Carboxylic acids

Preparation of carboxylic acids oxidation of primary alcohols oxidation of alkylbenzenes application of Grignard reagent in reaction with CO2

Preparation of carboxylic acids hydrolysis of nitriles

Reactivity of carboxyl group - M effect, - I effect - I effect < + M effect - I effect of oxygen Reactivity: 1) Sensitivity against bases (also majority of nucleophiles performs itself as bases) 2) Sensitivity against electrophiles – they activate carbonyl carbon atom for a nucleophilic attack 3) Sensitivity against nucleophilic attack is only limited formation of dimers

Infrared spektra of carboxylic acids nC=O = 1700 – 1725 cm-1 nc-O = 1450 – 1390 cm-1 nO-H = 2500 – 3300 cm-1 nC=O = 1700 – 1725 cm-1 nc-O = 1450 – 1390 cm-1

2 – chloropropionic acid NMR spektrum of carboxylic acids 2 – chloropropionic acid Solvent CDCl3 (traces of nondeuterated chloroform are visible at d = 7,3 ppm

pKa values of acids

pKa values of aromatic acids

Hammett equation

Taft equation

Taft equation s* CH3- 0,0 H- 0,49 C2H5- -0,1 Cl-CH2- 1,05 C3H7- -0,115 Cl2CH- 1,94 (CH3)3C- -0,30 Cl3C- 2,65 HO-CH2- 0,55 NC-CH2- 1,30 Taft constants of substituents with the value higher than zero are showing that the substituents are more electronwithdrawing than methyl; on the other side constants with value lower than zero are showing that the substituents are electrondonating species. Value of their electron influence may be this way quantify.

Reactivity of carboxylic acids By the treatment with bases salts of carboxylic acids are prepared sodium acetate ammonium butanoate potassium benzoate anilinium trichloracetate

Salts of carboxylic acids Basicity of carboxylate anion is low but will be sufficient base for activation some reactions as Perkin synthesis it can reacts with corresponding activated center: formation of nonsymmetrical anhydrides preparations of esters

Salts of carboxylic acids application of Ca2+ and Ba2+ salts for preparation of ketones in combination with calcium formiate aldehyd may be prepared

Reactivity of carboxyl group - M effect, - I effect - I effect < + M effect - I effect of oxygen Reactivity: 1) Sensitivity against bases (also majority of nucleophiles performs itself as bases) 2) Sensitivity against electrophiles – they activate carbonyl carbon atom for a nucleophilic attack 3) Sensitivity against nucleophilic attack is only limited formation of dimers

Reactivity of carboxyl group Acidic catalyst activate the carbonyl group for reactions proton causes formation of positive charge at carbonyl carbon atom and at the same time suppresses acid dissociation mechanism of the reaction was proved by experiments with 18O isotop and is characteristic for reactions of prim. and sec. alcohols mechanism typical for esterifications with tert. alcohols

Reactivity of carboxylic function Nomenclature: Alkyl (aryl) alkanoate Estery karboxylových kyselin methyl acetate 3-nitrophenyl-pentanoate ethyl-3-aminobenzoate methyl-3-methylcyclopentancarboxylate 2-methylcyclohexyl-butanoate

Reactivity of carboxylic acids esters Hydrolysis of esters acid catalysis base catalysis during a base catalysed hydrolysis salts of carboxylic acids are prepared