conducter - 9-4-2007 at 02:32
i have read lots of synths failed because of apparently-bad photograde p-benzoquinone.
well i was wondering if its possible to scale up the hydroquinone synth thats on rhodium
"From Hydroquinone using hydrogen peroxide [4]
55 g of hydroquinone, 115 g of isopropyl alcohol as a reaction medium, and 1 g of iodine as a catalyst were charged into a 300 ml four-necked glass
reaction vessel with a stirrer, a dropping funnel, and a thermometer. Then stirring was started, and after 58 g of a 35% hydrogen peroxide solution
were added over about 3 hours while keeping the temperature at 30-35°C, the temperature was raised to about 45°C, which was kept for about 3 hours
to complete the reaction. After the completion of the reaction, the reaction mixture was cooled gradually to about 15°C, and the reaction product was
filtered by suction. The reaction product was washed with a small amount of isopropyl alcohol, and dried under reduced pressure to yield 49.5 g of
p-benzoquinone. The yield was 91.6% (based on the charged hydroquinone, hereinafter the same being applied), the melting point was 111-112°C, and the
purity as measured by HPLC was 99.0%."
can this be done in an open beaker or open flask? because i dont know where or what price a 300ml 3 neck flask would be but i cant get that. Is it
possible to use a 500mL flat bottom flask?
Also how important is temp. because if i used a 1 neck flask it would be hard to have a thermometer in the mix, perhaps i can measure the temp of a
water-bath and use that as an indicator of the reaction temp?
Klute - 9-4-2007 at 13:49
You can always try using an open flask, keep something over r it is as celophane or something, and use an seperating funnel or something similar to
drip the H2O2... In that case simply place the thermometer on the side, away from the stirring magnet, hold it with a clamp or something. As this
seems like an exothermic reaction, monitoring the temp is vital. The temperature of the cooling bath won't indicate the temperature in the flask, so
definatively use a thermometer.