Sciencemadness Discussion Board
Not logged in [Login - Register]
Go To Bottom

Printable Version  
 Pages:  1    3  4
Author: Subject: chloral hydrate synthesis
garage chemist
chemical wizard
*****




Posts: 1805
Registered: 16-8-2004
Location: Germany
Member Is Offline


[*] posted on 11-9-2004 at 09:25
chloral hydrate synthesis


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?
View user's profile View All Posts By User
S.C. Wack
bibliomaster
*****




Posts: 1441
Registered: 7-5-2004
Location: Cornworld, Central USA
Member Is Offline

Mood: Enhanced

[*] posted on 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.
View user's profile Visit user's homepage View All Posts By User
Hermes_Trismegistus
International Hazard
*****




Posts: 603
Registered: 27-11-2003
Location: Greece, Ancient
Member Is Offline

Mood: conformation:ga

[*] posted on 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]




Arguing on the internet is like running in the special olympics; even if you win: you\'re still retarded.
View user's profile View All Posts By User
garage chemist
chemical wizard
*****




Posts: 1805
Registered: 16-8-2004
Location: Germany
Member Is Offline


[*] posted on 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]
View user's profile View All Posts By User
S.C. Wack
bibliomaster
*****




Posts: 1441
Registered: 7-5-2004
Location: Cornworld, Central USA
Member Is Offline

Mood: Enhanced

[*] posted on 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.
View user's profile Visit user's homepage View All Posts By User
garage chemist
chemical wizard
*****




Posts: 1805
Registered: 16-8-2004
Location: Germany
Member Is Offline


[*] posted on 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.
View user's profile View All Posts By User
Mephisto
Chemicus Diabolicus
****




Posts: 294
Registered: 24-8-2002
Location: Germany
Member Is Offline

Mood: swinging

[*] posted on 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)"




Visit the German synthesis collection LambdaSyn and our new LambdaForum!
View user's profile Visit user's homepage View All Posts By User
chemoleo
Biochemicus Energeticus
*******




Posts: 3005
Registered: 23-7-2003
Location: England Germany
Member Is Offline

Mood: crystalline

[*] posted on 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?



Never Stop to Begin, and Never Begin to Stop...
Tolerance is good. But not with the intolerant! (Wilhelm Busch)
View user's profile View All Posts By User
Mephisto
Chemicus Diabolicus
****




Posts: 294
Registered: 24-8-2002
Location: Germany
Member Is Offline

Mood: swinging

[*] posted on 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]




Visit the German synthesis collection LambdaSyn and our new LambdaForum!
View user's profile Visit user's homepage View All Posts By User
MadHatter
International Hazard
*****




Posts: 1034
Registered: 9-7-2004
Location: Mid-Atlantic
Member Is Offline

Mood: Patience growing thin !

[*] posted on 11-9-2004 at 16:57
Chloral Hydrate


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




Power comes from the barrel of a gun !
View user's profile View All Posts By User
Mephisto
Chemicus Diabolicus
****




Posts: 294
Registered: 24-8-2002
Location: Germany
Member Is Offline

Mood: swinging

[*] posted on 12-9-2004 at 03:00


Garage chemist: For your next attempt to synthesize choral hydrate, there might be the following improvements:
  • Adding HCl to speed up the reaction
  • Adding SbCl3 as catalyst
  • Gradually increasing from 0 °C to 90 °C during the process
  • Using a bubbler
  • Adding more chlorine (EtOH:Cl2 ratio = 1:4, but most Cl2 escapes unreacted)
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.




Visit the German synthesis collection LambdaSyn and our new LambdaForum!
View user's profile Visit user's homepage View All Posts By User
garage chemist
chemical wizard
*****




Posts: 1805
Registered: 16-8-2004
Location: Germany
Member Is Offline


[*] posted on 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.
View user's profile View All Posts By User
Dodoman
Hazard to Self
**




Posts: 79
Registered: 2-8-2004
Member Is Offline


[*] posted on 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
View user's profile View All Posts By User
BromicAcid
International Hazard
*****




Posts: 2479
Registered: 13-7-2003
Location: Wisconsin
Member Is Offline

Mood: Anxious

[*] posted on 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.




Shamelessly plugging my attempts at writing fiction: http://www.robvincent.org
View user's profile Visit user's homepage View All Posts By User
Mephisto
Chemicus Diabolicus
****




Posts: 294
Registered: 24-8-2002
Location: Germany
Member Is Offline

Mood: swinging

[*] posted on 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]




Visit the German synthesis collection LambdaSyn and our new LambdaForum!
View user's profile Visit user's homepage View All Posts By User
garage chemist
chemical wizard
*****




Posts: 1805
Registered: 16-8-2004
Location: Germany
Member Is Offline


[*] posted on 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.
View user's profile View All Posts By User
Mephisto
Chemicus Diabolicus
****




Posts: 294
Registered: 24-8-2002
Location: Germany
Member Is Offline

Mood: swinging

[*] posted on 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]




Visit the German synthesis collection LambdaSyn and our new LambdaForum!
View user's profile Visit user's homepage View All Posts By User
Darkfire
National Hazard
****




Posts: 292
Registered: 3-1-2003
Location: California
Member Is Offline

Mood: Wondering

[*] posted on 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.



\"I love being alive and will be the best man I possibly can. I will take love wherever I find it and offer it to everyone who will take it. I will seek knowledge from those wiser and teach those who wish to learn from me.\" Duane Allman
View user's profile View All Posts By User
Punk
Hazard to Self
**




Posts: 64
Registered: 22-2-2006
Member Is Offline


[*] posted on 26-2-2006 at 01:54
CHLORAL HYDRATE


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]
View user's profile View All Posts By User
a_bab
National Hazard
****




Posts: 449
Registered: 15-9-2002
Member Is Offline

Mood: Angry !!!!!111111...2?!

[*] posted on 3-3-2006 at 05:11


Be carefull as the chloral hydrate is known to screw up the liver. It's also toxic.
View user's profile View All Posts By User
Mr. Wizard
International Hazard
*****




Posts: 1037
Registered: 30-3-2003
Member Is Offline


[*] posted on 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.
View user's profile View All Posts By User
Mr. Wizard
International Hazard
*****




Posts: 1037
Registered: 30-3-2003
Member Is Offline


[*] posted on 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.
View user's profile View All Posts By User
garage chemist
chemical wizard
*****




Posts: 1805
Registered: 16-8-2004
Location: Germany
Member Is Offline


[*] posted on 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.
View user's profile View All Posts By User
mantis
Harmless
*




Posts: 38
Registered: 17-7-2005
Member Is Offline


[*] posted on 3-3-2006 at 14:38


@garage chemist: Have you ever testet this way?
View user's profile View All Posts By User
garage chemist
chemical wizard
*****




Posts: 1805
Registered: 16-8-2004
Location: Germany
Member Is Offline


[*] posted on 3-3-2006 at 14:40


No, but there's a synthesis on lambdasyn.
http://www.lambdasyn.com/synfiles/chloralhydrat.htm
View user's profile View All Posts By User
 Pages:  1    3  4

  Go To Top