Shechter-Kaplan oxidative nitration

What is Shechter-Kaplan oxidative nitration?

The Shechter-Kaplan oxidative nitration is a well-studied reaction that has been known since the early 1900s, with early reports by Angeli et al. This reaction converts primary and secondary nitroparaffins into vicinal or geminal dinitro compounds under basic conditions using silver nitrate AgNO3. The Shechter-Kaplan oxidative nitration is also known as the Shechter-Kaplan reaction, Shechter coupling, Kaplan-Shechter reaction, or Shechter-Kaplan process.

Shechter-Kaplan oxidative nitration - general reaction scheme - Shechter-Kaplan reaction - Shechter coupling - Kaplan-Shechter reaction - Shechter-Kaplan process
Shechter-Kaplan oxidative nitration

There are several variations of this reaction, depending on the oxidizing agent used. Anionic oxidants such as persulfates are the most effective reagents, although potassium ferricyanide is also useful for secondary nitroalkanes. In contrast, cationic oxidants like silver salts (e.g., AgNO3) can also be used, but yield lower product yields than persulfate.

Shechter-Kaplan oxidative nitration - general reaction scheme - Shechter-Kaplan reaction - Shechter coupling - Kaplan-Shechter reaction - Shechter-Kaplan process
Shechter-Kaplan oxidative nitration
  • R = alkyl

Additionally, the reaction can be performed electrochemically. However, this method is ineffective for nitroethane, nitroform, and 1,1-dinitroethane.

The Shechter-Kaplan oxidative nitration is particularly useful for the preparation of secondary gem-dinitro compounds and α,α,ω,ω-tetranitroalkanes, which are not accessible by the ter Meer reaction. The reaction proceeds smoothly in alkaline aqueous solution at 0–30 °C, and the pH of the reaction media plays a crucial role in the reaction.

The reaction proceeds slowly at a pH above 9.4 and is accelerated in a pH range of 7.2–9.4. It is essential to buffer the solution or add an additional base to prevent the reaction from becoming acidic, which regenerates the nitroalkane, leading to its decomposition into a ketone or pseudonitrole. Mercuric nitrate Hg(NO3)2 can also be used, but it results in a lower yield.

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