1-Phenyl-2-nitropropene (P2NP) Video Synthesis From Benzaldehyde and Nitroethane. Henry Reaction.

[Chemdog010297]

If you have no ability to freeze precipitate the p2np, can u separate the alcohol layer and evaporate solvent or acid extract ?

 

[GhostChemist]

Evaporation is bad idea
Better is adding some portions of water

 

[GhostChemist]

"p2np oil or acidify to salt" - p2np can't be forming the stable salts, this is nonsense (we do not consider anion salts in this case)

1. p2np decompose upon overheating
2. In the presence of base or acid, this instability is amplified: base may trigger Michael-type polycondensation, while acid can cause isomerization or hydrolysis

 

[P2NP_SELLER]

i just found out for the microwave synthesis at least with 600ml IPA for 500ml Nitroethane and so on that if you take out the mixture of the microwave and let it cool down for 15min. . Than you can start crystallization immediately without waiting 12 hours in the freezer by just adding one single drop either of water or hand wash soap. Sounds crazy but when i washed my hands of from the soap a drop mistakenly got into the reaction mixture flask and it immediately started to crystallize. Don't know why!? Cause of the water or the soap on my hands.

You should add this info to the synthesis description you posted in the forum bro.

Do you have any idea what could have happened here? I cannot believe that one single drop of water or water with rests of soap in it completely could possibly have ruined my p2np mixture.... it looks 1 to 1 like straight p2np crystals i got here in my flask.

i used the amounts for the microweave description instead of using 800ml of IPA , not 500ml which would be right regarding to your description.

 

[GhostChemist]

This synthesis is classical Henry Reaction

 

[mile123]

Hello @GhostChemist

In the medium scale instructions there is used n-butylamine 50 ml
conducted during 2-3 hours with constant stirring at 60 °С

What if I use 50ml of nitroethane, how to scale down n-Butylamine since it is catalyst and does conduction time remain the same?

Reagent	Scaled Amount (for 50 ml Nitroethane)
Nitroethane	50 ml
Benzaldehyde	50 ml
Glacial Acetic Acid	12.5 ml
n-Butylamine	10 ml

I got confused since for Microwave (small) scale we have 20ml

• n-Butylamine 20 ml;

 

[GhostChemist]

In most processes, the amounts of reagents and catalysts change proportionally.
But what is a catalyst? A catalyst is a substance that speeds up a reaction.
The speed or time of the reaction will depend on both the process parameters (for example temperature or pressure) and the amount of catalyst. But there is a limit to the amount of catalyst after which increasing the amount of this catalyst does not affect the process. Our reports provide optimal and checked quantities of reagents.

 

[mile123]

This helped a lot. Thanks.

 

[mile123]

Hello!

I tried medium scale, all works well but I get 16g (15.3% yield) of P2NP of 50ml scale where I would expect at least 50g, below are detailed steps

Equipment:
Ovherhead stirier
3- necked flask
pt100 temperature sensor
alighn sensor
oil bath

All reagents are fresh with appropriate packaing and 99% pure from popular seller from Poland.

Reagents:

• Benzaldehyde 50 ml; cas 100-52-7
• Nitroethane 50 ml; cas 79-24-3
• Glacial acetic acid 12.5 ml; cas 64-19-7
• n-Butylamine 2.5 ml; cas 109-73-9
• Isopropyl alcohol (IPA) ~50 ml; cas 67-63-0

Steps:

Medium scale:

1. 2.5 n-butylamine, Benzaldehyde 50 ml (are poured, white fog accurs like in video), GAA 12.5 (is added, fog appeared again), nitroethane 50 ml was added, placed into 1L flask.
2. A alighn 60cm reflux condenser is installed onto the flask without cooling water, it was 13 degrees outside, flask was placed in oilbath.
3. The stirrer and heater are turned on. The reaction mixture is heated up to 60 °С but did not exceed.
6:46 54°С,
6:57 58°С
7:28 57°С
9:35 (after 2:30h reactions was stopped) with constant stirring

4. I poured it in into glass container with lid, let it cool for 15min at 13°С with ouside temp, added 50ml of IPA, gave it a shake and watied for 12h in frezzer at -12°С.
5. I used another glass container, old t-shirt for filtration and let it drop under room temp 21°С.
The yield is 15%.

@GhostChemist can you see where I did mistake?

 

[GhostChemist]

Time of reaction at 60C - min 2-3 hrs and if the reaction is not full complete (see the video timeline (-3:35) test on the glass) continue heating the RM 2-3 hrs again

 

[wael 56]

If you have retained the parent solution from which you filtered the crystals (16 grams is very little), return the solution to the freezer for 12 hours until it reaches -18°C. Remove it and filter immediately. Add a small amount of frozen water as an antisolvent.

 

[Grerycristan]

Can I follow below mentioned route for synthesis of P2P?





Process 1:-



Chemical Reaction



C₆H₅CHO (Benzaldehyde) + CH₃COCH₃ (Acetone) → C₆H₅CH=CHCOCH₃ (Benzalacetone) + H₂O (Water)



Catalyst: NaOH (Sodium Hydroxide)



---



Apparatus and Chemicals Required



Apparatus:



· 250 mL Round Bottom Flask

· Büchner Funnel and Filter Paper

· Vacuum Pump/Aspirator

· Measuring Cylinder

· Weighing Balance

· Glass Rod/Spatula

· Ice-Water Bath

· Conical Flask/Beaker



Chemicals:



· Methanol - 25 mL

· Acetone - 5.8 grams (7.4 mL, 0.1 mol)

· Sodium Hydroxide (NaOH) - 0.5 grams (or 12-15 mL of a 4% solution)

· Benzaldehyde - 10.6 grams (10.1 mL, 0.1 mol)



---



Practical Procedure: Step-by-Step Guide



Step 1: Preparation of Solution



· Take 25 mL of methanol in a 250 mL round bottom flask.

· Add 5.8 grams (7.4 mL) of acetone to it and stir so that it mixes easily.



Step 2: Addition of Base (Catalyst)



· Now add 15 mL of 4% NaOH solution to the flask.

· Note: Exercise caution while adding NaOH, as it can cause skin burns. Wearing gloves is necessary.

· Stir the mixture until the NaOH is almost dissolved. This will create the basic medium required for the reaction.



Step 3: Addition of Benzaldehyde



· Now place the flask on an ice-water bath. This helps control the reaction rate and temperature.

· While stirring continuously, add 10.6 grams of benzaldehyde slowly over 5-10 minutes.

· It is essential to keep the flask cool while adding benzaldehyde because the reaction is exothermic.



Step 4: Reaction Period



· After adding all the benzaldehyde, keep the flask at room temperature (for about 30-45 minutes) and continue stirring.

· During this time, you will observe the mixture thickening and a yellow precipitate beginning to form. This is the benzalacetone.



Step 5: Completing Precipitation



· After the reaction time is complete, place the flask back into the ice-water bath.

· Keep it there for 10-15 minutes. This cooling helps complete the precipitation process and promotes further crystal formation.



Step 6: Filtration



· Place filter paper in the Büchner funnel and connect it to the vacuum pump.

· Pour the entire mixture from the flask onto the funnel and turn on the vacuum.

· The crystals will collect on the filter paper. Wash the flask and the crystals with a small amount of cold methanol to remove any residual impurities.

· Finally, dry the crystals.





Process 2:-





Chemical Reaction



C₆H₅-CH=CH-CO-CH=CH-C₆H₅ (Dibenzalacetone) + 4[H] → C₆H₅-CH₂-CO-CH₃ (Phenylacetone)



Hydrogen Source: NaBH₄ + CuSO₄ → Active copper catalyst + H₂



---



Apparatus and Chemicals Required



Apparatus:



· 500 mL Round Bottom Flask

· Reflux Condenser

· Heating Mantle/Water Bath

· Büchner Funnel and Filter Paper

· Vacuum Pump

· Separatory Funnel

· Measuring Cylinder

· Weighing Balance



Chemicals:



· Dibenzalacetone - Prepared in the previous reaction

· Methanol - 150 mL (Dry)

· Copper Sulfate (CuSO₄) - 4.0 grams

· Sodium Borohydride (NaBH₄) - 3.7 grams

· Diethyl Ether - For extraction

· Magnesium Sulfate (MgSO₄) - For drying



---



Practical Procedure: Step-by-Step Guide



Step 1: Preparation of Reaction Mixture



· Take the benzalacetone and 150 mL of dry methanol in a 500 mL round bottom flask.

· Stir the flask so that the benzalacetone dissolves.



Step 2: Addition of Catalyst



· Add 4.0 grams of copper sulfate (CuSO₄) to the mixture.

· Stir the mixture thoroughly so that the CuSO₄ is distributed evenly.



Step 3: Heating



· Connect the flask to a reflux condenser.

· Heat the mixture to a temperature of 45-50°C.

· Note: Since methanol's boiling point is 65°C, it is necessary to maintain this temperature in a controlled manner.



Step 4: Addition of Reducing Agent



· Add 1.8-2.0 grams of sodium borohydride (NaBH₄) in small portions over 15-20 minutes.

· Extreme Caution: NaBH₄ reacts vigorously with water and releases hydrogen gas. Therefore, it must be added very slowly.

· Stir the mixture well after adding each portion.



Step 5: Completion of Reaction



· After adding all the NaBH₄, continue stirring the mixture at 45-50°C for 2-3 hours.

· During this time, the color may change as benzalacetone converts to phenylacetone.



Step 6: Reaction Monitoring



· Check for completion of the reaction using TLC (Thin Layer Chromatography).

· Mobile Phase: Hexane : Ethyl Acetate (3:1)

· The reaction is considered complete when the benzalacetone spot disappears and a new spot for phenylacetone appears.



Step 7: Extraction



· After the reaction is complete, cool the mixture.

· Add water to it and transfer the mixture to a separatory funnel.

· Extract 3-4 times using diethyl ether.

· Combine all the ether layers together.



Step 8: Drying



· Add anhydrous magnesium sulfate (MgSO₄) to the combined ether layer.

· Let it stand for 15-20 minutes, so that moisture is absorbed.

· Filter off the dry ether layer.



Step 9: Evaporation



· Evaporate the dry ether layer (use of a rotary evaporator is best).

· The oily residue left behind is phenylacetone.



Yield: 8.5-9.5 grams (60-68%)