Increasing yield
Hi all. We discuss the attached file. At the very end of paper, a reaction was described at which it was possible to get 70.2%. A little higher, the
author indicates that the reaction time is very important. The aldehyde is unstable and turns further. At the same time, during the reaction, as I
understand it, the glycol completely dissolves in volume, and the formed aldehyde pops up to the top. I have an idea. That if organize the selection
of the formed aldehyde from the flask during the reaction without waiting for the complete end of the reaction time. This will avoid the further
transformation of the already formed aldehyde.
For example, this can be done so: using a 2 -throat flask in one insert a return refrigerator with a divert hose to a trap, into the second through a
fluoride rubber cork dividing funnel with a long nose. Adjust so that the nose is immersed in the upper layer. With one hand squeeze the outlet hose
and increase the pressure in the flask, the second open the crane of the dividing funnel. You can pour not a lot of water into the funnel to work
like a shutter. Aldehyde is supplanted into the funnel. Close the crane. Open the hose to the trap. Repeat the cycle. Of course, it will need to
accurately calculate the volume of reagents taking into account the expansion, but this is not a problem. In extreme cases, you can mortgage a one
-ruble flask and make the aldehyde gather in the throat and just take out the refrigerator and select what has formed, it will reduce the contact
area, although of course there are steam passing through aldehyde.
What do you think will this increase yield? Yeah i know about vapor phase transformation, but i interested with this.
Why is such a large volume of acid solution 150ml and such a large molar excess? Even if the entire glycol does not dissolve immediately, then as the
aldehyde forms, the place in volume will be freed? Although I have an assumption because the maximum output at 1.78mol/L increasing the volume of
acid, the author tried to hold this concentration smoothly reducing to the end of the reaction. That is, with a smaller volume, the negative effect of
reducing the yield will be noticeable. Your opinion?
Attachment: Reaction of styrene glycol with aqueos acids.pdf (566kB)
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