Preparation of Nitroalkanes Directly from Alcohols
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.
This article is in error, see proof in this article.
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
