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Benzoic Acid, 4-Nitro- is an aromatic carboxylic acid substituted with a nitro group at the para position, commonly known as 4-Nitrobenzoic Acid or PNBA. Benzoic Acid, 4-Nitro- serves as a key intermediate in the synthesis of dyes, pharmaceuticals, and agrochemicals. Benzoic Acid, 4-Nitro- is widely used in organic chemistry as a building block and as a reference standard in analytical applications.
CAS Number: 62-23-7
EC Number: 200-526-2
Molecular Formula: C7H5NO4
Molecular Weight: 167.12 g/mol
Synonyms: 4-Nitrobenzoic Acid, p-Nitrobenzoic Acid, PNBA, para-Nitrobenzoic Acid, 4-NBA, Benzoic Acid, p-Nitro-, p-Nitrobenzenecarboxylic Acid, NSC 7707, p-Carboxynitrobenzene, 4-Nitrophenylmethanoic Acid, PNB Acid, 1-Carboxy-4-Nitrobenzene, Nitrodracylic Acid, 4-Nitrodracylic Acid, AI3-00149, CCRIS 1185, HSDB 2140, UNII-G83NWR61OW, 4-Carboxynitrobenzene, MFCD00007352
APPLICATIONS
Benzoic Acid, 4-Nitro- is used as a key synthetic intermediate in the production of 4-aminobenzoic acid derivatives through catalytic reduction.
Benzoic Acid, 4-Nitro- serves as a precursor in the manufacture of local anesthetic compounds such as benzocaine and procaine.
Benzoic Acid, 4-Nitro- is employed in the dye industry for the synthesis of azo and other nitrogen-containing dye intermediates.
Benzoic Acid, 4-Nitro- is used in analytical chemistry as a reference standard for high-performance liquid chromatography (HPLC) method validation.
Benzoic Acid, 4-Nitro- functions as a calibration standard in titrimetric and spectrophotometric analyses.
Benzoic Acid, 4-Nitro- is applied in quality control laboratories to verify instrument accuracy and reproducibility.
Benzoic Acid, 4-Nitro- is used as a pharmacopeial reference standard to identify and quantify related impurities in benzocaine formulations.
Benzoic Acid, 4-Nitro- is used in organic synthesis as a starting material for esterification and amidation reactions.
Benzoic Acid, 4-Nitro- is incorporated into research applications involving the study of electron-withdrawing substituent effects on aromatic reactivity.
Benzoic Acid, 4-Nitro- is utilized in academic and industrial laboratories for teaching and demonstrating nitro-group reduction chemistry.
Benzoic Acid, 4-Nitro- is used as a co-catalyst in select organocatalytic alkylation reactions of ketones.
Benzoic Acid, 4-Nitro- is used in the pharmaceutical industry as a building block for active pharmaceutical ingredient (API) synthesis.
Benzoic Acid, 4-Nitro- is applied in the preparation of plant growth regulators and agrochemical intermediates.
Benzoic Acid, 4-Nitro- is used in polymer chemistry research for introducing nitro-aromatic functionality into specialty resins.
Benzoic Acid, 4-Nitro- is used in coordination chemistry research for the preparation of mononuclear metal carboxylate complexes.
Benzoic Acid, 4-Nitro- is used in the production of photographic and imaging chemical intermediates.
Benzoic Acid, 4-Nitro- is applied in corrosion inhibitor formulations for specialty industrial coatings.
Benzoic Acid, 4-Nitro- is used in the synthesis of liquid crystal intermediates for display technology research.
Benzoic Acid, 4-Nitro- is used as a monomer or comonomer precursor in the design of thermally stable specialty polymers.
Benzoic Acid, 4-Nitro- is used in method-development work for chromatographic separation of nitro-aromatic compounds.
Benzoic Acid, 4-Nitro- is applied as a model substrate in kinetic studies of ester hydrolysis and nucleophilic aromatic substitution.
Benzoic Acid, 4-Nitro- is incorporated into custom synthesis programs as a scaffold for structure-activity relationship (SAR) studies.
Benzoic Acid, 4-Nitro- is used in the manufacture of specialty surfactants and industrial performance chemicals.
Benzoic Acid, 4-Nitro- is applied in electroplating and metal-finishing chemical formulations as an additive intermediate.
Benzoic Acid, 4-Nitro- is used in the preparation of deuterated analogs for use as internal standards in mass spectrometry.
DESCRIPTION
Benzoic Acid, 4-Nitro- is a pale yellow to light tan crystalline solid, typically odorless or with only a faint characteristic odor.
Benzoic Acid, 4-Nitro- consists of a benzene ring bearing a carboxylic acid group and a nitro group in the para position, giving it distinct electron-withdrawing character.
Benzoic Acid, 4-Nitro- is typically manufactured through the nitration of benzoic acid using a mixture of nitric and sulfuric acids, followed by purification and recrystallization.
Benzoic Acid, 4-Nitro- crystallizes in a monoclinic form, appearing as leaflets or plates when recrystallized from water or benzene.
Benzoic Acid, 4-Nitro- exhibits limited solubility in cold water but shows improved solubility in hot water, ethanol, acetone, and other polar organic solvents.
Benzoic Acid, 4-Nitro- is chemically stable under normal storage and handling conditions but can decompose or react vigorously upon prolonged exposure to strong bases or reducing agents.
Benzoic Acid, 4-Nitro- is often used as a model compound in studies of aromatic electrophilic substitution due to the predictable deactivating effect of its nitro group.
Benzoic Acid, 4-Nitro- has a measured acidity (pKa) of approximately 3.4 in water, reflecting the electron-withdrawing influence of the para-nitro substituent on the carboxylic acid group.
Benzoic Acid, 4-Nitro- can undergo catalytic hydrogenation or chemical reduction to yield 4-aminobenzoic acid, a valuable pharmaceutical intermediate.
Benzoic Acid, 4-Nitro- forms esters and amides readily under standard coupling conditions, making it versatile for downstream synthetic applications.
Benzoic Acid, 4-Nitro- is available in various purity grades, including technical, purum, and analytical reagent grades, depending on the intended application.
Benzoic Acid, 4-Nitro- does not melt sharply but sublimes and decomposes on prolonged heating near its melting range, a behavior characteristic of many substituted nitrobenzoic acids.
Benzoic Acid, 4-Nitro- is classified as a conjugate acid of the 4-nitrobenzoate anion and readily forms metal carboxylate salts with divalent cations such as zinc and calcium.
Benzoic Acid, 4-Nitro- shows relatively low volatility and negligible flammability under standard ambient conditions, consistent with its crystalline, high-melting nature.
Benzoic Acid, 4-Nitro- is compatible with most standard laboratory glassware and equipment, though contact with strong reducing agents should be avoided due to the reactivity of the nitro group.
Benzoic Acid, 4-Nitro- is recognized across multiple regulatory and chemical inventories, reflecting its long-established use as a fine chemical and pharmaceutical intermediate.
PROPERTIES
Chemical Formula: C7H5NO4
Molecular Weight: 167.12 g/mol
Common Name: 4-Nitrobenzoic Acid (PNBA)
Appearance: Pale yellow to light tan crystalline powder
Odor: Odorless to faintly acrid
Solubility: Slightly soluble in cold water (<0.1 g/100 mL); soluble in hot water, ethanol, and acetone
Melting Point: 237–242°C
Boiling Point: Sublimes/decomposes before boiling
pKa: ~3.4 (in water)
Density: ~1.58 g/cm³
Flash Point: Not applicable (combustible solid)
Stability: Stable under recommended storage conditions; avoid strong reducing agents and bases
Storage Temperature: 15–30°C, in a dry, well-ventilated area
Shelf Life: 24–36 months in original sealed packaging
FIRST AID
Inhalation
Remove to fresh air immediately if inhaled.
Seek medical attention if coughing, irritation, or breathing difficulty persists.
Keep the affected person at rest in a position comfortable for breathing.
Skin Contact
Wash immediately with plenty of soap and water for at least 15 minutes.
Remove contaminated clothing and shoes before reuse.
Seek medical advice if irritation or redness persists.
Eye Contact
Rinse immediately with plenty of water, including under the eyelids, for at least 15 minutes.
Remove contact lenses if present and easy to do so, then continue rinsing.
Seek immediate medical attention if irritation persists.
Ingestion
Rinse mouth thoroughly with water; do not induce vomiting.
Seek medical attention immediately if a large quantity has been swallowed.
Never give anything by mouth to an unconscious person.
Note to Physicians
Treat symptomatically and supportively.
No specific antidote is known; monitor for methemoglobinemia in cases of significant exposure.
Provide supportive care and observe the patient for delayed symptoms.
HANDLING AND STORAGE
Handling
Wear appropriate personal protective equipment, including gloves, safety goggles, and protective clothing.
Avoid generating and inhaling dust during handling and transfer operations.
Wash hands thoroughly after handling and before eating, drinking, or smoking.
Ventilation
Use local exhaust ventilation or general ventilation to control airborne dust levels.
Ensure adequate ventilation in areas where the material is processed or transferred.
Storage
Store below 30°C in a cool, dry, well-ventilated area away from incompatible materials such as strong oxidizers, bases, and reducing agents.
Keep containers tightly closed and properly labeled at all times.
Protect from direct sunlight and sources of heat or ignition.
Spill and Leak Procedures
Sweep up spilled material carefully to avoid generating dust, and place in a suitable container for disposal.
Avoid contact with skin and eyes during clean-up operations.
Dispose of collected material in accordance with local, regional, and national regulations.
Handling Precautions
Handle only in areas equipped with appropriate safety and containment measures.
Maintain good industrial hygiene practices throughout handling and processing.
Avoid contact with incompatible substances, particularly strong reducing agents, which may increase reactivity.
