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Author: Subject: HCl Saturated Methanol Prep
mehcp
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[*] posted on 3-10-2013 at 21:15
HCl Saturated Methanol Prep


I want to prepare Hydrogen Chloride saturated Methanol by bubbling dry HCl gas into 1 L Methanol 0-4°C. I'm adding concentrated HCl to Calcium Chloride drop-wise via an addition funnel (as noted here http://curlyarrow.blogspot.com/2009/03/how-to-make-dry-hcl-g... and here http://chemtips.wordpress.com/2012/12/18/snap-crackle-pop-an...).

I'd like to know the following:
  • How much CaCl2 and HCl should be required to saturate 1 L methanol with HCl gas?
  • How long should it take to reach saturation?
  • What is the saturation concentration of HCl gas in Methanol?
  • I imagine the concentration can be verified via titration, but what is the best method for doing so?
  • I am using a glass Pasture pipette to bubble in the HCl gas, but it seems a diffuser of some sort would work better to get more of the gas into solution. Are there any recommendations or suggestions for this purpose? Or should I just draw out the pipette to a finer tip to get smaller bubbles?
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Mesa
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[*] posted on 4-10-2013 at 04:38


Quote: Originally posted by mehcp  

  • How much CaCl2 and HCl should be required to saturate 1 L methanol with HCl gas?
    I would just keep bubbling it through until it starts fuming.
  • How long should it take to reach saturation?
    Depends on the flow rate of HCL gas
  • What is the saturation concentration of HCl gas in Methanol?
  • I imagine the concentration can be verified via titration, but what is the best method for doing so?
    Any 'Introduction to Chemistry" type books will teach you basic titration. Essentially, add measured amounts of a base until it becomes neutral, then work out the stochiometry.
  • I am using a glass Pasture pipette to bubble in the HCl gas, but it seems a diffuser of some sort would work better to get more of the gas into solution. Are there any recommendations or suggestions for this purpose? Or should I just draw out the pipette to a finer tip to get smaller bubbles?
    Aquarium store's have "bubbler stones" which work extremely well. I often use a cigarette filter.
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mehcp
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[*] posted on 4-10-2013 at 04:52


Quote: Originally posted by Mesa  


    Any 'Introduction to Chemistry" type books will teach you basic titration. Essentially, add measured amounts of a base until it becomes neutral, then work out the stochiometry.
    True, and if someone has experience with a methanol soluble base and indicator I'd like to know about it.

    Aquarium store's have "bubbler stones" which work extremely well. I often use a cigarette filter.
    I thought of this, but will the stones hold up to HCl and not contaminate the methanol?
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ziqquratu
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[*] posted on 4-10-2013 at 07:10


You don't have to use a methanol soluble system - simply dilute a measured aliquot of your methanolic acid with water and titrate that. Somewhat less accurate, but possibly good enough depending on your needs - you could weigh the bottle before and after adding the HCl - if you do it cold (as you suggested), there should be minimal loss of MeOH so you should get a reasonable measure of the mass of HCl added, and thus the concentration.

As for bubbles - if you add it slowly, the HCl should dissolve quite readily without any sort of effort to make smaller bubbles. A capillary should help that, though. Alternatively, loosely plugging the end of a tube with some glass wool should serve as a makeshift diffuser that will be entirely stable.
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AndersHoveland
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[*] posted on 4-10-2013 at 08:43


Is it possible that too much HCl could dehydrate the methanol to dimethyl ether? Or can the methanol not dissolve the concentration of HCl gas that would require?
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kristofvagyok
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[*] posted on 4-10-2013 at 13:41


Quote: Originally posted by AndersHoveland  
Is it possible that too much HCl could dehydrate the methanol to dimethyl ether?

No.




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Nicodem
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frenchemist1
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[*] posted on 6-10-2013 at 12:01


It could maybe forms a very very very little amount of chloromethane, but it could absolutely not forms dimethylether...
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