| Pages:
1
2 |
Chemistry Alchemist
Hazard to Others
Posts: 403
Registered: 2-8-2011
Location: Australia
Member Is Offline
Mood: No Mood
|
|
Methyl Salicylate + HCl
In the reaction of Methyl Salicylic and Hydrochloric Acid, it forms Methanol and salicylic acid, does the salicylic acid precipitate out of the
methanol? could i use a stronger acid so i can have less water in the methanol?
C6H4OHCOOCH3 + HCl = CH3OH + C6H4OHCOOH
|
|
|
bbartlog
International Hazard
Posts: 1139
Registered: 27-8-2009
Location: Unmoored in time
Member Is Offline
Mood: No Mood
|
|
Salicylic acid is more soluble in alcohols than in water. So if you want it to precipitate, you'd want more rather than less aqueous HCl, up to a
point. But in any case, methanol, water and HCl are all volatile, so you could just evaporate to dryness after hydrolysis.
|
|
|
Nicodem
Super Moderator
Posts: 4230
Registered: 28-12-2004
Member Is Offline
Mood: No Mood
|
|
I hope you realize that the above equation does not equate and furthermore makes no sense chemically. I assume you are talking about methyl salicylate
hydrolysis, which is the reaction of methyl salicylate with H2O, not HCl. Obviously you want to have more water in the reaction mixture and less HCl.
You also need a cosolvent for a useful reaction rate.
Please note that it is conventional to this forum section to add the pertaining references. Else you should open referenceless threads only in the
Beginnings section.
|
|
|
Chemistry Alchemist
Hazard to Others
Posts: 403
Registered: 2-8-2011
Location: Australia
Member Is Offline
Mood: No Mood
|
|
that equasion was off google, i ding have time to do it my self, is it possible to salvage any methanol from the reaction? i wanna make Trimethyl
Borate with the methanol
|
|
|
redox
Hazard to Others
Posts: 268
Registered: 22-2-2011
Location: The Land of Milk and Honey
Member Is Offline
Mood: Chalcogenetic
|
|
The reaction you want is as follows:
C6H4OHCOOCH3 + H20 --(HCl)--> C6H4OHCOOH + CH3OH
My quite small but growing Youtube Channel: http://www.youtube.com/user/RealChemLabs
Newest video: Synthesis of Chloroform
The difference between chemists and chemical engineers: Chemists use test tubes, chemical engineers use buckets. |
|
|
Retard-3000
Hazard to Self
Posts: 55
Registered: 17-11-2010
Member Is Offline
Mood: No Mood
|
|
Hydrolyse the methyl salicylate with any concentrated acid, preferably sulphuric acid because it has a high boiling point. You'll then have a mix of
methanol, salicylic acid and some sulphuric acid, distill off the methanol then filter the sulphuric acid/salicylic acid and wash the salicylic acid
with water and recrystalize if needed.
|
|
|
Paddywhacker
Hazard to Others
Posts: 478
Registered: 28-2-2009
Member Is Offline
Mood: No Mood
|
|
This is a terrible way to obtain methanol, but if trimethyl borate is your goal then you might have more success with a transesterification reaction.
This is just a guess, but if you mix your methyl salicylate with boric acid and a catalytic amount of a strong acid, such as sulphuric acid, and heat
it up to the boiling point of trimethyl borate then it should distill over. You'll get some methyl salicylate in the distillate as well, so it will
smell funny, but it should burn with a nice green flame.
|
|
|
Chemistry Alchemist
Hazard to Others
Posts: 403
Registered: 2-8-2011
Location: Australia
Member Is Offline
Mood: No Mood
|
|
Say if i had 100mls of Methyl Salicylate, how much water and acid would i need? would i need to set up reflux for this reaction? once complete i can
just distill off the methanol and water to get the Salicylic Acid?
|
|
|
Retard-3000
Hazard to Self
Posts: 55
Registered: 17-11-2010
Member Is Offline
Mood: No Mood
|
|
C6H4OHCOOCH3 + H2O > C6H4OHCOOH + CH3OH
Methyl Salicylate (MW) = 152.1g
Density = 1.17g
100ml Methyl Salicylate = 117g
117g Methyl Salicylate = 0.77M
0.77M H2O = 13.86ml Water
Density Of H2O = 1.00g/ml
13.86g Water Is Need For The Reaction To Go To Completion.
100ml 36.5% HCl w/v = 36.5g HCl & 63.5g Water
If 13.86ml Water is need then a minimum of 21.8ml 36.5% HCl Needed.
So from this you can conclude that 21.8ml of a 36.5% w/v concentration of Hydrochloric Acid is needed, However using 36.5% HCl is completely
unneccessary as it's only acting as a catalyst and so a smaller amount is needed, I would say take 2.18ml of 36.5% HCl and dilute it with water so the
total volume becomes 21.8ml that way it'll only have a concentration of 3.65% and there will be enough excess water to shift the equilibrium to the
right.
And yes you'll want to reflux. Due to salicylic acid being a solid and having a boiling point of 211C at 20mmHg you can just heat your flask that
you're distilling in to 100C and the methanol and water will come over leaving the salicylic acid in the distillation flask. Remember not to boil to
dryness either.
[Edited on 30-10-2011 by Retard-3000]
|
|
|
Chemistry Alchemist
Hazard to Others
Posts: 403
Registered: 2-8-2011
Location: Australia
Member Is Offline
Mood: No Mood
|
|
If i used Sodium Hydroxide instead of water, would this be a better method to obtain methanol and sodium salicylate? then i can just acidify the
Sodium Salicylate to get salicylic acid and sodium salt?
|
|
|
Retard-3000
Hazard to Self
Posts: 55
Registered: 17-11-2010
Member Is Offline
Mood: No Mood
|
|
I think what you mean is can you use sodium hydroxide instead of ACID, not water. water is needed in the reaction.
But yes you can use sodium hydroxide in place of hydrochloric acid to obtain methanol and sodium salicylate.
[Edited on 30-10-2011 by Retard-3000]
|
|
|
Chemistry Alchemist
Hazard to Others
Posts: 403
Registered: 2-8-2011
Location: Australia
Member Is Offline
Mood: No Mood
|
|
how would ii know when reflux is complete?
|
|
|
Retard-3000
Hazard to Self
Posts: 55
Registered: 17-11-2010
Member Is Offline
Mood: No Mood
|
|
I'm not sure on how long to reflux for, personally i'd reflux for 1-2 hours.
|
|
|
Chemistry Alchemist
Hazard to Others
Posts: 403
Registered: 2-8-2011
Location: Australia
Member Is Offline
Mood: No Mood
|
|
is there a way to indicate if its finished?
|
|
|
Retard-3000
Hazard to Self
Posts: 55
Registered: 17-11-2010
Member Is Offline
Mood: No Mood
|
|
You could add phenolphthalein before the reaction and it'll turn pink due to the sodium/potassium hydroxide and when the reaction is complete it
should be colourless due to sodium hydroxide being consumed during the reaction forming sodium salicylate. If excess sodium hydroxide is used the
colour will not change so make sure to use a slight excess of methyl salicylate.
|
|
|
Chemistry Alchemist
Hazard to Others
Posts: 403
Registered: 2-8-2011
Location: Australia
Member Is Offline
Mood: No Mood
|
|
i dont have any phenolphthalein... id have to make it and i dont have any phenol or phthalic anhydride (or phthalic acid which ever it is)
|
|
|
Retard-3000
Hazard to Self
Posts: 55
Registered: 17-11-2010
Member Is Offline
Mood: No Mood
|
|
Phenolphthalein can be bought from ebay, alternatively you could extract the anthocyanins from red cabbage by boiling it in water, filtering out all
insoluble matter and boiling down the excess water which will give you a very basic pH indicator that may work.
|
|
|
TheNaKLaB
Hazard to Self
Posts: 51
Registered: 18-9-2011
Location: Australia
Member Is Offline
Mood: Elastic
|
|
You can get Phenolphthalein from pet stores as a pH tester for fish tanks. I've been meaning to get some.
|
|
|
Chemistry Alchemist
Hazard to Others
Posts: 403
Registered: 2-8-2011
Location: Australia
Member Is Offline
Mood: No Mood
|
|
Powder form or strips?
|
|
|
TheNaKLaB
Hazard to Self
Posts: 51
Registered: 18-9-2011
Location: Australia
Member Is Offline
Mood: Elastic
|
|
Liquid 
|
|
|
Resonance frequency
Harmless
Posts: 10
Registered: 23-10-2011
Member Is Offline
Mood: vibrating
|
|
Hello Alchemist,
I have a very simple option to recover salicylic acid after hydrolysis.Just follow the procedure given below.
1) Take methyl salicylate in suitable quantity of methanol ( sufficient quantity to solubilize all the methyl salicylate) and proceed with hydrolysis
by using dil. hydrochloric acid at reflux temperature. The progress & completion of hydrolysis can be monitored by using TLC.
2) After complete hydrolysis allow the reaction mass to cool ( which consist of methanol,aq.HCl,Salicylic acid & water)
3) start addition of chilled water to recation mass slowly under stirring till the salicylic acid precipitates out.Filter the precipitate & dry in
oven at 100°C
Note:- Make sure that all the methyl salicylate has been hydrolysed or you will get a mixture of salicylic acid & methyl salicylate as a
precipitate.
MUTUAL SOLUBILITY OF METHANOL & WATER THROWS OFF ANY ORGANIC CONTENT OUT of methanolic reaction mass,Please note that you must go on adding water
ignoring the quantity of water coz almost a litre or more quantity of water will be required for a litre of reaction mass.
|
|
|
Chemistry Alchemist
Hazard to Others
Posts: 403
Registered: 2-8-2011
Location: Australia
Member Is Offline
Mood: No Mood
|
|
Ive figured out a method to do it, i dont know if its 100% correct by the method of going it but the synthesis is all there...
the equation to this is as the following
Refluxing (Phenolphthalein added to indicate when all the base as reacted)
C<sub>8</sub>H<sub>8</sub>O<sub>3</sub> + NaOH = CH<sub>3</sub>OH +
C<sub>7</sub>H<sub>5</sub>NaO<sub>3</sub>
After distillation of the methanol + Drying
CH<sub>3</sub>OH + H<sub>2</sub>O + CaO = CH<sub>3</sub>OH + Ca(OH)<sub>2</sub>
Acidification of the Sodium Salicylate
C<sub>7</sub>H<sub>5</sub>NaO<sub>3</sub> + HCl =
C<sub>7</sub>H<sub>6</sub>O<sub>3</sub> + NaCl
Now it says up there distillation, because methanol is valuable to me, i want to extract it b4 i move on to acidification, so my plan is to add more
water to it after reflux and then distill off all the methanol yielding a solution of water with sodium salicylate, then ill move onto the
acidification to precipitate the Salicylic Acid
|
|
|
Chemistry Alchemist
Hazard to Others
Posts: 403
Registered: 2-8-2011
Location: Australia
Member Is Offline
Mood: No Mood
|
|
The whole synthesis will be posted on my blog page, wont be posting it for a while tho...
|
|
|
Resonance frequency
Harmless
Posts: 10
Registered: 23-10-2011
Member Is Offline
Mood: vibrating
|
|
Hi alchemist,
You can use the method that i have described above for precipitation coz methanol can be easily distilled out as it doesnt forms azeotrope with water
|
|
|
Chemistry Alchemist
Hazard to Others
Posts: 403
Registered: 2-8-2011
Location: Australia
Member Is Offline
Mood: No Mood
|
|
But woulnt the HCl do somthing to the methanol?
|
|
|
| Pages:
1
2 |
![[*]](images/xpblue/default_icon.gif){kind=icon}
