Chemical Properties
white to off-white crystalline powder
Uses
2,6-Dichlorobenzoic Acid is an di-halogenated benzoic acid derivative and is used in the synthesis of Lux-S enzyme inhibitor.
Definition
ChEBI: 2,6-dichlorobenzoic acid is a chlorobenzoic acid carrying two chloro groups at positions 2 and 6 respectively. It has a role as a bacterial xenobiotic metabolite. It is a chlorobenzoic acid and a dichlorobenzene. It is functionally related to a benzoic acid. It is a conjugate acid of a 2,6-dichlorobenzoate.
Preparation
2,6-Dichlorobenzoic Acid can be prepared through several synthetic routes. One common method is the chlorination of benzoic acid in the presence of a catalyst such as phosphorus pentachloride or thionyl chloride. The reaction takes place under reflux in anhydrous conditions, resulting in the substitution of two chlorine atoms at positions 2 and 6 of the benzene ring. The resulting product is then isolated and purified through recrystallization from a suitable solvent. Another method involves the chlorination of the methyl ester of 2,6-dichlorobenzoic acid, followed by hydrolysis to yield the desired compound. Alternatively, it can also be synthesized through the oxidation of 2,6-dichlorotoluene using potassium permanganate or other oxidizing agents.
Air & Water Reactions
Slightly soluble in water.
Reactivity Profile
2,6-Dichlorobenzoic acid is a halogenated carboxylic acid. Carboxylic acids donate hydrogen ions if a base is present to accept them. They react in this way with all bases, both organic (for example, the amines) and inorganic. Their reactions with bases, called "neutralizations", are accompanied by the evolution of substantial amounts of heat. Neutralization between an acid and a base produces water plus a salt. Carboxylic acids with six or fewer carbon atoms are freely or moderately soluble in water; those with more than six carbons are slightly soluble in water. Soluble carboxylic acid dissociate to an extent in water to yield hydrogen ions. The pH of solutions of carboxylic acids is therefore less than 7.0. Many insoluble carboxylic acids react rapidly with aqueous solutions containing a chemical base and dissolve as the neutralization generates a soluble salt. Carboxylic acids in aqueous solution and liquid or molten carboxylic acids can react with active metals to form gaseous hydrogen and a metal salt. Such reactions occur in principle for solid carboxylic acids as well, but are slow if the solid acid remains dry. Even "insoluble" carboxylic acids may absorb enough water from the air and dissolve sufficiently in 2,6-Dichlorobenzoic acid to corrode or dissolve iron, steel, and aluminum parts and containers. Carboxylic acids, like other acids, react with cyanide salts to generate gaseous hydrogen cyanide. The reaction is slower for dry, solid carboxylic acids. Insoluble carboxylic acids react with solutions of cyanides to cause the release of gaseous hydrogen cyanide. Flammable and/or toxic gases and heat are generated by the reaction of carboxylic acids with diazo compounds, dithiocarbamates, isocyanates, mercaptans, nitrides, and sulfides. Carboxylic acids, especially in aqueous solution, also react with sulfites, nitrites, thiosulfates (to give H2S and SO3), dithionites (SO2), to generate flammable and/or toxic gases and heat. Their reaction with carbonates and bicarbonates generates a harmless gas (carbon dioxide) but still heat. Like other organic compounds, carboxylic acids can be oxidized by strong oxidizing agents and reduced by strong reducing agents. These reactions generate heat. A wide variety of products is possible. Like other acids, carboxylic acids may initiate polymerization reactions; like other acids, they often catalyze (increase the rate of) chemical reactions.
Fire Hazard
Flash point data for 2,6-Dichlorobenzoic acid are not available; however, 2,6-Dichlorobenzoic acid is probably combustible.
Purification Methods
Crystallise the acid from EtOH and sublime it in vacuo.[Beilstein 9 IV 1005.] Aromatic acid impurities (to <0.05%) can be removed via the (±)--methylbenzylamine salt as described for 2,4-dichlorobenzoic acid [Ley & Yates Organic Process Research & Development 12 120 2008.]
