Is it ok, for general reaction, if the water use as a solvent contains high levels of phosphate? I was going to make some trimethyl borate so yeahBert - 21-10-2015 at 16:27
Spend the few cents extra for distilled or deionized water. Especially if you KNOW your tap water is not especially pure-Detonationology - 21-10-2015 at 18:20
Is it ok, for general reaction, if the water use as a solvent contains high levels of phosphate? I was going to make some trimethyl borate so yeah
What do you need water for? To recrystalize the H3BO3?DalisAndy - 21-10-2015 at 18:54
No, as a solvent for the reaction. My methonal is 99% pure so I will have to add water. Won't I?Detonationology - 21-10-2015 at 19:11
No solvent is needed, the reaction is not aqueous. Only double replacement reactions take place in solution. Alcohols do not form ions in water, so
therefore the reaction is considered a synthesis. In order to consider your final product pure, the ester will need to be separated from the water
byproduct via fractional distillation. In the case of trimethyl borate, the product is ~2:1 ratio of B(OCH3)3 to water by volume, and 1:3 mole ratio.
[Edited on 10-22-2015 by Detonationology]DalisAndy - 21-10-2015 at 19:32
Wouldn't it be easier to heat the reaction? It would allow the water to vaporize off. Or I could use a drying agent. I don't have any way of doing
any distillation. I have minimal equipmentDetonationology - 21-10-2015 at 19:43
A molecular sieve seems to be the most viable option for desiccate the final product. These threads should be merged with the other existing
alcohol/borate synthesis'.Amos - 22-10-2015 at 06:11
Wouldn't it be easier to heat the reaction? It would allow the water to vaporize off. Or I could use a drying agent. I don't have any way of doing
any distillation. I have minimal equipment
The synthesis of trimethyl borate is a condensation, or more correctly an esterification reaction. Water is produced as a byproduct in the reaction,
and due to the reaction equilibrium, any unnecessary water present will only serve to convert the products back to the starting materials, reducing
your yield.
If you don't have any method of doing distillation, then you're probably not able to do reflux, either. Making the borate ester of methanol usually
uses excess methanol as a solvent, boric acid, and a substantial quantity of sulfuric acid as a catalyst and water-sequestering agent. Reflux is then
carried out for a period of time and the trimethyl borate and excess methanol can be distilled off.
If you don't follow the procedure properly and just skip the reflux and distillation altogether, you're going to end up with a somewhat viscous and
highly corrosive(due to sulfuric acid) liquid containing some trimethyl borate. It will probably burn with a weak green flame and leave a puddle of
very troublesome sulfuric acid behind. It may even give off some toxic and corrosive sulfur oxides as it burns! Fun times. You could always just dump
some roach killer into HEET and see if that burns green, but at that point why even bother calling it chemistry?Metacelsus - 22-10-2015 at 06:24
Simply dissolving boric acid in methanol produces a solution that will burn green. No sulfuric acid is needed.Amos - 22-10-2015 at 06:25
