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Author: Subject: chloral hydrate synthesis
entropy51
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[*] posted on 26-10-2010 at 16:15


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

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Bezaleel
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[*] posted on 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.)
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Renaissance Man
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[*] posted on 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.
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AndersHoveland
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[*] posted on 4-5-2012 at 21:47
reaction mechanism for chloral hydrate


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]
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[*] posted on 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]




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[*] posted on 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.
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[*] posted on 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]
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[*] posted on 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.







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[*] posted on 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.
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[*] posted on 9-11-2015 at 16:48
Chloral hydrate synthesis


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]
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