

Sauron - 3-3-2007 at 19:30

I remember seeing it in a lab manual for med tech undergrads taking a lab course in the 50s. No telling how far back it dated, and I no longer have it. That prep used ethanol and hypochlorite, rather than chlorine, so it likely gave a bunch of side products including chloroform.

Chloral and chloral hydrate show up in Org.Syn. as regants but without any preparative details for making them. I'm not sure what that suggests. The stuff remained of industrial important till DDT was banned. It is still of some importance as a useful and versatile reagent (see review referenced above.)
------------
When faced with a chlorination or similar bi-phase rxn I like a tall form reaction vessel when possible. I found that locally I can buy 2 liter graduated cylinders with 45/40 standard taper joints at top, normally for PTFE stoppers. I replace these with an adapter to 29/42 ad add the gas inlet/outlet assy from a standard Corning gas washing bottle 500 ml size which has a 29/42 joint. To this I connect a tube with a fritted glass bubbler of medium porosity either permenently or by a section of an inert tubing. The length is such that the tip of the fritted section leaves just enough room at the bottom for a magnetic teflon spinbar.

The advantage is that the gas (Cl2 or whatever is obliged to pass through a tall column of liquid.

If a lot of gas still makes it out of the reaction mixture, connecting a second cylinder and even a third inline will maximize the utilization of the gas - better than having it go to waste in a scrubber. The cylinders can be inside a larger container for cooling, or can be heated by a bath, or by a wraparound mantle or heating tape, perferably with a thermocouple controller. They are Pyrex so I don't think a 100-120 C heat source is going to bother them.

A setup like this is more efficient than a RB flask and is essentually off the shelf with just a wee bit of integration to accomplish. The 2L size can easily accomodate a stirred 1500 ml reaction charge.

A Claisen adaper could be interposed for a reflux condenser to prevent escape of acetaldehyde in the early stages.


[Edited on 21-9-2007 by Sauron]

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Sandmeyer - 9-3-2007 at 16:37

Chloral is a very useful chemical for isatin synthesis, to make it a controlled substance once again shows their ignorance in the matter of things. But nothing surprises me since the ban of tryptophan in favour of benzos and $$RIs...

[Edited on 10-3-2007 by Sandmeyer]

Sauron - 9-3-2007 at 17:17

It's not so much Big Brother as Big Nanny and if youthink I'm wrong just watch Hillary run. She personifies Big Nanny. Mary Poppins with a law degree and a nasty agenda.

[Edited on 21-9-2007 by Sauron]

guy - 20-9-2007 at 14:17

I am playing around with making chloral hydrate.

I am adding NaDCCA to a solution of Ethanol and 29% HCl. When I did this reaction (outside) late in the evening, I noticed it proceeded fairly slowly and the green color lasted for about 20 minutes before it faded and the reaction temperature did not change that much.

Today I did it in the afternoon with strong sunlight and the green color of chlorine was removed almost instantaneously and the reaction mixture got quite hot. This indicates that Cl2 is being broken into radicals and reacting with the ethanol or acetaldehyde. Cl2 breaks up at 493 nm so this seems quite plausible.

Sauron - 20-9-2007 at 19:09

Yes you probably oxidized ethanol to acetaldehyde which promptly underwent the haloform reaction, which gets quite hot. You made chloroform not chloral.

That is what happens if you do not keep this reaction (targeting chloral hydrate) cold in the first stage.

[Edited on 21-9-2007 by Sauron]

chemrox - 20-9-2007 at 19:36

I think you've got water in the mixture. Also, until you get a condenser (I'm amazed and impressed you've done all these other things without one), rig up a reflux with glass pot and lid inverted with ice on top taking care to keep the melted ice from getting into the mix. or use a long neck flask and funnel .. several ways to do this just think. BTW, how do you get the URL above? It took me to lambdasyn.com/ and no further.

Have you tried to find the original procedure? All the rhodium syns I've seen were excerpted from papers, patents or books.

You might look here:

Winter field, K. - practical course that pharmaceutical chemistry, 6 organic präparativen. Edition, Steinkopff Verl., 1965 • Schwabe and Paffrath - medicine regulation report, Stuttgart: Fischer 1995 • Kuschinsky, Lüllmann, Mohr - short text book of the pharmacology and toxicology, 13. Edition, Stuttgart: Thieme 1993

I got these from a lambdasyn translation ala Google so don't blame the refs on me but should be possible to track down.


[Edited on 20-9-2007 by chemrox]

guy - 20-9-2007 at 20:06

Quote:
Originally posted by Sauron
Yes you probably oxidized ethanol to acetaldehyde which promptly underwent the haloform reaction, which gets quite hot. You made chloroform not chloral.

That is what happens if you do not keep this reaction (targeting chloral hydrate) cold in the first stage.

[Edited on 21-9-2007 by Sauron]


Its possible to get haloform reaction in highly acidic conditions??

Sauron - 20-9-2007 at 20:25

Ah, probably not.

chemrox - 20-9-2007 at 20:55

I think he's half done and has wet chloral in the pot

Sauron - 20-9-2007 at 21:07

The zip file I uploaded above, apparently has become corrupted.

It contained two US patents.

One is the file name so I reacquired it from freepatentsonline.com. It is attached. I am looking for the other patent file, or number so I can get it again too.

[Edited on 21-9-2007 by Sauron]

Attachment: 2669585.pdf (150kB)
This file has been downloaded 952 times


Sauron - 20-9-2007 at 21:28

And here are two more patents and a Chemical Reviews monograph on chloral, I found these in a folder on CD along with the other patent, so I am confident that one of these two was the second patent in the corrupted zip file..

I assembled these as a single pdf, rather than a zip for obvious reasons!

[Edited on 21-9-2007 by Sauron]

Attachment: chloral.pdf (1.4MB)
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MagicJigPipe - 22-9-2007 at 14:22

What about the sodium hypochlorite and NaOH that was probably produced in that reaction because of the water content of the liquor. There would have to at least be some left in there. That can't be good for you.

Sauron - 22-9-2007 at 20:08

What water content?

Ethanol. ANHYDROUS ethanol. Did you bother to read the references?

You were maybe planning to chlorinate vodka?

MagicJigPipe - 22-9-2007 at 22:55

The only post that refers to using LIQUOR.

"Some bacardi 151 proof rum [yellowish tint] was poured into a beaker along with more than enough iodized table that would disolve in it. "

[Edited on 9-23-2007 by Polverone]

Sauron - 22-9-2007 at 23:13

Oh, I DO see some rather stupidposts by a guy named punk quite appropriately, BACK ON PAGE 1. THIS IS PAGE 3.

If you insist on replying to ancient posts the standard practice is to use the Quotes key so that members will see what you are referring to.

[Edited on 9-23-2007 by Polverone]

S.C. Wack - 16-6-2008 at 00:27

US2443183 may be of interest to those interested in ethanol chlorination.
BTW it mentions the danger of explosions, which I'd not seen explicitly mentioned before.
It is related to US2478152, both by O.W. Cass for DuPont.

[Edited on 16-6-2008 by S.C. Wack]

Ritter - 22-6-2008 at 13:14

Quote:
Originally posted by S.C. Wack
US2443183 may be of interest to those interested in ethanol chlorination.
BTW it mentions the danger of explosions, which I'd not seen explicitly mentioned before.
It is related to US2478152, both by O.W. Cass for DuPont.

[Edited on 16-6-2008 by S.C. Wack]


I scanned this entire thread to see if anyone posted these patent refs. Way to go, Wack!

The usual procedure in chemical research is to first define the task or problem, then check ALL of the original source literature BEFORE starting any lab work. The saying goes: A day in the library is worth a week in the laboratory. The case of chloral hydrate raises an additional caveat: oxidizing absolute EtOH with chlorine can lead to fires & explosions. Spending the time required to check the background lit sure beats having to explain what you were up to in your home lab to the policeman & fire chief after they put your house fire out!

In general, I would never take something found on the Web & trust it as being accurate without checking the literature first. Mistakes get made, things that are wrong get repeated, things get left out. Webmasters at rhodium & erowid are not necessarily trained chemists or trained transcribers. And there are even errors in the literature, which is why you have to check as many references as you can before you start working with chemicals.

Since few of us have ready access to back issues to journal articles, a handy (as in free) reference database is in patents. A great tool is the new search engine by Google found at http://www.google.com/advanced_patent_search. They did an OCR scan of the entire U.S. Patent database and you can search it by key word, as in 'chloral hydrate.' The DuPont patents referenced above show up in the first page of results. But be careful: their database is not complete & the OCR process garbled a lot of names & words, so no search in this database is going to be even close to 100%. But at least it's a start.

For patents issued after 1976, the USPTO search interface at http://www.uspto.gov/patft/index.html is more thorough but it would miss the DuPont patents because they issued prior to 1976. You do need a TIFF viewer (free download) to see the patents in full image. To search patents prior to 1976 you have to search by patent Class, which can get very confusing & very time-consuming even for trained chemists/patent lawyers. For example, the DuPont US2478152 can be found in the following patent Classes: 204/157.9 ; 204/157.93; 568/487; 568/488; 568/599; 568/676

[Edited on 22-6-2008 by Ritter]

Sauron - 22-6-2008 at 13:55

When I was a student sometime after the Big Bang and before recorded history, it was pounded into me not to place too much faith in chemical patents. This is not to say ignore them; just don't take them at face value.

A half century in organic chemistry has done nothing to erode that pedagogy. Neither has extensive experience with patent lawyers, the application drafting process and prosecution of such application.

The chemical literature, particularly that of the last and present centuries, is terra firma. The rest is all too often a quagmire.

Ritter - 23-6-2008 at 05:18

Quote:
Originally posted by Sauron
When I was a student sometime after the Big Bang and before recorded history, it was pounded into me not to place too much faith in chemical patents. This is not to say ignore them; just don't take them at face value.

A half century in organic chemistry has done nothing to erode that pedagogy. Neither has extensive experience with patent lawyers, the application drafting process and prosecution of such application.

The chemical literature, particularly that of the last and present centuries, is terra firma. The rest is all too often a quagmire.


My point was that few here have ready access to the original journal articles but instead have free access to the patents. They are a major improvement over relying instead on syntheses found on clandestine drug web sites.

[Edited on 23-6-2008 by Ritter]

[Edited on 23-6-2008 by Ritter]

Sauron - 23-6-2008 at 05:57

Ritter, please be advised that many or most of us here do have access to a great many major primary journal archives. Some online, some on the ftp servers associated with the forum, some downloaded onto CD or DVD or HDD so that we don't have to go online at all in many instances. I have most of the Beilstein Hauptwerk in pdf for example, and quite a bit of Houben-Weyl, not to mention several editions of Merck, Ullmann's, Kirk-Othmer - all secondary lit. to be sure, but I also have many complete journal sets.

I can tell you that all of Chem.Ber. prior to 1902 is available free online. After that, from Wiley and some of us have access and share with each other. Ditto J.Prakt.Chem., Liebig's Annalen, Cptes Rend, etc.

And books, hundreds of gigabytes of organic chemistry books.

Sure the patent lit. has its place. But I recommend you get the PW for References, and have someone explain to you how to get onto the various ftp servers. I hope you have a lot of disk space. You will need it!

Ritter - 23-6-2008 at 06:35

Quote:
Originally posted by Sauron
Ritter, please be advised that many or most of us here do have access to a great many major primary journal archives. Some online, some on the ftp servers associated with the forum, some downloaded onto CD or DVD or HDD so that we don't have to go online at all in many instances. I have most of the Beilstein Hauptwerk in pdf for example, and quite a bit of Houben-Weyl, not to mention several editions of Merck, Ullmann's, Kirk-Othmer - all secondary lit. to be sure, but I also have many complete journal sets.

I can tell you that all of Chem.Ber. prior to 1902 is available free online. After that, from Wiley and some of us have access and share with each other. Ditto J.Prakt.Chem., Liebig's Annalen, Cptes Rend, etc.

And books, hundreds of gigabytes of organic chemistry books.

Sure the patent lit. has its place. But I recommend you get the PW for References, and have someone explain to you how to get onto the various ftp servers. I hope you have a lot of disk space. You will need it!


So you made my point: there can be no excuse for not performing an adequate literature search before starting a new synthesis project.

Sauron - 23-6-2008 at 08:18

That point was never in dispute as far as I am concerned.

Though in the case at hand I am skeptical about any explosion hazard in the chlorination of ethanol, a reaction that has been scrutinized for 180 years. Certainly none on the bench scale.

ScienceSquirrel - 23-6-2008 at 08:57

I think that the chance of an explosion is remote but possible.
The first step in the formation of chloral hydrate is the reaction of chlorine and ethanol to form ethyl hypochlorite.
This then breaks down to form ethanal ( probably via a radical mechanism ) and hydrogen chloride.
Accumulation of ethyl hypochlorite in the reaction mixture or overheating in the early stages could cause the ethyl hypochlorite to explode.
Protonation / deprotonation of the ethanal then yields the enol which undergoes electrophilic attack by chlorine.
Raising the temperature is required as the substitutions proceed as the mono and di substituted aldehydes are more resistant to reaction.

Ritter - 23-6-2008 at 10:15

Quote:
Originally posted by ScienceSquirrel
I think that the chance of an explosion is remote but possible.
The first step in the formation of chloral hydrate is the reaction of chlorine and ethanol to form ethyl hypochlorite.
This then breaks down to form ethanal ( probably via a radical mechanism ) and hydrogen chloride.
Accumulation of ethyl hypochlorite in the reaction mixture or overheating in the early stages could cause the ethyl hypochlorite to explode.
Protonation / deprotonation of the ethanal then yields the enol which undergoes electrophilic attack by chlorine.
Raising the temperature is required as the substitutions proceed as the mono and di substituted aldehydes are more resistant to reaction.


DuPont has a big thing about safety. They would not have mentioned that in the patent if it weren't a real possibility. Absolute EtOH is extremely flammable & a lot of energy is getting released in the chlorine oxidation.

[Edited on 23-6-2008 by Ritter]

Sauron - 23-6-2008 at 19:13

The literature of chloral is huge. It spans almost two centuries, and has been thoroughly reviewed in recent time. The patent literature continues well into the second half of the 20th century. Yet this mention in a single patent is apparently the only time that mention has been made of any such explosion hazard.

Of course EtOH is flammable. That does not mean distilleries burn down every week.

The normal procedure is to chlorinate not quite anhydrous ethanol (read the review of chloral I posted elsewhere) at 0-20 C until a certain mass gain and density are chieved and then to increase the chlorine flow, the heat of reaction will raise the pot temperature until reflux.

If anyone is concerned about chlorination of ethanol, you can just chlorinate acetaldehyde this skipping the whole ethyl hypochlorite phase.

As for flammability, try chlorinating CS2 sometime.

leu - 24-6-2008 at 17:12

It's said that ethyl hypochlorite can detonate if superheated, in the presence of copper powder or in bright sunlight :o An earlier review of the chemistry of choral and chloral hydrate was published by Hirwe in the Journal of the University of Bombay 6 Pt II, 182-198 (1937) :D Chloral has been used to dry halogenated fire extinguishing compounds :cool:

Attachment: DE554521C1.pdf (130kB)
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Ritter - 24-6-2008 at 17:31

Quote:
Originally posted by Sauron

Of course EtOH is flammable. That does not mean distilleries burn down every week.



Distilleries are not using a powerful oxidizing agent such as chlorine.

Sauron - 24-6-2008 at 18:20

Prudence is one thing. Paranoia and fear-mongering is quite another.

The patent mentions a remote possibility in context of an industrial scale chlorination of ethanol, the province of process C.E.s.

I would characterize the remoteness of the hazard in a bench scale chlorination of ethanol, conducted competently, as extreme. Extremely remote. Surely the essential absence of such hazard in the voluminous literature of chloral, supports my estimate.

In short it was simply not a very good example of the sort of detail to be unearthed in a prudent search of the lit.

I conducted a prudent search of the lit. on chloral and I intend to make chloral, for purpose of converting to CCl4. If I blow myself up, feel free to say "I told you so" as much as you like. :)

mrmz88 - 29-6-2008 at 19:10

ok can someone please give me/us a simple step by step procedure to making chloral hydrate. i can easily get 95% pure ethanol aka everclear/goldengrain. thats not an issue. just give me some simple step by step directions, i dont care for why this happens or the reactions and wut this means. just what to do, what happens, and then what else to do, etc. till finish.

like:'

1) mix this with this

2) heat this with that

3) do this

4) mix that here let it sit for a few days

5) mix this heat that

6) filter this

simple pls. and there may be fancy shmancy ways out there to make this stuff but i need a method that uses the simplest easiest to get chemicals. if something isnt easy to get then give me an easy way to cook it up myself.

[Edited on 29-6-2008 by mrmz88]

UnintentionalChaos - 29-6-2008 at 19:47

Quote:
Originally posted by mrmz88
ok can someone please give me/us a simple step by step procedure to making chloral hydrate. i can easily get 95% pure ethanol aka everclear/goldengrain. thats not an issue. just give me some simple step by step directions, i dont care for why this happens or the reactions and wut this means. just what to do, what happens, and then what else to do, etc. till finish.

like:'

1) mix this with this

2) heat this with that

3) do this

4) mix that here let it sit for a few days

5) mix this heat that

6) filter this

simple pls. and there may be fancy shmancy ways out there to make this stuff but i need a method that uses the simplest easiest to get chemicals. if something isnt easy to get then give me an easy way to cook it up myself.

[Edited on 29-6-2008 by mrmz88]




Absolutely not. Stop asking for blatant spoonfeeding and take your cookery elsewhere. First of all, this is a relatively simple concept. If you can't even take the time to read the thread and figure it out, I wouldn't trust you with a wooden cooking spoon, much less the necessary chlorine gas.

If the mods want to snip this post out along with the drek above it, go ahead.

[Edited on 6-29-08 by UnintentionalChaos]

Sauron - 29-6-2008 at 20:20

There's an excellent review of chloral chemistry from Chem.Rev. which I posted here some time back, perhaps in this very thread. If you read the thread perhaps you will find it. Early on the review described this preparation, which is rather simple.

mrmz88 - 29-6-2008 at 21:47

Quote:
Absolutely not. Stop asking for blatant spoonfeeding and take your cookery elsewhere. First of all, this is a relatively simple concept. If you can't even take the time to read the thread and figure it out, I wouldn't trust you with a wooden cooking spoon, much less the necessary chlorine gas.

If the mods want to snip this post out along with the drek above it, go ahead.

[Edited on 6-29-08 by UnintentionalChaos]


why? ur afraid ill asplode someones house up? well i probably will trying to figure out all this crap i dont care about. just give me simple directions and then i wont have to look up stuff and get confused and then nothing will blow up.

Quote:
There's an excellent review of chloral chemistry from Chem.Rev. which I posted here some time back, perhaps in this very thread. If you read the thread perhaps you will find it. Early on the review described this preparation, which is rather simple.


u said "its on page 15 in references" but i dunno how to get in and it says u need permission from moderator or something

[Edited on 29-6-2008 by mrmz88]

[Edited on 29-6-2008 by mrmz88]

MagicJigPipe - 29-6-2008 at 22:12

Judging from your intentions you do not need to be working with Cl2. Nobody is going to willingly do what you are asking so just stop. There are other sites that better suit your needs. I don't think I can mention them here but, you can figure it out. I think...

And it's not about "asploding" anything. It's about gassing yourself with chlorine or getting caught doing this and damaging the reputation of home chemistry which is very likely judging solely from the quality of your posts. No offense. Really. (but I sure hope "88" isn't your birth year). In that case it is my opinion that you are too old to be spoonfed. Get a knife and fork and chew your own food! *pathetic attempt at a "metaphor"/"analogy"*

[Edited on 6-30-2008 by MagicJigPipe]

cheeseandbaloney - 4-7-2008 at 21:28

Hey I'm young (my birth year is '84), but people like this are what give amateur chemists a bad name! More than half the time I'm more interested in the mechanisms of a reaction (mainly organic chem) than the final product itself! Long time lurker, first time poster by the way. Anyways, take the time to know what you're doing before you do it! You may just learn something, :-D

not_important - 4-7-2008 at 22:19

Quote:
but i dunno how to get in and it says u need permission from moderator or something


A good way to get that is to contribute to the discussions in a constructive way, using conventional language. Asking for recipes is generally frowned on here as the emphasis is on learning why as much as how.

Or you can learn how to use search engines and track down the old, out of copyright books that have descriptive preparation methods in them, download them, and go from there.

Bezaleel - 26-10-2010 at 15:06

Quote: Originally posted by guy  
I am playing around with making chloral hydrate.

I am adding NaDCCA to a solution of Ethanol and 29% HCl. When I did this reaction (outside) late in the evening, I noticed it proceeded fairly slowly and the green color lasted for about 20 minutes before it faded and the reaction temperature did not change that much.

Today I did it in the afternoon with strong sunlight and the green color of chlorine was removed almost instantaneously and the reaction mixture got quite hot. This indicates that Cl2 is being broken into radicals and reacting with the ethanol or acetaldehyde. Cl2 breaks up at 493 nm so this seems quite plausible.


I've read through this thread, and as far as I can see, there have been mentioned only two experimantal attempts at chloral or its hydrate:

1. chlorination of ethanol by bubbling chlorine through (cooled) ethanol;
2. the method quoted above.

This experiment is interesting as it gives experimental evidence of the influence of light on the speed of at least the intial chlorination step. I'm willing to take on an experimental attempt to produce chloralhydrate, but not if it requires bubbling chlorine for hours. My question is: what does DCCA stand for?

------------------------------

Since it is my aim to produce trichloroacetate, not chloralhydrate, does anyone know of an easy procedure to chlorinate acetic acid or an acetate solution? (rather than of producing chloralhydrate and oxidising it or trichloroacetate) Important to me is that I really want the trichloroacetate, not mono- and dichloroacetate, because they have a different behaviour in complexation.


entropy51 - 26-10-2010 at 16:15

Quote: Originally posted by Bezaleel  
My question is: what does DCCA stand for?

Use the Fantastic Search Engine

Bezaleel - 28-10-2010 at 16:06

I did a Google search and didn't get an answer in the first 2 pages. Maybe I was sleepy.
This forum, however, states here that DCCA stands for dichloroisocyanurate, or rather DiChloroisoCyanuric Acid. (Added it to wiki disambiguiation.)

Renaissance Man - 16-1-2011 at 15:17

I ran a very basic rig with a graham condenser on a ground glass flask with marbles inside to boost the volume of anhydrous ethanol and slow down bubble flow, chlorine went through a fish tank diffuser stone going into the flask. The chlorine was made from a hypochlorite style generator, and was dried with CaCl2. I barely got into the process when I realized that my Cl2 generator would need constant babying to keep running so I shut everything down for the day. I disconnected everything and poured the alcohol or whatever was formed (most likely a bit of acetaldehyde) into another flask. But before I could stopper it I noticed an odd smell, it was diffidently not chlorine, HCl, or ethanol; it most closely resembled chloroform but not quite.

I was curious so I wafted some more of the gas up to my nose. It was very chloroform-esque. I thought it might just be some acetaldehyde or something, no big deal at the fraction of a milliliter levels I would have inhaled, you would get more from an alcoholic beverage. But then about 15 minutes later I started to feel profoundly woozy, like I was sinking into my chair, and gravity was not quite right. I am feeling dizzy and perhaps a bit sedated right now. I never intended for this to happen, all the intermediates are mildly toxic. I just would not have thought that the little bit form the air would have gotten me this much. The strangest thing is that I did not put anywhere near enough Cl2 in to make any chloral, I would think I would have been lucky even to have gotten much acetaldehyde or monochloroacetaldeyde. It was not like the kind of dizziness that comes when you accidentally spill chloroform and smell a bit too much of it when you clean it up, that is immediate and I always get the hell out of the room before I pass out when it happens; No this took about 15 minutes to become noticeable.

Perhaps it is the acetaldehyde, but I would just expect nausea from that and not sedation, and I would have thought the amount of acetaldehyde to cause any effect would be much higher than what was just coming off of the flask. (this was at -5 C mind you) Perhaps a small amount of monochlorinated or dichlorinated intermediate was formed, but I would have thought that even if they had enough potency to do this that they would be too heavy/high boiling point to vaporize in enough quantity to have an effect.

Oh, and please excuse any grammar or spelling mistakes mistakes, its a bit hard to put my thoughts together at the moment. Any theories on what this could be? All I can say is the feeling is not very pleasant.

reaction mechanism for chloral hydrate

AndersHoveland - 4-5-2012 at 21:47

Some of you may be wondering how the reaction proceeds, why only one of the carbon atoms gets chlorinated, and what the reaction mechanism is. While I am not entirely sure, here is my speculation.

The chlorination of ethanol under different conditions can produce an ethyl hypochlorite ester.
http://www.sciencemadness.org/talk/viewthread.php?tid=1896&a...

CH3CH2OH + Cl2 --> CH3CH2OCl + HCl

I suspect ethyl hypochlorite is not particularly stable, and could decompose on heating, in a similar way to the tautomerisation of acetone into its enol form.

CH3‒CH2‒O‒Cl

CH3‒CH=O Cl[-] H[+]

H[+] CH2=CH‒O[-] HCl

CH2=CH2‒OH HCl
(this tautomer of acetaldehyde would immediately become chlorinated by more chlorine, and indeed it is likewise known that acetone can be chlorinated in the same way to chloroactetone)

Cl‒CH2‒CHCl‒OH

Cl‒CH2‒CHCl‒O[-] H[+]

Cl‒CH2‒CH=O Cl[-] H[+]

This chlorination process then repeats again two more times until the acetaldehyde is fully chlorinated on the β-carbon atom.

Cl3C‒CH=O
(at this point the chlorines are electron-withdrawing enough to make the aldehyde group acidic, and so it "hydrates" with water)

Cl3C‒CH(OH)2


[Edited on 5-5-2012 by AndersHoveland]

Steam - 30-8-2014 at 19:21

Sorry for bring this back from the dead but I have a few questions.
I know that primary alcohols have difficulty being halogenated by direct chlorination. This is why usually a catalyst is employed. I believe SbCl3 was mentioned as a catalyst.

The reaction of EtOH to Chloral is as follows
H3CCHO + 3 Cl2 + H2O → Cl3CCH(OH)2 + 3 HCl

If SbCl3 is used wont conditions have to be anhydrous to prevent hydrolysis of the salt? SbCl3 + H2O → SbOCl + 2 HCl

Perhaps I am missing something here and the SbOCl is the catalyst the RXN actually uses.


Second question. Wouldn't it just be easier to directly chlorinate acetylaldehyde? Disolve Cl2 gas in a solution of ethanal and expose it to hard UV light to initiate the reaction?







[Edited on 31-8-2014 by Steam]

Hawkguy - 14-8-2015 at 19:44

In the Erowid synthesis of Chloral Hydrate, two things stand out to me. 1: Would the use of Sulfuric Acid as a dehydrating agent form any unwanted byproducts/ hinder the total yield? 2: Apparently the presence of base can break down the Chloral Hydrate, would the Calcium Oxide used in the synthesis do that?

If any of these questions could be answered, that would be great. I understand the initial formation of Chloral, but not its stability during purification.

Hawkguy - 21-8-2015 at 20:39

Don't know think I have much Chloral Hydrate, but here's my results. 40ml 95% Ethanol was put in a 500ml round bottom flask. 5 drops of 12M Hydrochloric Acid was added. Attached was a 300mm Liebig Condenser, set up for crude reflux. A stoppered 500ml filter flask was set up alongside, with a tube attached to the tabulation. The tube led to a 200mm glass pipet, leading into the condenser from the top, extended until the end of the pipet was just at the level of the flask neck. Clorine was generated in the filter flask, and filled the round bottom flask. A green colour was observed in less than a minute. The colour went away after 2 minutes, as the Chlorine began to react with the Ethanol to form Hydrochloric Acid and Acetaldehyde. The Acetaldehyde refluxed gently. This continued for one hour. The Acetaldehyde mixture was now heated and refluxed. Two ice cubes were added. I know at this point that a lot of Acetaldehyde remained unchlorinated, so tomorrow I'll recover it and chlorinate it. Interesting way to make Acetaldehyde, if nothing else. I wonder if I inhaled any Chloral Hydrate vapour, as I am ridiculously tired for the time of day, I usually sleep 3 hours later than now, but at the moment I feel subdued and have a hard time keeping my eyes open.

[Edited on 22-8-2015 by Hawkguy]

GrayGhost - 23-8-2015 at 14:39

Hi, here in the german forum http://www.versuchschemie.de/topic,13125,-Chloralhydrat.html they synthetize chloral, is nasty stuff for chlorine and many hours of reactions.

I hope help you my friend.







_________________________________________________
Im don´t chemist, i am blacksmithing.

Hawkguy - 23-8-2015 at 16:55

Okay so it wasn't Chloral Hydrate just got wackered on Ethanol and Acetaldehyde vapour. Worst headache OF MY LIFE.

Chloral hydrate synthesis

erich_zurich - 9-11-2015 at 16:48

I talked about synthesis of chloral hydrate from trichloroethylene and hypochlorous acid. I also tried a improved synthesis of chloral hydrate from ethanol, chlorine gas and by utilizing UV light to initiate the free radical chlorination reaction, I will describe both procedures.

GENERAL PROCEDURE (1) WITH TRICHLOROETHYLENE


100ml of concentrated bleach is added to a 500ml flask and cooled to 0'C on an ice bath next 60ml of glacial acetic acid is added to 100ml of distilled H2O and cooled to 32'F and added to the cooled solution of bleach drop-wise over the course of 10 minutes, temperature must be keep low to prevent chlorine gas from evolving, next 90 ml of trichloroethylene is added and the temperature is allowed to rise to room temperature while stirring at a moderate speed. The reaction mixture is allowed to react for 48-72 hours, this mixture is then steam distilled collecting the first 100ml of distillate. The distillate is added to several grams of anhydrous sodium sulfate and filtered, the filtrate is added to an equal volume of concentrated sulfuric acid and distilled at 190'F with a fractionizing column, the first fraction is unreacted trichloroethylene which is discarded, then temperature is raised to 210F collecting this fraction which is chloral. Lastly the chloral that is collected was added to 1/9th its weight of distilled water and gently heated and cooled to produce crystalline chloral hydrate total yield 58%, other products accounting for total lost of yield hexachloroethane.

GENERAL PROCEDURE (1) MODIFIED REACTANTS.

Trichloroethylene 90ml, Trichloroisocyanuric 80g. then a 5:1 mixture of acetone/water as the solvent. This mixture is stirred at room temperature for 3 hours and then the liquid is gently boiled for a short time to evaporate off the acetone, and allowed to cool, after which the reaction mixture is extracted with ether, chloroform, or other suitable solvents, the substrate is gently evaporated on a hot water bath to leave chloral, chloral hydrate and unreacted trichloroethylene this step may be skipped but may cause chlorine to evolve in the next step if no fully reacted. Next the substrate is cautiously mixed with an equal volume of concentrated sulfuric acid. During this addition hydrogen chloride or chlorine may be evolved if not purified before hand. Then reaction mixture is distilled and the distillate is neutralized with calcium oxide or carbonate and redistilled. Further purification is performed by fractionation. AT 90° C chloral starts to distill. Chloral is a colorless mobile liquid, which boils at 94.5° C. When mixed with about one-fifth of its weight of water, the mixture slowly solidifies to a crystalline mass of chloral hydrate:



Method #2 MY FAVORITE! SEVERAL TIMES FASTER THAN THE ORIGINAL CHLORINATION METHOD!

100 ml of absolute ethyl alcohol is placed in a ice cooled flask with a black light 10cm away from the flask irradiating it with Ultraviolet light. to the flask a bubbler is added to which a current of dry chlorine gas is passed by maintaining the temperature below 10° C. The chlorine is quickly absorbed, and, after a short time, the reaction flask is connected with a reflux condenser. By gently warming of the liquid to 60° C the saturation of the solution is continued with chlorine gas until it is fully absorbed. The chlorination reaction is complete when the solution reaches density of 1.4 g/ml, then the liquid is gently boiled for a short time and allowed to cool after which it is cautiously mixed with an equal volume of concentrated sulfuric acid. During this addition hydrochloric acid and ethyl chloride are evolved. Then the reaction mixture is distilled and the distillate is neutralized with calcium oxide or carbonate and redistilled. Further purification is performed by fractionation. Remaining ethyl chloride with hydrogen chloride distills off first. Between 70° C and 90° C ethyl alcohol passes over, and from 90° C chloral starts to distill. Chloral is a colorless mobile liquid, which boils at 94.5° C. When mixed with about one-fifth of its weight of water, the mixture slowly solidifies to a crystalline mass of chloral hydrate:


[Edited on 10-11-2015 by erich_zurich]

[Edited on 10-11-2015 by erich_zurich]

[Edited on 10-11-2015 by erich_zurich]

[Edited on 10-11-2015 by erich_zurich]

[Edited on 10-11-2015 by erich_zurich]

[Edited on 10-11-2015 by erich_zurich]

[Edited on 10-11-2015 by erich_zurich]