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
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
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 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.
Uses
Preparation of organic derivatives for identification.
Uses
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.
Uses
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
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.
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.
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
