4-Aminophenylarsonic acid

Chemical properties

off-white fine crystalline powder

Chemical properties

p-Arsanilic acid is an off-white powder. It is slightly soluble in cold water. It is incompatible with oxidizing agents; on hazardous decomposition, p-arsanilic acid produces nitrogen oxides, carbon monoxide, carbon dioxide, nitrogen gas, and oxides of arsenic.

Originator

Arsanilic acid,Fleming Laboratories, Inc.

The Uses of 4-Aminophenylarsonic acid

4-Aminophenylarsonic acid is an organoarsenic compound. 4-Aminophenylarsonic acid is a highly toxic contaminant and can be found in plants growing in contaminated soil. 4-Aminophenylarsonic acid was used as an additive in animal feed. It has also been used in treating dysentery in swine as well as having potential chemotherapeutic activity.

The Uses of 4-Aminophenylarsonic acid

Arsanilic acid reacts essentially analogously to phenylarsonic acid. According to Chandelle, in the presence of relatively large amounts of accompanying ions the determination of zirconium gives more accurate results with this reagent than with phenylarsonic acid. This statement has not yet been confirmed. Nevertheless, the reagent is much more widely used than any other arsonic acid derivative.

The Uses of 4-Aminophenylarsonic acid

manufacture of medicinal arsenicals.

Definition

ChEBI: Arsanilic acid is an organoarsonic acid. It is a conjugate acid of an arsanilate(1-).

Manufacturing Process

342.0 g (2 mol) of 83% arsenic acid were added during 75 min to a rapidly stirred mixture of 372.5 g (4 mol) aniline and 111.0 g chlorobenzene while the temperature of the mixture was kept at 147°-150°C. After the addition of arsenic acid was complete the mixture was stirred for an additional 8 h while being maintained at 149°-153°C. Water was continuously removed by distillation, and the organic phase of the distillate was continuously recycled back into the reaction mixture. At the end of that time a total of 121.0 g of water, containing the condensation of aniline and arsenic acid has been removed. The mixture was then allowed to cool to 110°C. 562.0 g (2.81 mol) of 20% sodium hydroxide were added over a 2 h period while water, chlorobenzene and excess aniline were distilled off at a temperature of from 102°-113°C. The distillation was continued for an additional 2 h while the volume of the mixture was kept at about 700 ml by the addition of water.
The mixture was then diluted with water to a volume of 1400 ml and allowed to cool to 23°C. At this point, 52.0 g of by-product material, which was predominantly tri-(p-aminophenyl)-arsineoxide, were filtered out. The pH of the filtrate was then brought from 8.7 to 5.1 by the addition of 1.8 mol of hydrochloric acid while the volume of the mixture was increased to 2,200 ml by the addition of water. The mixture was stirred for 5 h at room temperature and again filtered. 108.0 g of by-product material comprising predominantly di-(p-aminophenyl)-arsinic acid was filtered off at this point.
The pH of the filtrate was lowered to 4.5 by the addition of 0.2 mole of hydrochloric acid, and an additional 5.0 g of by-products, the composition of which was not determined, was filtered off. The filtrate was then brought to a pH of 3.2 by addition of 0.6 mole of hydrochloric acid, and 128.0 g (29.5% based upon arsenic acid) of arsanilic acid were recovered as a precipitate.
The arsanilic acid filtrate was combined with the by-products filtered off during each of the three filtration steps. 2.8 mol of hydrochloric acid were added to the combined arsanilic acid filtrate and the mixture was heated at 80°C for 5 days. Arsanilic acid was then precipitated from the remaining hydrolyzed mixture in the manner described for the primary reaction product, and an additional 120.0 g (27.5% based on arsenic acid) were recovered. The filtrate contained 14.0 g (3.2%) of arsanilic acid which could be recovered at least partially in subsequent processing. Thus it can be seen from this example that an arsanilic acid yield of 59% was obtained.

Therapeutic Function

Antibacterial

Hazard

Toxic.

Health Hazard

Occupational workers exposed to p-arsanilic acid develop poisoning. The symptoms include, but are not limited to, eye and skin irritation, chemical conjunctivitis and corneal damage, hyperpigmentation of the skin and, perkeratoses of plantar and palmar surfaces, primary irritation and sensitization, digestive tract irritation, gastrointestinal hypermotility, diarrhea, hepatitis, hepatocellular necrosis, central nervous system depression, cardiac disturbances, and liver and kidney damage. The target organs include the kidneys, central nervous system, liver, and cardiovascular system. After a prolonged period of exposure to arsenic compounds, including arsenical dust, workers are known to develop shortness of breath, nausea, chest pains, garlic odor, and impairment of peripheral circulation. The toxicological properties of p-arsanilic acid have not been fully investigated.

Safety Profile

Poison by intravenous and intraperitoneal routes. Moderately toxic by ingestion. Flammable, decomposes with heat to yield flammable vapors. When heated to decomposition or on contact with acid or acid fumes it emits highly toxic fumes of As and NO,. See also ARSENIC COMPOUNDS and ANILINE.

storage

p-Arsanilic acid should be kept stored in a tightly closed container in a cool, dry, wellventilated area. It should be kept away from incompatible materials, dust generation, excess heat, and strong oxidants.

Purification Methods

Crystallise it from water or ethanol/ether. POISONOUS. [Beilstein 16 I 466.]

Precautions

Occupational workers should wash thoroughly after using p-arsanilic acid. Any contaminated clothing should be washed before reuse. Work areas should have adequate ventilation and minimum dust generation and accumulation. Workers should avoid any kind of contact of p-arsanilic acid with the eyes, skin, clothing, ingestion or inhalation.