malvaxman (Hive Bee)
11-14-01 04:32
No 236636
      Nitro ethane from alkohols  Bookmark   

Preparation of Nitroalkanes Directly from Alcohols
..from ../rhodium/chemistry /alcohol2nitro.html

Spengler described the synthesis of a few simple primary and secondary nitro aliphatic nitro alkanes using a mixture of NaNO2-H2O-HCl,however their method was not tested on a wide varity of substrates including tertiary alcohols. In continuation of our interest on the chemistry of nitro aliphatics and their application in the synthesis of bioactive natural products, we have observed that when a mixture of NaNO2-AcOH-HCl is treated with a varity of alcohols the corresponding nitro compounds are formed in excellent yields. The results are shown in the table below.

Substrate       Reaction time   Product             Yield

Benzyl alcohol  6h              Phenylnitromethane   85%
1-Phenylethanol 5h              1-Phenylnitroethane  90%
4-MeO-Phenethylalcohol 6h   4-MeO-Phenylnitroethane  90%
4-Cl-Phenethylalcohol 6h    4-Cl-Phenylnitroethane   87%
Octyl alcohol         6h     Nitrooctane             80%

Typical Procedure:
To a mixture of the benzyl alcohol (9.24 mmol) in CH2Cl2 (30 mL) was added NaNO2 (2g, 29 mmol). To this mixture was added acetic acid (1.5 mL, 26.2mmol) and left at room temperature for five minutes. Then concentrated HCl (0.5 mL) was added to this mixture and left at room temperature without stirring for about 14 hours while monitoring the reaction on TLC. The reaction mixture was diluted with CH2Cl2 (150mL) and the preceptiated NaOAc was filtered off. The organic phase was evaporated in a rotavapor and the gummy residue was dissolved in hexane (100 mL) and washed with cold water (5x200ml) to remove the acid. The organic phase was dried over anhydrous sodium sulfate to furnish the nitroalkane.

Reference: Synlett, No. 7, yr 2000, pages 1064-1066
..Now go and try ethanol and report back...tongue
(Commodore "Mole Bouncer")
11-14-01 07:33
No 236663
      Re: Nitro ethane from alkohols  Bookmark   

it works, but so do you. Incredible volumes of solvent to deal with.

"All those memories lost like rain..."
(Hive Bee)
11-14-01 08:44
No 236673
      Re: Nitro ethane from alkohols  Bookmark   

Why is so much solvenīt needed and why must it be DCM? Couldnīnt one just make the reaction, filter out NaOAc destill of nitroethane, then add new NaNO2, new ethanol, new Acetic acid and run it once more and so on... laugh
11-14-01 11:51
No 236719
      Re: Nitro ethane from alkohols  Bookmark   

Jim mentions this Post 205293 (not existing). Might be another procedure about.