Synthesis of carboxylic acids

The action of esterases consists essentially in the hydrolysis (or synthesis) of carboxylic acid esters according to the equation ... 

You will recognize the side chain oxidation of p xylene to terephthahc acid as a reaction type discussed previously (Section 11 13) Examples of other reactions encoun tered earlier that can be applied to the synthesis of carboxylic acids are collected m Table 19 4... 

SYNTHESIS OF CARBOXYLIC ACIDS BY THE CARBOXYLATION OF GRIGNARD REAGENTS... 

Synthesis of Carboxylic Acids by the Carboxylation of Grignard Reagents... 

The thermal decarboxylation of malonic acid derivatives is the last step m a multistep synthesis of carboxylic acids known as the malonic ester synthesis This synthetic method will be described m Section 21 7... 

Diethyl malonate has uses other than m the synthesis of carboxylic acids One particu larly valuable application lies m the preparation of barbituric acid by nucleophilic acyl substitution with urea... 

As mentioned in the Introduction, rearrangements of the intermediate alkyl cation in the Koch synthesis may compete with the carbonylation. Under the kinetically controlled conditions prevailing in the Koch synthesis of carboxylic acids, the rearrangements occur only from a less stable to a more stable carbonium ion, e.g. from a secondary to a tertiary ion. The reverse rearrangements—from a more stable to a less stable... 

This is unlikely to be a dominant factor. Steric effects have been observed in the Koch-Haaf synthesis of carboxylic acids (Pincock et al., 1959 Stork and Bersohn, 1960 Peters and Vs,n Bekkum, 1971), but these are ascribed to the steric requirements of the protonated carboxyl group (—COOHj) and not to those of the oxocarbonium group (—CO+). In FHSOs—SbFs, the product is the alkyloxocarbonium ion. 

First, the rates of carbonylation of secondary and tertiary alkyl carbonium ions can now be compared quantitatively with the known rates of competing intramolecular rearrangements of these ions. The product distribution in the Koch synthesis of carboxylic acids depends, amongst other things, on these relative rates. 

Carboxylic acids can be converted by anodic oxidation into radicals and/or carbo-cations. The procedure is simple, an undivided beaker-type cell to perform the reaction, current control, and usually methanol as solvent is sufficient. A scale up is fairly easy and the yields are generally good. The pathway towards either radicals or carbocations can be efficiently controlled by the reaction conditions (electrode material, solvent, additives) and the structure of the carboxylic acids. A broad variety of starting compounds is easily and inexpensively available from natural and petrochemical sources, or by highly developed procedures for the synthesis of carboxylic acids. 

The DPE reduction is used as a test reaction to characterize the materials and optimize the preparation conditions of the catalyst. Since hydroaluminations can also be used for the synthesis of carboxylic acids, deuterated products, or vinyl halides via quenching with CO2, D2O or Br2 [44], the method is also a valuable organic synthesis tool. However, as compared with molecular catalysts like Cp2TiCl2 that are known to catalyze hydroaluminations [44], the titanium nitride materials described here are solid catalysts and can be separated by centrifugation. Moreover, they can be reused several times, which is an advantage as compared to molecular catalysts. 

Malonic acid ester synthesis is a classic but still one of the most important C—C bond-forming reactions, because it is widely applicable to various types of compounds and the reaction can be performed under mild conditions without special care to remove the trace amount of water and oxygen contained in the solvent. This reaction is especially useful in the synthesis of carboxylic acids. One important class of carboxylic acids is arylpropionates because optically active ones are known to have anti-inflammatory activity and other interesting physiological... 

The chemistry of a-haloketones, a-haloaldehydes and a-haloimines Nitrones, nitronates and nitroxides Crown ethers and analogs Cyclopropane derived reactive intermediates Synthesis of carboxylic acids, esters and their derivatives The silicon-heteroatom bond Syntheses of lactones and lactams The syntheses of sulphones, sulphoxides and cyclic sulphides... 

To the best of our knowledge, only one other example of a carboxylic acid functionalized hyperbranched structure is known in the literature, and this concerns a polyamide [19]. The synthesis reported starts from A2 (aminofunctional) and B3 (carboxylic acid functional) units and leads to low molecular weight products due to low conversion in dilute solution. These conditions were mandatory to prevent gelation [20]. Two different approaches to the synthesis of carboxylic acid functional hyperbranched polyesteramides are presented below [21]. 

Fig. 14. Primary reaction step in the synthesis of carboxylic acid functional hyperbranched polyesteramides to obtain A2B-type monomers from HHPA and diisopropanolamine...

The above-mentioned concept of the synthesis of carboxylic acid functional hyperbranched polyesteramides is not limited to cyclic anhydrides as building blocks. It can be carried out with diisopropanolamine and any dicarboxylic acid as well. The same ratios as written above and calculated in Scheme 1 have been applied in the synthesis of carboxylic acid functional hyperbranched polyesteramides starting from adipic acid and diisopropanolamine. The first one (ratio 2.3 1) gelates as expected, the second one (ratio adipic acid diisopropanolamine 3.2 1) affords the expected product. Again, with GPC the amount of free adipic acid detected is in good agreement with theory (Fig. 17). 

A number of methods are used in the synthesis of carboxylic acids. Most of these methods involve the oxidation of some organic molecule, but other methods can be used. In this section we take a look at a few of these methods. 

The synthesis of carboxylic acids by the oxidation of alkenes is a two-step process. In the first step, a hot basic potassium permanganate (KMnO ) solution oxidizes an alkene, and in the second step, the oxidized alkene is acidified. The process cleaves the Ccirbon backbone at the carbon-carbon double bond to produce two smaller carboxylic acid molecules. For example, oleic acid (CH3(CH2)yCH=CI-l(CI-l2)yCOOH) yields of mixture of nonanoic acid (CH3(CH2)7C00H) and nonadioic acid (HOOC(CH2)7COOH). 

A method for enantioselective synthesis of carboxylic acid derivatives is based on alkylation of the enolates of /V-acyl oxazolidinones.59 The lithium enolates have the structures shown because of the tendency for the metal cation to form a chelate. 

A procedure for enantioselective synthesis of carboxylic acids is based on sequential alkylation of the oxazoline 8 via its lithium salt. Chelation by the methoxy group leads preferentially to the transition state in which the lithium is located as shown. The lithium acts as a Lewis acid in directing the approach of the alkyl halide. This is reinforced by a steric effect from the phenyl substituent. As a result, alkylation occurs predominantly from the lower face of the anion. The sequence in which the groups R and R are introduced... 

The compounds III and II are useful substrates for the synthesis of carboxylic acids and ketones,... 

Polymeric phosphonium salt-bound carboxylate, benzenesulphinate and phenoxide anions have been used in nucleophilic substitution reactions for the synthesis of carboxylic acid esters, sulphones and C/O alkylation of phenols from alkyl halides. The polymeric reagent seems to increase the nucleophilicity of the anions376 and the yields are higher than those for corresponding polymer phase-transfer catalysis (reaction 273). 

Synthesis of carboxylic acids, esters, amides and nitriles of thiophenes and... 

---