# Any one has good experience with the NaBH4\Cucl2 reduction?



## Bennychairman (Dec 1, 2022)

i want to ask if any of you have experience with best method and rates and tempratures for the reduction , i specifically talking about 2,5 dimethoxy-NS to 2ch 
lets say something like this my friend tried.

A 2 neck round bottom flask containing a 1:1 mixture of IPA:water by weight (250g/10g NS) was equipped with a condenser and 7.25 molar equivalents of NaBH4 were added, at once, under heavy stirring and left until bubbling stopped and all was dissolved. Afterwards, all of the NS (9.3g) was added at once to the flask.
*would adding the Nabh4 do a freezing -16 would be safe some nabh4 from decomposing? 

The mixture was refluxed for 15 minutes before 1.2g of CuCl2 dihydrate dissolved in a minimal amount of water was added to the refluxing reaction all at once. This was a mistake, and the mixture almost boiled out of the open side neck of the flask. Next time, I will add it in two parts. The reaction was then refluxed for another hour. A very faint methylamine smell was noted, implying my nitrostyrene was not clean enough and still had contained amounts of nitromethane that was being reduced into methylamine. This actually made me happy, though, because it was evidence the nitro groups were being reduced.

After refluxing the reaction was allowed to cool to about room temperature and concentrated acetic acid was added to neutralize the remaining NaBH4 until no more bubbling occurred upon addition of acetic acid. This took about 20mL of acetic acid.


Work up:

The solution was vacuum filtered and distilled until distillate came off at 100C, implying almost all the IPA had been boiled off. This was stored in a container and will be recycled for further reaction runs. 

After cooling the solution, dark oily what I assume to be crude 2C-H freebase was seen in the reaction mixture. Conc. HCl was added under stirring until the water was heavily acidic. This took more HCl that expected. Then the water was washed with 6x25mL of DCM, made basic with 20% KOH solution, extracted with 6x25mL of DCM, the extracts were pooled, washed with distilled water, and 5g of concentrated HCl was added followed by extraction with 3x40mL of water. The water was boiled off via azeotropic distillation with toluene until a sudden precipitation of white 2C-H HCl crystals took place.

Final yield: 6.8g of 2C-H HCl from 9.3g of 2,5-dimethoxy-beta-nitrostyrene. 65%



can something be done to improve the yield or save some materials?


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