this is an interesting but rather experimental reaction first we're going

to prepare a solution of glyoxylic acid then we're going to see if this can

react with phenol to produce a substituted mandelic acid

we're starting with 30 grams of oxalic acid dihydrate

we're going to be dissolving this in water so it's not important to use the

dehydrated acid just make sure your molar calculations take this into

account

now we have 100 mils of water

note that this isn't going to be enough to dissolve the acid completely at this

stage and a large magnetic stir bar now we weigh out six grams of magnesium

metal shavings this is a slight excess in theory to what we need

with the oxalic acid and water mixture stirring we slowly start to add the

magnesium metal this reacts pretty vigorously with the acidic solution

bubbling and giving off hydrogen gas there

is also quite a lot of heat evolved

keep adding them magnesium metal but not too quickly that the reaction gets

out of control and to the постоito-y acid mixture ran over into the gall lumbar primerainizte.

produced. As the temperature rises, we use an ice bath on the stirring plate to

cool the mixture. The last pieces of magnesium take a while to dissolve. The

mixture now has a quite strong characteristic aldehyde aroma. After 30

minutes we removed the mixture from the cooling bath and allowed it to warm to

room temperature and then continued stirring for an hour to ensure complete

reaction. Next we weighed out 13.4 grams of potassium hydroxide and dissolved

this in 20 mils of water to create a solution.

Whilst stirring the reaction mixture, we added this potassium hydroxide solution.

We think that the idea here is to precipitate a lot of the magnesium as magnesium hydroxide,

forming the potassium glyoxylate salt in solution. The result was a very pale yellow mixture

with a white precipitate as you can see here. We filtered this to a glass center to remove

the precipitate.

This was a little float, but we got there in the end.

Next we weighed out 24 grams of solid phenol. Be careful with this stuff, not only does

it stink, but it's toxic and causes bad skin burns.

And then we weighed out a further 15 grams of potassium hydroxide. And we dissolved this

in 70 mils of water to form a solution.

Ok so now we've got a solution of potassium hydroxide and our solid phenol. We're going

to dissolve the phenol in the hydroxide. Actually we did it the other way round. We

added the potassium hydroxide solution to the solid phenol and it dissolved. This is

now a solution of potassium phenol.

Ok so now we've got a solution of potassium hydroxide and our solid phenol. We're going

Our glyoxylate filtrate has now passed through the center.

So now we have the potassium phenylate solution we just prepared to this.

Here's the result, a rather murky slightly cream colored mixture which looks a little

bit like an emulsion.

We then covered this up with wrap and left for 48 hours to see if any reaction occurred.

Here we are after 48 hours.

It's hard to tell if this is two layers, a precipitate or an emulsion.

To start with we vacuum filtered this mixture through a glass center to remove any solids.

Then we tested the pH of the milky colored filtrate in order to check that it was still

strongly alkaline.

Oops.

Well that's a positive test at least.

Now we're going to acidify the mixture using concentrated hydrochloric acid.

As we added the acid some heat was produced, and small globules of unreacted phenol were

formed in the mixture.

We acidified to a pH of around 3, and then let the mixture settle.

The top layer is unreacted phenol, which is always a liquid in the presence of water.

We used a pipette to remove the top layer of phenol.

And then covered the beater in plastic wrap and left it in the fridge for one week to

chill and settle.

After a week of chilling, some crystalline precipitate had formed in the mixture at the

bottom.

So we set up for filtration again.

And again.

This is the final result.

It took a little while to filter off.

And we let the crystals dry thoroughly on the pump.

Here's what we ended up with.

3.2 grams of a crystalline mystery white solid.

It's acidic to indicator paper.

But it's entirely possible that this is just the oxalic acid that we started with.

It's acidic to indicator paper.

We tried testing the solubility in a few different solvents.

First water.

It doesn't seem very soluble.

It took a whole small beaker just to dissolve the tiny bit of solid.

Next up, dichloromethane.

And here it's completely insoluble.

Now for diethyl ether.

Regular mandelic acid is very soluble in ether, but we don't know about the hydroxy version.

Doesn't seem to be at all soluble.

Finally, sodium hydroxide solution.

Here it's a bit more soluble.

This is interesting.

The solubility behavior isn't consistent with it being oxalic acid, especially because of the low water solubility and the insolubility in ether.

But we're not sure exactly what we've got here.

We can't find much information about for hydroxymandelic acid.

One report says it's white crystals.

Another says it's a red powder.

If we've obtained this as a product as per the original reference, then it's a 6.5%.

But we can't yield on starting phenol.

If anyone has any info, then please let us know.

If there's a way to get this reaction to work, then it could be a very useful synthetic route to phenethylamine compounds.