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blogfast25
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I extracted some DOP from 111 g of vinyl flooring, by chopping it up and refluxing it with methylated spirits at BP. The solvent was then distilled
off until about 11 ml was left, presumably mainly DOP and some residual solvent.
The DOP was treated with a stoichiometric amount of 50 w% KOH and heated to BP. An oily liquid collected at the top and upon solidification of the
dipotassium phthalate solution/melt the oily phase was decanted off. It's presumed to be 2-ethyl hexan-1-ol.
It was washed twice with saturated CaCl2 solution and separated with a separating funnel, obtaining about 3.5 g of crude alcohol. It smells positively
weird and not like what some sources claim it should smell like.
The dipotassium phthalate was diluted with some water, heated until it melted/dissolved and strong HCl was added to it: quite a bit of white
precipitate formed: phthalic acid and evidence the extracted product is at least a phthalate.
But it’s not the alcohol I’m interested in but rather the methyl ester of the corresponding acid (2-ethyl hexanoic acid). So an attempt was made
to oxidise the alcohol by means of K2Cr2O7. 100 ml of about 0.2 M K2Cr2O7 (in 1 M H2SO4) was made up and the hot solution added gradually to the
alcohol. Reaction started immediately but gave an unexpected result: a dark brown/blackish sludge with an unpleasant smell resulted. I’ve oxidised
both MeOH and EtOH w/o problems using dichromate in the past.
Some more DOP has now been extracted, this time from 66 g of chopped up vinyl domestic gloves and methylated spirits for another test…
[Edited on 24-5-2011 by blogfast25]
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Magpie
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Quote: Originally posted by blogfast25  |
Some more DOP has now been extracted, this time from 66 g of chopped up vinyl domestic gloves and methylated spirits for another test…
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I'm predicting you'll have better success with the vinyl gloves. I bought a shower curtain to use as a source of DOP but was rather disappointed in
the low yield.
The single most important condition for a successful synthesis is good mixing - Nicodem
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Sedit
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I too suggest using HNO3 to perform the oxidation. This is the only reagent I have tried that gave me good results oxidising EtOH and MeOH to there
respective carboxylic acids without resorting to high PH condition. The runaway can be eliminated by using red nitric acid since the cause of the
runaway is the fact that pure Nitric must decompose and the NO2 is what catalyses the reaction. By the time its hot enough to decompose and start the
reaction its already to hot to control. I found I got some of my best results by forming very concentrated HNO3 using NaNO3 and 97% H2SO4. The heat
generated forming the nitric made sure it was red from the start and then it was a matter of slowly dripping the EtOH into the oxidant. NOx was formed
on a massive scale.
I am still curious about this reaction because the alcohol kept reacting even after equalmolar amounts where used. It seems very easy for HNO3 to
oxidise much more then one mol of substate and im not fully sure why.
Knowledge is useless to useless people...
"I see a lot of patterns in our behavior as a nation that parallel a lot of other historical processes. The fall of Rome, the fall of Germany — the
fall of the ruling country, the people who think they can do whatever they want without anybody else's consent. I've seen this story
before."~Maynard James Keenan
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Magpie
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| Quote: Originally posted by blogfast25 | It's presumed to be 2-ethyl hexan-1-ol.
It was washed twice with saturated CaCl2 solution and separated with a separating funnel, obtaining about 3.5 g of crude alcohol. It smells positively
weird and not like what some sources claim it should smell like.
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I smelled my 2-ethyl hexan-1-ol. It smells like vinyl gloves.
The single most important condition for a successful synthesis is good mixing - Nicodem
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PHILOU Zrealone
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| Quote: Originally posted by Sedit |
I am still curious about this reaction because the alcohol kept reacting even after equalmolar amounts where used. It seems very easy for HNO3 to
oxidise much more then one mol of substate and im not fully sure why. |
That's an easy one  
CH3-CH2OH + HNO3 --> CH3-CO2H + NO + NO2
NO + 1/2 O2 --> NO2
H2O + 3 NO2 --> 2 HNO3 + NO
So most of your NxOy are regenerated again as HNO3 for a second, a third, ....rounds again and again.
This would be infinite if there was no escape of NxOy and full supply of O2 from air...
PH Z (PHILOU Zrealone)
"Physic is all what never works; Chemistry is all what stinks and explodes!"-"Life that deadly disease, sexually transmitted."(W.Allen)
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blogfast25
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So 66 g of chopped vinyl gloves were refluxed for 2 h with 300 ml of methylated spirits at BP, at high reflux ratio (some solvent was allowed to come
over).
The obtained liquid (171 g) was slightly yellowish and slightly turbid but filtered (No 1 filter) well to a clear solution.
The solvent was distilled off in about 1h15 minutes, at oil bath 130 - 140 C, distillate consistently coming over at 78 - 79 C. After that time, no
more distillate came over and boiling had all but stopped.
20 g of bottom fraction were recovered. Assuming it’s mainly DOP that would be a yield of about 30 %. Magpie’s right (but somewhat predictably
so). The glove material is now quite hard and brittle, a clear indication that plasticizer had been removed.
The product has been washed twice with sat. CaCl2 solution and is yellow/amber in colour and milky in appearance. I’m taking it a bit slower with
this crop so it’ll be left to stand overnight, hopefully it’ll clear some more. I might ‘salt’ it tonight.
@Sedit:
Part of the problem with the oxidation of primary alcohols to acids is the high value of the reaction enthalpy, for EtOH estimated on three occasions
by me as about - 350 to - 400 kJ/mol. That’s a whopppper: about 7 times the heat of neutralisation (OH- + H3O+)! Enough heat to get severe
boil-overs, especially with low boiling alcohols...
If I can isolate the alcohol (2-ethyl hexan-1-ol), I’ll try oxidising it with nitric acid but I’ve only got 38 %. But 38 % nitric actually worked
even for the oxidation of sucrose to oxalic acid (albeit a bit sluggish).
If you have a suggested recipe, I’d be interested in hearing it.
‘In theory’ the redox reactions are:
R-CH2-OH + H2O === > R-COOH + 4 H+ + 4 e
HNO3 + 3 H+ + 3 e === > NO + 2 H2O
So:
3 R-CH2-OH + 4 HNO3 === > 3 R-COOH + 4 NO + 5 H2O
So the molar ration of acid to alcohol is ‘theoretically’ 4/3.
@PHILOU:
You’re nuts.
[Edited on 25-5-2011 by blogfast25]
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Jor
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If you have the methyl ester of 2-ethyl hexanoic acid, why don't you try to do a Grignard on this one with MeI or EtBr? This should give a long chain
t-alcohol, wich is you goal right?
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blogfast25
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| Quote: Originally posted by Jor | | If you have the methyl ester of 2-ethyl hexanoic acid, why don't you try to do a Grignard on this one with MeI or EtBr? This should give a long chain
t-alcohol, wich is you goal right? |
That's the goal of synthing the methyl 2-ethyl hexanoate, Jor. Correct. To obtain 2-methyl-3-ethyl-heptan-2-ol.
[Edited on 25-5-2011 by blogfast25]
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Jor
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| Quote: Originally posted by blogfast25 | | Quote: Originally posted by Jor | | If you have the methyl ester of 2-ethyl hexanoic acid, why don't you try to do a Grignard on this one with MeI or EtBr? This should give a long chain
t-alcohol, wich is you goal right? |
That's the goal of synthing the methyl 2-ethyl hexanoate, Jor. Correct. To obtain 2-methyl-3-ethyl-heptan-2-ol.
[Edited on 25-5-2011 by blogfast25] |
Sorry I read again way too quickly. I read that you obtained the ester instead of the alcohol you were interested in. Wich is impossible if I would
have read your post more carefully  This is the second time now in 2 days 
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Magpie
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| Quote: Originally posted by blogfast25 |
If I can isolate the alcohol (2-ethyl hexan-1-ol), I’ll try oxidising it with nitric acid but I’ve only got 38 %. But 38 % nitric actually worked
even for the oxidation of sucrose to oxalic acid (albeit a bit sluggish).
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38% nitric is 7.44M. I used 6M for the oxidation of 1,3-propane diol to malonic acid.
Check the reference I provided in the malonic acid synthesis in Prepublication.
The single most important condition for a successful synthesis is good mixing - Nicodem
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blogfast25
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Thanks Magpie. Got it. Looks very useful indeed, nice write up!
I'll probably want to give the alcohol some work up...
[Edited on 25-5-2011 by blogfast25]
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blogfast25
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Well, I tried the oxidation of ethanol with nitric acid, using Magpie’s method but adjusted for a mono alcohol and I’m totally sold in it. 20 ml
of 38 % HNO3 were measured up, along with 2.5 ml of EtOH (acid/alcohol ratio = 8/3, twice the stoichio ratio). 10 drops of the alcohol were added to
the cold nitric and no reaction took place but on gentle heating NO2 starts to come off. I then added the rest of the alcohol in 10 drop aliquots w/o
further external heating, just riding on the heat the reaction gives off. Works a treat. After some more simmering to get rid of the NO/NO2 the smell
of acetic acid was unmistakable.
The now clear but crude DOP (19 g) was then hydrolysed with 6.0 KOH flakes dissolved in 7 ml of water. The mixture was heated until reaction was over
and the oily alcohol was floating on top of some water and precipitated dipotassium phthalate. It was separated and will now be worked up to at least
being able to do a micro (capillary) BP. It’s quite turbid (bits of dipotassium phthalate and some water, I imagine) so it may need distilling. This
crop smelled much more agreeable and I agree with Magpie that the smell is indeed reminiscent of vinyl gloves.
The dipotassium phthalate was dissolved in hot, strong HCl (phthalic acid is quite soluble in hot water but practically insoluble in cold water) and
should crystallise out later.
Update:
I decided to try to oxidise the crude alcohol (it was fairly clear by then) with nitric acid rather than do further prior work up.
35 ml of 38 w% HNO3 were measured out, to correspond to 13 ml of the alcohol (a 8/3 molar ratio acid/alcohol, twice stoichiom.)
10 drops of the alcohol were added to the acid, which was then covered and heated on an electrical hot plate. No discernable reaction took place, so I
added another 10 drops, a bit later another 10, until the first humble signs of reaction took place: a slight whiff of NO2 and slight discolouring of
the acid.
Clearly this wasn’t going to cause runaways and was decidedly sluggish. Possible reasons are:
1. reagent mix is heterogeneous: the alcohol doesn’t dissolve in the acid,
2. steric hindrance of the ethyl group so close to the hydroxyl group.
I then added all of the remaining alcohol and slowly NO2 started to develop. After about 15 min it started showing signs of bumpiness which I
attribute to too much heat being developed, so I took it off the hot plate. Reaction continued for quite some time but eventually died and I carried
on for at least another hour by heating on and off. Every time I thought reaction was now over, more NO2 developed. Eventually it more or less
subsided and I added some twenty ml of DIW and poured everything into a separating funnel:
The organic phase is a pale yellow/green liquid, almost perfectly clear and quite viscous. It smells different than the alcohol, much fainter for one.
The volume obtained is roughly the same as the alcohol starting volume.
Assuming the oxidation to 2-ethylhexanoic acid was indeed successful then this is far from an ideal procedure. Possible stronger acid or reaction in
solution (acetone? ether?) would be preferable.
[Edited on 27-5-2011 by blogfast25]
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blogfast25
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Another attempt at oxidising vinyl-gloves-extracted 2-ethyl hexan-1-ol. Literature cites oxidation of 1-octanol (to octanoic acid) with CrO3 using
acetone as a solvent/diluent. So I prepared a solution of 1 g 2-ethyl hexan-1-ol and 1 g of acetone (perfectly clear mixture), and separately 1.5 g of
K2Cr2O7 in 30 ml of 1 M H2SO4 (the stoichiometric amount to oxidise the alcohol).
I set up a burette to be able to add the oxidiser very gradually. The alcohol/acetone mixture was heated gently on a hot plate. But the dichromate
chews up the compound almost immediately: after 1 ml of dichromate solution added, the reagent mix starts getting brown, after another ml the whole
thing is a stinky dark mess.
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Sedit
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Glad to see your having some success using HNO3 blogfast, Since NO2 is the initiator in the nitric acid oxidation perhaps adding a small amount of
NaNO2 to the alcohol which is running sluggish will aid in speeding up the reaction a bit and carrying it further to completion. Given that they are
not mixing well it might be a lot harder to form the first trace amounts of NO2 to really get this to take off.
Knowledge is useless to useless people...
"I see a lot of patterns in our behavior as a nation that parallel a lot of other historical processes. The fall of Rome, the fall of Germany — the
fall of the ruling country, the people who think they can do whatever they want without anybody else's consent. I've seen this story
before."~Maynard James Keenan
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blogfast25
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| Quote: Originally posted by Sedit | | Glad to see your having some success using HNO3 blogfast, Since NO2 is the initiator in the nitric acid oxidation perhaps adding a small amount of
NaNO2 to the alcohol which is running sluggish will aid in speeding up the reaction a bit and carrying it further to completion. Given that they are
not mixing well it might be a lot harder to form the first trace amounts of NO2 to really get this to take off. |
The problem, Sedit, is that it wasn't that succesful. The reaction product was very viscous, much more so than I would expect from an isomer
of nonanoic acid. The reaction also just never seemed really over, with more NO2 being generated each time a added a bit of heat. I suspect the
reaction product was either oligomerised or perhaps some esterification took place with yet unreacted alcohol.
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Sedit
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Yeh I know thats why I suggested the use of a NaNO2 initiator to aid the reaction a bit. Is there any possibility of an inertsolvent perhaps that
could thin it allowing it to proceed better.
Also when I oxidise EtOH with it I use much more concentrated acid then you have so maybe you will get lucky if you up the concentration of it. No
matter what though make sure there is NO2 there. Look in the reference request thread Nicodem posted me some papers that speak about the oxidation
using HNO3 a bit. There goal was to make the aldahyde but Im sure you may find some kind of useful information in there.
GL
~Sedit
Knowledge is useless to useless people...
"I see a lot of patterns in our behavior as a nation that parallel a lot of other historical processes. The fall of Rome, the fall of Germany — the
fall of the ruling country, the people who think they can do whatever they want without anybody else's consent. I've seen this story
before."~Maynard James Keenan
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m1tanker78
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Not sure if this thread has any relevance. It touches on the interactions of H2SO4 and acetone; may be worth a look.
| Quote: | | A similar experience I had with adding conc. H2SO4 to pure acetone. Immediately after adding the acid and swirling well, the liquid is colorless, but
it slowly turns yellow, orange, red, red/brown and finally almost black. The liquid also turned more viscous. This reaction takes many hours. Again, I
think that acetone molecules are broken down somewhat and some polymeric species is formed and with increasing molecular size the color of this
species intensified. |
Tank
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blogfast25
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Thanks guys but I won’t be pursuing this any longer. The time and effort to extract the alcohol are just a little too high, combined with the
difficulty of reliably oxidising the alcohol without IR ‘quality control’.
Instead I’ll be concentrating on extracting the C8/C10 fatty acids from fractionated coconut oil, for further synthesis into 2-methyl alkan-2-ols…
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