Sciencemadness Discussion Board

gasoline chlorination

Lithium - 3-3-2012 at 18:01

hello

i have added 20ml gasoline to a small beaker and added 8ml of 31% hcl and 20ml of water. i then slowly added solid calcium hypochlorite pellets with the release of chlorine gas. it started to turn red after 2 minutes.after ten minutes of chlorination it smells unbelievabley strongly of licorice, and is again yellow.
it also smells like a farmiliar solvent but i can't quite put my finger on it. there is now 3 layers, the water one, a milky intermediate and the gasoline layer.

does anyone know what i have made?

Li

weiming1998 - 3-3-2012 at 18:12

The gasoline layer contains mainly gasoline and a small amount of chloroalkanes that are formed. The water layer contains H2O and dissolved CaCl and the milky layer contains very fine undissolved CaCl+excess Ca(ClO)2

Is your goal to make chloroalkanes? If it is, then:
1, Use a clear vessel under heavy sunlight (Cl2 decomposes into the Cl. radical, which then reacts with the CH3. radical formed to create a variety of chloroalkanes
2, Use a large vessel or small amounts of material (stops unreacted chlorine gas from escaping.
3, I don't think such large chains of chloroalkane is polar enough to form homogeneous mixes with water, so decant the clear (not opaque, but doesn't matter the colour) layer out.it should be your chloroalkane.

Lithium - 3-3-2012 at 18:25

no i didn't intend on recovering anything, just wanted to see what would happen.

after that i am never doing it again.

it produduce a foul smelling product, and i think it might be very toxic.

i added all the solution to 1l of water and lots of little crystals formed, i presume these are undissolved CaCl2 crystals.

i have a headache( ahhh the smell of chlorinated hydrocarbons ), and not too well, and my eyes feel like there is something pushing them outwards, only gently though.

add
the smell is like i have been boiling black licorice.
Li

[Edited on 4-3-2012 by Lithium]

[Edited on 4-3-2012 by Lithium]

weiming1998 - 3-3-2012 at 18:39

You have probably breathed in too much chlorinated hydrocarbons and chlorine gas, so that's why the headache. If you still don't feel well after a few hours to a day, maybe go to the hospital. But I suppose it'll be hard to explain how a person came in contact with a chloroalkane to a doctor!

Lithium - 3-3-2012 at 18:51

yes, that would be an awkward conversation!:D

i feel a bit better now but my main problem is disposing of it.

should i get my shovel;), or should i take it to the tip?

Li

weiming1998 - 3-3-2012 at 18:55

If the amount is small, it can just be left to evaporate away. It degrades quickly in the atmosphere.

Lithium - 3-3-2012 at 18:59

that's the problem, it smells horrendous, and my mum would probably have an asthma attack if she got near it

ill take it WAY down the back

Li

ThatchemistKid - 3-3-2012 at 19:39

You should really be careful with halogenated alkanes as they tend to alkylate your DNA. Breathing in any of it is not really a good idea at all.

entropy51 - 3-3-2012 at 21:25

Quote: Originally posted by Lithium  
hello

i have added 20ml gasoline to a small beaker and added 8ml of 31% hcl and 20ml of water. i then slowly added solid calcium hypochlorite pellets with the release of chlorine gas. it started to turn red after 2 minutes.after ten minutes of chlorination it smells unbelievabley strongly of licorice, and is again yellow.
it also smells like a farmiliar solvent but i can't quite put my finger on it. there is now 3 layers, the water one, a milky intermediate and the gasoline layer.

does anyone know what i have made?

Li
You just randomly mixed some chemicals without having any idea what reaction would occur or what the products might be?

Every beginners chemistry book warns that this is not a good idea.

Even worse, the calcium hypochlorite package probably warns that this material is a strong oxidizer and is not to be mixed with organic materials since an explosion may occur.

You are sure to win a Darwin Award if you continue down this path,

weiming1998 - 3-3-2012 at 23:14

Quote: Originally posted by entropy51  
Quote: Originally posted by Lithium  
hello

i have added 20ml gasoline to a small beaker and added 8ml of 31% hcl and 20ml of water. i then slowly added solid calcium hypochlorite pellets with the release of chlorine gas. it started to turn red after 2 minutes.after ten minutes of chlorination it smells unbelievabley strongly of licorice, and is again yellow.
it also smells like a farmiliar solvent but i can't quite put my finger on it. there is now 3 layers, the water one, a milky intermediate and the gasoline layer.

does anyone know what i have made?

Li
You just randomly mixed some chemicals without having any idea what reaction would occur or what the products might be?

Every beginners chemistry book warns that this is not a good idea.

Even worse, the calcium hypochlorite package probably warns that this material is a strong oxidizer and is not to be mixed with organic materials since an explosion may occur.

You are sure to win a Darwin Award if you continue down this path,


It's probably not random mixing; I bet that he/she just want to see if gasoline, which is mainly made of alkanes, can be chlorinated like methane.

Calcium hypochlorite, especially in granule form, is not that bad. Provided, it can go hypergolic with glycerol or ethylene glycol, but the point here is the exposture time of the hypochlorite to the organic. Letting calcium hypochlorite sit inside unconfined glycerol for a few seconds won't even ignite, let alone a hydrocarbon like gasoline, which is, apart from oxygen, chlorine or fluorine or bromine directly oxidizing it, pretty inert. A few seconds later, the hypochlorite will react with the HCl at the bottom, producing chlorine gas and CaCl2. Not even any hypochlorous acid will form because it directly combines with the HCl to form chlorine gas and water.

The only potential safety issue of this is if you breathe in the vapours, or if the chlorine causes the gasoline to ignite (even alkanes are still vulnerable to the oxdizing power of chlorine).

Lithium - 4-3-2012 at 01:31

i thought that octane, a cosistuent of gasoline, could be chlorinated and then hydrolised to octanol. i did not get far enough to extract the chloro octane. the hypochlorite was in contact with the gasoline for 1-2 seconds before sinking to the bottom, which is where the water/hcl layer was. i have tried to get Ca hypochlorite and glycerin to flame but to no avail. i had a fire extinguisher at the ready if things got out of hand, and 2L of water in a bucket next to me. i don't feel sick anymore, so that's good. i did this on reasonably small scale so i doubt an explosion would result.( lucky i couldn't find those buckets:D )

thanks for sticking up for me weiming1998:)

Li

weiming1998 - 4-3-2012 at 02:00

Yes, it could be chlorinated to form a chloroalkane, but to convert that into an alcohol, you will need a basic solution (The H+ in H2O is too attracted to the OH- to steal the Cl- away from the chloroalkane). A sodium hydroxide solution should be enough to donate the OH- ion to the alkane. It will be difficult to separate the unreacted gasoline from the alcohol though. Try separating it by allowing the excess gasoline to evaporate, if it forms a homogeneous mix.

As for glycerol+Ca(ClO)2, wrap the hypochlorite up in Al foil first, or it will not burn, just smoke. Leave a small opening to pour the glycerol in. After this, pinch the opening shut and wait for a minute or so. If a white, opaque smoke rises up, it indicates that it is about to explode. After that, it makes a cracking sound and bursts in flames. I suppose the al foil did the job of sealing the heat to the decomposition temp of Ca(ClO)2, and pressurizing the mix.

Nicodem - 4-3-2012 at 03:08

Quote: Originally posted by weiming1998  
Yes, it could be chlorinated to form a chloroalkane

Where are the references for such unusual claims about octane or other alkanes being chlorinated? Where did you read that alkanes react with Cl<sub>2</sub> under non-radical conditions? I'm quite sure you confused the electrophilic addition of Cl<sub>2</sub> on alkenes with the radical chlorination of alkanes. The two reactions have nothing in common when it comes to their reaction mechanism and the required reaction conditions.

The only compounds in gasoline that can react with Cl<sub>2</sub> under the described conditions are the unsaturated hydrocarbons and the aromatic fraction.

PS: Like entropy51 said, ignorant behavior leads to undesirable awards.

weiming1998 - 4-3-2012 at 03:26

Quote: Originally posted by Nicodem  
Quote: Originally posted by weiming1998  
Yes, it could be chlorinated to form a chloroalkane

Where are the references for such unusual claims about octane or other alkanes being chlorinated? Where did you read that alkanes react with Cl<sub>2</sub> under non-radical conditions? I'm quite sure you confused the electrophilic addition of Cl<sub>2</sub> on alkenes with the radical chlorination of alkanes. The two reactions have nothing in common when it comes to their reaction mechanism and the required reaction conditions.

The only compounds in gasoline that can react with Cl<sub>2</sub> under the described conditions are the unsaturated hydrocarbons and the aromatic fraction.

PS: Like entropy51 said, ignorant behavior leads to undesirable awards.


I did not claim that it does not require free radicals. Cl2 spontaneous breaks down into Cl. radical under UV light, which can be provided by the sun. The free radical then attaches itself to small amounts of C8H17. radicals (not sure if these exist, but CH3. radicals do exist in dilute CH4) in the gasoline, producing the desired chloroalkane. This links proves the existance of a longer-chained chloroalkane. http://www.sigmaaldrich.com/catalog/ProductDetail.do?D7=0&am...
I suppose that if it isn't formed by chlorination, then you are right.

Brominator - 4-3-2012 at 03:38

Nicodem is correct alkanes can't be chlorinated by just cl2 with no free radicals if you want to chlorinate gasoline you would need a uv light source for maximum free radical generation ,
but if you are interested in making chloroalkanes i sujest using a much purer starting material than gasoline as even if you do isolate just the chloro-octane it will be many diffrent isomers of chloro octane leading to many different isomers of octanol e.g octan-(1/2/3/4)-ol

Endimion17 - 4-3-2012 at 03:54

Gasoline's contents include not only the simple chains, but branched ones, too. And alkenes. And arenes... It's a quite complex mixture.
Mixing it with calcium hypochlorite, while not knowing what could happen is one of the paths towards an accident. Never do such things again.

And be sure not to breathe in haloalkanes you get by doing this. Some of them really want to intercalate your DNA and proteins. You actually can't know for sure what's inside the reacted mixture. It's a horrifying mess that would have to be fractionally distilled few times, and then each fraction would have to be analyzed using, for example, an IR spectrometer. It's a mess and it isn't useful for a chemist who wants isolated compounds.

weiming1998 - 4-3-2012 at 04:01

I agree with the two posts above that gasoline contains too much other hydrocarbons (alkenes, aromatics, etc) to be successfully chlorinated and isolated without fractional distillation. But where would you get a purer source of alkanes(excluding lab supply stores as they don't sell to individuals)?

Edit: I mean liquid alkanes. Gas ones are too difficult to handle and an explosion hazard for the amateur chemist.

[Edited on 4-3-2012 by weiming1998]

Nicodem - 4-3-2012 at 04:16

Quote: Originally posted by weiming1998  
I did not claim that it does not require free radicals. Cl2 spontaneous breaks down into Cl. radical under UV light, which can be provided by the sun.

Hmm... Read Lithium's first post and then read my previous reply again. Perhaps you will see a certain discrepancy between what you just said and what was already said. That certain discrepancy is what I was already pointing your attention at.
Quote:
The free radical then attaches itself to small amounts of C8H17. radicals (not sure if these exist, but CH3. radicals do exist in dilute CH4) in the gasoline, producing the desired chloroalkane.

Nope. The reaction mechanism is quite different. The chlorine radical formed by the homolysis of Cl<sub>2</sub> first abstracts the hydrogen from the alkane thus forming the alkyl radical. This is then chlorinated by another molecule of Cl<sub>2</sub> forming an alkyl chloride and regenerating another chlorine radical (which reenters the radical chain reaction). See http://en.wikipedia.org/wiki/Free-radical_halogenation for a step-by-step representation.
What you described above is actually a so called chain termination reaction which is a side reaction that can inhibit the radical chain chlorination. Luckily, it is kinetically poorly relevant as the chances of two radicals coupling is very small due to the statistical improbability of such an encounter. If it would be a relevant reaction, then radical chain reactions would simply not work, at least not preparatively.
Quote:
This links proves the existance of a longer-chained chloroalkane. http://www.sigmaaldrich.com/catalog/ProductDetail.do?D7=0&am...
I suppose that if it isn't formed by chlorination, then you are right.

Nobody expressed doubts about the existence of 1-chlorooctane. It is thus sad that you post a link to Sig*a's catalog instead of posting a reference relevant to the topic. Anyway, to bring this on topic, radical chlorination of n-octane does not selectively give 1-chlorooctane, not even remotely so. The reaction step which determines the reaction selectivity depends mainly by three factors, C-H bond homolysis energy, statistics (number of different C-H bonds) and sterics. The first two factors work against the formation of 1-chlorooctane (6 methyl's C-H against 12 methylene's C-H bonds and about 4-fold selectivity of chlorine radicals toward methylenes). Only sterics very slightly works for it. For a more comprehensive review, see the attached excerpt from Free-radical chemistry; structure and mechanism (1974, by D. C. Nonhebel, J. C. Walton; also available as googlebook preview):

radicalhalogenation.gif - 153kB

weiming1998 - 4-3-2012 at 05:27

Quote: Originally posted by Nicodem  
Quote: Originally posted by weiming1998  
I did not claim that it does not require free radicals. Cl2 spontaneous breaks down into Cl. radical under UV light, which can be provided by the sun.

Hmm... Read Lithium's first post and then read my previous reply again. Perhaps you will see a certain discrepancy between what you just said and what was already said. That certain discrepancy is what I was already pointing your attention at.
Quote:
The free radical then attaches itself to small amounts of C8H17. radicals (not sure if these exist, but CH3. radicals do exist in dilute CH4) in the gasoline, producing the desired chloroalkane.

Nope. The reaction mechanism is quite different. The chlorine radical formed by the homolysis of Cl<sub>2</sub> first abstracts the hydrogen from the alkane thus forming the alkyl radical. This is then chlorinated by another molecule of Cl<sub>2</sub> forming an alkyl chloride and regenerating another chlorine radical (which reenters the radical chain reaction). See http://en.wikipedia.org/wiki/Free-radical_halogenation for a step-by-step representation.
What you described above is actually a so called chain termination reaction which is a side reaction that can inhibit the radical chain chlorination. Luckily, it is kinetically poorly relevant as the chances of two radicals coupling is very small due to the statistical improbability of such an encounter. If it would be a relevant reaction, then radical chain reactions would simply not work, at least not preparatively.
Quote:
This links proves the existance of a longer-chained chloroalkane. http://www.sigmaaldrich.com/catalog/ProductDetail.do?D7=0&am...
I suppose that if it isn't formed by chlorination, then you are right.

Nobody expressed doubts about the existence of 1-chlorooctane. It is thus sad that you post a link to Sig*a's catalog instead of posting a reference relevant to the topic. Anyway, to bring this on topic, radical chlorination of n-octane does not selectively give 1-chlorooctane, not even remotely so. The reaction step which determines the reaction selectivity depends mainly by three factors, C-H bond homolysis energy, statistics (number of different C-H bonds) and sterics. The first two factors work against the formation of 1-chlorooctane (6 methyl's C-H against 12 methylene's C-H bonds and about 4-fold selectivity of chlorine radicals toward methylenes). Only sterics very slightly works for it. For a more comprehensive review, see the attached excerpt from Free-radical chemistry; structure and mechanism (1974, by D. C. Nonhebel, J. C. Walton; also available as googlebook preview):



Ok, now I understand the reaction mechanism. I thought the chlorine radical joined with other radicals. Now I know that it did not. Thanks for helping!

bbartlog - 4-3-2012 at 11:40

Regardless of your goals, as a general rule your life will be easier if you purify first (in this case, by fractionally distilling to isolate octane or whatever it is you think your substrate is) and then perform the reaction. There are plenty of exceptions where prior isolation/purification is a waste of time but unless you have specific information to that effect go with 'purify first'...

Endimion17 - 4-3-2012 at 11:52

Quote: Originally posted by weiming1998  
I agree with the two posts above that gasoline contains too much other hydrocarbons (alkenes, aromatics, etc) to be successfully chlorinated and isolated without fractional distillation. But where would you get a purer source of alkanes(excluding lab supply stores as they don't sell to individuals)?

Edit: I mean liquid alkanes. Gas ones are too difficult to handle and an explosion hazard for the amateur chemist.

[Edited on 4-3-2012 by weiming1998]


That's why they should be separated first, because gasoline is consisted of so many different compounds from so many different families of compounds that their chlorinated derivatives might even react with each other. Not to mention that the chlorination itself almost always leads to a mess in the reaction mixture. It's better to reduce the mess in the beginning.

Lithium - 4-3-2012 at 21:31

okay, well i guess gasoline for chlorination is much too impure. i just had some gasoline in a bottle i found and the first thing that popped into my head was to chlorinate it, because that is my favourite thing to do. my second idea was to nitrate it, but i don't have any nitrate source. it was also a test to see if things would get quite bad if i tried chlorinating butane. i have some butane i have saved in a big bottle ( not pressurised ) with a layer of water under it, so it cannot escape. instead of cooling it to a liquid and then chlorinating that ( obviously unsafe, exothermic rxn ), i would like to know how i would go about doing this, or if there is a better way of obtaining butanol. i keep thinking alkanes and alkenes have the same properties, but then i think of the structure of cyclohexane and benzene.:)

Li