09-21-04 05:05
No 532486
Hello, i have tryed the route from 2,4,5-trimethoxybenzaldehyde to the styrene and followed the procedure described at rodiums page (../rhodium /nitrost
I have searced and searced.. are there anyone else that have tryed this with nitroethane? I think the yield was a little low (7,84 g aldehyde only gave 3,4 g styrene)it was sonicated for 4 h at 44 °C .. The rx-mixture had an deep orange/red colour and was vacuum destilled at 32 torr to remove all EtNO2 ,then it was poured into a beaker with dichlormethane and water. The organic layer was washed once with brine and solvent evaporated.. The oily residue was solved in hot MeOH and crystallized.. The styrene contains a lot of red material?? and i then rextallize it 2 more times... And the styrene is dryed under vacuum.. Mp =96,9°C .... A little low after all this crystallisations maybee?? could the yield get higher with an extra organic wash of the water i poured the reaction mix in? I got a lot of pictures of the whole process if someone is interested.. Which styrene route give the highest yield of this aldehyde?
(Hive Bee)
09-21-04 10:51
No 532527
What is your yield of product?
Please post the pictures, Legos like pictures of reactions like this
The tendency is to push it as far as you can
(Hive Adickt)
09-21-04 23:34
No 532642
It's hard to say, but it sounds like you have let the reaction run for too long time, and therby made a lot of the dimer/polymer material. Next time follow the rx on TLC, when all the starting material is gone it's time to stop.
(Hive Bee)
09-22-04 04:19
No 532680
yield is now 60% (molar). First time to try this reaction with this aldehyde, and it was pretty yellow and messy... I could probably got higher yield with fewer crystallisations and less messing around! today i tryed to extract the water from the first wash with DCM and crystallised it together with the MeOH from the rextallation.. this gave 2,55 g of crude nitrostyrene,total yield is then about 6 g.. so the method wasnt that bad after all...But next time i will put the rx-mix directly in the sep funnel and add DCM and Brine, no water.. And then wash the first layer of brine with an extra portion of DCM. No destillation, then evaporate all DCM and add 50 ml MeOH for this batch.. Cool to -30 °C and filtrate, evaporate half of the MeOH and Xtalise again.. Then one rextallation of all product.. fever step and less loss of product.. What wold be the best solvent for tlc? i use silika[sub]254 on aluminium sheet.. 1:1 EtOAc and hexane?? The styrene is pretty polar.. About this pictures, i dont manage to upload them, data isn`t my strong side.. he he..