Pinner reaction

The Pinner reaction is a reaction Names of organic chemistry. The main application of the Pinner reaction is the production of carboxylic acids, esters, thioesters and amides. It is named after the German chemist Adolf Pinner ( 1842-1909 ).

Survey

The starting material for all end products of the Pinner reaction is a so-called Pinner salt. This is made of a nitrile and an alcohol under the influence of hydrochloric acid and supplies the Pinner salt, the hydrochloride of imino ester.

The Pinner salt can be used as starting material for the synthesis of many organic compounds - are used amidines - carboxylic acid esters, orthoesters or protonated.

Mechanism

Production of a Pinner salt

In this reaction, a Pinner salt ( 4 ) is first generally formed. This salt may then be further processed by reaction with other reagents.

First you place a nitrile 1 with dry hydrochloric acid. Thus it comes about in its protonated form 2. Are you an alcoholic to this added onto the carbon of the nitrile group. The electrons of the triple bond of the nitrile encamp around, resulting in an imine 3 is formed. Following an intramolecular proton transfer takes place. Through these, the sogenannante Pinner salt forms 4

Preparation of esters from Pinner salts

After treating the Pinner salt with water, so you can win from a carboxylic acid ester. Superimposed one alcohol to the nitrile as described above, but a thiol or an amine, may be prepared also thioesters and amides.

After treating the Pinner salt ( 4) with water, an oxonium ion forms 5 Then an intramolecular proton transfer between the oxonium group and the amino group takes place. This creates an ammonium hydroxy group with 6 Rearrangement of an electron pair now deprotonated oxygen of the newly deposited water and forms a carbonyl group. In addition, ammonia is split off from the molecule. This refers to the hydrogen ion, which was released in the deprotonation. Thus, in the sum leaves an ammonium ion the molecule. This is a carboxylic ester to form 7

Producing a 1- amino-1- iminium salt

If the procedure is a Pinner salt with an amine on, then a iminium salt with an amino group.

Are you a primary or secondary amine to a Pinner salt ( 4), then the nitrogen particles of the amine on the carbon of the Pinner salt outsourced to. This makes the molecule 8 is formed. The newly accreted deprotonated amine, which is produced as intermediate 9. By rearrangement of an electron pair again forms a double bond between the nitrogen and the carbon atom. Furthermore, the pair of electrons between the carbon and the Sauerstofatom migrates. This leaves an alcoholate anion the molecule. This is very basic, and therefore it reacts with the proton previously cleaved to an alcohol. Through these steps, the iminium salt 10, said a chloride ion is the counterion.