Synthesis Arndt-Eistert

However with appropriate reaction control, the desired product can be obtained in high yield.  

The phosphonates obtained by the Arbuzov reaction are starting materials for the Wittig-Homer reaction (Wittig reaction), for example, appropriate phosphonates have been used for the synthesis of vitamin A and its derivatives/ 

Moreover organophosphoric acid esters have found application as insecticides (e.g. Parathion). Some derivatives are highly toxic to man (e.g. Sarin, Soman). The organophosphonates act as inhibitors of the enzyme cholinesterase by phosphorylating it. This enzyme is involved in the proper function of the parasympathetic nervous system. A concentration of 5 x 10 g/L in the air can already cause strong toxic effects to man. 

Chain elongation of carboxylic acids by one methylene group 

The Arndt-Eistert synthesis allows for the conversion of carboxylic acids 1 into the next higher homolog 4. This reaction sequence is considered to be the best method for the extension of a carbon chain by one carbon atom in cases where a carboxylic acid is available. 

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Arndt-Eistert synthesis A procedure for converting a carboxylic acid to its next higher homologue, or to a derivative of a homologous acid, e.g. ester or amide. 

The Kolbe synthesis of nitriles is an important method for the elongation of an alkyl chain by one carbon center (see also the Arndt-Eistert synthesis). The nitrile 2 can for example easily be converted to the corresponding carboxylic acid by hydrolysis. 

In the Arndt-Eistert synthesis an acyl halide is converted to a carboxylic acid with... 

The acid chlorides have served as useful synthetic intermediates leading to ketones via the malonic acid synthesis and Friedel rafts reaction, thiadiazole acetic acid derivatives, and halo ketones via the Arndt Eistert synthesis and carbinols by hydride reduction <68AHC(9)107>. The dialkylcadmium conversion of acid chlorides into ketones fails in the 1,2,5-thiadiazole series. The major product is either a tertiary carbinol or the corresponding dehydration product, by virtue of the high reactivity of the intermediate ketone. 

The reaction between acyl halides and diazomethane is of wide scope and is the best way to prepare diazo ketones.1714 Diazomethane must be present in excess or the HX produced will react with the diazo ketone (0-71). This reaction is the first step of the Arndt-Eistert synthesis (8-8). Diazo ketones can also be prepared directly from a carboxylic acid and diazomethane or diazoethane in the presence of dicyclohexylcarbodiimide.1715 OS III, 119 VI, 386, 613 69, 180. 

Arndt-Eistert reaction.2 This reagent is recommended for use in place of diazomethane in the Arndt-Eistert synthesis (equation I). 

Arndt-Eistert synthesis (—COC1—>—CH2C02H, Section 16-4A)... 

The Arndt-Eistert synthesis is useful for converting an acid to the next higher member of the series. Pyrazolines are important intermediates for the preparation of cyclopropanes ... 

The Arndt-Eistert Synthesis allows the formation of homologated carboxylic acids or their derivatives by reaction of the activated carboxylic acids with diazomethane and subsequent Wolff-Rearrangement of the intermediate diazoketones in the presence of nucleophiles such as water, alcohols, or amines. 

The Wolff rearrangement is the third step of the Arndt-Eistert homologation of carboxylic acids. Figure 11.25 picks up an example that was discussed in Section 7.2, that is, the homologation of trifluoroacetic acid to trifluoropropionic acid. The first step of the Arndt-Eistert synthesis consists of the activation of the carboxylic acid via the acid chloride. The Q elongation to an a-diazoketone occurs in the second step. 

Hendecanedioic acid has been prepared by hydrolysis of the corresponding dinitrile, obtained from 1,9-dibromononane or 1,9-diiodononane 4-6 by oxidation of 11-hydroxyhendecanoic acid 7,8 by the Arndt-Eistert synthesis from 9-carbethoxynonanoyl9 and nonanedioyl chloride 10 and by the Willgerodt reaction on un-decylenic acid.11 The present method, previously described briefly,12 13 appears to represent the most convenient preparation of dibasic acids having an odd number of carbon atoms greater than ten. It has been applied to several other dibasic acids.14... 

The Arndt—Eistert synthesis was investigated by Marquardt who obtained 3-diazoacetyl-l,2,5-thiadiazole (92) in good yield from 3-chlorocarbonyl-l,2,5-thiadiazole (81) and diazomethane. When the WolflF rearrangement of 92 was carried out in the usual manner, i.e., with silver oxide as a catalyst, ring degradation resulted and none of the expected l,2,5-thiadiazole-3-acetic acid (93) was isolated. By... 

A method for converting an acid into its next higher homologue or its derivative is known as the Arndt-Eistert synthesis. ... 

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