[hirdscemicals]

Hi i have done the fischer esterification on paba to benzocaine with 6grams, The reaction consists of 6 grams PABA, 40ml ethanol, and 6ml sulfuric acid refluxed for 82-90 min, then 10% solution NaOH added to make a ph 8, and then washed and filtered with distilled water. I'm wanting to do a 500g batch now but do i follow the basic calculations or can i save on any materials thank you.

[synthon]

My guess would be that the solvent can be reduced to a bit more than needed to dissolve the reagents.  I bet the total of sulfuric acid could also be reduced, close to the scale of the solvent.

[discodermolide]

Hi i have done the fischer esterification on paba to benzocaine with 6grams, The reaction consists of 6 grams PABA, 40ml ethanol, and 6ml sulfuric acid refluxed for 82-90 min, then 10% solution NaOH added to make a ph 8, and then washed and filtered with distilled water. I'm wanting to do a 500g batch now but do i follow the basic calculations or can i save on any materials thank you.

This is quite dilute make it 25-30% in PABA in ethanol.
Scaling now to 500 g means you need about 4L ethanol. and 1000g about 8 L, If you can handle these quantities ok then go ahead, but I would make it more concentrated. Watch out for diethyl ether formation, you should be OK on this scale and temperature, just make sure the exhaust is vented properly.

[hirdscemicals]

Hi I did the reaction using 3litre ethanol and 400ml sulphuric acid,it seemed to have converted the PABA to benZocaine, the problem is now I have put approx 3 litres of 10% solution of sodium hydroxide in the flask but it's still a very strong acid on the ph paper. Please could someone work out how I could do This much easier. Maybe some one give me an exact amount of how much sodium hydroxide and water to ph7 thank you

[discodermolide]

You would have been better to use 30% NaOH, 10% will take far too much. You should be able to work out yourself how much base it will take to get to pH 7.
Now use the stronger base to bring the pH down.
After you have done that ask yourself the question; how am I going to obtain my product from this aqueous mixture of salts?

[OC pro]

Please could someone work out how I could do This much easier. Maybe some one give me an exact amount of how much sodium hydroxide and water to ph7 thank you

Again someone doing organic experiments without any!! basic knowlegde. Sad but true...(*shaking the head*)

[DrCMS]

Should we really give anymore advise to a novice who is making a large amount of a potentially illegal drug?

[discodermolide]

Probably not, he won't be able to do it anyway.

[Arkcon]

Yep, I'd say this topic is as well covered as it should be.

*Topic Locked*