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Author Topic: Short Questions Thread  (Read 10823 times)

Satan

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Re: Short Questions Thread
« Reply #420 on: March 10, 2010, 04:34:47 PM »
@disposable stirbar

My book of inorganic preparation says:
To make anhydrous MgCl2, heat equeal parts of hydrated salt and ammonium chloride, and heat very strong under cover.

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Re: Short Questions Thread
« Reply #421 on: March 10, 2010, 05:32:35 PM »
That tech looks way easier, Satan. Thanks. With that tip I found:
"To obtain the anhydrous salt, the double magnesium ammonium chloride, MgCl2 NH 4 C1.6H 2 O, is prepared by adding ammonium chloride to a solution of magnesium chloride. The solution is evaporated, and the residue strongly heated, when water and ammonium chloride are expelled, and anhydrous magnesium chloride remains. Magnesium chloride readily forms double salts with the alkaline chlorides."
hxxp://www.1911encyclopedia.org/Magnesium

One will give it a shot and report back, eventually ;)

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Re: Short Questions Thread
« Reply #422 on: March 15, 2010, 02:39:51 PM »
What sort of containers are being used to store hot out of the oven drying agents?

Rubbermaid doesn't like the mol sieve temp and I'm not sure about throwing it in a reagent bottle because of the thermal stress. I might hop over to camping land super store and get a backpackers aluminum white gas fuel bottle to try.

badger

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Re: Short Questions Thread - Catechol, xylene, and benzodioxole
« Reply #423 on: March 18, 2010, 05:52:53 AM »
Catechol is 1,2-dihydroxybenzene. o-Xylene is 1,2-dimethylbenzene. Catechol can be methylenated to 1,3-benzodioxole by creating a catechoxide dianion thanks to those two -OH functional groups on the catechol (I'm totally cribbing from Strike here, credit where credit is due); is there a similar route to benzodioxole from 1,2-dimethylbenzene? Apart from, say, changing the CH3 to OH and then methylenating. (What reaction would be used to change the CH3 to OH, anyway? I have a lot to learn.)

Vesp

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Re: Short Questions Thread
« Reply #424 on: March 18, 2010, 06:12:46 AM »
I'm afraid it isn't simple at all to turn a R-CH3 group into a R-OH group. For this, you'll need to break the carbon bond, and replace it with an oxygen. Most reactions involving methyl groups on benzene rings are oxidation, so you are left with turning it into an aldehyde, a carboxylic acid, or perhaps some halogenated substance.

The carboxylic acid could be decarboxylate to produce R-H -- which, is useless , or perhaps formed into an amide and then a Hoffman rearrangement could be performed to form an amine -- I am not sure if this is possible, I doubt it is in any worth while sense. However, if you got to the amine, you could do a Sendmyer(sp?) reaction on it forming the R-OH.

It isn't very practical, unfortunately - I am sure better methods exist possibly from aspirin, or some other fairly OTC-ish compound. Good luck!
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Re: Short Questions Thread
« Reply #425 on: March 19, 2010, 05:25:37 PM »
If one were guessing, what is the amount of water in clumping NaOH? I know it isn't anhydrous. Is there way to guestamate?

Opened but looks dry is...

Clumping...

Clumping and looking wet...

Thanks

Vesp

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Re: Short Questions Thread
« Reply #426 on: March 19, 2010, 10:16:26 PM »
Add 10 grams to a pre-massed  test tube, heat it up till no more water vapor comes off and then mass the test tube w. NaOH in it, subtracting the mass of the test tube. Using ten grams ought to make math easy and that is enough to give a decent estimate I'd think. You'll get the % of water by how much mass it has lost.
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Re: Short Questions Thread
« Reply #427 on: March 20, 2010, 02:27:53 AM »
I was under the impression that NaOH doesn't dehydrate nicely, or at least it is not recommended to try to dry it. Thanks, I guess I should try the easy before getting crazy.

Will putting the NaOH in toluene and boiling it off get it dry? If you can't tell, I am in love with toluene ;)

Enkidu

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Re: Short Questions Thread
« Reply #428 on: March 20, 2010, 03:16:17 AM »
Why not just throw it in the microwave? Just be careful, or it'll eat things...

Vesp

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Re: Short Questions Thread
« Reply #429 on: March 20, 2010, 04:13:49 AM »
That is a really interesting idea with the toluene -- I doubt it though, however, it is worth experimentation. Perhaps a solvent with a higher boiling point would work better. Possibly distilling the toluene with anhydrous alcohol would really help, as this would dissolve the NaOH to some degree, and work as a dehydrating agent, as well as help carry over the water, as would the toluene. I guess there really wouldn't even need to be toluene if one were to use dry alcohol -- that is, if it worked how I hope it might.

I'm not to sure how well it would dry -- but in a test tube, one can get it pretty hot, and this would dehydrate almost all of it I think, which should give you a good idea of how much water is in the NaOH.

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Happyman

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Re: Short Questions Thread
« Reply #430 on: March 20, 2010, 04:27:31 AM »
Maybe Xylene for a aromatic solvent with high boiling point?

Would methyl nitrite / nitromethane work for a Sandmeyer reaction? You wouldn't have the salt to get out at the end but I have a feeling it wouldn't work.

Enkidu

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Re: Short Questions Thread
« Reply #431 on: March 20, 2010, 05:04:13 AM »
Quote from: Vesp on March 20, 2010, 04:13:49 AM
That is a really interesting idea with the toluene -- I doubt it though, however, it is worth experimentation. Perhaps a solvent with a higher boiling point would work better. Possibly distilling the toluene with anhydrous alcohol would really help, as this would dissolve the NaOH to some degree, and work as a dehydrating agent, as well as help carry over the water, as would the toluene. I guess there really wouldn't even need to be toluene if one were to use dry alcohol -- that is, if it worked how I hope it might.

No, you'll make alkoxides if you add alcohol.

Enkidu

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Re: Short Questions Thread
« Reply #432 on: March 20, 2010, 05:16:40 AM »
Quote from: Happyman on March 20, 2010, 04:27:31 AM
Would methyl nitrite / nitromethane work for a Sandmeyer reaction? You wouldn't have the salt to get out at the end but I have a feeling it wouldn't work.

Why do you propose this? [Edited out a misunderstanding of the post.] Those won't work. Nitromethane + HCl ---> aldehyde (or carboxylic acid, i can't remember) + hydroxylamine. You need the nitrite ion and an acid to form HONO in situ.
« Last Edit: March 20, 2010, 05:22:34 AM by Enkidu »

Vesp

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Re: Short Questions Thread
« Reply #433 on: March 20, 2010, 05:32:02 AM »
Quote from: Enkidu on March 20, 2010, 05:04:13 AM
Quote from: Vesp on March 20, 2010, 04:13:49 AM
That is a really interesting idea with the toluene -- I doubt it though, however, it is worth experimentation. Perhaps a solvent with a higher boiling point would work better. Possibly distilling the toluene with anhydrous alcohol would really help, as this would dissolve the NaOH to some degree, and work as a dehydrating agent, as well as help carry over the water, as would the toluene. I guess there really wouldn't even need to be toluene if one were to use dry alcohol -- that is, if it worked how I hope it might.

No, you'll make alkoxides if you add alcohol.

Are you sure? I was thinking in those conditions the hydroxide would still be strongly favored, and very little to no alkoxides would form.
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Enkidu

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Re: Short Questions Thread
« Reply #434 on: March 20, 2010, 06:40:40 AM »
Generally, it is, but NaOH + EtOH <<<---> EtONa + H2O is an equilibrium, even if it is pushed far to the left. So if you start removing water (by azeotropic distillation) you will push the equilibrium to right.

Edit: see also http://www.sciencemadness.org/talk/viewthread.php?tid=9474&goto=search&pid=110165
« Last Edit: March 20, 2010, 06:43:27 AM by Enkidu »

Enkidu

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Re: Short Questions Thread
« Reply #435 on: March 20, 2010, 06:11:00 PM »
For my own questions, does anyone know where I can pick up some glass tubing? Also, can anyone link me to information on the purification of fertilizer grade urea? I'm thinking that it may be similar to the purification of fertilizer grade ammonium nitrate (since both compound have some similar properties, i.e., both compounds undergo an endothermic reaction when mixed with water).

Vesp

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Re: Short Questions Thread
« Reply #436 on: March 20, 2010, 10:42:36 PM »
I would purify AN or Urea by dissolving them in a conc. solution and adding something that dissolves the waxes instead -- I.e Isopropyl alcohol, at least in ammonium sulfate, that doesn't dissolve since it gets salted out, and it takes all of the wax particles out, leaving a nearly clear solution.

The urea I have seen though seems to be very pure and is as white as white gets.
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Evilblaze

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Re: Short Questions Thread
« Reply #437 on: March 29, 2010, 08:26:31 PM »
The goal would be to synth 2 chloro propionyl chloride.


The basic idea would be the "OTC" synthesis from lactic acid and SOCl2.

Reflux this two compound for a while and hope the best. The only problem is that there is no synthesis on the net.
For propionyl chloride there is this:
Quote
propionic acid and phosphorus trichloride, phosphorus pentachloride, thionyl chloride or phosgene C system can respond chloride.
1. Propionic acid with phosphorus trichloride refluxed 6h. Still 1-2h, points to lower phosphorous acids, ie C chloride. The acid : PCl3 for versa conditions, the yield was 95%.

The industrial method is from 1,2 dichloro propane, this is oxidized to 2 chloropropionyl chloride. But 1,2 dichloro propane is not available, so another route should be chosen.

The big question is that how does the conversion goes with SOCl2 and if there is an extra OH what should be turned to Cl, than how many time it should be refluxed?
Or maybe using PCl3 or PCl5 instead of the SOCl2. So, any ideas? ;)

Enkidu

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Re: Short Questions Thread
« Reply #438 on: March 29, 2010, 09:52:35 PM »
Start form alanine, HNO3/HCl to the 2-chloropropionic acid, S/Cl2 to the acid chloride. UTSE for experimental details.

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Re: Short Questions Thread
« Reply #439 on: March 29, 2010, 09:57:30 PM »
When forming a Grignard reagent from an alkyl halide and Mg, what keeps the newly formed reagent from just immediately reacting with other alkyl halide molecules to form di-alkyls?
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