marsheng
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Trimethyl Borate
I live in New Zealand and I cannot get a specific welding flux any more. The components are 20% Methanol 25% Acetone and 55% Trimethyl Borate.
I am going round in circles trying to find out how to make Trimethyl Borate. Each web page I get to, I get a different formula.
I have managed to find Borax and I have the other 2 items but I'm not sure how to continue. There are a few web posting about making green flames with
Borax and this is correct, as when I used the original flux, it did burn with a green colour.
Any suggestions or pointers as to where to go from here. I would like to make about 2-3 litres.
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Nicodem
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Thread Moved
4-7-2015 at 04:43 |
UC235
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There are other threads on this forum about making trimethyl borate, such as this one: http://www.sciencemadness.org/talk/viewthread.php?tid=10778
Was this flux painted on to the part or injected into the gas line? I suspect the latter, but if the former, you could simply paint a solution of
boric acid in methanol onto the part. Producing trimethyl borate is not particularly easy without lab equipment and a whole liter of it would take
quite a bit of work even with it.
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Magpie
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Here's my procedure for making pure methyl borate. If you are not concerned with the methanol impurity you can skip most of the workup steps.
http://www.sciencemadness.org/talk/viewthread.php?tid=16439
The single most important condition for a successful synthesis is good mixing - Nicodem
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marsheng
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>> Was this flux painted on to the part or injected into the gas line?
The process used for Jetflux is to bubble the acetylene through the liquid.
However, having the option to paint on the flux would be an advantage. Often when brazing around a tube, once you get back to the start there is
oxidation in the tubes. Possibly painting on the flux before starting to heat the tubes may help with this.
Brazing with Jetflux is really far superior to dipping or coated rods.
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marsheng
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It was a long time ago I did chemistry (30 + years) so I'm quite rusty.
As for the web, anyone can post and so anyone's opinion will come up, hence I'm here at this forum to hopefully find out the right answers.
To clear a few things up
From what I have read Boric acid is a white salt at room temperature.
To create Boric acid from Borax
Take 25 ml of hydrochloric acid and dilute it with 75 ml of water. Next take 6 - 7 gms of borax and dissolve it in boiling water. Now add equal amount
of hydrochloric acid. Crystals of boric acid will start forming. They are completely insoluble in cold water. After about half an hour, filter it and
you have the boric acid crystals. Wash the beaker only with cold water to prevent loss of any boric acid.
The link from Magpie is to make Methyl Borate CH3BO3. I need to make Trimethyl Borate C3H9BO3.
Is there a possibly to make Trimethyl Borate directly from Borax ?
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Magpie
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These names are synonymous.
The single most important condition for a successful synthesis is good mixing - Nicodem
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marsheng
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The can't be, they have different compositions ?
Methyl Borate CH3BO3, Trimethyl Borate C3H9BO3.
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Magpie
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http://www.sigmaaldrich.com/catalog/product/fluka/92330?lang...
The single most important condition for a successful synthesis is good mixing - Nicodem
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DraconicAcid
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Is monomethyl borate actually stable?
Please remember: "Filtrate" is not a verb.
Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
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marsheng
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Thanks for the reply. Still confused as they have different compositions.
Could it be that Methyl Borate is the powder form and Trimethyl Borate is the same just dissolved in Methanol ?
Looking at the parts
2 x Methanol CH3OH + Methyl Borate CH3BO3 may well be
Trimethyl Borate C3H9BO3. (However 2 too many O's)
Thanks Wallace
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DraconicAcid
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Methyl borate and trimethyl borate are the same things, just like sodium phosphate and trisodium phosphate are the same things.
Boric acid is H3BO3. If you replace the acidic hydrogens with methyl groups, you get (tri)methylborate. It is a liquid at room temperature, with an
unpleasant smell, and it burns with a lovely green flame.
Please remember: "Filtrate" is not a verb.
Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
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Magpie
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I believe that methyl borate is the archaic name. In the old references listed at the bottom of my procedure it is called by that name.
Borate (BO3---) has a valence of three. One methyl doesn't make any sense - it's just an old name that is not used anymore.
The single most important condition for a successful synthesis is good mixing - Nicodem
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marsheng
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Sorry I got the previous post wrong. Is this correct then ?
2 x Methanol CH3OH + Boric Acid CH3BO3 makes
Trimethyl Borate C3H9BO3.
Thanks Wallace
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Magpie
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Did you look at my procedure? I give the reaction there.
The single most important condition for a successful synthesis is good mixing - Nicodem
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marsheng
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Thanks for all the info. I think I have finally got it all together. Youtube made it look so easy, but it is not so.
I need to buy a few more things to get this all up and running now. Sounds like a fun project. I really need to only make 250 mm at a time.
The alternative to just buy Trimethyl Borate but even that was confusing as some suppliers sold it by the litre and others by the KG. However no-one
stocks this in NZ and the delivery time is 4 +weeks and around $200 per litre.
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Hickory
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I have successfully made MeO)3B•MeOH azeotrope by baking borax dry and heating with methanol (and glycerine, soap, and lye, but probably they're
optional - waste glycerine layer from biodiesel).
Monomethly borate exists, as the cyclic trimer when dry, which is why methyl borate as a synonym for trimethyl borate is frowned on now.
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