Alkylation of Carboxylic Acids

[java]

Polymer-Supported Triazenes as Smart Reagents for the Alkylation of Carboxylic Acids
Bernhard Erb, Jean-Philippe Kucma, Sandrine Mourey, Fritz Struber
  
Chemistry - A European Journal
Volume 9, Issue 11, 2582-2588,2003.
DOI:

10.1002/chem.20039024

Abstract:
Starting from polystyrene, a simple four-step synthesis of polymer-supported alkyltriazenes (alkyl=Me, Et, benzyl) is described. With
this synthesis, a loading capacity of 2.2 mmolÊg-1 can be reached. The most prominent application of these polymer-supported reagents is the rapid, highly selective and high-yielding esterification of carboxylic acids, which involves a simple mix and filter off procedure at room temperature. If stored in a refrigerator, these reagents are stable for many months and they can be recycled several times.

Note: I have the article Rhodium , I can scan it and upload it to you so it can be made available....java

[Rhodium]

Polymer-Supported Triazenes as Smart Reagents for the Alkylation of Carboxylic Acids
Bernhard Erb, Jean-Philippe Kucma, Sandrine Mourey, Fritz Struber

Chemistry - A European Journal, Volume 9, Issue 11, 2582-2588 (2003)

(https://www.thevespiary.org/rhodium/Rhodium/pdf/triazenes.carboxylic.acid.alkylation.pdf)
DOI:

10.1002/chem.20039024

My summary: Polystyrene, after para-nitration (HNO₃), reduction (Phenylhydrazine), diazotization (NaNO₂/HCl) and reaction with an an alkylamine (RNH₂) forms a triazine reagent [essentially being Polystyrene with a -N=N-NH-R group in the para position, the R coming from the amine], which in turn can transfer the R group (room temp, 1-24 h) to a carboxylic acid, forming the alkyl ester.

In essence, the following transformation takes place: R₁-COOH + R₂-NH₂ R₁-COOR₂
(With polystyrene, phenylhydrazine, nitric and nitrous acids merely being mediators of the transformation).

java: Did you have any specific applications in mind, or did you just think it was a neat reaction?

[java]

Rhodium,...... Aside from being a state of the art tool that is recyclable and re-usable and has the advantage to convert carboxylic acids into esters for applications like phenylalanine converted to an ester easily and in minutes without affecting the amine group, I thought it was a neat article......java