PICRIC ACID

Description

Picric acid is a white to yellowish crystalline substance, soluble in most organic solvents and highly flammable. Picric acid is a derivative of phenol. It reacts with metals to form metal picrates, which like picric acid itself are highly sensitive. It is often used for tissue fixative (Bouin solution) for histology specimens, as a booster to detonate another, less sensitive explosive, such as trinitotoluene (TNT). It is used in the manufacture of fireworks, matches, electric batteries, coloured glass, dyes, antiseptics, explosives, disinfectants, leather industries, pharmaceutical, and textile. Picric acid is also used as a yellow dye, as an antiseptic, and in the synthesis of chloropicrin, or nitro-trichloromethane. Picric acids are highly sensitive to heat, shock, or friction and because of the explosive nature it is among the most hazardous substances found in the laboratory.

Chemical properties

Also known as picronitric acid, trinitrophenol, nitroxanthic acid, carbazotic acid or phenoltrinitrate, C6H2(N02)3OH is yellow crystals that are soluble in water, alcohol, chloroform, benzene, and ether with a very bitter taste. It is derived by the nitration of phenolsulfonic acid, obtained by heating phenol with concentrated sulfuric acid, and is used for explosives, matches, electric batteries, and etching copper.

Chemical properties

Picric acid is a highly flammable, white to yellowish crystalline substance. It used in the manufacture of fi reworks, matches, electric batteries, colored glass, explosives, and disinfectants. Pharmaceutical, textile, and leather industries also make use of picric acid.

Chemical properties

Picric acid is a pale yellow, odorless solid. Usually found in solution with 10%
20% water. Must be kept wetted; the crystalline form is highly unstable. The dry crystal form is explosive upon rapid heating or mechanical shock.

Physical properties

White to yellow crystals. Usually present in moist forms because dry picric acid is shock sensitive.

The Uses of PICRIC ACID

Picric acid and its metal salts are used as explosives. It is also used in making matches; electric batteries, colored glass; in etching copper; and for dyeing textiles.

The Uses of PICRIC ACID

Preparation of organic derivatives for identification.

The Uses of PICRIC ACID

Explosives, matches; in leather industry; electric batteries; etching copper; manufacture of colored glass; textile mordant; also as reagent.

Definition

A yellow crystalline solid made by nitrating phenolsulfonic acid. It is used as a dye and as an explosive. With aromatic hydrocarbons picric acid forms characteristic charge-transfer complexes (misleadingly called picrates), used in analysis for identifying the hydrocarbon.

Production Methods

Picric acid is used in making explosives; as a burster in projectiles; in rocket fuels, fireworks, colored glass, batteries, and disinfectants; in the pharmaceutical and leather industries; as a fast dye for wool and silk; in metal etching and photographic chemicals; and as a laboratory reagent.

General Description

A paste or slurry consisting of the yellow crystalline solid mixed with water. The dry compound is a sensitive high explosive. The mixture with water is considered safe for storage, handling and shipping. Can be detonated with a number 8 electric blasting cap. The primary hazard is blast where the entire load explodes instantaneously and not from flying projectiles fragments. Can explode under prolonged exposure to heat.

Air & Water Reactions

Water soluble.

Reactivity Profile

PICRIC ACID undergoes vigorous reactions with both oxidizing or reducing agents. Burns if ignited by a flame and continues to burns quietly if the quantity is small or, if large, is thinly spread over an area. The dry compound can explode if shocked or exposed to heat. Wetting significantly reduces the tendency to explode. Readily forms salts on contact with many metals (including copper, lead, mercury, zinc, nickel, iron) . The salts are sensitive explosives when subjected to heat, friction, or impact. Contact with concrete floors may form the friction-sensitive explosive calcium picrate [Urbanski, 1964, vol. 1, p. 518]. Contact with metallic zinc or lead can cause detonation. Salts with ammonia, amines and complexes with hydrocarbons are less sensitive [Kirk-Othmer, 1965, vol. 8, p. 617].

Health Hazard

Some are toxic and may be fatal if inhaled, swallowed or absorbed through skin. Contact may cause burns to skin and eyes. Fire may produce irritating, corrosive and/or toxic gases. Runoff from fire control or dilution water may cause pollution.

Health Hazard

Exposures to picric acid cause different adverse effects on the skin of animals and humans, such as allergies, dermatitis, irritation, and sensitization. Absorption of picric acid by the system causes headache, fever, nausea, diarrhea, and coma. In high concentrations, picric acid is known to cause damage to the erythrocytes, kidneys, and liver.

Health Hazard

Picric acid is a highly toxic substance. Ingestion can cause severe poisoning in humans. The toxic symptoms are headache, nausea, vomiting, abdominal pain, and yellow coloration of the skin. High doses can cause destruction of erythrocytes, gastroenteritis, nephritis, hepatitis, and hematuria. Contact with the eyes can produce irritation and corneal injury. Skin contact with powder can result in sensitization dermatitis. The lethal dose (oral) in rabbits is 120 mg/kg.

Fire Hazard

Picric acid is a high explosive. It is as stable as TNT and about as sensitive to explosive decomposition as TNT. It reacts with many metals and bases, readily forming metal picrates, which are highly sensitive explosive compounds. Metal picrates of iron(III), copper(II), and lead in the dry state are as sensitive as PETN. Its sensitivity is reduced by wetting with water. It explodes when heated above 300°C (572°F).

Contact allergens

Contact dermatitis occurred primarily in the explosives industry.

Safety Profile

Poison by ingestion and subcutaneous routes. Mutation data reported. An irritant and an allergen. Shin contact can cause local and systemic allergic reactions. Flammable solid when exposed to heat or flame; can react vigorously with oxidzing materials. Very unstable. A severe explosion hazard when shocked or exposed to heat. It forms salts easily, and many of its salts, known as picrates, are more sensitive explosives than picric acid. It forms unstable salts with concrete, NH3, bases, and metals (e.g., copper, lead, mercury, and zinc). Many of these are heat-, friction-, or impact- sensitive. Mixtures with uranium perchlorate are extremely powerful explosives. mxtures with aluminum and water igmte after a delay period. Can react vigorously with reducing materials. Used in synthesis of dyes, as a drug, to manufacture explosives and matches, to etch copper, and to make colored glass. See also NITRO COMPOUNDS OF AROMATIC HYDROCARBONS and EXPLOSIVES, HIGH.

Potential Exposure

Picric acid is used in the synthesis of dye intermediates and in manufacturing picrates; in the manufacture of explosives, rocket fuels; fireworks, colored glass; matches, electric batteries; and disinfectants. It is also used in the pharmaceutical and leather industries; in copper and steel etching; forensic chemistry; histology, textile printing; and photographic emulsions.

Carcinogenicity

Picric acid was mutagenic in the Ames Salmonella assay in the presence of metabolic activation.

Environmental Fate

Chemical/Physical. Picric acid explodes when heated >300 °C (Weast, 1986). Shock sensitive! (quoted, Keith and Walters, 1992).

Shipping

UN0154 Picric acid, dry or wetted with ＜30% water, by mass, Hazard Class: 1D; Labels:1D-Explosive (with a mass explosion hazard); D-Substances or articles which may mass detonate (with blast and/or fragment hazard) when exposed to fire. UN1344 Picric acid, wetted with not less than 30% water, Hazard Class: 4.1; Labels: 4.1-Flammable solid.

Purification Methods

Crystallise the acid first from acetic acid, then acetone, toluene, CHCl3, aqueous 30% EtOH, 95% EtOH, MeOH or H2O. Dry it in a vacuum for 2hours. Alternatively, dry it over Mg(ClO4)2 or fuse (CARE) and allow it to solidify under a vacuum three times. Because it is EXPLOSIVE, picric acid should be stored moistened with H2O, and only small portions should be dried at any one time. The dry acid should NOT be heated. [Beilstein 6 IV 1388.]

Toxicity evaluation

Metabolic and respiratory acidosis is thought to be the main consequence of picric acid exposure, and is typically the cause of death when reported. An uncoupler of mitochondrial metabolism, picric acid can destroy erythrocytes, cause gastroenteritis, hemorrhagic nephritis, and acute hepatitis. Reduction to the N-acetyl derivative may also play a role in its inherent toxicity.

Incompatibilities

Explosive when dry. Violent reaction with oxidizers and reducing materials. Air or oxygen is not required for decomposition. Shock sensitive compounds can be formed on contact with plaster, concrete. An explosive mixture results when the aqueous solution crystallizes. May explosively decompose from heat, shock, friction, or concussion. Copper, lead, zinc and other metals, or their salts can form other salts that are initiators and much more sensitive to shock than this chemical. Corrodes metals.

Waste Disposal

Controlled incineration in a rotary kiln incinerator equipped with particulate abatement and wet scrubber devices.

Precautions

Workers should use protective clothing, avoid skin contact, and use goggles and face masks to avoid dust.

References

https://en.wikipedia.org/wiki/Picric_acid
https://pubchem.ncbi.nlm.nih.gov/compound/picric_acid#section=InChI