Novel 2cb synthesis + problems with pictures , please help me to figure it out

[Babazik]

i've come around this novel way and tried to do it , but run into problems i hope you can help me figure it out.

i've ordered 1kg of 2,5 Dmba from china.

this is the steps :

1. Dissolve 8.3g (50mmol) 2,5-Dimethoxy Benzaldehyde in 50ml Methanol and 6.1g(100mmol) Nitromethane in 1L beaker. Stir the solution and cool it to 0~5 degree C.

2. Dissolve 8.4g(150mol) Potassium Hydroxide in 25ml Methanol. Stir the solution and cool it to 0~5 degree C.

3. Place the beaker with 2,5-Dimethoxy Benzaldehyde solution in(1) in a big container with ice-salt baths and setup the big container on the magnetic stirrer. Use thermometer to monitor the temperature inside beaker and turn on stirrer.

4. Use dropper to add Potassium Hydroxide solution slowly into the beaker. Avoid the temperature exceed 5 degree C.

5. After addition is done (typically within 1 hour), stir the mixture for another 30 min.

6. Prepare 300ml 10% HCl solution and cool it to 5-10 degree C when you stir the mixture.

7. Add cooled 10% HCl solution into beaker with mixture in 5 times every 5 min (roughly 60 ml once) with stirring.

8. Now you can see yellow colored crystal inside the mixture. Prepare Buchner funnel and flask and use the suction source to collect the crystal. You do not need to dry and weight the crystal.

***first pic when you see yellow (the darker one is unreacted DMBA ans was removed.

9. Mix 300ml 32% HCl solution and 150ml IPA in 1L beaker. Cool the solution to 5 degree C.

10. Add the wet crystal from (8) into the HCl/IPA solution from (9). Place the beaker in a big container with ice-salt baths and setup the big container on the magnetic stirrer.

11. Prepare 45g zinc powder. Add the powder into the stirring solution within 1 hour. Do not be hurry or you will get many yellow bubble. Use small spoon and add slowly.


12. After addition is done. Stir the mixture for another 2 hour, now you can see the solution become transparent and there might be some un-dissolved zinc in the bottom. On the surface of the un-dissolved zinc powder, you will see very small hydrogen bubble. Put the mixture with cover into the refrigerator for one night. At the same time, mix 100g Sodium Hydroxide with 150ml water. Add NaOH into water in 3 or 4 times to avoid temperature increasing. Put the NaOH solution into the refrigerator, too.

13. Place the beaker with mixture in a big container with ice-salt baths and setup the big container on the magnetic stirrer. Add NaOH solution into the stirring mixture slowly to avoid temperature increasing.

14. After addition is done, another 50g NaCl is added into the mixture and sit the mixture for few hour until you can see the IPA layer well separated.

15. Use dropper to suck the IPA layer carefully into a container. Add 50ml IPA into the mixture and suck to collect the product two times.
16. Put the IPA with 2C-H under a fan to evaporate it. Few hours later, you will get yellow color oil(2C-H). You can mix 200g Sodium Hydroxide with 300ml water. Add NaOH into water in 3 or 4 times to avoid temperature increasing. Put the NaOH solution into the refrigerator.

17. Weight the oil and record it. If you have scale upper limit issue, prepare a smaller container and record the empty weight. During IPA evaporation, you can transfer the mixture into the smaller container.

*** PIC here i got the 2ch extracted with dmba with ipa and was dried (my 2ch was kinda dark looking even tho i really watched temperature.

18. For 100mmol 2C-H, dissolve it in 50ml GAA in a 1L beaker and put the beaker into ice bath on stirrer.

19. Mix 120ml GAA, 40ml water, 11.8g Sulfuric acid(120mmol) and 14.3g Potassium Bromide(120mmol) into another beaker. Add 5.8g 35% hydrogen peroxide solution(60mmol) into the mixture with stirring. You will see the color changed.

20. Use dropper to add the mixture from (19) into the mixture from (18) slowly with stirring. After addition is done, add 5.8g 35% hydrogen peroxide solution(60mmol) into the mixture with stirring. Wait for another 20 min with stirring.

*here is the brommination stage , i think i got it right ... just mix all the things together.


21. Add NaOH solution from (16) into the mixture in ice-bath slowly.

* thats the picture with the black goo floating

22. The color should be dark brown now. Add 100ml Toluene into the mixture with stirring. After 5 min stirring, sit the mixture to wait the layer separation. Suck the Toluene out by dropper and collect the Toluene. Repeat this step until the Toluene become transparent. You need to add Toluene maybe 3 times or more depends on your skill.

*add the pic with soluene extraction with the layers . i then also used a separatory funnel to make sure the toluene was as clean as possible with no water in it.


23. Put the Toluene on stirrer and add 13.6g 32% HCl solution(120mmol). With stirring, you will see some salt generated in the Toluene. Few minutes later, stop stirring and use funnel and filter to collect the salt powder. It should be dark brown color.

***thats where i can into a problem , i add hcl to the toluene , and instead of salt generated , just a black goo is generated that drops to the bottom and i endded up with a large amount of it T_T


24. Use Acetone to wash the powder on filter by dropper until the color become white.

now i really dont know what to do? , i have that black goo that sinked at the bottom , i guess is 2cb ? that cant form salt? and it became protenated and became insolubale at toluene and sinked at the bottom ?
i have access to DCM i wonder what should i do next? should i collect the black sinked goo and do something with it ?
also my 2ch oil was kinda dark looking , is this significant ?

 

[Babazik]

edit : i've took a chunk that floated after the addition of NAOH which makes 2cb not soluble in water and dropped it into a clean toluene and added hcl and it did generate white salt , my guess is there are other stuff in the toluene that prevent the salt from generating , so i thought of an idea to add hcl to the toluene and all the protenated 2cb will sink to the bottom seperate the toluene with funnel then add NAOH which will generate 2cb chunks insoluble in water , then take them , add them to new clean toluene and add hcl again.

 

[G.Patton]

Add 5.8g 35% hydrogen peroxide solution(60mmol)

BabazikActually, I think H2O2 35% with sulfuric acid destroy (over-oxidize) your product. Can you get elemental bromine and carry out the reaction as I wrote?

edit : i've took a chunk that floated after the addition of NAOH which makes 2cb not soluble in water and dropped it into a clean toluene and added hcl and it did generate white salt , my guess is there are other stuff in the toluene that prevent the salt from generating , so i thought of an idea to add hcl to the toluene and all the protenated 2cb will sink to the bottom seperate the toluene with funnel then add NAOH which will generate 2cb chunks insoluble in water , then take them , add them to new clean toluene and add hcl again.

Does this substance melt with same temperature as 2C-B*HCl?

 

[Babazik]

Actually I think H2O2 35% with sulfuric acid destroy (over-oxidize) your product. Can you get elemental bromine and carry out reaction as i wrote?

Does this substance melts with same temperature as 2C-B*HCl?

G.Pattondidnt had a chance to check
i dont think i can get elemental bromine since you need special approval but ill ask maybe in small quantity , i know for a fact that my friend in other country was successful with the synthesis 100% so its just me doing something wrong , he told with that i need to watch the temp to even less then 10C in the zinc reduction or ill get darker looking 2ch oil.
i am almost sure that my toluene is just dirty with other product since it didnt become clear after adding the HCL , and the the protenated 2cb just sinked to the bottom , but i did get salt if i took a chunk from the picture and added to clean toluene it did give me small amount of salt , so i wonder how should i extract the 2cb goo from the toluene?
add hcl and let it sink ? then throw out the dirty toluene , add base water to the good with stirring to make it insoluble in water and will generate chucks of 2cb oil , then throw it again to clean toluene and add hcl again ? it might work ? what do you think ?

 

[G.Patton]

It is really hard to read, man, but I understand.

so i wonder how should i extract the 2cb goo from the toluene?

BabazikEvaporate toluene, distill your toluene and repeat

base water

Do you mean NaOH aq. solution, right?

chucks

what is it?

 

[Babazik]

It really hard to read, man, but I understand.

Evaporate toluene, distill your toluene and repeat

Do you mean NaOH aq. solution, right?

what is it?

G.Patton
sorry for bad english ill try to be more clear , i meant chunks , the photo where there are 2cb chunks floating , i took one of them a dropped them into a clean toluene and added hcl and salt was generated , so i guess that the toluene that used for extraction carrys with it stuff that doesn't allow the salt to form , now i have toluene with goo at the bottom after the hcl addition and i wonder how should i separate it from the dirty toluene (along with the stuff that in it other then 2cb) so i could add it to a new toluene and try add hcl to form salt

 

[Uncle Lee]

I think you have a problem in the first step, in Henry reaction, you should use some kind of primary amine as catalyst instead of sodium hydroxide, if you can't get a good catalyst, you can use ammonium acetate, then reflux the catalyst with the reactants, a certain temperature to allow the dehydration of β-nitro alcohol to form Nitroalkene, this temperature is at least room temperature, not under and in conditions.
You add hydrochloric acid to the reaction, I guess your purpose is to terminate the reaction, in fact I think this step is redundant, after the reaction is finished you can put the reaction in the refrigerator and then pump and rinse with IPA or recrystallize
The Nitroalkene you obtained should be orange to red, and after recrystallization the crystal shape shows needle-like crystals, your product is yellow, I don't think this is correct, it is possible that you just reduced the aldehyde to alcohol and then brominated to get these black products

 

[G.Patton]

Evaporate toluene, distill your toluene and repeat

G.PattonOr repeat synthesis with DCM.