3-Нитробензойная кислота

Химические свойства

White or light yellow monoclinic leaf-like crystal. Soluble in acetone, chloroform, ethanol and ether, slightly soluble in benzene, water, carbon disulfide and petroleum ether, more soluble in hot water. It smells like almonds. 3-nitrobenzoic acid is quite a strong acid, it is soluble in a relatively weak base. It is about ten times more acidic than benzoic acid.The conjugate base of benzoic acid is stabilised by the presence of the electron withdrawing nitro group which explains its increased acidity in comparison to unsubstituted benzoic acid.

Использование

3-Nitrobenzoic acid was used to investigated the role of ozone as additional decomposition or finishing reagent in the degradation of o-, m- and p-nitobenzoic acids

Подготовка

3-Nitrobenzoic acid is prepared by nitrating benzoic acid at low temperature. Approximately 20% of the 2-nitro isomer and 1.5% of the 4-nitro isomer are co-produced. The 3-nitrobenzoic acid can be purified by recrystallization of the sodium salt. The oxidation of 3-nitrobenzaldehyde, prepared by the controlled oxidation of benzaldehyde, gives a higher yield.

Общее описание

Off white to yellowish-white crystals. Bitter taste. Melts in hot water.

Реакции воздуха и воды

Insoluble in water.

Профиль реактивности

3-Nitrobenzoic acid is incompatible with strong oxidizers. 3-Nitrobenzoic acid is also incompatible with strong bases. 3-Nitrobenzoic acid may react with cyanides.

Пожароопасность

Flash point data for 3-Nitrobenzoic acid are not available but 3-Nitrobenzoic acid is probably combustible.

Методы очистки

Crystallise the acid from *benzene, H2O, EtOH (charcoal), glacial acetic acid or MeOH/H2O. Dry and store it in a vacuum desiccator. The amide has m 143o (from H2O or *C6H6). [Beilstein 9 III 1489, 9 IV 1055.]