Bromination of 4-methylpropiophenone with NBS/PTSA and solvent-free conditions (large scale)

[WillD]

Reaction scheme:

Synthesis:
1. 1000 g 4-methylpropiophenone and 117 g of anhydrous p-toluenesulfonic acid were added to the flask.
2. Start stirring an over-head stirrer at room temperature.
3. 1200 g NBS added with small portions with constant stirring.
4. Control the temperature of the mixture to 75*C.
5. The entire reaction takes about three hours.
6. At the end of the reaction, discoloration and thickening of the solution, we pour gradually cold water and stirring.
7. Filter the resulting crystals from water, can be used crude bromoketon, theoretical yield: 1400 g.

 

[Venom2021]

1000g 4methylopropiophenone how much will be ml?

 

[Venom2021]

this synthesis can be done 3 times faster in the microwave.

 

[G.Patton]

1000 g/0.991 g/ml= 1009.08 mL

 

[hustla]

So first I should make my ptsa anhydrous if I have monohydrate, right? Melting and boiling it in 115C for 2h will do?

Or I should strictrly follow preparation and keep it molten in 115C for 14+h in inert gas like nitrogen (which I want to avoid)?

 

[Chronos777]

Push! Nobody?
In my opinion it isn't necessary to do vacuum dry. but please can somebody guess if melting for 2 hours at room preassure is enough?

 

[w2x3f5]

the microwave will give the maximum yield close to 95 percents of the substance and works very quickly

 

[cartelloszetas]

Do u made this way bro ??

 

[w2x3f5]

I read a report from one of the manufacturers. synthesis took 10 minutes

 

[cartelloszetas]

Do u know how to do it ?

 

[w2x3f5]

heating from the technique is replaced by irradiation in the microwave. the exact exposure time depends on the volume of the reaction, the power of the microwave, plus do not overheat above 80, cool as necessary. Control the end of the reaction by tcl, or set trial syntheses in a smaller volume to select the optimal time. For a load of 1000 grams, it is assumed that the irradiation is about 5 minutes at a power of 900-1000, THIS IS ONLY A SUGGESTION, there is no indication of the microwave power in the report.

 

[w2x3f5]

same variant

http://bbzzzsvqcrqtki6umym6itiixfhni37ybtt7mkbjyxn2pgllzxf2qgyd.onion/threads/synthesis-2-iodo-4-methylopropiophenone-with-microwave.5388/

 

[Toddler]

its workable synthesis?

 

[w2x3f5]

1400 g a large yield of bromeketone, about 90+ percent, but theoretical yield is about 1500 g.
6.74 mol 4-methylpropiophenone and NBS, not taking into account the purity of these reagents.
Reaxys leads for a similar reaction of 4-methylpropiophenone, NBS and p-toluenesulfonic acid: 54 percent in acetonitrile at 60 degrees, or with urea peroxide 78 percent at 60 degrees. As I understand it, either impurities are formed, or not the entire 4-methylpropiophenone reaction.