The p-nitrophenol or 4-nitrophenol is a phenolic organic compound, since it has a benzene ring attached to a hydroxyl group. The letter "p" means "for", and indicates that its radicals are located in position 1 and 4 of the benzene ring.
The groups present are hydroxyl at position 1 and nitro group at position 4. The chemical formula of p-nitrophenol is C6H5NOT3. P-Nitrophenol is a pH indicator that is colorless at pH below 5.4 and is yellow above 7.5.
On the other hand, this compound is used for the synthesis of various substances of importance to health, such as paracetamol (also known as acetaminophen), which is a recognized analgesic and antipyretic.
Likewise, it serves as a precursor to synthesize phenethidine, which is an anticonvulsant, and acetophenethidine, which serves as an analgesic. Other substances that can be derived from p-nitrophenol are various raw materials necessary for the manufacture of certain fungicides and pesticides..
Apart from this, it is also a raw material for the production of dyes, used to darken leather..
However, despite its benefits, p-nitrophenol is a substance that must be handled with great care, since it poses a high risk to health. It has slight flammability and moderate reactivity, as indicated by the NFPA (National Fire Protection Association).
Article index
P-Nitrophenol is a synthetic chemical, meaning it is not produced from natural sources.
It is characterized by being a yellowish-white or light yellow crystalline powder. P-nitrophenol has a molecular mass of 139.11 g / mol, a boiling point of 279 ° C, a melting point of 110-115 ° C, and an autoignition temperature of 268 ° C. This substance does not evaporate at room temperature.
The solubility in water at room temperature is 16 g / L. It is soluble in ethanol, chloroform and in diethyl ether.
P-nitrophenol is a complex compound, since its solid state (crystals) is made up of a mixture of two molecular forms: one called alpha and the other beta.
In the alpha form (4-nitrophenol) it is colorless, shows instability at room temperature and does not show changes in the face of sunlight (stable).
While the beta form (4-nitrophenolate or phenoxide) appears as yellow crystals and behaves in the opposite way; that is, it is stable at room temperature, but in the face of sunlight it gradually turns red..
This substance has its isosbestic point at 348 nm for the alpha and beta forms.
Despite the fact that this compound has the function of a pH indicator, it is not widely used for this purpose. In relation to color changes according to pH, it has a lot of similarity with other pH indicators such as thymophthalein and phenolphthalein. They have in common that they are colorless at low pH.
P-nitrophenol is a compound used in the pharmaceutical industry to synthesize substances with beneficial effects on health..
For example, acetaminophen or paracetamol can be synthesized from p-nitrophenol, which is one of the drugs with analgesic and antipyretic action most used by the community in general..
Phenethidine, an anticonvulsant used in cases of CNS disorders, is also derived from it. As well as, acetophenethidine with analgesic action.
4-Nitrophenyl phosphate is a synthetic substrate used for the determination of alkaline phosphatase. When the enzyme acts on this substrate it forms p-nitrophenol (colorless substance).
Later, 4-nitrophenol loses protons to become 4-nitrophenolate, which is yellow in color. The reaction must occur at alkaline pH> 9.0 to promote conversion to the beta form (4-nitrophenolate).
The generated color is measured spectrophotometrically at 405 nm, and thus this enzyme can be quantified.
The same is true for other enzymes on other substrates. Among them we can mention the action of the carbonic anhydrase enzyme on 4-nitrophenyl acetate and glycosidases on 4-nitrophenyl-β- D-glucopyranoside.
According to the NFPA (National Fire Protection Association), p-nitrophenol is classified as a substance with a grade 3 health risk. This means that the damage it causes to health is severe..
On the other hand, it presents a flammability risk of 1, which means that the risk of it producing fire is slight. Finally, it has a risk of reactivity grade 2 (moderate risk). This means that under certain conditions this substance is capable of emitting energy.
Among the most prominent effects of this substance on health are those that we will mention below.
At the skin level it produces irritation, inflammation and burns. In addition, contact with the skin represents a route of absorption of the product. An exaggerated exposure to p-nitrophenol can affect the Central Nervous System (CNS).
On the ocular mucosa it can cause a severe burn, with severe eye damage. At the respiratory level, inflammation, coughing, and suffocation. In case of accidental ingestion, it causes vomiting with severe abdominal pain, mental confusion, tachycardia, fever and weakness..
If absorbed in large amounts, it can cause a disease called methemoglobinemia, characterized by an increase in the amount of methemoglobin in the blood..
This disease significantly affects oxygen transport, and therefore generates a symptomatology characterized by headache, fatigue, dizziness, cyanosis, and respiratory distress. In severe cases it can also cause death.
People exposed to small amounts will pass the product through their urine. Finally, despite all the harmful effects described, it has not been proven to have a carcinogenic effect.
If you have come into contact with the product, it is necessary to remove contaminated clothing, and wash the affected area (skin or mucous membranes) with plenty of water. In case of inhalation, take the victim to a well-ventilated place. In case the patient is not breathing, apply assisted respiration.
After this, it is necessary to transfer the victim to a medical care center as soon as possible.
- You must work under a fume hood, or otherwise wear respirators. Wear suitable clothing (gown, gloves, safety glasses, closed shoes and hat).
- Immediately wash clothing contaminated with the product.
- Do not take contaminated work implements home.
- The workplace should be equipped with eyewash and emergency showers.
- While handling this substance, do not wear contact lenses.
- Do not smoke, eat or drink inside the facilities where this substance is handled.
- Note that p-nitrophenol is incompatible with certain substances, and therefore must be stored separately from strong alkalis, such as sodium hydroxide or potassium hydroxide. It is also incompatible with peroxides, perchlorate, permanganates, chlorine, nitrates, chlorates, bromine and fluorine, among other oxidants..
- Bear in mind that in case of fire, containers containing this substance may explode..
Yet No Comments