The first experiments with hydroquinone only got as far as the formylation stage where a number of factors conspired to prevent anything else being done.
Hydroquinone --> p-Methoxyphenol
- Weighed ~1g dry benzoquinone and 10g hydroquinone into 250mL FBF.
- Added 55mL MeOH and 11mL H
2SO
4 (acid stupidly added quickly to MeOH, causing some to boil off, so an extra couple mL's MeOH added to make up. Also plunged into ice bath to cool it down to RT).
- Stirred at RT for ~24hrs
- Mixed with 100mL NaCl solution, then extracted with 50+30mL Xylene.
- Xylene mostly distilled off (forgot to neutralize here... stupid!! Added a little xylene, did the NaHCO
3 swirl, filtered and redistilled)
- Gently heated in a beaker to remove remaining xylene. The beaker was left on the hotplate to cool (the stirrer remained on) overnight. The next morning, there was a snazzy crop of crystals on the bottom of the beaker! Dark brown, perhaps a slight red-ish tinge, but definitely crystals!).
- Weighed while still smelling slightly of xylene - 6.30g of (presumably) p-MeO-Phenol - 64.3% based on hydroquinone - not too bad!.
This yeild was somewhat less than Antoncho's, which can probably be explained partly by some sloppy chemistry and lack of following directions, but more likely because of sublimation (a repeat batch was heated a little too much at the xylene-removal stage, resulting in a large crop of brilliant white, needle-like crystals at the top of the beaker). This reasserts Antoncho's reccomendation to use a lower boiling solvent than his original toluene, however xylene was chosen so as to screw with the procedure as little as possible, being the closest thing to benzene or toluene available. Would DCM be a possible choice for future experiments?
The formylation was then attempted:
- 6.3g p-MeO-phenol was placed in a 100mL RBF with 16g NaOH in 18mL H
2O.
- Flask was fitted with a condenser, flushed with butane and magnetically stirred in a water bath at 65-70*C (temperature did not leave this range the entire time, and was almost always at 70).
- Over three hours, ~8mL of chloroform was added through the condenser, about 1mL every half hour (this seemed like the best course of action, as all the procedures, from Antoncho's with 12g to Karl's and the other paper I followed so closely with >100g taking 3 hours for addition).
- After addition was finished the reaction was left to go for another hour.
- Acidified with ~50mL of 25% H
2SO
4, and the expected oil layer formed on top.
- Extracted with DCM, swirled with NaHCO
3 and the solvent removed.
This left perhaps 3-4mL of black oil in the flask, approximately what was anticipated. A sample of maybe .25mL was shaken with a saturated sodium bisulfite solution. It seemed to change fairly quickly from an oil that happily floated on the water to a black tar-like substance that stuck quite happily to the sides and lid of the vial - is this a positive result? Steam distillation was planned, but due to a range of interruptions it never happened. The oil was placed in a flask, flushed with butane, tightly stoppered and put in the freezer. If that doesn't protect it, nothing will. It might get pulled out and played with some time in the future!
Also, regarding the DMS synth (which was also attempted) - procedure from Rhodium's site was followed more or less exactly (with the same molar amounts of reagents, changed from EtOH to MeOH, of course), oil bath at ~150*C, using a pump that should have pulled DMS over at around 120-130*C. However at some point it became obvious that a whole bunch of stuff wasn't coming over, but was collecting in the boiling flask and trying to bubble over and carry sodium sulfate goop into the condenser... in the end, about 4mL of (presumably) DMS was collected (formed a layer below distilled MeOH, was about the right density, and when the receiving flask was left for maybe a day, the tiny little bit of bottom layer that the pippette couldn't get had dissapeared, presumably hydrolysed - apart from BP, are there any other simple tests for DMS?). Anyone with suggestions as to what went wrong (because this is gonna have to be attempted again
)? In hindsight, the stuff in the boiling flask was probably mostly DMS, considering that any H
2SO
4 should be mopped up by the sodium sulfate...