Odin
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Synthesis of 2-chloropropane
This is a simple synthesis procedure but exceedinlly long. It took me about 8 hours to synthesize 10 ml of the stuff.
Take one part of isopropanol and one part hydrochloric acid and mix together. Over low heat(not over 80 Degrees) distill.
Final product should have a swet almond scent.
CAUTION : ***Highly Flammable...Fumes will Ignite and set liquid on fire *** USE IN A WELL VENTILLATED AREA ***
(Chloropropane - CH3CHClCH3)
EbC: Title/spelling.
[Edited on 28-11-2005 by chemoleo]
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Thomas Winwood
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I do so hate trivial names for organic molecules - IUPAC names are so much more helpful in visualising the structure. You of course refer to
propan-2-ol, which reduces this to a bog-standard nucleophilic substitution of the alcohol with the chlorine, where the protons donated by the acid
help by producing the water leaving group -OH<sub>2</sub><sup>+</sup>.
In any case refluxing speeds this up no end.
[Edited on 28/11/2005 by Thomas Winwood]
I\'ve been told having a sig is banned, despite the facility being available. Um...contradiction?
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Odin
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There is Chlorpropane which is
CH2ClCH2CH3 (or CH3CH2CH2Cl )
and 2-Chloropropane
(CH3CHClCH3 )
where 2-chloropropane define the chlorine bond on the second carbon of the hydrocarbon structure.
Chloropropane has the chlorine on either the 1st or 3rd carbon atom and not nessecary to identify the carbon bond.
H H H
Cl- C - C - C-H
H H H
Then there is sec or tris-chloropropane :
Cl H H
H-C- C- C-H
H H H
What I am referring to is indeed 2-chloropropane and not chloropropane or sec-chloropropane.
This is evident from the structure of isopropanol alcohol it is evident where the chemical reaction occurs upon refluxing.
HCl +CH3CH(OH)CH3 =CH3CHClCH3 +H2O
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Odin
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Cant do diagrams on this thread as is obviously observed so spare the sarcasm of the chemical diagrams out of whack
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sparkgap
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Thomas Winwood was correct when he said this is better done with reflux. It would be otherwise "exceedinlly long". 
sparky (~_~)
P.S. "tris-chloropropane"... ouch, that was not a damn correct systematic name... only one chlorine, ya know...
P.P.S. The fact that you were not quite aware of "drying agents" speaks a bit of your experience in organic synthesis. 
[Edited on 29-11-2005 by sparkgap]
"What's UTFSE? I keep hearing about it, but I can't be arsed to search for the answer..."
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Odin
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| Quote: | Originally posted by sparkgap
Thomas Winwood was correct whene he said this is better done with reflux. It would be otherwise "exceedinlly long".
sparky (~_~)
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But if you want an anhydrous product you dont want to evaporate water into the final product so you have to use lower heat procedures or you will have
to distill the product twice.Why do it twice when you only need to do it once
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sparkgap
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If I wanted an anhydrous product, I'd use an appropriate drying agent.
sparky (~_~)
"What's UTFSE? I keep hearing about it, but I can't be arsed to search for the answer..."
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Odin
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| Quote: | Originally posted by sparkgap
If I wanted an anhydrous product, I'd use an appropriate drying agent.
sparky (~_~) |
What are you talking about?
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Darkblade48
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What I think is meant so far is that you should reflux to get the reaction to move along, then if you want an anhydrous product, just stick one of
those drying tubes on top of your reflux condenser to dry your product.
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garage chemist
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Maybe using a column to selectively distill out the 2-chloropropane while gently boiling the mixture might be a good idea. That way the product is
constantly being removed, shifting the equilibrium to the right side.
This reaction (esterification of alcohols with hydrogen halides) is actually very useful, since the formed alkyl chlorides can be used to form
grignard reagents.
Secondary alcohols are esterified much easier than primary alcohols. Chloroethane can't be made by simply distilling ethanol with HCl because the
yields are very low.
Anhydrous zinc chloride has to be used as a catalyst here, and in fairly large amounts.
HBr esterifies much easier, giving good yields of primary alkyl bromides like e.g. ethyl bromide by simple distillation of the HBr/ethanol mix.
The halides are purified by shaking with water, then with bicarbonate solution and then drying with a few pieces of CaCl2.
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neutrino
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>I would think that 50 ml of 100% ethonal and 50ml of 100% HCl would give exactly 50 ml of chloroethane and 50 ml of H2O
First of all, we're talking about numbers of molecules, not volumes.
100% HCl is a gas and I doubt you would mix 50mL of the liquid with anything in a home lab.
Finally, these things don't quite work like this. This is not such a straightforward reaction because an equilibrium is formed:
R-Cl + HOH <---> R-OH + HCl
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kclo4
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I recently tried this..sorta, I mixed an unknown amount of 29% HCl solution with an unknown amount of 70% IPA, i added more HCl then IPA. And I
started refluxing, my reflux wasn't good enough and gases were coming out like a mother. so i added on my other 200mm condenser, and it was still
coming off but not as much, after a short while i decided that i didn't want to lose all my 2-chloropropane so i shut off the heat source and let it
cool in my mini fridge. so i don't have good enough cooling i cant really reflux it, so i added about 25mls of chloroform mainly because i was in
need of the bottle it was in, and that's all that was in that bottle i thought it could extract the 2-chloropropane, i don't know if it did or not or
even if it can!
So i am asking does anybody know if this is a way to go about getting the 2-chloropropane out with the chloroform?
to get the chloroform and 2-chloropropane apart, i could try to distill it with my two 200mm condensers... the heat source can be the sun haha
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orgie
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| Quote: | Originally posted by Odin
This is a simple synthesis procedure but exceedinlly long. It took me about 8 hours to synthesize 10 ml of the stuff.
Take one part of isopropanol and one part hydrochloric acid and mix together. Over low heat(not over 80 Degrees) distill.
Final product should have a swet almond scent.
CAUTION : ***Highly Flammable...Fumes will Ignite and set liquid on fire *** USE IN A WELL VENTILLATED AREA ***
(Chloropropane - CH3CHClCH3)
EbC: Title/spelling.
[Edited on 28-11-2005 by chemoleo] |
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orgie
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2-chloropropane
I recently mixed isopropanol (0.25 mol) with 40 mL konc. HCl (47.g) and anhydrous ZnCl2 68g (o.5mol) and reflux gently for 2 hours.
After that I distilled the reaction product and collected fraction up to 75C. To this fraction I added conc. H2SO4 and refluxed 20 min. to remove some
imuprities that cannot be removed by distillation.
Reaction mixture was washed with 25mL H2O, 10 mL 5% NaOH, 25mL H20. To every wash there was emulsion in upper layer, and I tried to lower it by adding
NaCl-not very succesful.
To sepparated upper layer (2-chloropropane) I added CaCl2 to collect water and reaction mixture distilled (Tv=35C).
I was dissapointed with yield which was 10%.
Any suggestion for better yield???
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vovan78
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orgie: just wash with H2SO4, dont reflux
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eLz
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've tried to synthesize 2-chloropropane, but failed.
whether the results reflux isopropanol, konc. HCl and anhydrous ZnCl2 formed 2 layers?
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