in somes youtube benzocaine synthesis, guys use ethanol but do you know if it's possible to use isopropanol or other more cheaper than ethanol?
i have try something today... but FAIL 
1st test
10gr of PABA + 100ml isopropanol
Note: cold it does not want to dissolve I had to heat it
once dissolved, I cooled it slightly
Addition of 12.5ml h2so4, a precipitate is created directly... I added it in 3 times but I think too quickly... My blend is pink instead of white
After 1h20 of reflux, my mixture is still not dissolved and always pink.
Adding a little isopropanol to see...
1 hour more reflux... still pink and not clear...
I stop and add an alkaline solution to test…nothing…the ph remains very high and nothing happens; not even hot...
fail
1st test
10gr of PABA + 100ml isopropanol
Note: cold it does not want to dissolve I had to heat it
once dissolved, I cooled it slightly
Addition of 12.5ml h2so4, a precipitate is created directly... I added it in 3 times but I think too quickly... My blend is pink instead of white
After 1h20 of reflux, my mixture is still not dissolved and always pink.
Adding a little isopropanol to see...
1 hour more reflux... still pink and not clear...
I stop and add an alkaline solution to test…nothing…the ph remains very high and nothing happens; not even hot...
fail
the test of today :
- Dissolve 10gr PABA in 100ml isopropanol until transparent, heating is necessary
- Once dissolved, cool the mixture
Note: once cooled, the mixture will turn white again.
- Addition under magnetic stirring of 12.5ml H2SO4 slowly in the mixture
Note: added slowly this stays white
- Reflux
Note: after 45min the solution was still white, I decided to increase the temperature. Arrived at 90 minutes the solution has become pink/orange…
I decide to continue 35min. At this stage it is transparent orange. I decide to continue another 30 min to see if it becomes clear or not.
it stayed orange.
Is the color due to the quality of the PABA or to the isopropanol? to check.
- Let cool the mixture
- Addition of the solution saturated with soda ash until the pH reaches 8
- Vacuum Buchner filtration (if possible, I broke mine yesterday...)
- Apply two washes with H2O
- Collect the benzocaine in the filter and let it dry
yield : 7.4 gr
Tips :
Soda saturated solution:
The solubility of sodium carbonate in water increases with temperature, up to 33% by mass at 40°C, then decreases beyond this, to tend towards a slightly lower value, at 30% by mass. The saturation solubility for 100 g of pure water is 7.1 g at 0°C, 45.5 g at 100°C.
- Dissolve 10gr PABA in 100ml isopropanol until transparent, heating is necessary
- Once dissolved, cool the mixture
Note: once cooled, the mixture will turn white again.
- Addition under magnetic stirring of 12.5ml H2SO4 slowly in the mixture
Note: added slowly this stays white
- Reflux
Note: after 45min the solution was still white, I decided to increase the temperature. Arrived at 90 minutes the solution has become pink/orange…
I decide to continue 35min. At this stage it is transparent orange. I decide to continue another 30 min to see if it becomes clear or not.
it stayed orange.
Is the color due to the quality of the PABA or to the isopropanol? to check.
- Let cool the mixture
- Addition of the solution saturated with soda ash until the pH reaches 8
- Vacuum Buchner filtration (if possible, I broke mine yesterday...)
- Apply two washes with H2O
- Collect the benzocaine in the filter and let it dry
yield : 7.4 gr
Tips :
Soda saturated solution:
The solubility of sodium carbonate in water increases with temperature, up to 33% by mass at 40°C, then decreases beyond this, to tend towards a slightly lower value, at 30% by mass. The saturation solubility for 100 g of pure water is 7.1 g at 0°C, 45.5 g at 100°C.
-
NEW VIDEO
MDA Synthesis. Part 1 of 3.