P2P Synthesis From P2NP

[GhostChemist]

Phenylacetone (P2P) synthesis

• Novator
• Apr 3, 2023
• 20

Phenylacetone (P2P) synthesis from P2NP.
https://bbgate.com/threads/p2p-synthesis-from-p2np.188/

Reagents:

• 1-Phenyl-2-nitropropene (P2NP; cas 705-60-2) 1000 g;
• Methanol (MeOH) 10 L;
• Sodium borohydride (NaBH4) 470 g;
• Hydrogen peroxide (H2O2) 30% 6 L;
• Potassium carbonate (K2CO3) 1800 g;
• Hydrochloric acid (HCl) 37% aq;
• Dichloromethane (CH2CI2) 5 L;
• Sodium hydroxide (NaOH) 5 L 25% aq;
• Distilled water (H2O) 5 L;

Equipment and glassware:

• 20 L Round bottom flask;
• Water bath, ice;
• HCl gas source;
• Magnetic or top stirrer;
• Retort stand and clamp for securing apparatus;
• Vacuum source;
• Glass rod and spatula;
• Rotovap machine;
• pH indicator paper;
• Laboratory scale (1-1000 g is suitable);
• Measuring cylinders 1000 mL;
• 1000 mL x3; 2000 mL x3; 5000 mL x3 Beakers;
• Several buckets;

Reaction scheme:

​

Synthesis:

1. 1-Phenyl-2-nitropropene 1000 g is dissolved by methanol (MeOH) 10 L in 20 L flask.
2. The reaction mixture is cooled to 0 °C by an ice/salt bath with good stirring.
3. Sodium borohydride (NaBH4) 470 g is added to reaction mixture in small portions with a constant stirring in order to control reaction temperature below 15 °C.
4. The ice/salt bath is removed after an exothermic reaction end.
5. The solution is stirred at room temperature for 2 h.
6. Then, the solution is cooled to 0 °C in ice/salt bath again.
7. Hydrogen peroxide (H2O2) 30% 6 L and potassium carbonate (K2CO3) 1800 g are added into the reaction flask.
8. The solution is stirred for 24 h at room temperature.
9. Next, hydrochloric acid (HCl) 37% aq is poured into the mixture dropwise to reach pH 6.5-7. The reaction is exothermic, CO2 is released (caution!).
10. The mixture is extracted with dichloromethane (CH2CI2) 5 L, extract is washed with sodium hydroxide (NaOH) 5 L 25% aq. and distilled water (H2O) 5 L.
11. Dichloromethane (CH2CI2) is distilled off under vacuum to give a clear phenylacetone (P2P, cas 103-79-7) yellow oil. The yield is 70%.​

 

[primitiveintelectual]

Is this Synthesis suitable for Beginners?
When mixing,cooled the 20 L Round bottom flask must be closed?
In what step do we use Rotovap?

Step 9.:
How much HCl will we need?
On Erowid Forum, this P2P method of P2NP with NABH4, but in a small scale. They give 300ml HCl to achieve acidity, so in yours method in a big scale, how much HCl will we need?
about 10L HCl? So I don't have to dropwise it, Can I pour straight on?

 

[G.Patton]

yes
A mixing of what? I can't guess what do you mean.
Do you know what does it means "distilled off under vacuum" ? There is link special for you.
Enough to reach pH 6.5-7. You can count it by moles in according with you load, if you want.
No, you'll spoil your product.

 

[primitiveintelectual]

When mixing,cooled the 20 L Round bottom flask must be closed?
A mixing of what? I can't guess what do you mean.

I mean
Steps 1 to 8.
When stirred, cooled and again stirred, care should be taken to keep the Flask close or not?
Step 3 Do you need to take care of the Flask to be closed?
Or step 8 Do you need to take care to be closed?
Or does it not matter?

 

[primitiveintelectual]

How much HCl will we need?

Enough to reach pH 6.5-7. You can count it by moles in according with you load, if you want.


I don't know how to count it

 

[G.Patton]

No, in opposite case reaction flask can explode with very upset consequences.
You can pure HCl 37% acid and stir it until ph 6.5-7, if you can't count.

 

[gmo]

Master, Why do we need this ph?

 

[G.Patton]

In order to neutralize the reaction mixture.

 

[primitiveintelectual]

Thanks for clarification

 

[tweaker2]

the refraction index for p2p is 1.5155-1.5175 and if impure the value goes higher
so the end product in this video is not p2p

 

[G.Patton]

Where did you take such info?
1.5102 Is okay, difference isn't so big. In case you want to get pure p2p for following reactions, you have to distill it.

 

[tweaker2]

what info?that is how refractometry goes,we take sample in this case what we assume p2p then take the index value of p2p and compare if the sample is impure but majority is p2p the index value just gets little higher so 1.5102 is not okay it just tells you that majority of the sample is not p2p it may contain p2p but only small amount.so the reaction in this video is either incomplete or failed we dont know he should distill the product to see if there is any p2p present

 

[G.Patton]

I asked about this range.

 

[tweaker2]

from chem database

 

[G.Patton]

It is okay by reason that it has appropriate boiling point, density. DCM traces change product density, hence refraction index as well. Anyway, you can repeat synthesis and shot your own video to prove that we try to deceive you.

 

[K-Cyanide]

looking at the color, one can easily see that it is not pure p2p. This compound has a pale yellow color. (if any). However, it is strongly recommended to vacuum distill the P2P prior further use.

 

[Multivitamin]

After distilling DCM off. Can i use it in NaBHr4 reaction as it is?Or is it absolutely necessary to distill the p2p first to be able to use it in reaction?

 

[G.Patton]

I would recommend you to distill it before following synthesis. As @K-Cyanide said, it will increased reaction yield and you'll get less by-products.

 

[Multivitamin]

Okay i will distill it no way around it.

 

[K-Cyanide]

No, absolutely in the sense, the reaction won´t work using undistilled P2P, is it not.
However, the final product is always of higher quality when you use distilled compounds. And not to forget, dirty P2P hurts the yield, no doubt. Its a tedious work, but it pays off.

 

[Multivitamin]

Okay will distill it.Guess no way around it.Do you think that it is absolutely necessary to measure pressure in in system when vacuum distilling p2p oil/meth freebase oil?Or can i just plug-in vacuum pump to vacuum adapter on new empty receiving flask when DCM has been distilled off (cause DCM with low boiling bp. of 50c would distill even without vacuum) turn on the vacuum crank up the heat until i see first signs of p2p oil coming over to receiving flask and hold temperature until distillation is over.

Am i missing something here?Do i have to measure that pressure of the vacuum?Or can i just slowly crank the heat up until i see oil coming over in receiving flask?

 

[G.Patton]

Read about Distillation and distillation systems, it would be very helpful for you.

 

[K-Cyanide]

No, you dont need to know the absolute value of the pressure. But you need to be sure, that your vacuum pump is strong enough, to lower the boiling point of P2P/Meth freebase significantly. (+- 100 C is acceptable. A useful tool is the online Nomograph from Sigma Adlrich:
Nomograph Sigma
A good practical test is to connect a small RBF filled with water (1/4 to 1/2 of the volume) to your vacuum source. Under ambient conditions the water should begin to boil in the flask. This means your vacuum source is able to produce an ultimate vacuum of appr. 50 mmHg (Torr). This is basically sufficient when your pump can also suck a certain volume per minute. It should be greater than 20 liters per minutes.
And finally, yes correct first apply the vacuum and then raise the temperature, in the beginning full blast and adjusting when approaching the boiling point. Hope that helps.